Nutrition, Physical Activity, and Health in Early Life, Second Edition

Second Edition

Nutrition, Physical Activity, and Health in Early Life

Second Edition

Nutrition, Physical Activity, and Health in Early Life ˆ

Jana Parízková

Boca Raton London New York

CRC Press is an imprint of the Taylor & Francis Group, an informa business

CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2010 by Taylor and Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number: 978-1-4200-8231-9 (Hardback) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright. com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Parízková, Jana. Nutrition, physical activity, and health in early life / Jana Parízková. -- 2nd ed. p. ; cm. Includes bibliographical references and index. ISBN 978-1-4200-8231-9 (hardcover : alk. paper) 1. Children--Nutrition. 2. Child development. 3. Exercise for children--Health aspects. 4. Preschool children--Health and hygiene. I. Title. [DNLM: 1. Child Nutritional Physiology Phenomena. 2. Child Development. 3. Child. WS 130 P234n 2010] RJ206.P34 2010 618.92--dc22 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com

2009034138

To my husband, Jirˇí Parˇ ízek

Contents Foreword to Second Edition ............................................................................. xv Foreword to First Edition ................................................................................. xvii Acknowledgment ............................................................................................. xix Author .............................................................................................................. xxi Abbreviations ................................................................................................... xxiii Chapter 1

Chapter 2

Introduction: First Steps to Optimal Health and Fitness throughout Life ..................................................................

1

1.1 1.2 1.3 1.4 1.5 1.6

Potential for Health .............................................................. Historical Aspects: Pedagogy and Education ...................... Physiology of Children ........................................................ Secular Trend: Acceleration of Growth ............................... Influence of Environmental Factors .................................... What Are the Aims? ............................................................

1 2 2 4 6 7

Theoretical Considerations: What Can We Learn from the Natural and Experimental Models? ................................................

9

2.1

2.2

2.3 2.4 2.5

Influence of Diet Early in Life and Its Delayed Effects ...... 2.1.1 Growth, Body Composition, and Physical Activity .... 2.1.2 Lipid Metabolism during the Fetal Period .............. 2.1.3 Influence of a Temporary Diet with Lower Energy and Protein ...................................... 2.1.4 Changes of Lipid Metabolism in the Offspring due to Lactation Period ........................................... 2.1.5 Other Consequences of Early Dietary Manipulations ......................................................... Influence of Increased PA during Pregnancy on the Later Development of Offspring ......................................... 2.2.1 Metabolic Reactions during Pregnancy .................. 2.2.2 Lipid Metabolism .................................................... Influence of Other Factors during Pregnancy ..................... Exercise during Pre- and Postnatal Ontogeny and Cardiac Microstructure of the Offspring ............................ Influence of PA on the Development of Experimental Cardiac Necrosis .................................................................. 2.5.1 Exercise during Postnatal Life ................................ 2.5.2 Spontaneous Activity and Cardiac Damage ........... 2.5.3 Delayed Consequences of Temporary Exercise ......

9 9 12 13 13 17 17 17 18 20 22 24 24 26 26 vii

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2.6

2.7 Chapter 3

26 27 27 30

Nutrition of Pregnant Mothers and Their Children in Early Life: Human Studies ......................................................... 33 3.1 3.2 3.3 3.4

3.5

3.6 Chapter 4

Impact of the Interactions between Early Diet and PA on Experimental Cardiac Necrosis ................................ 2.6.1 Impact of Early Diet ................................................. 2.6.2 Spontaneous PA Influenced by Early Diet and Cardiac Resistance to Isoprenaline .................. General Considerations .......................................................

Variability of Practices during Pregnancy and Lactation in Different Societies ............................................. Position in Industrially Developed Countries ...................... Influence of Genetic Factors on Growth and Health Risks in the Offspring .............................................. Impact of Maternal Status on Offspring ............................. 3.4.1 Influence of Mother’s Nutritional Status and Birth Weight ............................................................ 3.4.2 Effect of Breast-Feeding ......................................... 3.4.3 Effect of Early Postnatal Nutrition on Later Development .................................................. 3.4.4 Influence of Physical Activity and Exercise of Mothers ............................................................... Relationships among Anthropometric, Dietary, and Serum Lipid Variables of the Mother and the Newborn ........................................................................ General Considerations .......................................................

33 35 37 38 38 39 41 43

44 51

Growth and Somatic Development of Preschool Children ............ 53 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Introduction ......................................................................... Evaluation of Somatic Growth ............................................ Cross-Sectional Surveys of Anthropometric Variables ....... Longitudinal Studies of Children from 3 to 6 Years of Age ..................................................................... Body Composition and Fat Pattern ...................................... 4.5.1 Study of Czech Preschoolers .................................. Somatotypes ........................................................................ Body Posture ....................................................................... Relationship between Heights and Weights of Parents and Anthropometric Variables of Preschool Children ............... Other Surveys ........................................................................ General Considerations .......................................................

53 54 61 74 81 82 85 89 93 93 94

Chapter 5 Nutritional Status and Dietary Intake in Early Life ....................... 97 5.1 5.2

Introduction ......................................................................... 97 Energy Requirements .......................................................... 98

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5.3 5.4 5.5 5.6 5.7

5.8 5.9 5.10 5.11 5.12 5.13 Chapter 6

Protein Requirements .......................................................... Fats ..................................................................................... Carbohydrates .................................................................... Minerals and Trace Elements ............................................ Vitamins .............................................................................. 5.7.1 Fat-Soluble Vitamins .............................................. 5.7.2 Water-Soluble Vitamins ........................................ Methods for the Evaluation of Dietary Intake ................... Dietary Intake and Energy Output in Czech Preschoolers: Results of Cross-Sectional and Longitudinal Surveys ....... Food Intake and Energy Output in Other Preschool Child Populations .............................................................. Food Habits, Preferences, and Aversions in Preschool Age .................................................................... RDAs for Preschool Children: Is There a Need for Further Revision? ............................................................... General Considerations and Recommendations ................

106 108 110 110 114 114 116 118 119 125 129 131 133

Functional Development and Physical Activity during Early Childhood ........................................................................... 135 6.1 6.2 6.3 6.4

6.5

6.6

6.7 6.8

Introduction ....................................................................... PA, EE, and Physical Fitness in Young Children .............. Evaluation of PA and Physical Fitness .............................. Cardiorespiratory Fitness .................................................. 6.4.1 Methods of Testing ................................................. 6.4.2 Results of Cross-Sectional and Longitudinal Surveys .................................................................. 6.4.3 Surveys in Other Child Populations ..................... Motor and Sensomotor Development: Gross and Fine Motorics ..................................................................... 6.5.1 Methods of Testing ............................................... 6.5.1.1 Speed ........................................................ 6.5.1.2 Endurance ................................................. 6.5.1.3 Muscle Strength and Skill ........................ 6.5.1.4 Balance ..................................................... 6.5.1.5 Rhythm, Response, and Coordination ....... 6.5.2 Results of Motor and Sensomotor Testing ............ 6.5.3 Motor Development in Other Surveys of Preschool Children ............................................... Metabolic and Biochemical Characteristics ...................... 6.6.1 Methods and Subjects ........................................... 6.6.2 Results: Blood Lipids as Related to Somatic Development, Dietary Intake, and Cardiorespiratory Efficiency ................................ Studies of Biochemical Variables, Blood Pressure, and Fatness in Other Populations ............................................. General Considerations .....................................................

135 136 139 141 142 144 149 149 150 150 151 151 151 152 152 164 166 166

167 169 170

x

Chapter 7

Contents

Influence of Varying Nutrition and Environment on Somatic Development and Physical Fitness ................................. 173 7.1 7.2 7.3 7.4

7.5 7.6 7.7 Chapter 8

Introduction ....................................................................... Growth and Development .................................................. Influence of Different Types of Nutrition and Dietary Intake .................................................................... Surveys in Populations Varying in Environment and Dietary Intake ............................................................. 7.4.1 Somatic Development ........................................... 7.4.1.1 Italian Survey ........................................... 7.4.1.2 Turkish Survey ......................................... 7.4.1.3 Senegalese Survey .................................... 7.4.1.4 Zapotec Survey ......................................... 7.4.2 Functional Development: Cardiorespiratory Fitness ................................................................... 7.4.2.1 Italian Survey ........................................... 7.4.2.2 Turkish Survey ......................................... 7.4.2.3 Senegalese Survey .................................... 7.4.3 Motor Development .............................................. 7.4.3.1 Turkish Survey ......................................... 7.4.3.2 Senegalese Survey .................................... 7.4.4 Muscle Strength .................................................... 7.4.4.1 Turkish Survey ......................................... 7.4.4.2 First Senegalese Survey ............................ 7.4.4.3 Tunisian Survey ........................................ 7.4.4.4 Second Senegalese Survey ....................... 7.4.4.5 Zapotec Survey ......................................... 7.4.4.6 Other Functional and/or Motor Development Surveys ............................... Influence of Severe Malnutrition ....................................... Problems of Child Labor ................................................... General Considerations .....................................................

173 174 175 179 179 179 180 181 183 183 183 184 185 186 186 188 189 189 189 190 191 191 192 193 198 199

Development of Obesity and Its Influence on the Functional Capacity of Children and Youth ................................................... 201 8.1 8.2 8.3

Obesity in Young Children ................................................ Changes of Obesity Prevalence with Time in Different Countries ............................................................ Genetic and Hereditary Factors in Early Childhood Obesity ............................................................. 8.3.1 Genetic Endowment: Twin and Family Clustering .............................................................. 8.3.2 Genes and Excess Fatness .................................... 8.3.3 Polymorphisms and Mutations of Genes: Their Role in Obesity Development ..................... 8.3.4 Main Aspects of the Role of Genetics ..................

201 203 209 210 214 216 220

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Contents

8.4 8.5 8.6

8.7

8.8 8.9

8.10

Chapter 9

Maternal and Familial Factors in the Development of Childhood Obesity .......................................................... Early Factors in Obesity Development .............................. Evaluation of Obesity .......................................................... 8.6.1 Anthropometric Methods for the Evaluation of Adiposity .......................................................... 8.6.2 Assessments of Body Composition and Fatness ............................................................ Results of Studies in Young Obese Subjects ....................... 8.7.1 Morphological Characteristics and Body Composition in Czech Preschoolers ..................... 8.7.2 Food Intake in Obese Preschoolers ...................... 8.7.3 PA and Energy Expenditure in the Obese .............. 8.7.4 Functional Capacity .............................................. 8.7.4.1 Cardiorespiratory Fitness ........................... 8.7.4.2 Motor Development .................................. 8.7.5 Biochemical Characteristics ................................. 8.7.6 Hormonal Variables .............................................. Health Complications of Obesity in Children ................... Management of Obesity: Prevention and Treatment at an Early Age .................................................................. 8.9.1 Procedures Used to Reduce Body Weight during Growth ...................................................... 8.9.2 Morphological, Functional, and Biochemical Changes after Reduction Treatment ..................... General Considerations: Role of Obesity Interventions for Optimal Development at an Early Age ........................

220 224 228 228 230 233 234 236 236 239 239 240 241 243 243 245 246 249 251

Influence of Environmental Factors ............................................. 253 9.1 9.2

9.3 9.4 9.5 9.6 9.7 9.8 9.9

Introduction ....................................................................... Influence of Living Conditions in the Capital and in Other Parts of the Czech Republic ................................ 9.2.1 Somatic Development and Body Posture .............. 9.2.2 Motor and Sensomotor Development ................... 9.2.3 Influence of Lifestyle on Food Intake, Blood Lipids, and Performance ............................ 9.2.4 Body Size and Function: Is Bigger Also Better? .......................................................... Economic Level and Birth Rank ....................................... Environment, Risk Pregnancy, Family Conditions, and Health .......................................................................... Effect of Birth Weight ....................................................... Effect of Family Situation ................................................. Effect of Education of Parents ........................................... Health Status of Children .................................................. General Considerations .....................................................

253 256 256 257 261 264 265 266 269 270 271 272 272

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Chapter 10 Influence of Motor Stimulation, Physical Education, and Spontaneous Physical Activity .............................................. 275 10.1 10.2 10.3

Introduction ....................................................................... Motor Development of Infants .......................................... Experimental Observations on the Impact of Motor Stimulation in Infants ............................................. 10.4 Toddlers ............................................................................. 10.5 Motor Development and Education of Children Aged 3–6 Years ................................................................. 10.6 What to Avoid in the Motor Stimulation of Young Children ................................................................. 10.7 Influence of Exercise in Preschoolers ................................ 10.7.1 Somatic Development and Body Posture .............. 10.7.2 Physical Performance, Skill, and Sensomotor Development ......................................................... 10.7.3 Variability of the Impact of Exercise in Early Life .............................................................. 10.8 Spontaneous PA, Somatic and Functional Development, Food Intake, and Blood Lipids ................... 10.9 Other Surveys on the Effect of PA and Exercise at an Early Age ...................................................................... 10.10 General Considerations .....................................................

275 275 280 282 283 287 288 288 291 291 292 298 300

Chapter 11 Criteria for the Evaluation of Morphological and Functional Development in Preschool Children: Recommendations ............. 301 11.1 11.2 11.3 11.4 11.5

Body Size and Body Composition ..................................... Functional Measurements: Cardiorespiratory Fitness ....... Motor Development ........................................................... Sensomotor Development .................................................. Dietary Intake and Biochemical Characteristics ...............

301 305 306 307 307

Chapter 12 Summary of Experimental Results .............................................. 309 12.1 12.2 12.3 12.4 12.5 12.6

Studies in Experimental Models with Laboratory Animals ............................................................................. Observations on the Influence of Maternal Nutrition on the Newborn .................................................. Morphological and Functional Surveys in Preschool Children ............................................................ Surveys of Children with Various Environmental Conditions and Different Levels of Nutrition .................... Obesity in Young Children ................................................ Influence of Exercise .........................................................

309 311 312 315 317 318

Contents

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Chapter 13 Perspectives: Physical Activity, Early Prevention of Diseases, and Development of Positive Health ............................................ 321 Appendix 1 Body Posture ................................................................................ 327 Appendix 2 Step Test ....................................................................................... 329 Appendix 3 Motor Performance ...................................................................... 331 Appendix 4 Sensomotor Tests .......................................................................... 333 References ......................................................................................................... 335 Index .................................................................................................................. 391

Foreword to Second Edition Many changes have taken place in the field of child development since the 1st edition of this monograph, most of them undesirable: along with the increasing prevalence of overweight and obesity and all the accompanying present and future health problems, levels of cardiorespiratory fitness and physical activity have reduced. Changes in lifestyle have been blamed for this, and explanations for the negative consequences have been sought. A lot of new information has been gained, especially on genetic, pre-, and perinatal factors and others that influence the growing organism during the initial weeks, months, and years of life until school age. This information concerns especially nutrition and weight gain from the initial periods of life, timing of adiposity rebound, physical activity, and overall lifestyle in the present world. Despite the enhanced attention being given to these developmental problems, the increase of obesity prevalence has not been reversed—more to the contrary. This concerns again nearly all countries of the world, including those where only social and economic conditions have changed recently, and too rapidly. Nutrition and physical activity, which influence the organism from the very beginning of its life, have been others considered to be essential, as some of their character might deviate following growth and development in different ways—both positive and negative. Not only genetic but also epigenetic factors might increase or decrease the sensitivity of the organism to other factors to enhance or reduce the deposition of fat, along with changed physical fitness and health. As emphasized in the 1st edition, such consequences may manifest not only immediately but also during later periods of life, depending on the additional influences of environmental factors, and also on early modified sensitivity of the organism. Changes concern not only adipose but also many other tissues and functions. The timing of various periods of growth and the range, intensity, and duration of such influences can have a decisive role, especially in the very early periods of life. Recently, an increasing number of publications have appeared—especially where the interaction of both nutrition and physical activity has been considered. All of them would be difficult to analyze, but at least mentioning them seems to be important as their topics indicate the essential role they have played in the changes of child growth and development, including obesity development. These data concerned also the initial nutritional status and body mass index of the mother, her regimen of nutrition and physical activity, the resulting birth weight of her offspring, duration of breast-feeding, start of bottle-feeding, and complementary diet—especially the amount and ratio of protein, the size of weight increments during the initial weeks and months of postnatal life, and the changes in body mass index and age of adiposity rebound of the offspring. Even the beginning of independent walking and increased physical activity of the child have been analyzed in relation to weight and adiposity development; all this can vary considerably in individual children and can also be significantly influenced by stimulation and overall education. Family situation and xv

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model, the educational level of parents and caretakers, living conditions, and lifestyle play an additional and very important role. Not only nutritional but also motor stimulation have been elaborated for infants and children, and showed significant positive consequences. As noted in the 1st edition, some of the mentioned aspects have also been studied in experimental models using laboratory animals, which followed the effect of various stimuli—mostly early nutrition and physical activity during the longer lifespan until adulthood. Such experiments, however, can give only some incentives. Delayed effects during adulthood, as well as the consequences of the physical activity level during pregnancy, and changes in adult offspring have not yet been sufficiently reported in the literature. The significant effects of activity on so many metabolic, biochemical, hormonal, and cardiorespiratory parameters of the organism might be transferred to the fetus—similar to nutritional influences. In this respect, further studies are necessary, but are possible only in experimental models in laboratory animals. Despite the increasing amount of information on young children, this information is still rare compared with that on schoolchildren and adolescents. Somatic data concern height, weight, BMI, and skinfolds, but rarely other parameters. The evaluation of more physiological parameters—cardiorespiratory system of the young child, body posture, gross and fine motor functions, food intake, level of physical activity, and resulting energy output—has been studied again, more rarely in complex studies following development from more aspects of the same preschool children, and also longitudinally. According to the undesirable changes during the last decades, information from previous studies is still important, as it represents more suitable and adequate criteria on body mass index, body composition, and physical fitness than the average data assessed recently or at present. The development of motor habits and skills is important in a manner similar to adaptation to an adequate diet. As defined by psychologists, a child can learn to learn or not to learn, and the child can learn to eat properly or not, or can learn to move or not to move. All this is essential for following food behavior and physical activity habits, preferring or avoiding improper foodstuffs and sedentarism, which may result from inadequate or understimulated development of all the necessary body systems. Even when not enough is known, it does seem that old truths are repeated. However, increasing deterioration of cardiorespiratory fitness and reduction of physical activity regimens repeatedly assessed, along with overweight and obese schoolchildren and adolescents during the last decades, indicates that more attention should be paid to these problems. Resulting health problems manifested mostly later in life—for example, diseases of the cardiovascular system, especially hypertension, atherosclerosis, and others—are another reason for this. Diabetes, metabolic syndrome, and orthopedic and psychological problems represent, in addition, a heavy burden on health care and economic expenses. Preservation of health and overall fitness until an advanced age, along with desirable life expectancy with full activity, is closely associated with lifestyle at an early age, as indicated by observations in some long-living populations. Prevention is better than cure—which emphasizes in addition an early start at the very beginning of life. According to continuing changes to the environment and resulting lifestyle changes in the present world, fresh new ideas and innovative educational approaches have to be defined as early as possible.

Foreword to First Edition Childhood is surely the time of sowing: later life produces the harvest. It is clear therefore that the most salutary thing that can happen to young people is to be wisely taught from their earliest years at every possible opportunity. In a word, ever-lasting happiness depends on good health, good death, good life on good training habits formed by practice in well-doing, but this begins with foundations well laid in childhood … . Therefore, the most important nurturing of the human race occurs in our cradles. —J.A. Comenius* (1592–1670), Panpaedia

The health of children is key to the health of the adult population, and thus to the prosperity of the whole of society. The factors that not only limit pathological situations but also develop and promote above-average health should be defined and developed for the benefit of children. During the last few years, more attention has been focused on the early stages of life, starting with the fetal period, even though the principle that diet during the early stages of life might influence the rate of growth and development was formulated more than 30 years ago (McCance and Widdowson 1974). Some of the most dangerous diseases have fetal and infant origins (Barker 1990, 1992, Jackson 1992), some of which may depend on early diet and general lifestyle. Until recently, the majority of data on morphological, nutritional, functional, and metabolic development concerned either infants or schoolchildren and adolescents. The period of early and preschool age has been studied considerably less, but some new data have recently appeared. Relatively much more has been known about the influence of negative and/or pathological factors than about natural, favorable factors such as nutrition and physical activity in promoting adequate and/or optimal development of the human being. In those studies, the actual consequences were investigated the most, but the delayed effects of certain influences that affect the organism at the very beginning of life were studied much less. This applies both to experimental models and to studies in humans, where this problem was only tackled marginally. Human growth and development was followed and analyzed extensively. The majority of data focus on the morphological changes in the growing organism as well as on the psychological, social, and nutritional parameters. Less attention was paid to the studies of the functional, motor, and biochemical characteristics of growth in normal, healthy young children. Comprehensive studies that simultaneously cover * J.A. Comenius (1592–1670) was a Czech philosopher and theologist, a theoretician of education, a social reformer, and the founder of pedagogy. Born in Southern Moravia, Comenius studied in Germany and was active as a Protestant preacher and teacher in the Moravian Church (Unitas Fratum). He was forced into exile at the beginning of the Thirty Years Wars, and he worked in Poland, England, Sweden, and Hungary. He died in Amsterdam and was buried in Naarden in Holland.

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several aspects are rare, because most growth studies focus on one particular or very few of the above-mentioned issues. This volume aims to report on the results of comprehensive studies of development during preschool years, as it relates to environmental conditions, including nutrition, with special attention to physical activity and performance. Some of the problems, for example, the influence of the composition of the maternal diet during pregnancy on the newborn, could only be dealt with marginally, as few studies of this sort exist. Therefore, select ontogenetical problems could only be followed in experiments using laboratory animals, as many observations could not be made in humans for ethical reasons and due to time constraints. Conclusions on the influence of dietary and physical activity manipulations in laboratory animals cannot be transferred directly to other species or to humans. They could provide, however, some general ideas on how to promote health in preschoolers using adequate diet and physical regimens, starting at the beginning of life. They could also eventually point out how to use these simple natural factors to promote health in humans. Under the present conditions, nutrition and physical activity reveal two extremes: malnutrition and/or overeating, on the one hand, and excess workload and/or hypokinesia, on the other. The right amount of dietary intake and physical workload—so as to achieve optimal results—has not yet been exactly defined and implemented. Contrasting examples from the industrially developed and the developing countries give a vivid picture of this fact. Of course, research cannot provide an answer to all these problems because the causes must be solved using different means: scientific data, however, can be useful as a guideline. This book cannot offer complete information on the rather broad topic of nutrition and physical activity, but it cites certain examples from experimental models as well as from human studies. The material presented is not homogeneous, but it does have one common denominator: motion, its relationship with diet, and its influence on the development of the organism. Selected examples should serve as motivation for early intervention, especially using adequate diet, along with motor stimulation and exercise from the very beginning of life.

Acknowledgment Special thanks to all the participating coworkers and also the authors given in the Reference list, who contributed significantly, were committed and enthusiastic about the experimental measurements, and were also involved in evaluation and publication.

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Author Professor Jana Parˇízková, MD, PhD, DSc, is a senior scientist at the Centre for the Management of Obesity, Institute of Endocrinology in Prague, the Czech Republic. She received her medical degree from Charles University in Prague, where she graduated summa cum laude. She then pursued her PhD degree in medical physiology at the Institute of Physiology of the Czechoslovak Academy of Sciences, and received her DSc degree in nutrition and metabolism. She became an associate professor in medical physiology—nutrition and metabolism, 2nd medical faculty, Charles University (1992), and full professor in preventive medicine, hygiene, and epidemiology, medical faculty, Masaryk University (2003). She was also given a fellowship at the Laboratoire de Nutrition Humaine, Hôpital Bichat in Paris, France in 1965–1966. Dr. Parˇ ízková conducted the first measurements of total body fat (using hydrodensitometry) and skinfolds during childhood, adolescence, and advanced age, and also in athletes and obese subjects of all age categories, as related to dietary intake, physical activity regimens, functional capacity, physical performance and fitness, lipid metabolism variables, development of gross and fine motor skills, etc. Special focus was also on the preschool period from the mentioned points of view, with regard to health promotion and the reduction of health risks later in life, through early or later nutritional and physical activity interventions. Experiments in laboratory animals focused mainly on the actual and especially delayed consequences of adaptation to exercise and/or hypokinesia, and various diets starting with the earliest periods of life (including the fetal one), with regard to lipid metabolism, cardiac microstructure, and sensitivity to noxious factors in adult age. At present, the main area of research is obesity with joined metabolic and clinical problems as related to actual diet, physical activity level, biochemical and hormonal characteristics, psychological traits, etc. Dr. Parˇ ízková is the author of 18 monographs, including Development of Lean Body Mass and Depot Fat in Children and Body Composition and Lipid Metabolism in Different Regimes of Physical Activity, which is in Czech, and English by Martinus Nijhoff, B.V. Medical Division (The Hague, 1977) and further updated and translated to Portuguese by Editora Guanabara Dois (Rio de Janeiro, 1982) entitled Body Fat and Physical Fitness. In 1996, she published the monograph Nutrition, Physical Activity and Health in Early Life, CRC Press—Taylor & Francis; the second edition was requested and prepared in 2008. Then she published Childhood Obesity: Prevention and Treatment, which was published in 2001 and updated in the second edition in 2005 (along with A.P. Hills and published by CRC Press). Another new updated monograph Obesity in Childhood and Adolescence, coedited with L. Lisá, was published in 2007 in Czech. In addition, she coauthored and edited 10 other monographs, including Physical Fitness and Nutrition during Growth (S. Karger, Basel, 1998, coedited by A.P. Hills). She is also the author of ca. 530 articles in international and national scientific journals, in monographs, and in many proceedings of xxi

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international congresses. She has been an invited speaker at more than 150 international congresses, conferences, symposia, etc., for example, IUNS, where she has been a chairperson and an organizer of symposia and workshops, and/or a keynoter in 1975, 1978, 1981, 1989, 1997, 2001, and 2005. Science Citation Index has included more than 1200 references to her articles, monographs, chapters of monographs. The World Health Organization (WHO) appointed J. Parˇ ízková as a visiting professor, International Course on Nutrition and Hygiene, Hyderabad, SEARO WHO, 1977; consultant to WHO, Geneva, 1978; member of the panel of experts, Food and Agricultural Organization/World Health Organization/United Nations University (FAO/WHO/UNU; FAO, Rome, 1981), on “Energy and Protein Requirements,” WHO, Geneva, 1985; and a member of the consultation group on “Epidemiology of Obesity” of the Regional Office of WHO for Europe, in Warsaw, Poland, 1987. She was also visiting professor at Instituto Universitario de Bromatología y Nutrición, Universidad Complutense, Madrid (1985); University of Connecticut (1993, 1995); University of Perugia, Italy (1993, 1995). Among other rewards, she has received the Philip Noel Baker Prize, ICSPE by UNESCO in 1977, Memorial Medal from Charles University in 1978, Prize of the Rector of Charles University in 1996, and International Memorial Medal of Aleš Hrdlicˇ ka in 1996. Dr. Parˇ ízková is a member of the Czech Medical Association of J.E. Purkyneˇ (CzME JEP), the International Commission for Anthropology of Food (ICAF) through the International Union of Anthropological and Ethnological Sciences (IUAES), the European Academy of Nutritional Sciences (EANS), the Czech Association of Nutrition, the Czech Society for the Study of Obesity, and the Czech Anthropological Society. In addition, she also has memberships in the following organizations: the European Association for the Study of Obesity, International Association for the Study of Obesity, International Society for the Advancement of Kinanthropometry (ISAK), and European Anthropological Association. She served previously as chairperson of the “Nutrition and Physical Performance” committee through the International Union of Nutritional Sciences (IUNS), as a member of the Scientific Committee of the International Council for Sport and Physical Education (ICSPE) through UNESCO. She was also elected a member of the New York Academy of Sciences (1963) and has been conferred with an honorary appointment to the Research Board of Advisors of the American Biographic Institute. She has been a member of redactions, for example, World Review of Nutrition and Dietetics, Karger, Basel; Canadian Journal of Sport Sciences, Toronto; Indian Journal of Sport Sciences and Physical Education, Punjab University, Patiala; Revista Brasileira de Ciencias & Movimiento, Universidade Catolica, Brasilia.

Abbreviations AEE AI AMC AR BC BIA BMI BMR CEI CK CNS DLW DRI EAR EC ED EE EFA EI EU FA FAO FFA FFM HDL HWR IGF 1 IOTF LBM LCPUFA LDL LGA MRI MS NIDDM PA PAL PUFA RDA

activity energy expenditure adequate intake arm muscle circumference adiposity rebound body composition bioelectrical impedance analysis body mass index basal metabolic rate cardiac efficiency index creatine kinase central nervous system doubly labelled water method dietary reference intake estimated average requirement European Community energy density energy expenditure, energy output esterified fatty acids energy intake European Union fatty acids Food and Agricultural Organization free, non-esterified fatty acids fat-free mass high density lipoproteins height/weight ratio insulin-like growth factor 1 International Obesity Task Force by WHO lean body mass long-chain polyunsaturated fatty acids low density lipoprotein large for gestational age magnetic resonance imaging metabolic syndrome non-insulin dependent diabetes mellitus physical activity physical activity level polyunsaturated fatty acids recommended dietary allowances xxiii

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REE REP RMR SES STI TC TEE TG T2D UFA UNU WC WHO

Abbreviations

resting energy expenditure animals with reduced energy and protein intake at the beginning of life resting metabolic rate social economic status step test index total cholesterol total energy expenditure triacylglycerols type 2 diabetes upper arm fat area United Nations University waist circumference World Health Organization

1

Introduction: First Steps to Optimal Health and Fitness throughout Life

Give me a child until he is seven and I will give you a man. —Seventeenth-century Jesuit maxim

1.1 POTENTIAL FOR HEALTH The human being is born with great potential that may or may not be actualized later on in life. Select stimuli may enhance and/or suppress the development of this potential, resulting in either adequate, optimal health or a deteriorated, inferior form. According to the World Health Organization (WHO), health is the status of full mental, physical, and social well-being, and not the mere absence of illness and/or infirmity (World Health Organization 1985, 1990). It is, therefore, necessary to make substantial efforts to ensure the full realization of the potential of all children, in order to facilitate further development in them using all available means. Moreover, positive health is also defined as an above average status of the physiological, mental, and social abilities of humans. The WHO, the Food and Agricultural Organization (FAO), and the United Nations University, along with other organizations, have paid considerable attention to growth and development in various populations in relation to nutrition. Numerous documents exist concerning these problems (Waterlow et al. 1977). Among the most important are documents on Energy and Protein Requirements (World Health Organization 1985) and Prevention of Adult Cardiovascular Diseases in Early Childhood, as well as many others (World Health Organization 1995a,b, 1997a). As related to health and fitness, attention has also been focused on energy output due mainly to physical activity (PA), as related to proper energy balance and turnover. Practical experience and theoretical studies allow for the evaluation of factors that negatively influence growth and development—malnutrition, lack of social and mental stimulation, and physical overloading. On the other hand, excess food intake and a lack of physical and overall activity can also be harmful. The global problem of overweight and obesity and its increasing prevalence, which also concerns children and adolescents, bears witness to the risks of modern lifestyle. To achieve positive health, it is therefore necessary to define the optimal range of both nutrition and PA, especially during growth and development.

1

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Nutrition, Physical Activity, and Health in Early Life

1.2 HISTORICAL ASPECTS: PEDAGOGY AND EDUCATION In his philosophy on the formation of man (formatio hominis), J.A. Comenius— Komenský (1592–1670; Comenius—renewed editions in 1959, 1956, and 1984), the founder of pedagogics and “the teacher of nations,” stressed the importance of education in early childhood. From his monographs, we can deduce that the education of the child starts in the womb of the mother. This Czech philosopher, theologist, and scientist was already ahead of his time in recognizing that the condition of the expectant mother and the various stimuli influencing her during pregnancy, that is, both her physical and her mental status, may be later reflected in the development of the child. Comenius was celebrated by the UNESCO anniversary in 1992 all around the world. Comenius considered the period of childhood as an important stage of open possibilities regarding development during subsequent life. As in nature, he recognized motion as a basic principle. For the human world, this includes the activities of the body and the spirit in mutual harmony. These physical and spiritual activities were considered an important contribution in any educational effort. Comenius (1983) also appreciated children’s games as an essential means for natural development and education, just as important as nutrition and sleep (1984). In the development of the overall system of education and the perfection of man, physical education had a firm position as one of the components in the process of the perfection of the human being. These ideas appear in the School of Infancy (Schola Infantiae 1632). Comenius also stressed the importance of the early development of the abilities and skills of the hand in order “to make people active beings, diligent and skilful. Human nature is full of life, likes motion and activity and does not need anything, except wise direction.” He also defined three principles of early development: starting to exercise early, being active, and gaining mobility, which will not be lost when developed by repetition. In addition, he emphasized that “… it is necessary to allow boys to play, to run, and always to do something.” All of this should be executed with enthusiasm, not with reluctance, always keeping some goal in mind. The more the child is employed in something, runs about, is occupied, is doing something, the sweeter is its sleep, the more easily it digests, the more richly it grows, becomes vigorous and flourishing both in body and mind. (J.A. Comenius, Schola Infantiae, 1650–1654)

Numerous pedagogues followed the ideas of Comenius because these concepts were so advanced for his period (Cˇ apková 1987). In some respects, these ideas have not been fulfilled, even in the present time.

1.3

PHYSIOLOGY OF CHILDREN

In 1867, E. Allix published “Étude sur la Physiologie de la Première Enfance,” material that covers the first 2 years of life. A more detailed analysis was presented by K. Vierordt (1877) in his textbook on “Physiology of Childhood,” in which he compared the absolute and the relative development of body weight during different stages of development as well as the composition of the organism (changes in individual organs) in newborns and adults (Tables 1.1 and 1.2).

Introduction: First Steps to Optimal Health and Fitness throughout Life

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TABLE 1.1 Weight of the Individual Organs as a Percentage of Total Body Weight Organs Skeleton Muscles Skin Brain Spinal chord Eyes Salivary glands Thyroid gland Lungs Heart Thymus Stomach and intestines Pancreas Liver Spleen Adrenals Kidneys Testicles

Newborn

Adult

16.7 23.4 11.3 14.34 0.20 0.28 0.24 0.24 2.15 0.89 0.54 2.53 0.12 4.39 0.41 0.31 0.88 0.037

15.35 43.09 6.3 2.32 0.067 0.023 0.12 0.05 2.01 0.52 0.0086 2.34 0.15 2.77 0.346 0.014 0.48 0.08

Source: Modified from Vierordt, K., Physiologie des Kindesalters, Verlag der H. Laupp’schen Buchhandlung, Tübingen, 1877.

It is regrettable that more normal anatomical data during growth have not been available; obviously, it may be more difficult nowadays to gain access to the results of sections of healthy normal children who died, for example, by accidents and the like. Comparisons are interesting. Some organs change, that is, show a marked increase in their relative weight (muscles) or a decrease in their relative weight (brain, medulla, skin, adrenals, thymus, etc.). Others, such as heart, lungs, skeleton, stomach and intestines, spleen, pancreas, etc. do not change markedly (see Table 1.1). However, this may have changed over time. Vierordt analyzed the changes in several body segments during different growth periods, which also enabled evaluation of their functions. His results are interesting with respect to the description of the nature of growth at different stages of development and as data on the growth of children and youth in the second half of the nineteenth century. Vierordt (1877) also examined the relationship of body height and pulse rate, deriving a formula for the calculation of pulse rate from body length, which yields fairly good results. The changes in nutrition and function in the gastrointestinal system were also described along with respiration, metabolic changes, vegetative

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Nutrition, Physical Activity, and Health in Early Life

TABLE 1.2 Development of Body Weight (BoW) after Quetelet, Expressed as a Percentage of Birth Weight (BiW), and Changes of Weight Increments Expressed in Absolute (WI-A) and Relative (WI-R) Values Age (Years) 0 1 2 3 4 5 6 7 10 15 18 25

Boys

Girls

BoW (kg)

% BiW

WI-A

WI-R

BoW (kg)

% BiW

WI-A

WI-R

3.20 9.45 11.4 12.47 14.23 15.77 17.24 19.10 24.52 43.62 57.85 62.93

100 295.3 354.4 389.7 444.7 492.8 538.8 569.9 766.3 1363 1807 1966

— 6.25 1.89 1.13 1.74 1.54 1.47 1.86 5.42 19.1 14.3 —

— 1.960 0.200 0.099 0.141 0.108 0.093 0.108 0.086 0.122 0.099 0.08

2.90 8.79 10.67 11.79 13.00 14.36 16.00 17.54 23.52 40.37 51.03 53.28

100 302.1 366.7 405.2 446.7 403.5 549.8 602.8 808.3 1387 1753 1831

— 5.88 1.88 1.12 1.21 1.36 1.64 1.54 5.98 16.85 10.66 —

— 2.020 0.214 0.105 0.103 0.105 0.115 0.096 0.102 0.114 0.080 0.019

Source: Modified from Vierordt, K., Physiologie des Kindesalters, Verlag der H. Laupp’schen Buchhandlung, Tübingen, 1877.

functions, chemical reactions during breathing and voiding, neuromuscular function, and thermoregulation. For the first time, his book analyzed the development of function during growth from the time of birth. The research of the German anatomists has been essential for the understanding of child growth and development. In the subsequent years, there has not been much anatomical addition to this essential work. Many other textbooks followed the writings of Vierordt. Among them are Auxology by DeToni et al. (1968), covering both fetal and postnatal ontogeny; Human Growth by Falkner and Tanner (1979); and Clinical Paediatric Physiology by Godfrey and Baum (1979). Monographs of the time mostly covered the whole period of growth or only certain growth periods such as adolescence (Tanner 1962). The period of preschool age (i.e., from 3 to 6 years), was usually not analyzed in great detail or in all of its complexity.

1.4 SECULAR TREND: ACCELERATION OF GROWTH Along with the environmental changes occurring during last century, many of the conditions of life have also changed. Growth acceleration is mainly related to morphological parameters, sexual maturation, etc. A comparison of the heights and weights of Czech children measured by Matiegka (1927) in 1895, more recently by Hajniš (1993), and later by Bláha and Vignerová (2002, 2004) shows a significant increase in the heights and weights of 6–7-year-old children. Boys of this age in the

Introduction: First Steps to Optimal Health and Fitness throughout Life

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Czech Republic were 11.5 cm and girls 13.5 cm taller in 1993 than they were in 1895 (Matiegka 1927). Similar changes also occurred in the body weight and body mass index (BMI) of children of the same age. These numbers are higher today, and changes still continue. Subsequent measurements of Czech children since the 1980s up to the beginning of this millennium have shown a further acceleration and there is also a shift in the adiposity rebound (AR; Rolland-Cachera 1995; see Chapter 4) earlier by ca. 1.5 years in both genders (Bláha and Vignerová 2002, 2004). This would seem to indicate a predisposition toward an increase in adiposity and an enhanced prevalence of obesity during growth, a problem that has in the last few decades manifested itself in the Czech Republic and similarly elsewhere. Changes in the development of body composition, the individual systems, organs, and tissues, have not been described in detail; body size during growth has been increasing but not proportionately. The same applies to the development of the functional capacity of the whole organism as well as to various functions, especially of the cardiovascular system (Parˇ ízková 1977). Recent studies have shown in greater detail the reduction of the aerobic fitness and cardiorespiratory efficiency in present youth, both in industrially developed countries and elsewhere (Tomkinson 2007). Some studies, for example, Shephard (1991), indicate that the acceleration of physical growth and the increase in body size are not always paralleled with accelerated functional development. This happened in, for example, Canadian Inuits, who changed their lifestyle and adopted a westernized diet and now have an increased body size along with an increased fat ratio. Simultaneously, the levels of functional capacity and fitness deteriorated as in other parts of the world (Tomkinson et al. 2003). Therefore, extending the potential for body size does not automatically parallel the extension of the functional potential. A similar phenomenon has also been described in other populations; for example, Guminskyi et al. (1972) compared the body size and aerobic power (characterized by oxygen uptake during a maximal workload as related to body weight in kilograms) of Russian children and adolescents shortly after World War II, and then approximately 15 years later. The heights and weights of the children had increased but their aerobic power had decreased. Comparing the diets of both samples, it was found that both energy and protein intake were at a lower level just after the war than later on. Increased energy intake, along with all other dietary components including highquality protein, resulted in increased body size but not in improved aerobic power (i.e., a higher level of cardiovascular fitness), which applies mainly to dynamic performance. In the Czech population, the recent average values of BMI (correlating with depot fat) not only increased compared to those assessed at the end of the nineteenth century (Matiegka 1927, Parˇ ízková 1989), but were also higher compared to other present-day populations, for example, the French (Prokopec and Bellisle 1993). Recommended dietary allowances (RDAs) for the Czech population were higher (Kajaba et al. 1992) than those in Western Europe (i.e., the European Community: Nutrient and Energy Intakes for the European Community 1993) and the United States (Recommended Dietary Allowances 1989). More often than not, the real intake was even higher (Parˇ ízková et al. 1984), which ran parallel to the

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Nutrition, Physical Activity, and Health in Early Life

increasing adiposity. The prevalence of cardiovascular diseases and death rate were also higher in the Czech population compared to other countries (Uemura and Píša 1988). The practice of prevention has, therefore, become of prime importance in Central and Eastern Europe.

1.5 INFLUENCE OF ENVIRONMENTAL FACTORS Environmental factors can have an influence on humans from the very beginning of life. For example, Papoušek (1961, 1975) showed that in 3–5 months old infants, it was possible to elaborate conditioned reflexes for the turning of the head in response to a sound signal. With infant the lying in a cot and from the direction of his/her feet, a soft sound signal was given. Then, after 5 s, an illuminated moving toy appeared in a small window at the side of the infant. At the beginning of these experiments, the infant reacted by turning his/her head toward the window with the toy only after it was illuminated (unconditioned, orientation reflex). When this situation was repeated several times, the infant began to turn his/her head toward the window after just the sound (conditioned reflex). For elaboration of this reflex, it was always necessary to illuminate the window. When this was not done, the reflex disappeared (Koch 1977, 1978; see Chapter 6). This example confirms the possibility of elaborating certain reflexes and habits much earlier than was originally assumed; the consequences of this may be manifested in some developmental changes of the child later on in life or even in adulthood. The influence of motor stimulation on the infant was demonstrated by Koch (1977, 1978), who showed that stimulated children were more advanced in their development in certain respects (see Chapter 6). This principle has been adopted in some systems of childhood education and has proven to be beneficial for the actual and future development of children (see Chapter 10). The influence of an inadequate diet during fetal and postnatal ontogeny can also have negative consequences, possibly persisting throughout life. This condition could not always be followed up longitudinally for a longer period of time in the same human subjects. An adverse diet may influence many aspects of later development of the individual. The greatest concern at present is the global epidemic of obesity, which has been spreading everywhere, including the developing countries—along with persisting malnutrition. This has focused more attention on the delayed effects of various stimuli, especially nutrition, influencing the organism during the earliest periods of life. Different environments may have a significant influence on the development of children, both positive and negative. Air and water pollution can have an influence on the outcome of pregnancy and on the subsequent development of the child, as well as later in life (WHO 1997a). For example, lower birth weights were observed in newborns of smoking mothers (Underwood et al. 1967). Air pollution and noise can also reduce birth weight, thus affecting the future development of the child, who may remain smaller, may become sick more frequently, and may show other handicaps. The negative impact of some medicines and/or drugs ingested by mothers during pregnancy was also proven.

Introduction: First Steps to Optimal Health and Fitness throughout Life

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The growth and development of children may be negatively influenced at any period of growth, but during certain periods (called “critical,” e.g., the weaning period), more serious delayed consequences can occur later in life. Preschool age was also defined as a “critical period” for the predisposition of later obesity (Dietz 1994). Sensitive, critical periods exist for learning about food, that is, the first 2–3 years (Cashdan 1994). The same applies to motor development and PA (Koch 1977, 1978, Parˇ ízková 1977).

1.6

WHAT ARE THE AIMS?

We know much about the influence of negative factors on the development of children and eventually on the impact of their elimination. However, the impact of the opposite situation (i.e., when conditions during the earliest periods of life are optimal in all necessary aspects, which could improve human development and prevent present health problems including obesity) has not yet been assessed and analyzed sufficiently—not only cross-sectionally but also longitudinally. This includes the influence of natural factors affecting young children—that is, what happens when infants, toddlers, and preschool children live under various conditions of PA, dietary intake, and other environmental factors that vary markedly but may still remain within normal limits. (However, good pedagogues, parents, caretakers, educators, etc., are aware of all these factors and have been able to use these views and experiences in families, schools, and other available institutions.) For many reasons, these principles still have not been advanced generally and systematically for all. This situation is understandable because far more urgent and actual problems exist concerning negative conditions for the development of children. Unfortunately, many of these problems can be avoided even without much scientific knowledge. Environmental and lifestyle changes, including nutrition and PA, have been developing and changing significantly in recent years, and so it is necessary not only to renew old knowledge and experiences but also to define innovated and actualized ideas, and determine how to proceed so as to ensure the best possible conditions for the development of the next generation. Under any circumstances and adverse conditions, it is always worthwhile to develop a creative approach for positive health and overall fitness development aiming at the optimal evolution of human beings.

2

2.1

Theoretical Considerations: What Can We Learn from the Natural and Experimental Models?

INFLUENCE OF DIET EARLY IN LIFE AND ITS DELAYED EFFECTS

2.1.1 GROWTH, BODY COMPOSITION, AND PHYSICAL ACTIVITY “Early diet, later consequences” (Conning 1991) was the topic of the 13th British Nutrition Foundation Annual Conference in 1991. It was shown that animals from large litters (Seitz 1954) grew more slowly than animals from small litters, who received more mother’s milk. This difference was evident long after birth. Such observations would be quite difficult to make in the human species—not only because assessments during the whole life span to confirm or not such conclusions cannot be realized, but also because humans are genetically very different; it would not be possible to change only one condition in a completely homogeneous group during a longer lifespan. Conclusions from an experimental model using laboratory animals cannot be transferred to humans, but they at least provide a stimulus and orientation with regard to the possible biological consequences of early dietary manipulations later in life. Classical observations of Widdowson and McCance (1960, 1963) showed, in greater detail, the impact of early nutrition on the later somatic development of rats. Two litters of rats, born on the same day, were combined. Then, three animals were taken at random and returned to one mother to suckle. The result was that those in the small nest grew much more rapidly than the remaining 15–20 rats in the larger nest. When these animals were weaned at 3 weeks, each individual from the small group weighed two to three times as much as those from the large nest because they received more milk (Conning 1991). The mother with the large number to suckle produced a greater total volume of milk, but not the five to six times as much that would have been necessary for all the animals in the large nest. Thus, the sucklings from the large nest grew more slowly. These animals never caught up in body size; even when they later had access to food intake ad libitum, they still ate less. This

9

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Nutrition, Physical Activity, and Health in Early Life

occurs because of a later maturation of the appetite centers in the hypothalamus, which can only fully develop 10 days after birth. Realimented children are usually able to catch up in growth after a period of malnutrition because the appetite centers in the human infant are fully developed at birth. The consequences of malnutrition depend significantly on its degree and duration; marginal malnutrition (which mainly reduces body weight and fat ratio, but not the size of vital organs and essential muscle groups) is easier to compensate for and does not always have a deteriorating impact functionally. The realimentation and “catch-up” growth of malnourished children is further accelerated with certain levels of PA (Viteri, Torun et al. 1973, 1979), which can have a natural anabolic effect, especially in the development of lean body mass. In two series of our experiments with rats breast-fed and weaned in nests with different numbers of litters, that is, in small nests with less than 6 (Group A) and in large nests with more than 12 animals (Group B) up to the 28th day of life, it was shown that animals from the large nests were not only smaller (Figure 2.1a) but also leaner, with smaller epididymal fat pads and a lower percentage of total body fat. In this experiment, the body weights of animals from Group B were significantly lower at certain periods of growth, and this difference disappeared gradually. The intake of food as related to body weight tended to be temporarily higher (Figure 2.1b; Parˇ ízková and Petrásek, 1978, 1979a,b). The sizes of vital organs, such as the heart and adrenal glands and/or the soleus muscle, were not affected, but the weight of the epididymal fat pads (which correlates significantly with the total body fat assessed gravimetrically) (Parˇ ízková 1977, Parˇ ízková and Stanˇ kova 1964) was significantly reduced in Group B. There are other consequences resulting from different dietary intakes in early life, which have not yet been studied. The level of spontaneous PA was measured in the mentioned groups in rotation activity cages (which enable the measurement of distance run in m/day) and it was significantly higher in rats from large litters (Group B), that is, with a lower intake of mother’s milk and with a lower final body weight (Figure 2.1c). The average distance covered during 1 day in the rotation cages was more than 6 km, indicating a satisfactory level of functional development of these animals. This was also confirmed in other experiments (Parˇ ízková and Petrásek 1978, 1979a,b). Thus, it seems that a more modest food intake at the beginning of life and smaller body dimensions, along with a lower percentage of body fat, may not be deleterious in all respects, even though it was generally believed that the reduced implementation of the potential for developing maximal body size is highly undesirable. However, achieving the maximum growth potential does not seem to be ideal when other potentials are also considered. A high level of spontaneous PA and an increased capacity for running may be considered to be linked to a higher level of functional capacity of the organism along with an adequate functioning of vital organs and systems (suggested by their unchanged size), which is also associated with a desirable health status. In addition, in Franˇ ková’s experiments on laboratory rats (Franˇ ková 1970, 1981, 1982, Franˇ ková and Barnes 1968), she demonstrated that early overnutrition was not beneficial for later exploratory behavior, learning ability, and resistance to pharmacological or nutritional stress.

11

Theoretical Considerations (a) 360 320

g

* 280 Group A

240

Group B 200 56–62

69–74 Days

75–79

(b) 12

* 8 g

*

4 Group A Group B 0 56–62

69–74

75–79

Days (c)

*

8000

*

m

6000

4000

2000

Group A Group B

0 56–62

69–74

75–79

Days

FIGURE 2.1 Changes in body weight (a), food intake (b), and PA (c) in rotation wheels in groups of male rats suckled in different-sized litters (A < 12, B > 6). *Indicates a statistically significant difference between groups (Parˇ ízková 1977). The sizes of vital organs, such as the heart and adrenal glands and/or the soleus muscle, were not affected, but the weight of the epididymal fat pads, which correlates significantly with the total body fat assessed gravimetrically (Parˇ ízková 1977, Parˇ ízková and Stanˇkova 1964), was significantly reduced in Group B.

12

2.1.2

Nutrition, Physical Activity, and Health in Early Life

LIPID METABOLISM DURING THE FETAL PERIOD

There exist important findings that have shown the possibility of a significant effect on offspring of prenatal factors. Lipid metabolism can be influenced by the mother’s diet during pregnancy, for example, which was studied in some species including humans. For example, under fasting conditions, free fatty acids (FFAs) are used for ketogenesis by the mother, and ketone bodies are used as fuels and lipogenic factors by the fetus. Maternal glycerol is preferentially used for glucose synthesis, saving other glucogenetic substrates, such as amino acids, for fetal growth. Triglycerides (TGs) are not transferred, but essential fatty acids derived from maternal diet, which are transported as TGs in lipoproteins, become available to the fetus owing to the presence of both lipoprotein receptors and lipase activities in the placenta. Fat accretion occurs essentially during the last trimester of intrauterine life. This is sustained by the intense transfer of glucose and by its use as a lipogenetic substrate, as well as by the placental transfer of fatty acids and their low oxidation capacity. Following changes in lipolytic activity, lipogenesis and lipolysis contribute to the sequential steps of adipocyte hyperplasia and hypertrophia occurring during extrauterine white adipose tissue development in the rat, which can be extrapolated to intrauterine adipose tissue development in other species including humans (Herrera 2002, Herrera et al. 2006, Haggarty 2002). All of the n-3 and n-6 fatty acid structures acquired by the fetus have to cross the placenta, and fetal blood is enriched in long-chain polyunsaturated fatty acids (LCPUFAs) relative to maternal supply. There is unsatisfactory evidence that placental delivery of fatty acids limits normal fetal growth, although the importance of the in utero supply may be to support postnatal development. Most of the LCPUFAs accumulated in the fetus are stored in the adipose tissue for use during postnatal life (Haggarty 2002). A beneficial effect of LCPUFAs during pregnancy is assumed, which should contribute toward optimizing substrate intake during pregnancy and lactation. This may improve fetal growth and development as well as pregnancy outcome (Koletzko et al. 2007). The composition of individual fatty acids of the maternal diet can have substantial effects on LCPUFA delivery to the fetus (Haggarty et al. 1997). Placental clearance of free fatty acids (FFAs) from maternal circulation was not significantly changed by alterations of the umbilical flow rate in rabbits. There was a significant relationship between increasing maternal–fetal gradient and increasing transfer of FFAs across the placenta. The net transfer of FFA from the fetus to the mother occurred when the umbilical arterial FFA concentration exceeded the maternal arterial concentration by 1.3 mmol/L (Stephenson et al. 1991). This may change, for example, during repeated PA. Diabetes in pregnancy promotes lipid transfer to the fetus by increasing the maternal–fetal gradient, which can contribute toward increasing the fat tissue in newborns of diabetic mothers. Greater skinfold thicknesses were found in the offspring of diabetic mothers during the first and second days after delivery (Parˇ ízková 1963, 1977). The results described seem to indicate the possibility of a significant influence of lipid metabolism on the offspring during the fetal period by the affected mother.

Theoretical Considerations

13

Placental transfer of, for example, fatty acids and their changes due to various stimuli may play an important role from the point of view of delayed consequences in the offspring that are manifested only later in life (Wilson et al. 1980). However, the results presented have mostly been followed up quite early during the postnatal life of the offspring, and not later during their adult life. In spite of significant changes in the metabolic, biochemical, hormonal, and circulatory parameters that occur in a pregnant mother during, for example, increased PA and eventual adaptation to it, their effect has not yet been studied sufficiently.

2.1.3

INFLUENCE OF A TEMPORARY DIET WITH LOWER ENERGY AND PROTEIN

The influence of food intake with reduced energy and proteins was studied in another series of experiments (Parˇ ízková and Petrásek 1978, 1979a,b, Parˇ ízková et al. 1979). During the lactation period, rat mothers were fed a diet with a reduced content of proteins (10%) up to weaning (28th day). The offspring (males) had a diet with 5% protein up to the 49th day of life, and their intake of this diet was spontaneously reduced (i.e., the intake of protein and energy was reduced in these animals—Group REP; this temporary reduction can be considered as marginal only). These animals were then fed a normal laboratory diet similar to that of the control group (20% casein—Group C), which had it since weaning. The overall dietary intake in absolute values (g/day) of the REP group was lower than in the control group. The growth and body weight of animals in Group REP were significantly reduced by ca. 21% compared to the control animals, up until adulthood (end of the experiment), that is, 125 days, due first of all to reduced body fat. Moreover, the development of spontaneous PA in rotation activity cages was followed up in both groups (REPA and CA). REPA animals gradually developed a significantly higher level of spontaneous PA than CA animals. The energy cost of growth increments in the REPA subgroup (expressed as g food/1 g of weight increment) was significantly lower than that in CA animals. The energy economy of growth and development was thus more effective, especially when we also consider the increased energy output necessary for running as much as 9 km/day. Such an increase of spontaneous PA in the rotation cages was observed in several subsequent and similarly arranged experiments (Parˇ ízková et al. 1980, 1982, Parˇ ízková and Petrásek 1978, 1979a,b). Concentration of lipids and liposynthesis was significantly changed (Figure 2.2).

2.1.4

CHANGES OF LIPID METABOLISM IN THE OFFSPRING DUE TO LACTATION PERIOD

Changes in lipid metabolism due to the intake of mother’s milk during lactation were also found in male rats breast-fed in large (A) and small nests (B), which developed different physical activity levels (PALs) as mentioned above (Figure 2.1c). The lipid concentration in the small intestine was significantly higher in the females of Group A (Figure 2.3a; Parˇ ízková 1977, Parˇ ízková and Petrásek 1978, 1979a,b). The synthesis of lipids in the small intestine was significantly higher in both sexes of Group A (Figure 2.3b). The concentration of fatty acids in the liver and in the small

14

Nutrition, Physical Activity, and Health in Early Life 20 18

*

16 14

%

12 REPA CA

10 8

*

6 4 2 0

Concentration—total lipids

Liposynthesis

FIGURE 2.2 Changes in lipid metabolism in the liver of male rats with different diets at the beginning of life (REPA—reduced energy and protein, CA—control diet) living in rotation activity cages. *Indicates a statistically significant difference between groups. (a)

8 7 6

*

%

5 4

3 2 1 0 Males

Females

(b) 0.14

% of applied activity

0.12 0.1

*

*

0.08 0.06 0.04 0.02 0 Males

Females

FIGURE 2.3 Concentration of lipids in the small intestine (a), synthesis of lipids in the small intestine (b), concentration of fatty acids in the liver and small intestine (c1,2), synthesis of fatty acids in the liver and the small intestine (d1,2), synthesis of cholesterol in the liver (e), and synthesis of cholesterol in the carcass (f) in groups of male rats suckled in different-sized litters (A < 12, B > 6). *Indicates a statistically significant difference between groups (Parˇ ízková and Petrásek 1978, 1979a,b).

15

Theoretical Considerations (c1)

5.0

*

4.5

*

4.0 3.5 %

3.0 2.5

2.0 1.5 1.0 0.5 0 Males

(c2)

Females

9 8

*

7 6 5 %

*

4 3 2 1 0 Males

(d1)

Females

0.16

% of applied activity

0.14

0.12

*

0.1 0.08 0.06

*

0.04 0.02

0 Males

FIGURE 2.3

(Continued).

Females

16

Nutrition, Physical Activity, and Health in Early Life (d2)

0.08

% of applied activity

0.07 0.06

*

*

0.05 0.04 0.03 0.02 0.01 0 Males

Females

(e) 0.025

% of applied activity

0.02

* *

0.015 0.01 0.005 0

Males

(f)

Females

0.6

% of applied activity

0.5 0.4

* *

0.3 0.2 0.1

0 Males

Females Group A

FIGURE 2.3

(Continued).

Group B

Theoretical Considerations

17

intestines was significantly greater in both males and females from Group A (Figure 2.3c1,2). The synthesis of fatty acids was significantly increased in both sexes of Group A in the small intestine (Figure 2.3d) and significantly lower in the liver. The cholesterol concentration in the liver and carcass was the same in all groups; however, the synthesis of cholesterol in the liver was significantly lower in Group A (Figure 2.3e) and in the whole carcass in both sexes (Figure 2.3f; Parˇ ízková and Petrásek 1978, 1979a,b). The impact of early diet and the resulting development of the level of spontaneous PA were closely interrelated, and their interaction had, in many respects, a significant delayed effect on lipid metabolism in various organs. The mechanisms and importance of such changes have not yet been fully elucidated; however, the impact of early nutritional manipulations seems to be important and may be associated with present and later lipid metabolism problems with possible simultaneous pathologies.

2.1.5

OTHER CONSEQUENCES OF EARLY DIETARY MANIPULATIONS

Manipulation of the diet after weaning may also influence the spontaneous selection of foodstuffs (Parˇ ízková 1961). In another experiment, groups of male rats were followed from birth up to the age of 230 days. The animals were weaned at the age of 18 days and fed a high-fat diet ad libitum up to the 30th day (FI) and/or the 42nd day (FII). Then, both groups had a free selection of pure foodstuffs—starch, fat, casein, water, vitamin B complex, and KCl and NaCl solutions ad libitum. The third group was fed the self-selected foodstuffs as mentioned above immediately after weaning; that is, from the 18th day of life (S), without any intermediate diet. The last (fourth) group was provided the usual laboratory diet permanently (C). Both groups with the temporary high-fat diet (FI, FII) grew in a manner similar to the control group (C). The group with the self-selection of pure foodstuffs from the 18th day (S) was retarded in growth and remained the smallest and leanest of the groups until the end of the experiment (i.e., with the lowest percentage of depot fat). Both groups with the temporary high-fat diet (FI, FII) then had an altered selfselection of foods; that is, they consumed significantly more fat during certain periods of growth (days 41–91) and then they consumed significantly more casein (days 101–111) than Group S. The consumption of starch was the same in all three groups. Apparently, the introduction of a certain kind of diet very early in life may have a delayed effect with regard to the self-selection of foodstuffs later on during ontogeny along with growth and body composition changes (Parˇ ízková 1961). This especially concerned the high-fat diet.

2.2 INFLUENCE OF INCREASED PA DURING PREGNANCY ON THE LATER DEVELOPMENT OF OFFSPRING 2.2.1

METABOLIC REACTIONS DURING PREGNANCY

PA and workload is a marked and significant metabolic, hormonal, biochemical, and higher nervous activity stimulus that influences the organism at present, and possibly

18

Nutrition, Physical Activity, and Health in Early Life

also from the point of view of adaptive consequences in later life. Characteristic changes may appear, reflected not only in the maternal organism during pregnancy but also in the organism of the offspring, either immediately or later on. This applies not only to the dietary intake but also to the PA of the pregnant mother. Metabolic changes in the maternal organism during pregnancy may be transmitted to the fetus (Dancis 1975). The maternal FFA level is related to adipose tissue development of the offspring (Szabo et al. 1975). A number of hormonal, neurohumoral, metabolic, and biochemical parameters in the blood (glycemia, FFAs, and lactate levels) change during increased PA, and have a significant impact during all periods of life. This also applies to the period of pregnancy. For example, the increased PA of pregnant rabbits increased the frequency of movement in the fetus. This was explained by an increased lactic acid level in the blood of the mother (Arshavskyi 1967). The effects of PA during pregnancy with regard to delayed consequences in the adult offspring have not yet been reported.

2.2.2

LIPID METABOLISM

Changes in selected indicators of lipid metabolism in the liver of female and male offspring of rat mothers exercised during pregnancy were measured. Exercise started 2–3 days after mating for 1 h/day at a speed of 14–16 m/min (which is a mild exercise that is aerobic in nature—Group E). Offspring of exercised and inactive control mothers (C) were followed up. Male offspring of exercised mothers (Group E) were heavier at age 35 days and lighter at 90, 100, and 108 days. The concentrations of total lipids and fatty acids in the liver were elevated in female offspring at ages 35 and 90 days, and they did not differ nor did they reduce in male offspring of exercised mothers (Group E) compared to controls (C). The cholesterol concentration in the liver was increased in both female and male adult offspring of exercised mothers (E). Liposynthesis, studied in vivo after injection of Na-acetate-1-14C, tended to be lower in female offspring and varied in male offspring of exercised mothers (E). In a subsequent in vitro study in which liver slices were incubated with Na-acetate-1-14C, a lower total lipid and fatty acid concentration in the liver of 108-day-old male offspring of exercised mothers was found along with a higher level of FFA serum level and unchanged liposynthesis (Parˇ ízková and Petrásek 1978, 1979a,b). Finally, a higher cholesterol concentration, lower cholesterogenesis, and higher fatty acid synthesis in the small intestine of 100-day-old male offspring of exercised mothers, compared to those of control inactive mothers, were seen (Figure 2.4a–c). These data seem to indicate that a daily aerobic workload of the mother during pregnancy results in significant changes of lipid metabolism in the liver and the small intestines of the offspring during their later ontogenesis, that is, in adult age (Parˇ ízková and Petrásek 1978). On the basis of all the above experimental data, it is difficult to explain the mechanisms and the impacts of these delayed changes. However, these results demonstrate the possibility of changing the future development of selected parameters, which could have an impact on further metabolism in the offspring of systematically

19

Theoretical Considerations

(a)

3.0 2.5

* %

2.0 1.5 1.0

0.5 0 Exercise

(b)

Control

0.01

% of applied activity

0.009 0.008

*

0.007 0.006 0.005

0.004 0.003 0.002

0.001 0 Exercise (c)

Control

0.1

% of applied activity

0.09 0.08

*

0.07 0.06 0.05 0.04

0.03 0.02 0.01

0 Exercise

Control

FIGURE 2.4 Cholesterol concentration (a), synthesis of cholesterol (b), and synthesis of fatty acids (c) in the small intestine in the offspring of rat mothers exercised during pregnancy and in the offspring of control rats (Parˇ ízková and Petrásek 1978).

exercised mothers. This especially applies given the possible participation of these delayed effects concerning lipid metabolism in the pathogenesis of some metabolic and/or cardiovascular diseases (e.g., atherosclerosis). As mentioned above, Szabo et al. (1975) showed that the FFA level of the mother has an important impact on the development of the adipose tissue of the fetus. Fluctuations of the FFA level (and also

20

Nutrition, Physical Activity, and Health in Early Life

of other metabolites) in the blood of pregnant rats exercising daily may also occur in other organs and may apply to other characteristics of the offspring. Numerous hormonal, neurohumoral, and biochemical changes occurring during a workload in the mother’s milieu intérieur may be transmitted to the fetus, causing some changes that may appear immediately and/or as delayed effects later in life. There are no data in the available literature on the impact of exercise during pregnancy and the resulting metabolic changes in the adult offspring of laboratory animals; this deserves attention due to possible relationships with predispositions for possible future health problems.

2.3 INFLUENCE OF OTHER FACTORS DURING PREGNANCY The placenta is considered to be a barrier through which not all metabolites can be transported; however, some studies showed some effects in the fetus due to the change in maternal metabolic status. This concerns, for example, the effect of maternal fasting on the fetal and placental lipid metabolism in pigs, as was investigated by Ruwe et al. (1991). Fasting caused maternal FFA levels to increase 2.5-fold, betahydroxybutyric acid levels to increase 4.8-fold, and TG levels to decrease 1.8-fold, while no change in the plasma glucose concentration (compared to controls) was found. Fasted fetuses showed, for example, a 1.3-fold increase in FFAs, a 1.9-fold decrease in TGs, a 1.5-fold decrease in glucose, and no change in beta-hydroxybutyric acid levels compared with controls. The distribution of FFAs in fetal plasma was different from the distribution of FFAs in maternal plasma. Esterification of 14C-palmitate by maternal placenta and fetal adipose tissue was reduced by fasting; the other parameters of fatty acid metabolism were unaffected. Fasting decreased lipoprotein lipase activity in the placenta by 35%, and by 44% in fetal adipose tissue. These data suggest that fasting mobilized maternal fuel stores, but that these stores are not effectively used by the placenta and/or by the fetus for storage, as carcass lipids were not altered. Changes in other organs or tissues were not investigated. However, changes were found in plasma levels of the fetus, which run parallel to those of the fasting mother. Studies of the effects of altering umbilical blood flow and umbilical FFA concentration on the transfer of FFAs across rabbit placenta showed that placental FFA clearance from the maternal circulation was not significantly affected by the umbilical blood flow rate. It was shown, though, that the maternal–fetal FFA concentration gradient varied between +1.58 and –2.81 mmol/L, and that there was a significant relationship between the increment of the maternal–fetal gradient and the increasing transfer of FFA across the placenta. Moreover, the net transfer of FFA into the umbilical circulation was observed even with a zero concentration gradient (Stephenson et al. 1991). Placental transfer of essential and non-essential fatty acids was studied in diabetic rats. The results indicate that increasing maternal glycemia is associated with a decrease in the unidirectional transfer of both essential and non-essential fatty acids. This reduced transfer of both essential and non-essential fatty acids depends on uteroplacental blood flow, which is compromised in diabetic animals. The transfer of essential fatty acids was always twice as high as that of non-essential fatty

Theoretical Considerations

21

acids, regardless of the total amount of lipids transferred, indicating a selective mechanism in the transfer of these moieties (Honda et al. 1990). It was shown that the long-term effects of feeding a high-carbohydrate (HC) diet to rat pups in the preweaning period by gastrostomy resulted in the development of obesity later in life, even though there was no change in the body weight of this group compared to normally breast-fed pups (MF) during the actual weaning period. HC rats were hyperinsulinemic, and their growth rates were greater than those of MF rats. The lipogenic capacity of the liver, as well as adipose tissue, was also higher in HC rats. The adipose cell size of HC rats in adulthood was greater. This experiment can serve as an enhancement model of adult obesity by practising early overfeeding with an HC diet, which did not correspond to the composition of mother’s milk; this did not occur with a high-fat diet, which mimics mother’s milk (Hiremagalur et al. 1993). The transfer of metabolites across the placenta (Dancis 1976) was studied under various physiological and pathological conditions (Percy et al. 1991). However, the impact of workload of the pregnant mother with regard to possible changes of this transfer was not studied. The above-mentioned experiments show that FFAs can move across the placenta to the fetus, and that changes in the maternal organism could be transmitted to the fetus, mainly without any apparent immediate metabolic effect. The energy contribution may be relatively small (Thulin et al. 1989, Honda et al. 1990, Bleyl et al. 1991, Cunnane and Chen 1992). In addition, the situation varies markedly in different species. The transfer of metabolites may be influenced by an excess intake by the mother; however, the fetus seems to be protected against an increased intake of dietary lipids by the pregnant mother (Hausman et al. 1991). This situation, though, was not studied in greater detail with respect to delayed effects in the adult offspring. More discrete changes may not be immediately apparent, but may manifest later only in certain respects and only in selected tissues and organs of the offspring. But even on the basis of our limited actual knowledge of delayed effects, it does not seem probable that, for example, considerable excesses in food intake before and during pregnancy and early after delivery during lactation (especially an unbalanced diet with too much protein, sugar, saturated fat, etc.) could be completely indifferent—especially when exceeding a certain significant range—for the actual and later development of the offspring, from both the physiological and the pathological points of view. The same applies to the effect of workload and more marked changes in PA accompanied by hormonal, neurohumoral, metabolic, and biochemical changes. The example of athletic mothers training also during pregnancy could hardly serve as an example in this respect, as it would be difficult to differentiate and analyze the simultaneous effect of selective genetic factors, various kinds of exercise, nutritional status and dietary intake, and further individual factors of such mothers that are not always homogeneous. However, a significant effect of the continuation of exercise during pregnancy was revealed—that is, smaller birth weight and reduced deposition of fat in the newborn without changing body length (Clapp et al. 2002). Later changes in the offspring were not followed up.

22

Nutrition, Physical Activity, and Health in Early Life

2.4 EXERCISE DURING PRE- AND POSTNATAL ONTOGENY AND CARDIAC MICROSTRUCTURE OF THE OFFSPRING The impact of exercise during pregnancy was not sufficiently studied with regard to possible delayed changes in, for example, cardiac muscle of the offspring. In two series of experiments, body weight and the microstructure of cardiac muscle in the male offspring of exercised and inactive control mothers were investigated in subsequent experiments. In 50-day-old male offspring, the total body weight and heart weight did not differ. In 100-day-old offspring, the heart weight was significantly higher in those from mothers exercising throughout pregnancy (Group E), that is, similar to the previous experiment, for 1 h, 5 times per week, 14–16 m/min; this workload was again of a mild, aerobic nature, as compared to offspring of control inactive mothers (C). With regard to the microstructure of the cardiac muscle (contrasted with the PAS reaction; Parˇ ízková 1978a,b, 1979), the differences were significant, both in younger and in older animals. The number of muscle fibers and capillaries per mm2 in the heart was significantly higher in male offspring of exercised mothers. The capillary to fiber ratio was significantly higher, and the diffusion distance (i.e., the distance between the center of a capillary and the center of a muscle fiber) was significantly shorter in male offspring of exercised mothers. During the prenatal period, a favorable effect of workload for the offspring could be induced more easily, even with mild aerobic and short daily exercise, than later during postnatal life (Parˇ ízková 1975). Exercise after weaning also had a significant impact on the microstructure of the cardiac muscle, but the changes were relatively smaller (Parˇ ízková 1978a,b, 1979), as were the changes in the excitability of the central nervous system (CNS) (Parˇ ízková 1977, Parˇ ízková and Lát 1973). Our later experimental study focused on the combined effect of aerobic exercise during pregnancy and exercise during postnatal ontogeny of the offspring. In this experiment, male rats were again used (in females, the analysis of the impact of running activity is more complicated due to marked changes of spontaneous PA during the estrous cycle). The same aerobic workload on a treadmill (1 h) was used in pregnant rats. Some male offspring, selected at random after weaning, from both exercised and control mothers, did/did not start to exercise on the treadmill at the age of 28 days, and the workload was practically the same as that of the pregnant mother rats. After weaning, the animals were divided into four subgroups: Exercised offspring of exercised mothers (EE) Exercised offspring of control mothers without exercise (EC) Exercised offspring of control mothers (CE) Control offspring of inactive, control mothers without exercise (CC). All animals were sacrificed at the age of 110 days (Parˇ ízková 1978a,b). The results confirmed the conclusions of the previous experiments. Mild aerobic exercise during pregnancy significantly increased the number of capillaries and fibers, increased the value of the capillary to fiber ratio, and decreased the diffusion distance, especially in subgroup EE. Such a microstructure of the cardiac muscle is

Theoretical Considerations

23

considered favorable from a functional point of view and as a characteristic of a higher level of functional capacity and physical fitness: similar characteristics were found in wild animal species, as compared to domesticated ones, as was shown for wild and laboratory rats by Wachtlová and Parˇ ízková (1972). There seems to be evidence that aerobic exercise during pregnancy is more effective than a more intensive and longer daily workload during later periods of life (Parˇ ízková 1979). During the fetal period, the organism may be more sensitive to various stimuli than later during postnatal ontogenesis; this also includes the impact of workloads of the pregnant mother. This was also apparent in this experiment from the significant differences in the number of fibers and capillaries, the capillary to fiber ratio, and the diffusion distance between subgroups EC and CE. These parameters were always better in subgroup EC male rats (Parˇ ízková 1978a). No significant differences appeared in the number of capillaries per mm 2 between subgroups EC and EE, even when subgroup EE had more favorable results. However, these differences were significant between subgroups CC and CE. The same situation was found in the capillary to fiber ratio and the diffusion distance. Exercise during postnatal ontogenesis results in a significant difference in the offspring of inactive control mothers, that is, a significant increase in the number of capillaries and fibers per mm2 in the heart, a significant increase in the capillary to fiber ratio, and a significant decrease in the diffusion distance. Even when there is some other change due to exercise during postnatal ontogenesis of the offspring of exercised mothers, the difference is not significant, indicating the relatively greater importance of maternal exercise during pregnancy. Extreme differences in all characteristics of heart microstructure were apparent between groups of exercised offspring of exercised mothers (EE) and inactive control offspring of control mothers (CC; Parˇ ízková 1978a). As follows from our data, the positive effect of a regular, optimal workload can be transmitted to the offspring when work is performed during pregnancy, and subsequent exercise of the offspring potentiates this effect even more. This experiment shows that changes in the microstructure of the heart are not necessarily accompanied by changes in total body weight or heart size. Moreover, these changes in heart size and body weight are not always apparent after regular and more intensive aerobic exercise performed by rats during postnatal ontogenesis (Parˇ ízková 1977, Parˇ ízková et al. 1972). Finally, the same experiment was repeated in both males and females subdivided in the same way (CC, CE, EC, and EE male and female subgroups; Figure 2.5a and b). As the animals were followed up for a longer period, that is, until 120 days of life, the possible effect of the fluctuation of spontaneous PA during the estrous cycles could be reduced. No remarkable differences occurred in the reaction of female and male offspring, caused by prenatal and postnatal exercise (Parˇ ízková 1979), that is, both in males and in females there were changes in cardiac microstructure that were considered favorable from the functional point of view (Figure 2.5a and b). According to available experimental evidence, the mechanisms of these changes have not yet been elucidated. Differences among groups were evaluated statistically using the Duncan test; underlined groups do not differ significantly (Parˇ ízková 1979).

24

Nutrition, Physical Activity, and Health in Early Life (a)

4000 3500

Number

3000 2500 2000 1500 1000 500 0

(b)

CC f

CC m

CE m

CE f

EC f

EE f

EE m

EC m

CC f

CC m

CE m

CE f

EC f

EE f

EC m

EE m

4000 3500

Number

3000 2500 2000 1500 1000 500 0

FIGURE 2.5 Number of capillaries (a) and fibers/mm 2 (b) in the heart muscle in male (m) and female (f) offspring of exercised (E) and control, inactive rat mothers (E,C—first capital letter) that exercised or were inactive during their postnatal life (E,C—second capital letter).

2.5 INFLUENCE OF PA ON THE DEVELOPMENT OF EXPERIMENTAL CARDIAC NECROSIS 2.5.1

EXERCISE DURING POSTNATAL LIFE

Previous experiments showed that adaptation to aerobic exercise during postnatal ontogenesis starting with weaning up to adult age may reduce the risk of the development of experimental cardiac necrosis induced by the administration of isoprenaline (Faltová and Parˇ ízková 1970, Faltová et al. 1983, 1985). Various levels of PA, started at different ages, were tested. Male rats started to run on a treadmill at ages of 21, 32, and 55 days, and continued until 90, 100, 125, and 205 days (E). Simultaneously, other groups of animals of the same age were placed in small spaces (8.75 × 21.25 cm) with wire net walls [limitation of isolation stress, six animals in a subdivided normal

Theoretical Considerations

25

laboratory cage, limited activity (LA)]. Control groups of animals living in usual laboratory cages were always followed up simultaneously (C). With regard to body weight, only the group of 205-day-old animals showed significant differences from the E and LA groups. The weight of the soleus muscle always varied according to the intensity of PA (i.e., was highest in Group E), except for the oldest group. The percentage of body fat (estimated gravimetrically, using a chloroform extract of the carcass saponified in a mixture of 30% KOH in 50% ethanol) was always the lowest in Group E. As a rule, heart weight was not affected. Myocardial necrosis was induced by the administration of two doses of isoprenaline given subcutaneously at an interval of 24 h to each rat at the end of the experimental period. Rats that did not die were decapitated 24 h after the second injection. The hearts were removed and the degree of cardiac damage was estimated, using the scale described by Rona et al. (1, no damage; 5, spontaneous death) (Parˇ ízková 1977, Parˇ ízková and Faltová 1970). Isoprenaline produced less cardiac damage in exercised rats (E) than in controls (C) and rats with LA. Animals that died following the injection of isoprenaline had a higher percentage of body fat than animals with minimal cardiac damage. It was not possible to compare the results of separate experiments, as the doses of isoprenaline were always set individually for a particular group of animals followed at different periods of time (Faltová and Parˇ ízková 1970, Faltová et al. 1983, 1985). Exercised animals with a lower percentage of body fat were more resistant to the impact of isoprenaline compared to control or inactive animals, similar to young animals as compared to older ones (i.e., young animals are more spontaneously active, less fat, and more resistant to isoprenaline). The same difference was found in animals weaned in large (14) or small (3) nests that also differed in fatness and weight: light and leaner animals, that is, young animals or those with a reduced food intake at the beginning of life, were more resistant to the cardiotoxic impact of isoprenaline (Faltová and Parˇ ízková 1970, Parˇ ízková 1977). (The same differences were also found between genetically lean strains of rats, i.e., Lewis and Wistar rats [Faltová and Parˇ ízková 1970].) These results seem to indicate that an organism with a certain metabolic stereotype, characterized inter alia by a higher ratio of depot fat, is more prone to developing cardiac damage under the same conditions of exposure to noxious factors. With regard to the influence of exercise, after 3 weeks of induced running on the treadmill (2–4 h), the cardiotoxic effect of isoprenaline was reduced. The adequate daily dose of exercise depended on both the distance run per day and the rate and intensity at which the animals ran. If the training regimen continued for a few more weeks with the same daily dose of exercise, there was no significant increase in its protective effect (Faltová et al. 1985). In animals less than 3 months old, myocardial resistance changed only after much higher daily doses of running than those needed for the same effect, that is, the same difference between Group E and Group C, in older animals, similar to body composition (percentage of fat), metabolic activity of adipose tissue, etc. This may be explained by a naturally high level of spontaneous motor activity in all growing animals (Parˇ ízková 1977), and achievement of a significant increase in PA might be difficult (and may not be necessary). The cardioprotective effect of increased motor activity was moreover not conditioned by an increase in the weight of the heart (Faltová et al. 1985).

26

2.5.2

Nutrition, Physical Activity, and Health in Early Life

SPONTANEOUS ACTIVITY AND CARDIAC DAMAGE

The impact of motor activity level was also followed up using rotation cages, rendering possible the evaluation of the level of 24-h spontaneous PA. In one of our experiments, it was shown that the level of spontaneous PA increased with age until the end of puberty and young adulthood (6562 m/day at the age of 3 months). Then, the level of spontaneous PA in rotation cages decreased. At adult age, that is, 10 months, the activity was, on average, only 561 m/day. In all experimental groups in which spontaneous activity was higher than this limit, a decrease in the cardiotoxic effect of isoprenaline was found after 2–3 weeks in rotation cages (Faltová et al. 1983). The extent of heart lesions in the individual animals was not proportional to the degree of their motor activity. The slightest myocardial damage was not found in animals that ran the longest distance and vice versa. A marked decrease in the extent of cardiac lesions occurred when the motor regimen was prolonged to 70 days (Parˇ ízková 1977, Parˇ ízková and Faltová 1970, Parˇ ízková et al. 1982). The condition of the positive effect of running was at a certain level (i.e., a certain intensity and duration) of running and with a permanent regular impact of workload (Faltová et al. 1983).

2.5.3

DELAYED CONSEQUENCES OF TEMPORARY EXERCISE

There was a question as to how long the protective effect of increased motor activity in the rotation cages would persist when the animals were transferred to normal laboratory cages and did not have the opportunity to run any longer. After a 3-day break, reduction of the cardiotoxic effect of isoprenaline still persisted. The extent of heart lesions after a 2-week interruption of exercise corresponded to the values found in animals not allowed access to rotation cages (Faltová et al. 1983). The condition for the protection of the heart was thus an uninterrupted PA regimen or one with only brief pauses of decreased activity. In conjunction with studies on the impact of exercise during postnatal ontogenesis, the influence of exercise throughout pregnancy on the cardiotoxic effect of isoprenaline in the offspring was investigated. The same protocol as mentioned above was used regarding the aerobic workload of pregnant rats and the evaluation of cardiac damage after isoprenaline administration. Male offspring of exercised mothers showed lower damage of the heart after isoprenaline administration compared to offspring of inactive control mothers. Thus, aerobic exercise of pregnant mother rats was manifested in a positive way regarding delayed effects in their offspring (Parˇ ízková 1978b). This may be related to the above-mentioned changes in cardiac microstructure, as well as to changes in lipid and cholesterol metabolism, or other factors that have not yet been investigated.

2.6

IMPACT OF THE INTERACTIONS BETWEEN EARLY DIET AND PA ON EXPERIMENTAL CARDIAC NECROSIS

Previous experiments seem to indicate that the possibility for spontaneous PA is a more favorable and more important stimulus than induced running on a treadmill. This was also proved by Suzuki et al. (1978), who demonstrated a significant decrease

Theoretical Considerations

27

of systolic blood pressure in genetically hypertensive rats that had access to rotation cages. In contrast to that group, a similar group of rats with induced exercise of similar intensity on a motor-driven treadmill exhibited an increase in blood pressure. As mentioned above, PA is highest during the growth and development period, decreasing later in life. Thus, this is a feature that characterizes the young organism in addition to many other morphological and other parameters: a lower proportion of adipose tissue, which is metabolically more active (i.e., it releases in vitro, spontaneously or after adrenaline, more FFAs), and a higher activity of lipid metabolism in skeletal muscles indicating increased lipid utilization along with a higher food intake, especially when related to body weight. In many respects, physically active organisms have characteristics similar to younger ones (Parˇ ízková 1977). The opportunity for increased spontaneous exercise in the rotation wheels also decreased the cardiotoxicity of isoprenaline, which was lower in exercising animals. This difference was similar to that between younger and leaner and older and fatter animals. The former were also more resistant to the cardiotoxic effect of isoprenaline (Parˇ ízková 1977).

2.6.1

IMPACT OF EARLY DIET

Increasing or reducing the number of animals in one nest, which results in decreased and/or increased fatness and weight, can change the heart’s resistance to noxious factors. When we compared the cardiotoxicity of isoprenaline in smaller and leaner animals from large nests (14 litters) with heavier and fatter animals from small nests (3 litters), it was significantly lower in the first group (Parˇ ízková 1977). As mentioned above, the level of spontaneous PA was also higher in the first group with lower food intake early in life (Parˇ ízková et al. 1980). This means that changes in early nutrition, with all its consequences, may also change the sensitivity of cardiac muscle to isoprenaline.

2.6.2

SPONTANEOUS PA INFLUENCED BY EARLY DIET AND CARDIAC RESISTANCE TO ISOPRENALINE

Some of the above-mentioned experiments also show that animals with a decreased food intake at the beginning of life develop a higher level of spontaneous PA in rotation cages. This concerned not only male rats weaned in large (A) and small (B) nests (Parˇ ízková et al. 1979); the introduction of a diet with reduced protein content in lactating rats and later in their offspring up to 7 weeks of age also increased the level of spontaneous PA in rotation cages (REPA), resulting in lower body weight and fatness. We also used this experimental model to examine the impact of this interactive situation on the cardiotoxicity of isoprenaline. Groups of rats with reduced protein and energy (REP) intake during lactation and up to the age of 49 days, along with a group of control animals with the usual laboratory diet (C), were investigated. Half of the animals from both groups were always placed individually in rotation cages. Thus, four subgroups of animals could be compared: those from mothers with REP that continued with the same diet until puberty, starting with the C diet later, were placed in rotation cages where they could be

28

Nutrition, Physical Activity, and Health in Early Life

active (REPA) or were placed in normal laboratory cages where they were relatively inactive (REPI). Then, we simultaneously followed the animals from C mothers, which were placed in either rotation cages (CA) or normal cages (CI). REPA animals developed higher levels of spontaneous PA, were lighter and leaner than controls (Figure 2.6a), and also showed higher levels of energy economy because the food intake per 1 g of body weight gain during the period of realimentation after the 49th day of life was significantly lower. In this experiment, we also found significant changes in the relative weight of the heart (Figure 2.6b), the right ventricles (Figure 2.6c), and the left ventricles (Figure 2.6d); animals with the opportunity for spontaneous exercise in this experiment developed relatively larger hearts (Parˇ ízková et al. 1982). In this experiment, we were also able to test the resistance of cardiac muscle to the impact of isoprenaline using 203HgCl2 administration to show the increased (a)

600 500

g

400 300 200 100 0 CI

CA

REPI

REPA

REPI

CI

(b)

4000 3500

mg/kg

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FIGURE 2.6 Body weight (a), heart weight/body weight (b), weight of right ventricle/body weight (c), weight of left ventricle/body weight (d), and counts per minute/mg heart tissue (e), after application of 203HgCl2, characterizing the degree of cardiac damage in male rats with reduced energy and protein diet at the beginning of life (REP) and control diet (C) living in rotation, in activity cages (REPA, CA) or in normal laboratory cages (REPI, CI). Differences among groups were measured using the Duncan test; underlined groups do not differ significantly (Paízková et al. 1982).

29

Theoretical Considerations (c)

900

800 700 mg/kg

600

500 400 300

200 100 0

(d)

REPA

CA

REPA

CA

REPI

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3000 2500

mg/kg

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cpm/mg

(e) 50 45 40 35 30 25 20 15 10 5 0 CI

REPI

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REPA

FIGURE 2.6 (Continued).

permeability of membranes of the necrotic cardiac muscle cells (Hunt 1990). This comparison (Figure 2.6e) showed the best situation in REPA animals and the worst in CI animals. Therefore, modest food intake with less protein until puberty, resulting in a significantly lower body weight and less body fat and higher levels of spontaneous PA, was related to a greater resistance of the cardiac muscle.

30

Nutrition, Physical Activity, and Health in Early Life

Animals with a higher level of energy turnover were more protected from the impact of isoprenaline, shown by a lower degree of cardiac damage that was demonstrated in REPA animals by significantly lower values of cpm/mg heart tissue (Figure 2.6e). The differences in cardiac resistance to isoprenaline were again similar to those between groups of young and old animals (Parˇ ízková 1977, Parˇ ízková and Faltová 1979, Faltová and Parˇ ízková 1990) or to animals of mothers exercised during pregnancy and/or during a much longer period of time during postnatal ontogenesis. However, it is necessary to mention that the level of motor activity, resulting spontaneously from a changed diet at the beginning of life, was markedly higher when the animals had access to rotation cages, reflecting a free choice to either run (more than 9 km per day) or remain inactive. Such a workload and performance was impossible to achieve when inducing daily running on a motor-driven treadmill. Thus, the best results were achieved by influencing the level of spontaneous PA with an early diet, reduced in protein and energy compared to controls. On the other hand, the worst results regarding cardiotoxicity were always found in rats fed ad libitum that were restricted in spontaneous activity by placing them in small spaces after weaning. These conditions resulted in a larger body size and a higher body fat ratio.

2.7 GENERAL CONSIDERATIONS Obviously, results from experimental models using laboratory animals may only suggest the possibility that certain early manipulations may have some meaningful effects later in life. Even when different degrees of maturity are achieved with different species at the time of birth, all these studies seem to indicate that influencing the organism during the fetal period, the subsequent period of lactation, and early growth may be of utmost importance for a better prognosis in later development. More detailed information was therefore presented to demonstrate this phenomenon in spite of an actual lack of explanation. The impact of simple natural stimuli such as food and motor activity may substantially affect, in both positive and negative ways, the actual and later ontogenetical development, thus resulting in a different health status, size of the body, and size of its compartments. Positive effects were revealed, mainly along with a reduced deposition of fat, which as a marker experienced a significant threshold effect of PA, either spontaneous or induced. Early diets had later consequences, significant only after a period of delay. Significant consequences of the early manipulations of both diet and exercise may appear at different levels of functional capacity in different systems, in higher and/or lower sensitivity and reactivity to positive and negative stimuli, and also in changes of the resistance of the cardiac muscle to noxious factors. There seems to be evidence that various individual variations explained by inborn, genetic factors may often be elicited more naturally by using various manipulations of the organism during the critical period before and around birth and during the first stages of life. The rate of growth and mature weight has an important relationship with lifespan (Widowson 1962), as energy balance and turnover have a significant role. Ross (1964) and Ross et al. (1976) showed that longevity correlates with both

Theoretical Considerations

31

the amount and the type of diet an animal chooses to consume before mid-life. Dietary practices during early life are particularly important (see Chapter 3). The quantity and composition of food determine, in large part, the weight changes during a lifespan. Growth rate and other body-weight-related expressions may also correlate with lifespan: rats that grew slowly (especially between 50 and 150 days of age) were shown to have, in general, an extended lifespan. Chronic underfeeding of complete diets was shown to be the only means known to increase the length of life in homoiothermic laboratory animals beyond the limits characteristic for the species; chronic overfeeding and other excesses or imbalances curtailed the lifespan. None of these changes were considered in relation to energy output; however, they did show that slower weight gain during growth periods was a favorable prerequisite for a longer lifespan, and that this may be related to the factors that regulate the susceptibility to some age-related diseases (Ross 1964, Ross et al. 1976). There also exists evidence of similar observations in long-living human subjects (Kozlov 1987). The study, conducted in cooperation with Russian and U.S. scientific institutions, showed that in a long-living population in the Abkhasian mountains (at ca. 600 m of altitude and living in small communities), children were weaned later, grew more slowly (Miklashevskaya 1994), their adiposity was lower, overfeeding was excluded, and PA and workload were higher during the whole life. This contrasted with an ethnically comparable population living in a large city in the same area. Clinical observations also showed, for example, lower levels of serum lipids, less cardiovascular problems, and full overall activity until an advanced age. The long-living subjects remained active and were respected in their communities until the end. It should be emphasized, however, that all the results mentioned above are not a basis for advocating and recommending malnutrition or an excessive workload at the beginning of life. Rather, it is necessary, under permanently changing environmental conditions, to re-evaluate and define more precisely, and on a physiological basis, the adequate energy balance and turnover; this results from an optimum diet, desirable PA and workload level, and stimulating exercise from the beginning of life. The effect of PAL, which has a significant effect on a mother’s metabolism, hormonal level, and blood circulation, and eventually changes placental blood flow and transfer of metabolites, has not yet been studied in the offspring sufficiently, especially from the point of view of delayed effects in later life. In conjunction with all the results mentioned above, it should also be emphasized that the goal of these experiments was not to develop maximal performance but, mainly, to promote health and the early prevention of diseases, especially those of the cardiovascular system. Exercise training can have an important role in the management of hypertension associated with a high-fat diet (Tipton and Barnard 1996). Some reduction of the contemporary RDAs, along with the elimination of hypokinesia, so common nowadays, would be highly desirable. The actual trend for increasing body weight and fatness, for example, in the U.S. population (Kutzmarski et al. 1994, and others), seems to be another reason to consider prevention early in life (Reilly 2008). The effort “to achieve maximal growth potential,” which has too often been identified with achieving maximal body size, is not always the best way to promote health

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and optimal life expectancy (Miklashevskaya 1994, Ross 1964, Ross et al. 1976). As mentioned above, adequate body size, lower adiposity, and a higher level of functional capacity are more desirable, especially with regard to health, longevity, and productivity from all points of view. PA and its role have been especially emphasized more recently in the prevention of obesity, accompanied by comorbidities, starting with early childhood.

3

Nutrition of Pregnant Mothers and Their Children in Early Life: Human Studies

… the mother should be careful not to indulge in excessive sleep, indolence, or torpor, but perform with all agility her usual employment, with all the promptitude, and celerity of which she is capable; for as she then is, such will be the nature of her offspring … —J.A. Comenius (1592–1670), School of Infancy

3.1

VARIABILITY OF PRACTICES DURING PREGNANCY AND LACTATION IN DIFFERENT SOCIETIES

All that happens in the maternal organism during pregnancy can have a decisive impact on the future of the child. Many diseases that cause premature death originate during the fetal and infant period (Barker 1990, 1992). Up to now, it has generally been believed that genetic and possibly pathological factors determine most of the characteristics of the offspring. Less attention was paid to natural factors within physiological conditions, namely diet and physical activity during pregnancy and their influence on the offspring. Experiences from previous historical periods and different societies have importance at present, in spite of the fact that scientific studies could hardly be conducted previously. At present, they cannot be repeated, because of changes in the environment and way of life. In industrially developed countries, it is not easy to spot the delayed consequences of early nutritional and/or other practices because of their great variability and the interference of a number of other factors influencing a child’s development, resulting from various genetic, social, economic, and cultural situations. This had an impact, inter alia, on body composition, amount and distribution of fat, and the functional and metabolic characteristics of the maternal and child organism. In more traditional societies, where conditions were simpler and much more homogeneous for generations, some interesting phenomena were observed, and summarized by Erikson (1950). It would be difficult to repeat such experiences at the present time; this information, however, can focus on selected issues, such as early diet, behavior during pregnancy, weaning practices, handling of the infant, and possible delayed consequences of the infant: for example, the oldest Sioux boy was nursed the longest, with the average nursing period being about 3 years. Today, this 33

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period is much shorter, although instances of prolonged nursing still persist. A teacher reported that an Indian mother had recently come to school during recess to nurse her 8-year-old boy, who had a bad cold. He was nursed with the same worried devotion with which we ply our sniffing children with vitamin pills (Erikson 1950). Among the Sioux, there was no systematic weaning at all. The children were weaned by the mother with the gradual introduction of other foods. Before finally abandoning the breast, the infant may have been fed for many months on other food, allowing time for the mother to give birth to the next child and to restore her milk supply. The privilege of this practically unlimited access to the mother’s breast had some limitations. To be permitted to suckle, the infant had to learn not to bite the breast. The biting child was “thumped,” and he would usually fly into a rage. Sioux mothers used to say what our mothers said much earlier in their babies’ lives: let him cry, it will make him strong. (Crying is also an important exercise for the infant, who is able to move in a very limited way.) Good future hunters could be recognized by the strength of their infantile fury. The Sioux baby, when filled with rage, was strapped up to his neck in the cradleboard. He therefore could not express his rage with the usual violent motion of his limbs. This was not meant to be a punishment. On the contrary, babies are comfortable in the firm, womblike compartments in which they are wrapped, rocked, and bundled for the mother to carry around while working. However, it may be assumed that the construction of the board, its customary placement in the household, and the duration of its use are variable elements used by different cultures as amplifiers of the basic experiences and the principal traits that they develop in their young (Erikson 1950). Generosity and fortitude were the main virtues of Sioux life. First impressions suggest that the cultural demand for generosity had its early foundation in the privilege of enjoying the nourishment and reassurance emanating from unlimited breast-feeding, while the necessity of suppressing the biting rage contributed to the tribe’s ferocity in that this rage was stored, channeled, and diverted toward prey and enemy. Naturally, certain ways of handling the child do not guarantee a definite and fixed predisposition; rather, their early start, reinforced in later development with the continuing support of these characteristics by public opinion, has lasted for generations. However, these traits are presumably anchored in early childhood training. In contrast to the Sioux way of handling babies and the resulting traits of character, Yurok child training was very different. Yuroks are shy, polite, and timid. Many attempts are made to accelerate the autonomy of the child, beginning in utero; the pregnant mother eats little, carries much wood, and preferably does work that forces her to bend forward, so that the fetus “will not rest against her spine,” that is, relax and recline. She rubs her abdomen often, especially when daylight is waning, in order to keep the fetus awake and to forestall an early tendency to regress to the state of prehistory which, as Western culture says, is the origin of all neuroses. The newborn Yurok is not breast-fed for 10 days, but is given a nut soup from a tiny shell. Then, the breast-feeding begins with typical Indian generosity and frequency. However, unlike the Sioux, the Yurok have a definite weaning time of around the

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35

sixth month, that is, around the teething period, a minimal breast-feeding period for American Indians. Weaning is called “forgetting the mother” and, if necessary, is enforced toward the end of the first year by the mother going away for a few days (Erikson 1950). The child’s first solid food is salmon or deer meat well salted with seaweed. Salty foods are the Yurok “sweets.” The child is taught never to grab food in haste, never to take without asking, always to eat slowly, and never to ask for a second helping—an oral puritanism hardly equaled among other tribes. Later, not only does early weaning further require the child to release his mother, the baby’s legs are often uncovered in the Yurok version of the cradleboard and, from the 20th day on, they are massaged by the grandmother to encourage early creeping. The cooperation of the parents in this matter is assured by the fact that they may resume intercourse when the baby makes vigorous strides in creeping. The baby is also kept from sleeping in the late afternoon and early evening, lest dusk close his eyes for the whole night. The first postnatal crisis, therefore, has quite a different quality for the Yurok child than for the little Sioux. It is characterized by proximity during teething, enforced weaning, encouraged creeping, and the mother’s early return to former sexual practices and eventually new children. Yurok children are discouraged, in a number of ways, from feeling comfortable with and around their mothers. The child is trained to be a fisherman, “one who has his nets ready for a prey” that (only if he behaves nicely and says “please”) must come to him. A good Yurok is characterized by the ability to cry while praying, thus gaining influence over the food-sending powers beyond the visible world (Erikson 1950). A number of other observations in the late consequences of the behavior and physical traits of the Sioux and Yurok people were explained by early nutritional and other manipulations. At the present time, it would be difficult to validate this information with experiments using humans in other populations. However, some general conclusions on the profound impact of early manipulations, dietary and behavioral, may be derived. If possible, it would be desirable to verify them with further observations.

3.2 POSITION IN INDUSTRIALLY DEVELOPED COUNTRIES Even under physiological conditions, nutritional events that take place in a woman’s body in industrially developed societies are subject to a wide range of variations. This results not only from dietary intake and nutritional status based on heredity, but also from energy balance and psychological, social, cultural, and other influences due to different and permanently changing environments. Up to now most attention has been focused on nutritional factors. Their qualitative and quantitative assessments have not yet been completed. However, numerous studies were carried out, and some will be mentioned here. The nutritional behavior of the mother, her psychic and emotional status, and many of her habits before and during pregnancy (including the level of physical activity) can affect the final output of this system (Alberti-Fidanza et al. 1995a,b, 1998). This can apply to any population group, even at the present time.

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Due to the influence of environmental and organism-related stressors, pre- and postnatally, the effort to develop long-life “positive health” and to reduce the risk of “diseases of civilization”—mainly cardiovascular and metabolic diseases—has focused on the earliest periods of life. However, long-term studies are rare, which have moreover used longitudinal data from previous follow-ups, mostly aimed at other topics. In this respect, body composition and its relation to health risks (starting with obesity, diabetes, cardiovascular diseases, and orthopedic and psychological problems) have come to the forefront of attention. Studies concerning adult body composition and birth weight, influenced inter alia by dietary intake of the mother during pregnancy, showed an important relationship. Fetal programming of body composition can be revealed as, for example, a relation between birth weight and body composition in older Englishmen. Low birth weight was associated with a higher trunk-tolimb fat ratio [after control for fat mass or its percentage assessed by dual-energy x-ray absorptiometry (DEXA)]. The same BMI predicted a greater percentage of body fat in the low- than in the high-birth-weight group, and the same ratio of trunkto-limb skinfold thickness (or waist–hip ratio) predicted a higher trunk-to-limb fat ratio. These results show that lifelong differences in adult body composition and fat distribution between the low-birth-weight groups are consistent with programming in early life (Kensara et al. 2005). Associations of size at birth and body composition measured by DEXA at 9–10 years of age were found (Rogers et al. 2006). Fetal and early growth and BMI from birth to early adulthood were shown to be related in a longitudinal study of a 1958 British cohort (Parsons et al. 2001). Maternal weight and BMI largely explained the association between birth weight and adult BMI, and it may be a more important risk factor for obesity in children than birth weight. More evidence now exists for programming body composition by early growth and nutrition; it was shown that growth patterns in early life are associated with risk for metabolic syndrome (MS) in adulthood (Wells et al. 2007a). Children born small-for-gestational age (SGA) remain significantly shorter than children born large-for-gestational age (LGA) and do not seem to catch up until 36–83 months. LGA children may be prone to greater accumulation of fat in early childhood (Hediger et al. 1999). A higher ponderal index at birth is associated with both higher fat and lean mass development as measured by DEXA in 9–10-year-old children (Rogers et al. 2006). A longitudinal study revealed associations between birth weight and height in both genders, and a fat-free mass (FFM)/height ratio in boys (Chomtho et al. 2008). Parental eating attitudes involving high levels of disinhibited eating, especially when coupled with high dietary restraint, may foster the development of excess fat in children (Hood et al. 2000), which may be mediated by direct parental role modeling of unhealthy eating behaviors or through other indirect, probably unconscious, behavioral consequences such as suppression of the child’s innate regulation of food intake. An increased intake of protein early in life has been more recently considered as a factor that enhances the risk of later obesity (Rolland-Cachera et al. 1995; see Chapter 4), which can also be related to breast-feeding. Therefore, it is recommended

Nutrition of Pregnant Mothers and Their Children in Early Life

37

that we gain information on these risk factors as early as possible and introduce measures to rectify the situation.

3.3 INFLUENCE OF GENETIC FACTORS ON GROWTH AND HEALTH RISKS IN THE OFFSPRING Numerous studies estimated the genetic correlations between growth parameters and adult health outcomes. Heritability estimates for growth parameters (serial stature data, i.e., birth through adulthood, Fels longitudinal study) usually achieve magnitudes ranging from 0.65 to 0.98, and heritability estimates for adult health outcomes are also statistically significant ranging from 0.32 to 0.98. The results of phenotypic correlation analysis show that stature growth parameters are significantly related to body weight, BMI (see Chapter 4), body composition, skeletal muscle mass, bone mass, and systolic and diastolic blood pressure. Genetic correlation analysis gives evidence of common genetic pathways underlying selected aspects of growth and adult health outcomes, including body composition and blood pressure (Czerwinski et al. 2007). The study contributed to understanding the genetic influences on growth rate in nutritionally stable populations, including consequences of BMI centile crossings (Demerath et al. 2004, 2007; see Chapter 4), indicating the importance of the effect of the interplay of genetic and environmental factors in early life. A twin birthcohort study (Quebec Newborn Twin study, QNTS) showed that genetic factors accounted for 40% of birth-weight variance, and intrauterine environment influence explained almost half (Dubois et al. 2007). The Viva la Familia Study also provided evidence of strong genetic contribution to the high prevalence of obesity and related comorbidities in Hispanic children in the United States (Butte et al. 2006). The results of the study of Swedish young male twins suggested persistent genetic regulation of BMI from age 1 to 18 years. Environmental factors, which were not shared by siblings, also affected correlations of BMI. A small correlation was found between ponderal index (which also expresses the relationship between weight and length, or height, as BMI) at birth and BMI at age 18, which may reflect the effect of neonatal environmental factors on adult BMI (Silventoinen et al. 2007). Further research should identify chromosome regions and specific genes influencing the development of BMI along with environmental factors affecting BMI through the growth period independently, or interacting with genetic factors. The long-term observation of monozygotic twins who shared their genetic background showed that the initially larger twin tends to remain larger, revealing the long-lasting effect of fetal environment on final body size in early adulthood (Pietilainen et al. 2002). A longitudinal genetic study of height and weight in Dutch twins showed that for weight at 2 years of age, heritability was approximately 58% for both genders, and there were similar values for height (van Dommelen et al. 2004). Genetic factors can influence fat mass and BMI independently, as shown in a pediatric twin sample by Faith et al. (1999). Many studies have examined blood lipid levels in neonates and infants in relation to the blood lipid levels of their parents (e.g., the Bogalusa heart study; Croft et al. 1988), thus screening possible familial hypercholesterolemia (Blade et al. 1988). Children of parents with high levels of beta and/or prebeta cholesterol, caused by any factor, were

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Nutrition, Physical Activity, and Health in Early Life

considered as individuals with an enhanced risk of cardiovascular diseases because they reflect their parents’ lipoprotein cholesterol levels (Croft et al. 1988). Studies of cross-trait familial resemblance for body fat with plasma glucose, insulin, blood pressure, etc. (Quebec Family Study—Rice et al. 1995, 1996, 1997; The Heritage Family Study—An et al. 2000) did not show significant polygenic and/ or common familial environmental effects. But a significant parent–child correlation for various indices of adiposity in an endogamous Indian population of 11–17-yearold children in Punjab was shown (Sinha and Kapoor 2006). When energy homeostasis was followed in infants aged 3 months, those who later became obese had an energy output 20% lower than the other infants who maintained normal body weight. There is the question of whether later obesity was the consequence of low energy output early in life, or whether there were some genetic traits conditioning both these phenomena. Genetic predisposition for developing obesity has also been previously identified in humans (Bouchard and Johnston 1988, 1994; see Chapter 8). Thus, genetic endowment may be demonstrated very early in life. Blood lipid values at the beginning of life may predict the later development of atherosclerosis (Newman et al. 1986). Children who have a high serum level of cholesterol at birth have elevated values even at the age of 3 years (Vobecky and Vobecky 1982, 1988). The interaction of genetic factors, dietary habits and nutrient intake, and other lifestyle-associated factors were scrutinized from early childhood in longitudinal studies (Vobecky et al. 1993), and the importance of early intervention was stressed. An increased intake of protein early in life has been recently considered as a factor that enhances the risk for later obesity (Rolland-Cachera et al. 1995). Therefore, it is recommended that we gain information on all possible risk factors, which indicate, however, a complicated interplay among numerous factors during longer-lasting developmental periods over time.

3.4 IMPACT OF MATERNAL STATUS ON OFFSPRING Even during completely normal, physiological pregnancies, a great variability in anthropometric, nutritional, metabolic, and biochemical characteristics has always been demonstrated in mothers (Dolezal and Gutwirt 1975), including their lifestyle. There is a significant relationship between birth weight and maternal lipoprotein, fuels, hormones, and body weight at 36 weeks of gestation in normal healthy women, as reported by Knopp et al. (1985).

3.4.1

INFLUENCE OF MOTHER’S NUTRITIONAL STATUS AND BIRTH WEIGHT

Many of the above-mentioned variables (i.e., body weight, fatness, etc.) are influenced significantly by dietary intake and energy balance. The impact of malnutrition and supplementation has been defined in a number of studies (Lechtig and Klein 1981, King et al. 1987, Rush et al. 1988). Thus, supplemented African women gained more weight and body fat during pregnancy and gave birth to heavier children (Lawrence and Lawrence 1991). The impact of increased food intake was most evident, however, when compensating for previous malnutrition or starvation.

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39

Nutritional influences under conditions in which most mothers in developed countries live, with an energy margin large enough to ensure the needs of the fetus and/ or the maternal organism, are less clear and may seem less important. Such influences depend on a number of additional factors, especially the initial, pregestational nutritional status (characterized by body composition, biochemical parameters in the blood and tissues, and so forth). In developed countries, women with adequate nutritional status who gain too much fat during pregnancy may still not have bigger children; surplus energy normally results in ample fat deposition in the mother (Lawrence et al. 1991). An increased food intake during pregnancy (i.e., the proverbial “eating for two”) with the intention of providing enough nutrition for mother and fetus has not always been advocated by a number of experts (e.g., Pitkin 1981, Widdowson 1981). However, it is very difficult to define such a dietary intake and a proper energy balance, especially when considering the energy output of the mother, due mainly to her physical activity. Maternal BMI and child birth weight are predictors of the child’s BMI z-scores; both together produced a better model than either alone (Watkins et al. 2007). It was also shown that in an industrialized country the mother’s dietary intake may correlate very weakly with the birth weight of the child, or there is no relationship at all (Lawrence et al. 1991), and women who gain more fat may not have heavier babies. Such a relationship between the dietary intake of the mother and birth weight, as well as body composition of the full-term child, may obviously appear only when extreme differences exist, that is, when comparing malnutrition and deficient intake, on the one hand, and excessive dietary intake of the mother who is eventually obese, on the other. Additional factors should be considered too, for example, energy output, energy balance, etc. In other studies it was shown that mothers with higher prepregnant BMI or upper mid-arm circumference during pregnancy tended to have children with greater adiposity at 9 years of age (Gale et al. 2007). Shapiro et al. (2000) showed that obese women (BMI > 25) gained the least weight and had babies with higher birth weights. An increased concern of mothers about overfeeding or becoming overweight was associated with higher fatness at 5 years, and explained some of the associations between maternal obesity and child adiposity (Burdette et al. 2006). In line with that, laymen press and television (TV) programs advise pregnant women to cut out junk food for their children’s sake because, in fact, obesity may begin in the womb.

3.4.2

EFFECT OF BREAST-FEEDING

Infant weight gain is associated with maternal prepregnant BMI and with the interaction between duration of breast-feeding and timing of complementary food introduction (Baker et al. 2004). Women who are overweight or obese before pregnancy breast-feed for a shorter duration than normal women. Inconsistent associations were found among breast-feeding, its duration, and the risk of being overweight in young children (Hediger et al. 2001). Despite a slower growth rate, the adult

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Nutrition, Physical Activity, and Health in Early Life

heights, weights, and BMIs of breast-fed and bottle-fed Israeli infants did not differ (Zadik et al. 2003). Another study showed that neither breast-feeding nor the timing of the introduction of complementary foods was associated with adiposity at the age of 5 years (Burdette et al. 2006a,b). Within the range of usual dietary intake, even if it is wide, it is practically impossible to find significant relationships between actual food intake and weight. This applies not only to mothers during pregnancy but also to all individuals during postnatal ontogeny, in all age categories, including children (RollandCachera et al. 1990). Maternal BMI SD correlated with offspring BMI SD at the age of 18 years. The effect of prolonged and exclusive breast-feeding did not reduce the measures of adiposity, increase stature, or reduce blood pressure at the age of 6.5 years (Kramer and Kukuma 2004, Kramer et al. 2007). Acceleration of growth may occur in the first few months, which supports current WHO and UNICEF recommendations for breast-feeding (Krammer et al. 2002). Another study showed leaner breast-fed infants than formula-fed infants at 1 year of age (Darling Study; Dewey et al. 1993). Formula-fed infants had higher plasma levels of insulin-like growth factor-1 (IGF-1), insulin, and certain amino acids than breast-fed children. The protein intake of breast-fed infants decreases with age, matching the recommendations during early periods of growth, and the protein intake of formula-fed infants exceeds them after the first 1–2 months of life. These results (Ziegler 2006) are consistent with the hypothesis that differences in protein intake are mainly responsible for differences in growth between breast-fed and formula-fed infants. Differences in energy intake (EI) are probably responsible for differences in adiposity during later growth. However, breast-fed infants were shown to be capable of adaptation and normal growth, despite the variability in nutrient intake (Mutil et al. 1997). The benefit of relative undernutrition and slower growth associated with breast-feeding rather than formula feeding—the growth acceleration hypothesis— has been considered as related to later reduced obesity development (Singhal et al. 2003, Singhal 2007). This is also consistent with the findings in experimental models with laboratory animals (see Chapter 2; Parˇ ízková 1977, Parˇ ízková and Petrásek 1979). A systematic review of studies concerning the optimal duration of exclusive breast-feeding results in a recommendation of 6 months in both developed and developing countries considering all possible benefits from the points of view of somatic, mental, and health development (Kramer and Kakuma 2004, Toschke et al. 2007). The protective effect of breast-feeding with regard to fat development was found to be attenuated after adjustment for confounders (e.g., duration of breast-feeding, trunk fat mass), which indicated that confounding may explain this association. Breastfeeding may protect against obesity if maintained for more than 6 months (Toschke et al. 2007). The reviews on breast-feeding concluded that its duration is associated with a reduced risk of many diseases in infants and mothers from developed countries. Observational studies did not, however, infer causality (Ip et al. 2007), and further studies and analysis on a larger number of factors are needed. The children of mothers who breast-fed their children for a longer period showed less restrictive behavior regarding their feeding at the age of 1 year (Taveras et al. 2004).

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41

The increased concern of mothers about an infant over-eating or becoming overweight was associated with higher fatness at 5 years, and explained some of the associations between maternal obesity and child adiposity (Burdette et al. 2006b). Programming of body composition by early growth and dietary intake was considered on the basis of more studies. Fast growth and higher weight gains, due to a number of reasons (e.g., mothers’ weight and weight gain during pregnancy, duration of breast-feeding, introduction of higher protein intake during early life, birth weight, fat distribution, etc.), were considered inter alia as health risks for later life, for example, obesity, MS, etc. (Wells et al. 2007a). This was followed up in both animal (Symonds and Gardner 2006, Parˇ ízková 1996, Bellinger and Langley-Evans 2005) and human studies. Special concerns on the development of hypertension later in life in subjects whose babies were small in relation to their placenta (Barker 1990, 1992, 1994). When the effect of breast-feeding is discussed on the basis of different studies, it is difficult to eliminate the following effect and interplay of numerous additive factors during subsequent periods of children’s growth, which are obviously not the same in different studies. Breast-feeding is recommended, but may not always be as influential as dietary and physical activity habits later on in the family, when predisposition for obesity is considered. An important finding concerned the effect of increased physical activity: the consequences of early diet, that is, weaning of rats in nests of different sizes (4 or 22 rats), which results in higher caudal blood pressure, higher insulin level, increased body weight, and fatness in animals overfed during this period, could be reduced by regular exercise until the age of 38 weeks (Tipton et al. 1978).

3.4.3

EFFECT OF EARLY POSTNATAL NUTRITION ON LATER DEVELOPMENT

The effect of early nutrition during initial periods of postnatal development was considered not only from the point of view of the duration of breast-feeding, but also from other points of view—especially with regard to the composition of complementary food, namely the amount of protein. As shown by the studies of Gunther et al. (2007a,b), high protein intakes during the complementary feeding of infants and the transition to family diet are associated with an unfavorable body composition development. The protein source is important—dairy protein intake at 12 months from a higher animal may be positively associated with later body fatness at the age of 7 years. A special study has been developed for the evaluation of protein intake in the first year of life and its effect on later obesity development (The European Childhood Obesity Programme; Koletzko et al. 2005, Toschke et al. 2005). A vigorous feeding style in infants, that is sucking more rapidly, at higher pressure, with longer suck and burst duration, and shorter intervals between bursts of sucking, is associated with higher caloric intake and greater adiposity. The early manifestation of this feeding style suggests that it may be a genetically endowed behavior (Agras et al. 1987). As mentioned above, the effect of breast-feeding was also considered with regard to various protein intakes and EIs, and their effect on speed of growth and size of weight increments at the beginning of life (Heinig et al. 1993).

42

Nutrition, Physical Activity, and Health in Early Life

Fast growth during this period is presently regarded as a possible risk for easier development of overweight and obesity later on in life. According to Rolland-Cachera et al. (1995), the higher protein intake at 2 years in her observations of French children was associated with earlier adiposity rebound (AR, i.e., earlier increase of BMI than the usual 5–6 years; see Chapter 4) and higher increase of BMI at the age of 8 years. General comparisons concerning inter alia the duration of breast-feeding and obesity prevalence in Czech children (Parˇ ízková and Rolland-Cachera 1997) corresponded to the conclusions of Rolland-Cachera et al. (1995). Lower protein intake in breast-fed than in formula-fed children (Heinig et al. 1993) might be related to the protective effect of breast-feeding against later excess fat deposition and obesity, as shown in U.S. children already at 1 year of age (Darling Study; Dewey et al. 1993). Reduction of obesity due to breast-feeding was confirmed, for example, in a cross-sectional study conducted in 9377 children 5–6 years old (Von Kries et al. 1999). A higher protein intake at the age of 1 year was shown in 5-year-old obese Italian children, compared to their normal-weight counterparts (Scaglioni et al. 2000). Other studies have not confirmed this observation (Vobecky et al. 1983); however, the positive effect of breast-feeding has been considered from numerous points of view—not only from growth, nutritional, and health status, but also from psychological, cognitive, and emotional aspects (Kramer et al. 2008). Evidence on the special effect of increased protein intake at the beginning of life has been less consistent, and a more complicated interplay of additional factors along later development obviously has an important role in obesity and other health risks. Special observations were conducted in a group of preterm born infants followed until 7 years of age, and no association between protein intake early in life and degree of adiposity was found: predominantly breast-fed and formula-fed children did not differ in body composition (Hainer et al. 1999). These subjects, born at 34 weeks (28 girls) and either predominantly breast-fed or formula-fed, did not differ in age, birth weight and length, and BMI, and were followed longitudinally until 10 years of age. Anthropometric parameters, body composition, and fasting blood samples of leptin and IGF-1 were also examined at the age of 10 years (Hainer et al. 2004). Statistical analysis of data revealed significant differences in energy and nutrient intake early in life, and a trend for higher values of anthropometric parameters and serum leptin level in predominantly formula-fed children at the age of 10 years was found. Only the IGF-1 level exhibited a significantly higher level in this group. The results of correlation analysis in our groups concerning relationships between postnatal energy and nutrient intake, anthropometric parameters and hormonal levels as well as parental BMI did not show any correlation between BMI at birth and maternal BMI. Paternal BMI was significantly related to fat mass and all the anthropometric parameters, as well as to serum leptin levels at the age of 10 years of these girls. Postnatal intake of carbohydrates and fats significantly correlated at the age of 10 years with leptin and IGF-1 level, and with all the determined anthropometric parameters except for height, BMI, and fat mass. Correlation between postnatal intake of fat and waist circumference at 10 years was significant (r = 0.502, p < 0.007). In contrast to significant correlation of postnatal intake of

Nutrition of Pregnant Mothers and Their Children in Early Life

43

protein with IGF-1 level at 10 years (r = 0.518, p = 0.005), no such significant correlation was revealed with leptin level. Early postnatal intake of protein did not correlate with the percentage and absolute amount of fat (DEXA) and serum leptin level at the age of 10 years. Both Parson’s analysis and factor analysis revealed significant association of paternal BMI with BMI, height, fat mass, sagittal diameter, and all the calculated circumferences of girls at 10 years of age (Hainer et al. 2004). Protein intake during the first postnatal month of life significantly correlated with IGF-1 level at 10 years, and according to multiple regression analysis remained the single significant predictor for IGF-1 level at 10 years (r = 0.519, p = 0.0047). Factor analysis also revealed IGF-1 as a single link between early postnatal energy and macronutrient intake and anthropometric parameters at 10 years. We speculate that an early postnatal diet encodes IGF-1 level in later life and is thus involved in programming body size (Hainer et al. 2004). Former observations showed significant correlation, that is, the plasma IGF-1 level correlates in humans with body size, and tall children have higher levels of IGF-1 (Gourmelen et al. 1984). IGF-1 level is regulated by protein intake (Keteslegers et al. 1995). Both IGF-1 and insulin are required for the differentiation of adipocytes and adipogenesis (Sorisky 1999). RollandCachera et al. (1995) explains the adipogenetic effects of high protein by the proteininduced increase of IGF-1 level. Appropriate IGF-1 levels play an important role not only in body size development but also in insulin sensitivity, as IGF-1 deficiency is associated with hyperinsulinemia and insulin resistance. The results of this study, which differed in initial design, age of subjects, etc., from other studies (e.g., Rolland-Cachera 1995), did not confirm the effect of early protein intake on later somatic and body composition development, similar to some other studies (Hoppe 2004). However, the role of IGF-1 as a link between early postnatal energy and macronutrient intake and anthropometric parameters and serum leptin level at 10 years of age was revealed (Hainer et al. 2004, Zamrazilová et al. 2007).

3.4.4 INFLUENCE OF PHYSICAL ACTIVITY AND EXERCISE OF MOTHERS The impact of increased energy output through hard physical work and/or athletic activities during pregnancy was also considered (Sady and Carpenter 1989). Pregnant women who continued, for example, in endurance exercise gave birth to children with significantly lower birth weights, lower ponderal indexes, smaller fetoplacental weight ratios, and lower skinfold thicknesses. However, crown–heel lengths and head circumferences were not influenced (Clapp and Capekess 1990). Later consequences in the offspring were not followed, and other parameters were not investigated (e.g., blood lipids, body composition, etc.); measurements of the above-mentioned anthropometric characteristics in older age of the offspring were also not reported. It is necessary to consider that mothers who exercise or train in some sports are mostly women who are genetically predisposed in skill and endurance, that is, there is a strong participation of genetic factors and heredity. It would hardly be possible to conduct a longitudinal study on the separate effect of only exercise during pregnancy in sufficiently numerous and homogeneous groups from all other points of view

44

Nutrition, Physical Activity, and Health in Early Life

(genetic factors, nutrition, health status, etc.). Important data from long-term studies on exercise effects in the adult offspring, which could give some indication, were therefore gained mainly from animal studies. It would be interesting to know whether some functional parameters of the human offspring could be modified by the workload of the mother during pregnancy, when considering all metabolic, biochemical, circulatory, neurohumoral, and hormonal changes during regular and sufficiently intensive, but adequate, workload, and possible long-term, adaptational consequences. Some results on this effect were gained in laboratory animals, as mentioned in Chapter 2, not only in rats but also in sheep, etc. (Arshavski 1967). In this connection, we have in mind not only later development of the functional capacity of the offspring, but also lipid metabolism, morbidity, and mortality from metabolic, cardiovascular, and other diseases in individuals with identical genetic and hereditary backgrounds and social and economic conditions, but with a different dietary and physical activity regimen at the very beginning of life. Animal studies can only give some incentives, as human studies would be too difficult to conduct. The same question arose regarding the delayed consequences of a restricted dietary intake of a mother during pregnancy and lactation (marginal malnutrition), and there is a theoretical possibility of a similar situation with regard to the impact of simultaneous marked workload. But such long-term studies are too demanding and too difficult to interpret, mainly due to the interference of additional economic, social, nutritional, and psychological factors that occur simultaneously in groups of pregnant women who have to work hard during their pregnancy. To our knowledge, there are no such data available in the literature. Only the sad, practical experiences of the effect of serious malnutrition and excessive workload during pregnancy, mainly in some developing countries, are known at present.

3.5

RELATIONSHIPS AMONG ANTHROPOMETRIC, DIETARY, AND SERUM LIPID VARIABLES OF THE MOTHER AND THE NEWBORN

A longitudinal complex study, showing how selected nutritional variables of the mother during pregnancy are related to similar variables in the newborn, was conducted; attention was focused on selected indicators that have also been assumed to be possible markers of some pathological conditions, that is, the fat pattern. Seventy Italian women were followed up longitudinally during the first, second, and third trimesters of pregnancy (Alberti-Fidanza et al. 1995a,b, 1998). The average ages of the mothers at the beginning of pregnancy were 26.3 ± 4.6 years, their heights were 160.5 ± 5.9 cm, the average weights at the time were 57.6 ± 9.2 kg, and the BMIs were 22.5 ± 3.8. These characteristics did not differ significantly from the characteristics of women in other populations. Anthropometric variables and blood lipid levels of the newborns were assessed after birth. The mothers were mostly sedentary, with a generally low level of physical activity and a light workload. Only women with more than one child displayed a slightly higher activity level than primipara.

45

Nutrition of Pregnant Mothers and Their Children in Early Life

Significant variations from the first trimester to 5 days postpartum for abdomen, thigh, and calf circumferences, body weight, and BMI were shown by ANOVA analysis in the survey by Alberti et al. (1995b). The arm circumference did not change. The thickness of seven skinfolds was assessed, and the suprailiac and thigh skinfolds, as well as the sum of all skinfolds, increased significantly from the first to the third trimesters. After delivery, they decreased again. The changes were similar to those in other studies (Taggart et al. 1967). The indices of fat distribution also varied significantly (Table 3.1). Hand grip strength did not vary during pregnancy, decreasing slightly after delivery (Alberti et al. 1995b). Food intake analysis revealed a low intake of milk, cheese, fish, eggs, and legumes with an increased intake of meat. There were no significant differences regarding dietary intake during pregnancy except for a significant increase in carbohydrate intake between the second and third trimesters (Table 3.2). The highest food intake was observed during the second trimester, but the differences between trimesters did not differ significantly. The energy content and composition of the diet did not differ significantly from the diets of pregnant women in other industrially developed

TABLE 3.1 Changes of Anthropometric Variables during Various Trimesters of Pregnancy and 5 Days Postpartum 1st Trimester Weight (kg) BMI (kg/m2) Circumference Thigh (cm) Abdomen (cm) Skinfolds Suprailiac (mm) Thigh (mm) Sum of 7 (mm) Indices 1 2 3 4 5

x–

2nd SD

x–

59.1 23.0

10.1 4.0

55.0 86.0 12.2 30.8 114.6 0.96 0.63 1.26 0.38 0.67

3rd

5 Days pp

SD

x–

SD

x–

SD

65.6 25.6

10.1 3.9

71.2 27.7

9.9 3.8

64.8 25.2

9.4 3.6

4.9 11.6

57.0 96.3

4.6 9.2

57.8 104.3

4.6 7.7

54.6 95.6

10.8 8.8

6.6 7.0 35.5

18.1 35.1 133.2

6.1 6.0 31.3

18.0 37.0 135.0

6.3 6.7 30.0

15.2 35.4 125.7

5.9 6.5 30.7

0.36 0.21 0.42 0.13 0.21

1.00 0.66 1.31 0.45 0.80

0.33 0.19 0.38 0.11 0.20

1.02 0.68 1.37 0.44 0.81

0.35 0.23 0.46 0.12 0.22

1.05 0.69 1.39 0.42 0.77

0.35 0.22 0.43 0.12 0.21

Sources: Adapted from Alberti-Fidanza, A. et al., Eur. J. Clin. Nutr., 49, 289, 1995b; Acta Med. Auxol., 30, 19, 1998. Note: pp, post partum; SD, standard deviation. Index 1, subscapular/triceps; index 2, subscapular/ triceps + biceps; index 3, subscapular/(triceps + biceps) ¥ 0.5; index 4, subscapular + suprailiac/ triceps + biceps + thigh + calf; index 5, subscapular + suprailiac/triceps + biceps + thigh.

46

Nutrition, Physical Activity, and Health in Early Life

TABLE 3.2 Dietary Intake of the Macrocomponents of the Diet of Mothers Before (0) and at Different Trimesters of Pregnancy Ranging from 1 to 3 (Intake of Individual Nutrients Expressed as a Percentage of Total EI) and of Cholesterol 0

Energy (MJ) Protein (%) Fat (%) CHO (%) Chol (mg)

1

2

3

x–

SD

x–

SD

x–

SD

x–

SD

9.0 16.0 34.4 47.5 287

2.6 2.3 4.8 6.7 111

8.9 15.9 33.8 47.6 275

3.0 3.4 4.5 5.4 138

9.5 15.8 33.7 47.0 280

2.4 2.5 5.0 6.4 139

9.0 16.3 35.2 45.1 265

2.4 2.7 5.3 7.1 98

Sources: Compiled from Alberti-Fidanza, A. et al., Eur. J. Clin. Nutr., 49, 289, 1995b; Acta Med. Auxol., 30, 19, 1998. Note: CHO, carbohydrates; Chol, total cholesterol.

countries (Pitkin 1981). The paired t-test showed significant differences for the relative intake of protein, fat, and polyunsaturated fatty acids between the second and third trimesters. Blood lipids during pregnancy also increased significantly; the most relevant changes were observed for total TGs and total cholesterol (AlberiFidanza et al. 1995b). Anthropometric variables and blood lipids of the newborn are given in Table 3.3. After 24 h the usual decrease in body weight and BMI was observed. Cord blood lipids did not differ significantly in newborn boys and girls, but indices 1 and 3 were different. Significant correlations were found most often in mothers for BMI, sum of seven skinfolds, and indices 4 and 5, which were present in all trimesters. No relationship between anthropometric variables and blood lipids was found in the mothers in any trimester of their pregnancy. Anthropometric variables of the mother during pregnancy were also correlated with her dietary intake. Very few significant relationships were found between the percentage of energy from protein and anthropometric variables. The percentage of energy from fat was significantly related to the characteristics of body composition and fat distribution (sum of skinfolds at the first trimester, indices 4 and 5 during the first and third trimesters, and BMI during the third trimester). Similar correlations with the percentage of energy from carbohydrates were significantly negative. No significant correlation between anthropometric variables and absolute intake of energy and protein, fat, and carbohydrates during various trimesters of pregnancy was found (Alberti-Fidanza et al. 1986, 1995b). Maternal blood lipids, that is, total cholesterol and TGs, were most often related to total EI and/or the percentage of energy derived from individual nutrients during various trimesters. During the first trimester, significant correlations were found

47

Nutrition of Pregnant Mothers and Their Children in Early Life

TABLE 3.3 Birth Weight and Cord Blood Lipids of Boys (n = 23) and Girls (n = 19) Boys

Age (weeks) Birth weight (g) TChol (mmol/L) HDL (mmol/L) HDL/T (Chol) TG (mmol/L) Index 1 Index 2 Index 3

x– 39.5 3223 1.74 0.85 0.50 0.46 0.8 0.5 0.9

Girls SD

x–

SD

1.6 455 0.64 0.30 0.10 0.33 0.1 0.1 0.1

40.0 3274 1.70 0.72 0.4 0.64 1.0 0.5 1.1

1.3 398 0.3 0.11 0.1 0.22 0.1 0.1 0.1

Sources: Modified from Alberti-Fidanza, A. et al., Eur. J. Clin. Nutr., 49, 289, 1995b; Acta Med. Auxol., 30, 19, 1998. Note: TChol, total cholesterol; HDL/T, total high-density lipoproteins; Chol, cholesterol; TG, triacylglycerols. Index 1, subscapular/ triceps; index 2, subscapular/triceps+biceps; index 3, subscapular/ (triceps + biceps ¥ 0.5).

between total EI and total cholesterol (a negative correlation). A positive correlation was found between the energy from protein and TGs. During the second trimester, TGs were correlated negatively with the percentage of energy from fat and polyunsaturated fatty acid (PUFA), and positively with the energy from carbohydrate. During the third trimester, TGs were correlated negatively with energy from PUFA, and with the P/S ratio (polyunsaturated/saturated fatty acid). This ratio correlated positively with total cholesterol. High-density lipoprotein (HDL) cholesterol correlated negatively with the percentage of energy from carbohydrates (Alberti-Fidanza et al. 1995). In newborns, only a significant relationship between TGs and index 2 of fat distribution (r = 0.4027, p = 0.0414) was found. Regarding the relationships between variables of the pregnant mother and those of the newborn, a significant relationship between birth weight and maternal weight during the first, second, and third trimesters was found only in boys. The mother’s BMI during the first and second trimesters correlated with the birth weight of boys. Individual skinfolds of the mother correlated in different trimesters with similar variables of the newborn. Mother–son correlations were more frequent than mother– daughter correlations (Alberti-Fidanza et al. 1995, 1998). Maternal subcutaneous fat distribution, as characterized by indices (Table 3.4), correlated significantly in only a few cases in the group of all newborns. Significant correlations were found most often for the fat distribution of the mother during the

48

Nutrition, Physical Activity, and Health in Early Life

TABLE 3.4 Relationships between the Indices of Subcutaneous Fat Distribution of Mothers during Different Trimesters of Pregnancy and Similar Indices in Newborns (Evaluated Always for the Maximum Number of Pairs) Newborns (All) Mothers

Trimester

Index 1 1st 2nd

3rd

Index 2

r

p

Index 2 0.30 Index 1 0.32 Index 2 0.33 Index 1 0.37 Index 2 0.42 —

Index 2 0.050 Index 1 0.037 Index 2 0.032 Index 1 0.016 Index 2 0.006 —

1st

—

—

2nd

3rd

Index 4

Index 1 0.31 Index 2 0.37 —

Index 1 0.043 Index 2 0.018 —

2nd

3rd

Index 2 0.31 0.046

Index 2 0.046

Boys

Girls

r

p

— Index 1 0.71 Index 2 0.58 Index 1 0.73 Index 2 0.62 Index 1 0.50 Index 2 0.44 Index 1 0.70 Index 2 0.61 Index 1 0.73 Index 2 0.64 Index 1 0.52 Index 2 0.47 Index 1 0.42 Index 2 0.44

— Index 1 0.0001 Index 2 0.0039 Index 1 0.0001 Index 2 0.0039 Index 1 0.0148 Index 2 0.0334 Index 1 0.0002 Index 2 0.0018 Index 1 0.0001 Index 2 0.0013 Index 1 0.0103 Index 2 0.0236 Index 1 0.0503 Index 2 0.0401

r

p — — — — — — — — — — — — — — —

Sources: Adapted from Alberti-Fidanza, A. et al., Eur. J. Clin. Nutr., 49, 289, 1995b; Acta Med. Auxol., 30, 19, 1998.

Nutrition of Pregnant Mothers and Their Children in Early Life

49

second and third trimesters of pregnancy and that of their newborn sons. No significant correlations were found for girls. Some relationships exist between weight gain during pregnancy (calculated in absolute values and as a percentage of the prepregnant value) and anthropometric variables in the newborn. Negative correlations were found between maternal weight gain and biceps and triceps skinfolds and BMIs of their sons. Positive correlations were found between maternal weight gain and birth weight, subscapular skinfold, and BMIs of their daughters. Similar correlations were also found for mothers and preschool children (see below). In relationships between prepregnant body weight and anthropometric variables at birth, significant correlations with body weight (r = 0.5943, p = 0.022) and recumbent length (r = 0.5675, p = 0.038) were found only in boys. Anthropometric variables in boys were generally correlated negatively with the absolute nutrient intake of their mothers, while the correlation coefficients for girls were mostly positive (Alberti-Fidanza et al. 1995b, 1998). Some correlations between the relative intake of nutrients (percentage of EI) of the mother and a combined group of newborns were, however, found; the correlations were mostly frequent between the maternal dietary intake during the second and third trimesters of pregnancy and the anthropometric variables of boys. Correlations were usually positive for protein and fat and negative for carbohydrate. Significant correlations for girls were rare (Alberti-Fidanza et al. 1995b, 1998). Maternal diet was also significantly related to cord blood lipids. Most relationships were established for carbohydrate intake, total cholesterol, and HDL-cholesterol, which were significantly negative in the group of boys and then in the combined group of all newborns, while no significant correlations were found in newborn girls (Alberti-Fidanza et al. 1995b). A significantly negative correlation between the mother’s EI and total cholesterol in boys was revealed. The same was established between energy from carbohydrate and HDL-cholesterol. The percentage of energy from protein was positively correlated with total cholesterol in boys (Table 3.5). The energy from fat and carbohydrate correlated with HDL-cholesterol in newborn boys, positively for fat and negatively for carbohydrate (Alberti-Fidanza et al. 1995b, 1998). Very few relationships were found between maternal and neonatal blood lipids. Maternal TGs correlated negatively with cord blood HDL-cholesterol, and total maternal cholesterol and HDL-cholesterol were correlated in the combined group of newborn boys and girls and/or only in girls, that is, total maternal cholesterol level and HDL-cholesterol correlated positively with TGs and with HDL-cholesterol/total cholesterol ratios in girls only. It would be difficult, on the basis of existing data, to explain the sex-linked relationships and their different characteristics in boys and girls. These peculiarities may be related to the effect of sex hormones from the earliest periods of life. As described before, sex-linked differences in subcutaneous fat amount and distribution are already apparent at birth; the suprailiac skinfold is significantly larger in girls (Parˇ ízková 1963, 1977). In this study, sex-linked differences were observed for indices 1–3 (Table 3.3).

50

Nutrition, Physical Activity, and Health in Early Life

TABLE 3.5 Relationships between Daily Energy and Nutrient Intake (as % of Energy) of Mothers during Different Trimesters of Pregnancy and Cord Blood Lipids (Only Significant Values Are Given) Newborns (All) Maternal Diet Energy Proteins (% of energy) Fat

Trimester

r TChol

p TChol

r TChol

1st 2nd

−0.44 −0.48

0.023 0.011

−0.56 −0.56

p TChol −0.56 −0.56

r

p

— —

— —

1st

0.43

0.024

0.53

0.027

—

—

0.51

0.006

0.51

0.036

—

—

1st 2nd

(% of energy)

Girls

2nd

(% of energy)

CHO

Boys

—

—

—

—

−0.75

HDL

HDL

HDL

HDL

—

0.44

0.020

0.63

0.017 —

0.007

3rd

0.55

0.003

0.78

0.0002

—

—

2nd

−0.46

0.015

−0.52

0.0323

—

—

3rd

−0.59

0.001

—

—

—

—

−0.74

0.0007

TChol

TChol

−0.49

0.048

Sources: Adapted from Alberti-Fidanza, A. et al., Eur. J. Clin. Nutr., 49, 289, 1995b; Acta Med. Auxol., 30, 19, 1998. Note: CHO, carbohydrates.

Our results on the different relationships between mothers and newborn boys and girls may also be influenced by the different number of males and females in our study. However, this does not seem to be the case: when comparing the values of correlation coefficients for all and/or just male newborns, in most instances we found higher r values for males alone than for the combined group of males and females. Studies by Kesteloot and Dodion-Fransen (1975), Vobecky and Vobecky (1982), and Vobecky et al. (1988, 1993) found similar relationships of blood lipids in larger groups of newborns. The correlation coefficients found in these studies were also low, that is, for total cholesterol of the mother and that in cord blood (r = 0.30 measured in 556 pairs of mothers and newborns). Therefore, there surely exists a weak, nevertheless significant, relationship. Relationships between maternal anthropometric variables, including fat distribution, were also found in another study of preschool children 2–5 years old. Again, there were significant relationships between the skinfolds of mothers and their children (chin, thigh, calf), which were significant for boys, with only one exception for thigh skinfolds in girls. The relationships between the indices of the fat pattern were again significant for mothers and their sons only (Table 3.6; Parˇ ízková 1995).

51

Nutrition of Pregnant Mothers and Their Children in Early Life

TABLE 3.6 Relationships between Anthropometric Variables and Indices of Fat Distribution of Mothers and Preschool Children (2–5 Years of Age)

Height Sitting height Biacromial breadth Thigh circumference BMI Fat pattern index 1 Fat pattern index 2

Boys + Girls (n = 73)

Boys (n = 43)

0.422** 0.614** 0.412**

0.571** 0.777** 0.548**

Girls (n = 29)

0.387* 0.686** 0.669** 0.421**

0.764** 0.534**

Source: Parˇ ízková, unpublished data, 1986–96. Note: *p < 0.05; **p < 0.01; index 1, subscapular/triceps skinfold; index 2, chest 1,2 + abdomen + suprailiac/cheek + chin + triceps + thigh + calf.

3.6 GENERAL CONSIDERATIONS Significant associations and relationships between maternal dietary intake during pregnancy, her nutritional status, lifestyle, etc., and numerous similar characteristics in the offspring at the beginning of life were revealed. Even when the comparison of individual studies is difficult due to varying design, characteristics of subjects followed, etc., the findings indicate the importance of the maternal situation, including her food intake and lifestyle, for her offspring. Most of these studies could follow anthropometric, metabolic, biochemical, and other parameters postnatally, or during earlier periods of life, but not later in life. Animal studies indicate that consequences of the mentioned factors might manifest in adult age. The results of Alberti et al. (1995b, 1998) presented here indicate that maternal nutritional status—body weight, fat, and its distribution during pregnancy—is significantly related to a number of variables in newborns. These relationships seem to be different in boys and in girls; regarding investigated variables, the relationships are more frequent in paired mothers and newborn sons and much less frequent for daughters. These sex-linked relationships were weak, nevertheless significant, and occurred regularly. In preschool boys, these relationships were closer, as is apparent from the higher values of correlation coefficients (Table 3.6). The fat pattern is assumed to be related to metabolic and cardiovascular characteristics (Bouchard and Johnston 1988) and can serve as a marker for some health risks of cardiovascular diseases later on in life. Therefore, it may be speculated that if the fat pattern in sons is significantly related to the same indicator in mothers, the health risks manifested in mothers might also appear later on in life for their sons. Even when correlations are weak, they were found regularly, and some were also proved in other studies. These relationships may indicate some sort of predisposition,

52

Nutrition, Physical Activity, and Health in Early Life

which was more obvious in boys. This association was also found for mothers and offspring aged 2–6 years. Maternal diet has an influence on a number of parameters, including serum lipids, mainly in sons. It is, therefore, not inconsequential what the future mother eats during pregnancy. It seems that under conditions of satisfactory EI, the composition of the diet, that is, relative amounts of individual nutrients and their mutual relationships, is more important than absolute amounts in the diet. However, the absolute amount of carbohydrate (g/day) correlates significantly with total cholesterol in boys only. Girls seem to be more protected than boys against the possible negative impact of their mother’s diet during pregnancy. This difference in the relationship of the blood lipids of the newborn to the mother’s diet may be further related to other female characteristics that differ, such as depot fat ratio and distribution, and the lower risk of deviations of lipid metabolism, which may less frequently result in the development of cardiovascular diseases later in life. Obviously, it would be necessary to validate these findings in larger groups of mothers and newborns (the homogeneity of which would be extremely difficult to ensure), while also following up longer on the children. The study continues, and it should bring further instructive data that either confirm or deny the above-mentioned conclusions. Because some relationship between subcutaneous fat in Italian newborns (i.e., a significant relationship between the serum level of TGs and fat distribution, index 2) was found, we may speculate that the changes in the blood lipids of mothers adapted to endurance exercise, which limit the deposition and distribution of fat, may also influence the blood lipid levels in their offspring. However, no valid data are available on this issue, as was the case with the other data mentioned above. In preschool children, a significant relationship between total cholesterol, TGs, and skinfold thicknesses and the percentage of fat was also found at the age of 4.6 years (Parˇ ízková 1989). Further studies focusing on these relationships in mothers with different diets and also with different physical activity regimens with regard to their offspring are needed.

4 4.1

Growth and Somatic Development of Preschool Children

INTRODUCTION

Numerous growth charts were prepared and used for the evaluation of growth levels in children (Wetzel 1942, Tanner 1962, Tanner et al. 1966, 1970, Rolland-Cachera 1995, Bláha and Vignerová 2002, 2004, Hall et al. 2008). Most studies concern the whole growth period from birth to maturity, especially those focused on changes in height and weight. More detailed data on growth, including further anthropometric measurements such as length, breadth, circumferential variables, body composition, and body posture, are less common, similar to studies assessing body composition, functional capacity, gross and fine motorics, and cardiorespiratory efficiency, which may be more important than just body size—even at preschool age. All the mentioned morphological characteristics of the organism are significantly influenced not only by genetic, hereditary factors and environmental conditions, but also by special factors affecting the organism since the very beginning of life (including the fetal period). This was partly given in Chapters 2 and 3. The development of basic parameters such as height, weight, and body mass index (BMI), and especially body composition, and eventually health risk starting with obesity have been shown to be significantly changed by various environmental factors, especially during initial periods of development (including the fetal one). This concerned, for example, nutrition (Cole and Rolland-Cachera 2002), and the impact was followed mainly from the point of view of individual characteristics. It is interesting to note how all these characteristics are interdependent. All are influenced by various and changing environments, which vary markedly not only in different parts of the world, especially when considering the social and economic status (SES) of different population groups, but also within the same country; their interrelationship may play an essential role. The previous monograph Human Growth, Physical Fitness and Nutrition and further publications (Parˇ ízková 1977, 1985, 1987, 1989a,b, 1991, 1993a,b) mainly included data on schoolchildren and adolescents. The continuation of these efforts was seen in the symposium on Human Growth, Dietary Intake and Other Environmental Influences, organized within the framework of the 13th International Congress of Anthropological and Ethnological Sciences in Mexico City in 1993 (Parˇ ízková and Douglas 1995, Proceedings, Institute Danone, Paris). The main aim of both these meetings was integration of the results of research concerning numerous aspects of human growth and development as 53

54

Nutrition, Physical Activity, and Health in Early Life

related to environmental conditions in different parts of the world. The period between infancy and school age has been relatively neglected regarding comprehensive studies on functional, motor, nutritional, and metabolic evaluations.

4.2 EVALUATION OF SOMATIC GROWTH Standard values for the evaluation of height and weight changes have been prepared in numerous countries and have been used for a long time. More recently, BMI (weight kg/height m2) was introduced as a criterion for the evaluation of child growth (RollandCachera et al. 1982, 1985, 1989, 2002). Figure 4.1a and b shows the changes of BMI development from childhood until 7 years of age set for European countries (RollandCachera 1995) and the United States (Figure 4.2a and b; National Center for Health Statistics and National Center for Chronic Disease Prevention and Health Promotion, 2000). 2000 CDC Growth Charts for the United States were developed (Kuczmarski et al. 2002). Anthropometric reference data for U.S. children and adults based on health examination surveys (NHANES) 1999–2002 were reported and used for comparisons and knowledge about trends in child growth (McDowell et al. 2005).

(a) BMI 24

(b) BMI 24

23

23

22

22

21

95

20 90

19

95

21 20

90

19

85

18

75

85

18 75

17

17

50

16

50

16

15

25

15

25

14

10 5

14

10 5

13

13

12

12

kg/m2

kg/m2 2

3

4

5

6

7

8

9

2

3

4

5

6

7

8

9

FIGURE 4.1 BMI (weight kg/height m ) percentiles from 2 to 9 years of age for boys (a) and girls (b) (CDC, National Center for Health Statistics, National Center for Chronic Disease Prevention and Health Promotion, 2000). 2

55

Growth and Somatic Development of Preschool Children (a)

Skinfolds (3–4 years)

Cheek Chin Chest 1 Triceps Subscap.

Girls

Chest 2

Boys

Abdomen Suprail. Thigh Calf Biceps 0

2

4

6 mm

8

10

12

Skinfolds (4–5 years)

(b) Cheek Chin Chest 1 Triceps Subscap. Chest 2

Girls

Abdomen

Boys

Suprail. Thigh Calf Biceps 0

1

2

(c)

3

4

5 mm

6

7

8

9

10

Skinfolds (5–6 years)

Cheek Chin Chest 1 Triceps Subscap. Chest2

Girls

Abdomen

Boys

Suprail. Thigh Calf Biceps 0

1

2

3

4

5 mm

6

7

8

9

10

FIGURE 4.2 Skinfold thicknesses in boys and girls 3–4 (a), 4–5 (b), 5–6 (c), 6–7 (d) years of age (survey A; measured by modified Bests’s caliper).

56

Nutrition, Physical Activity, and Health in Early Life (d)

Skinfolds (6–7 years)

Cheek Chin Chest1 Triceps Subscap. Chest 2

Girls

Abdomen

Boys

Suprail. Thigh Calf Biceps 0

1

2

3

4

5 mm

6

7

8

9

10

FIGURE 4.2 (Continued).

The mean values of weight, height, and BMI increased in all age categories in the United States from 1960 to 2002 (Ogden et al. 2004). BMI correlates significantly with many parameters of body composition and fatness. WHO (1997, 1998) recommended this characteristic as an important marker of growth and development, especially when local standards are available; cut-off points for different categories from the point of view of adequacy of growth can vary, and may thus give spurious data on the prevalence of both under- and overnutrition in different countries. This concerns especially subjects from Asian countries. BMI growth charts based on local growth data are available in many countries (USA, UK, France, the Czech Republic—formerly part of Czechoslovakia, etc.). Somatic parameters at the beginning of life, starting with the fetal period (including birth weight), and changes in weight and BMI shortly after have been recognized as very important markers of overall development and also of health risks such as obesity later on in life (Taeymans et al. 2008). The prevalence of overweight and obesity has been recognized by WHO as a major public health concern worldwide (James 2007), in developed countries as well as in some strata of developing countries. It has also been evaluated using BMI charts, which is currently the main tool for this purpose. BMI standards can vary in different countries, mainly due to ethnic differences and SES. Moreover, evaluation with the help of the same BMI charts has changed with time, especially with regard to cut-off points for overweight and obesity. Height-specific BMI reference curves have also been derived for preschool and later-age children (Tokumura et al. 2004). In the United Kingdom, the prevalence of overweight in children was 14.7% in 1989 and 23.6% in 1998, while that of obesity increased from 5.4 to 9.2% during the same period. Similar changes occurred in Germany, especially when comparing the prevalence before and after political changes in the country. In France, according to the International Obesity Task Force (IOTF by WHO), the prevalence of overweight (including obesity) in 2000 was similar to the prevalence recorded in the late 1980s

57

Growth and Somatic Development of Preschool Children

in the United States, and the prevalence of obesity in 2000 in France was similar to the prevalence of obesity in the late 1970s in the United States. Data in France are comparable with those reported in other studies conducted in Western Europe (Rolland-Cachera et al. 2002). Special attention is paid to early changes of BMI development. It increases until the first year, then decreases up to 5–6 years, and increases again—which is defined as adiposity rebound (AR; Rolland-Cachera et al. 2006). When this occurs earlier, for example, at 4 years, the individual is at a greater risk of later obesity than subjects in whom AR occurs at the proper time. AR can also occur differently under different nutritional, environmental, and health conditions (Figure 4.1a and b). The fat gain rate is faster in girls undergoing early AR (Taylor et al. 2004). The use of BMI charts made the evaluation of a preschooler’s growth possible and gave researchers the opportunity to define overweight and obesity during this period of growth (Figures 4.1a and Table 4.1; see Chapter 8). As mentioned above, BMI correlates significantly with total body fat, not only in adults (Parˇ ízková 1989a) but also in children. Excess fatness can be evaluated in comparison with skinfolds (Figure 4.2). During the second half of the last century, obesity was relatively rare. Increased dietary intake and overall energy disbalance were reflected mainly in accelerated growth—increase in body size, including circumferential and other parameters. Adiposity had not increased much, and the percentage of overweight children was very low. Obesity was exceptional (Parˇ ízková et al. 1984). However, recently and at present the situation has changed: for example, the GENESIS study, which followed growth and development in a representative sample of children 1–5 years old in Greece (1216 boys and 1156 girls), found subjects with increased weight. No significant differences were found between genders regarding the prevalence of risk of overweight and obesity (ca. 16–20%) (Manios 2006,

TABLE 4.1 BMI (Weight kg/Height cm2) Variations (Mean ± SD) in Czech Children Aged 3–7 Years Boys Age (Years) 3.0 3.5 4.0 5.0 6.0 7.0

x– 16.0 15.7 15.7 15.5 15.9 15.9

Girls SD

x–

SD

1.4 1.4 1.4 1.4 3.0 1.7

15.7 15.5 15.4 15.4 15.6 15.9

1.5 1.5 1.6 1.6 1.8 1.9

Source: Adapted from Prokopec, M. and Bellisle, F., Ann. Hum. Biol., 20, 517, 1993. Note: SD, standard deviation.

58

Nutrition, Physical Activity, and Health in Early Life

Manios et al. 2008). Gender differences in height were apparent only up to the age of 3 years. The effect of centile crossing of BMI during childhood, that is, when a child crossed upward his/her BMI development across the previous channel, was one of the greatest early risks for the development of later obesity. Centile crossing was associated with greater adulthood stature, fat mass, and percent body fat than a decrease or stability in weight z-score, as revealed in the Fels Longitudinal Study (Demerath et al. 2004, 2007). Upward weight percentile crossing in infancy and early childhood predicts overweight in young adults (SWEDES study; Ekelund et al. 2006). Infant weight gain is associated with mother prepregnant BMI, and with interaction between the duration of breast-feeding and the timing of complementary food introduction (Baker et al. 2004). Another study showed that children born to nonsmoking mothers and with increased birth weight, who were overweight until 5 months, were more often overweight also at the age of 4.5 years. But children born to smoking mothers and who were overweight at 4.5 years started life with a birth weight around that for the population means, and gained more weight in the first 5 months of life than children of non-smoking mothers. With regard to prevention of obesity, children of smoking mothers should be targeted more than children of non-smoking mothers, as well as non-smoking pregnant women at risk for giving birth to high-birth-weight children. Lower birth weight resulting inter alia from the poor nutrition of pregnant mothers indicates a higher risk for metabolic syndrome (MS) in young adults, particularly through higher serum TGs and higher systolic blood pressure (Ramadhani et al. 2006). Particular attention should be paid to rapid weight gain during the first few months (Dubois and Girard 2006), which has been shown to be a risk factor for later overweight and obesity. Determinants of rapid growth and overweight were followed up in, for example, Dutch children: overweight at 12 years was predicted by an early rapid increase in body weight and also by paternal influences (parental BMI, scores of the Three-Factor Eating Questionnaire, i.e., a high dietary restraint score of the mother). No significant genetic relation was observed (three polymorphisms; see Chapter 8). Overweight of the child was negatively associated with the child’s PA score and positively related with dietary restraint (Vogels et al. 2006). Rapid growth during the fi rst year of life was also associated with an increased BMI at the age of 6 years in both boys and girls. A higher intake of protein in infancy can also contribute to obesity development, which was found only in boys (Gunnarsdottir and Thorsdottir 2003). International comparisons of growth during childhood, adult BMI, and nutritional conditions could help in defining factors that are at least partly responsible for increasing the prevalence of obesity. Comparisons of the values of BMI in the Czech Republic and France showed that Czech children above the age of 7 years are heavier, that is, obviously fatter, than French children (Parˇ ízková and Rolland-Cachera 1997). Regarding health, some data indicate that being overweight as an adult and other weight-related pathological conditions were more prevalent in the Czech Republic and other East European countries than in most countries in Western Europe, the United States, Japan, etc. (Uemura and Píša 1988). This comparison indicates that

Growth and Somatic Development of Preschool Children

59

predisposition for overweight and later health problems start at an early age (Parˇ ízková 1993c, 1994). The RDAs for protein and fat in former Czechoslovakia were always much higher, including those for children (Kajaba et al. 1992), than in the United States (National Research Council, Washington 1989) or Europe (Nutrient and Energy Intakes for the European Community 1993); for the most part, the real intake was even higher (see Chapter 5). In spite of more recent improvements, some consequences exist even now. The BMI values of the 90th percentile are higher in Czech children than in French children aged 5 and 6 years (Prokopec and Bellisle 1993); this applies to both boys and girls. Above 7 years, Czech children are heavier in all percentiles of BMI distribution than French children. AR, that is, an increase in adiposity (as indicated by an increase in BMI), occurs earlier in fat than in thin children, as confirmed by the French. As shown by Rolland-Cachera et al. (1984, 1988, 1991, 2006), early AR can predict obesity in both adolescence and adulthood. Repeated cross-sectional measurements in hundreds of thousands of Czech children conducted regularly at 10-year intervals since the 1950s made it possible to evaluate the shift of AR in the same growing population (see Chapter 8; Vignerová and Bláha 2007, Vignerová et al. 2008). Changes in BMI values in Czech children spanning a hundred years were calculated from the values of height and weight measured by Matiegka in 1895 (CˇAVÚ, Prague 1927) and similar values measured by Hainiš (1993) in 1988–1989, or those of Bláha and Vignerová (2001), Bláha and Parˇ ízková (2007), and Vignerová and Bláha (2007) measured in 2001. The measurements of Hainiš (1993) showed an increase in the average BMI values from 14.87 to 15.88 in boys aged 6–7 years (values of height and weight for younger children in 1895 were not available) and from 15.09 to 15.71 in girls of the same age. Changes of BMI in older age categories are even more obvious. The same applies to comparisons using later measurements of Bláha et al. (2001), where the differences were even greater. Bláha et al. (2004) evaluated more anthropometric parameters in younger children, for example, circumferential measures, breadth, skinfold thicknesses, etc. A cross-sectional study of BMIs in adults in former Czechoslovakia revealed that a high (>25%) proportion of individuals had, at the present time, BMIs >25 kg/m2, which is generally accepted as the cut-off point defining overweight. More recent measurements by Hainiš (1993) showed higher ratios of individuals with increased BMIs in the Czech population. Although it can be argued that body frame or even muscular mass could account for some of the differences in BMI between subjects from former Czechoslovakia and other countries such as England, Finland, France, the Netherlands, and the United States (Rolland-Cachera et al. 1991), it is likely that the high BMIs reflect a high adiposity level, the origin of which lies in a combination of bad eating habits and lifestyle since early childhood. This is also reflected by earlier AR. The prevalence of subjects with higher BMIs in the United States increased considerably too (Kaczmarski et al. 1994). A high intake of protein and fat in the Czech Republic seems to be responsible: early rebound and higher average BMI values during growth, as well as in adulthood, run parallel to a greater prevalence of obesity, higher morbidity, and mortality from cardiovascular diseases in the Czech population (Uemura and Pisa 1998).

60

Nutrition, Physical Activity, and Health in Early Life INDEX - IB

(a) 0.5 0.4 0.3 0.2 0.1 0

3–4 years

(b)

4–5 years

5–6 years

6–7 years

INDEX - IH

0.5 0.4 0.3 0.2 0.1 0

3–4 years

(c)

4–5 years

5–6 years

6–7 years

INDEX - II

0.5 0.4 0.3 0.2 0.1 0

3–4 years

4–5 years Boys

5–6 years

6–7 years

Girls

FIGURE 4.3 Indices of subcutaneous fat distribution in boys and girls 3–6 years of age as measured by the modified Best caliper (a) and the Harpenden caliper (b); centrality index, that is, subscapular/triceps, and by Best’s caliper (c) index relating five skinfolds on the trunk/ five skinfolds on the extremities, (see Figure 4.2 and Table 4.9a; survey A).

Growth and Somatic Development of Preschool Children

61

A high intake of protein during childhood is considered as one of the main causes of later obesity (Rolland-Cachera 1995). Increased BMI values during growth can predict whether a child will be overweight at the age of 35 (Guo et al. 1994). During the last two decades, the trend of changes in BMI, cholesterol level, and morbidity is due to changed diet and some other positive changes, which is reflected by a prolonged lifespan in both genders. However, the prevalence of childhood obesity has been simultaneously increasing, and there is a problem of how this will be reflected by the aforementioned health parameters in the future. This also applies to many other countries. Cole et al. (2000, 2005, 2007) established standard definitions for child overweight and obesity, and also thinness, on the basis of international review, which are recommended as criteria for the adequacy of development. However, efforts in different parts of the world—especially in Asia—continue so as to establish proper local criteria. Therefore, higher BMI values above critical percentiles during childhood do not seem to be, under the present living conditions in industrially developed countries, an advantage for the child. This has been shown in more recent years by a number of studies, and the attitudes to children’s BMI have changed, which also include functional and metabolic parameters. It is therefore necessary to check not only the amount of fat as an important indicator of obesity and health risks (being overweight may not always imply a high fat depot ratio), but also the level of functional capacity and physical fitness. Moreover, nothing is known about how vital organs and tissues may change along with the acceleration of growth and increase in BMI.

4.3 CROSS-SECTIONAL SURVEYS OF ANTHROPOMETRIC VARIABLES Complex and more detailed findings on developmental changes in normal healthy children during preschool age, compared to school age and adolescence, have remained limited until now. Attention has also been focused on clinical and biochemical parameters, mainly in children with some health problems. Studies in normal healthy children usually do not include more anthropological, functional, and gross and fine motor parameters, body posture, etc., in one study of the same children. Repeated cross-sectional and longitudinal measurements in the Czech Republic were compiled mainly from representative samples. In these groups, data on environmental, social, family, and health characteristics along with data on height, weight, BMI, etc. (Parˇ ízková et al. 1984) were collected. More detailed measurements (anthropometric, body composition, functional capacity, gross and fine motorics, food intake, biochemical characteristics, body posture, robusticity of the skeleton, and psychological evaluation) were repeatedly executed in smaller samples (Table 4.2). According to the secular changes of BMI and adiposity, which are not considered positive (increased fatness, decreased functional capacity, and decreased aerobic fitness), results from previous decades can still be useful as orientation standards for preschool children. In our first survey (A), 238 children from Prague kindergartens were followed up. (In the former Czechoslovakia and/or now in the Czech Republic, more than 80% of preschool children attended day-care centers, where they spent 7–8 h per day.) Day-care centers were selected to represent different environmental conditions in

62

Nutrition, Physical Activity, and Health in Early Life

TABLE 4.2 Individual Surveys of Preschool Children and their Program (A, B, C, D1, D2, G, H, I, J—Cross-Sectional; E, F—Longitudinal Follow-Ups) Survey A 238

B 5598

C 3712

D1 9587

D2 1005

E 58

F 764

Anthropometry 1

+ +

+ −

+ −

+ −

+ −

+

Anthropometry 2

+

+ −

Skinfolds

+

−

−

−

−

+

+

Somatotypes

+

−

−

−

−

+

+

Body posture

+

−

+ −

+

+

+ −

−

Step test

+ −

+

+ −

Performance

+

+

+

−

+

+

+

Skill

+

+

+

−

+

+

+

Sensomotor tests

+

+

+

−

+

+

+

Questionnaire 1

+

+

+

+

+

+

+

Questionnaire 2

+

+

+

+

+

+

+

n

Source: Compiled from Parˇ ízková, J., unpublished data, 1986–96. Note: Anthropometry 1, simple program (see text and tables); Anthropometry 2, detailed simple program (see text and tables); Questionnaire 1, family, social, environmental, etc., characteristics; Questionnaire 2, participation, character of physical education. In addition to the above-mentioned assessments: dietary intake (food record forms)—surveys G, H, I, J; blood lipids (total, HDL, LDL cholesterol, TGs)—surveys H, I, J.

Prague, where our research team was given the official consent and opportunity to make the necessary measurements. Examinations were always made in the morning between 7:30 a.m. and 9:00 a.m. when the children played freely in the playroom and our examinations generally did not interfere with their daily schedule (study A, n = 238, 142 characteristics assessed; Table 4.2). Day-care centers were subordinated to the Ministry of Education. Teachers have to absolve special pedagogic high schools. The daily program was prepared by the Ministry of Education and included free games, educational programs, physical education, walks, and other outdoor activities. Relaxation and sleep took place after lunch. Another survey included only children 6.4 years of age from all over the Czech Republic (study B, n = 5598, 42 indicators measured; see Table 4.2). Study C included children of similar age groups (n = 3712) from the whole country. Study D comprised cross-sectional groups of children 4–6 years old (n = 9587, subsample n = 1005) from different districts of the country. Study E was longitudinal, starting at 3–6 years of age (n = 58), and included some Prague children from study A who were available for repeated measurements. Study F was again longitudinal, from 4 to 6 years, that is, children (n = 764) from the whole country were measured three times. All measurements were made at regular intervals from the beginning of the

Growth and Somatic Development of Preschool Children

63

1970s (1971) until the end of the 1980s (1989). Surveys in smaller samples G and H also included dietary intake, and surveys I and J included the assessment of serum lipids (Table 4.2; see also Chapters 6, 9, and 10). Dietary intake (15 items) was also assessed longitudinally in a group of children from survey E. A questionnaire was given to parents to assess data pertaining to their ages, heights, and body weights; occupation; per capita income in the family; number of family members; health status of the entire family; birth rank of the child; case record of the child, including its birth weight, period of breast-feeding, and motor development (i.e., age at the beginning of sitting and independent walking); and sanitary standard of housing. These data helped characterize the living conditions of the child outside of the day-care centers (Parˇ ízková et al. 1984). The protocols and arrangements of our measurements varied in the individual surveys, depending on the given possibilities under various settings of our surveys. The formulae for the individual assessments are given in Appendices 1–4. Questionnaires concerning social, familial, and economic information were not included as these assessments are specific for individual countries. In total, more than a hundred items, measured and derived, were assessed and evaluated. The development of height, weight, and BMI corresponded to reference values (Table 4.3a; Figure 4.1a and b). In comparison to the standards of Rolland-Cachera et al. (1984), the average values of the BMI of our children were slightly higher, especially above the age of 5 years. This corresponds to the findings of Prokopec and Bellisle (1984), who also found higher average BMI values in another group of Prague preschool children. Similar conclusions resulted from comparisons of other child groups (studies B, C, and D; see the values of height and weight along with other characteristics in Tables 4.4, 4.5, and 4.6a and b). A longitudinal study of 58 boys and girls in Prague (E), which covered approximately the same age span (see Table 4.7a), also showed higher average BMI values (i.e., at the level of the 55–70th percentiles of our standards) and even slightly higher at the age of 5–6 years when compared with French BMI standards (Rolland-Cachera et al. 1984, 1987, 1990, 1991). Survey F (see Table 4.8) showed slightly lower values of BMI at the age of 4–5 years, which further decreased at the second measurement but then increased at the last measurement. When we evaluated BMIs from representative samples of children measured in all of the Czech Republic (B and D), we found average values close to the 50th percentile (Bláha 1991) but higher values when comparing the data with French BMI standard values. However, these values were still within the normal range of the standards for height and weight. BMI values were usually higher in boys than in girls, which also corresponds to other findings in our and other child populations (Prokopec and Bellisle 1992). Further anthropometric variables such as length, breadth, and circumferential measures were assessed (see Table 4.3b–f) in a cross-sectional study of 238 preschool children (A) and in study E where some of the same children were followed up repeatedly (n = 58; see Table 4.7a–d). In studies B, C, and D only circumferential measurements were recorded. Measurements were made as recommended for the International Biological Programme (IBP; Eveleth and Tanner 1990, Parˇ ízková 1985, Seliger 1977).

64

Nutrition, Physical Activity, and Health in Early Life

TABLE 4.3a Height, Weight, Sitting Height, and Body Mass Index (BMI) in 238 Children from 3 to 6 Years of Age in Prague (Survey A) Age (Years) 3–4

4–5

5–6

6–7

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

Height (cm)

Weight (kg)

Sitting Height (cm)

BMI (kg/m2)

101.6 4.5

16.62 1.97

57.8 2.8

16.0 1.6

99.5 5.0

15.69 2.24

56.3 3.2

15.8 1.2

109.0 3.9

19.18 2.86

62.0 2.3

16.2 1.3

107.7 5.9

18.34 3.48

60.0 2.4

15.8 1.3

113.5 5.8

20.85 2.76

63.8 2.7

16.2 1.4

112.8 4.4

19.65 2.52

62.5 2.5

15.4 1.5

119.2 4.1

22.10 2.68

65.5 2.6

15.6 1.4

118.6 4.9

21.59 2.81

64.7 2.8

15.3 1.3

Source: Modified from Parˇ ízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a. Note: SD, standard deviation.

As detailed data on the morphological development of preschool children are relatively rare, all variables measured in studies A and E are given. Tables 4.3a–h show the results of measurements in individual age categories from 3 to 4, 4 to 5, 5 to 6, and 6 to 7 years, separately for boys and girls (survey A). Also with sexlinked differences, the comparison of lengths reveals slightly higher values in boys (Table 4.3b), but rarely do these differences in this smaller Prague group reach statistical significance. With breadth measures, there is a trend toward higher values of shoulder width (biacromial breadth) in boys, which again is not significant (Table 4.3c). The width of the chest is markedly greater in boys, and this difference is significant in older

65

Growth and Somatic Development of Preschool Children

TABLE 4.3b Length Measures on the Extremities in 238 Children Aged 3–6 Years in Prague (Survey A) Age (Years) 3–4

4–5

5–6

6–7

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

1

2

3

4

5

6

42.5 2.0

17.2 1.0

13.6 1.0

56.8 2.8

26.0 1.5

21.6 1.7

40.9 2.5

16.8 1.1

13.0 1.0

55.1 3.2

25.5 1.9

21.4 2.3

46.0 2.2

18.9 1.2

14.9 1.1

62.1 3.3

30.9 2.1

23.1 1.6

44.9 2.4

18.8 1.3

14.6 1.3

61.7 3.3

30.3 2.4

22.6 1.2

48.9 3.2

20.0 1.1

16.1 1.0

65.5 3.9

32.6 2.4

24.3 1.7

46.8 2.5

19.4 1.2

15.1 1.0

65.2 3.3

32.5 2.7

23.9 1.4

51.1 1.9

20.8 0.8

16.4 0.7

69.1 2.6

34.1 1.9

25.8 1.4

50.0 2.4

20.4 1.1

16.4 0.9

69.1 3.1

34.1 2.5

25.8 2.1

Source: Adapted from Parˇ ízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a. Note: 1, total of upper extremities; 2, acromion-radiale; 3, radiale-stylion; 4, total of lower extremities; 5, iliospinale-tibiale; 6, tibiale-sphyrion. Individual measures: total length of upper extremity, that is, acromion-dactylion, acromion-radiale, radiale-stylion; total length of lower extremity, that is, iliocristal-base, iliospinale-tibiale, tibialesphyrion.

age groups. The same applies to the depth of the chest. The breadth of the pelvis (bi-iliocristal breadth) was at this age period smaller in girls. The differences in this case were significant at the age of 5–6 years (Table 4.3c). The robusticity of the skeleton was evaluated according to selected dimensions, that is, five breadth measurements on the upper and lower extremities (Table 4.3d). Boys had a more robust skeleton—the dimensions were significantly larger in the majority of age groups. This applied particularly to the breadth of the hand, humeral

66

Nutrition, Physical Activity, and Health in Early Life

TABLE 4.3c Breadth Measurements of the Trunk (cm) of Children Aged 3–6 Years in Prague (n = 238; Survey A) Age (Years) 3–4

4–5

5–6

6–7

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

Biacromial

Chest Breadth

Chest Depth

Bi-iliocristal

23.1 1.0

17.1 0.5

12.7 0.8

16.8 0.8

22.8 1.2

16.6 0.7

12.0 0.8

16.5 1.0

24.6 1.0

18.1 0.8

13.2 0.9

18.0 1.2

24.3 1.4

17.8 1.2

12.5 0.7

17.7 1.1

25.6 1.4

18.7 0.9

13.5 0.7

18.6 0.9

25.5 0.9

17.8 0.7

13.5 1.7

18.0 1.5

26.2 1.0

19.2 0.8

13.7 0.6

19.4 0.9

26.1 1.1

18.6 1.2

13.2 0.9

19.2 1.1

Source: Modified from Parˇ ízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a.

and femoral condyles, and the breadth of the ankles. In the width of the wrist, a significant sex-linked difference was found only at the age of 6–7 years. The comparison of circumferential measurements showed that the head circumference was significantly greater in boys of all age groups, and the neck circumference in all except the 4–5-year-olds. Sex-linked differences in the chest circumference were relatively smaller and significant only in 3–4- and 5–6-yearold children. Also, the waist (abdomen) circumference differed less, the difference being significant only in children aged 5–6 years. Waist circumference differs the most in obese subjects, similarly in both genders, and is used as a significant marker of excess adiposity (Wake et al. 2007). Thus, sex-linked differences of the head were somewhat more marked than those of the trunk.

67

Growth and Somatic Development of Preschool Children

TABLE 4.3d Breadth Measurements of the Extremities (cm) of Children Aged 3–6 Years (n = 238) in Prague (Survey A) Age (Years) 3–4

4–5

5–6

6–7

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

Hand

Wrist

Humeral Condyle

Femoral Condyle

Ankle

5.4 0.3

3.8 0.2

4.4 0.2

7.1 0.3

5.2 0.3

5.2 0.4

3.7 0.2

4.2 0.4

6.6 0.4

4.9 0.3

5.9 0.5

3.9 0.2

4.7 0.3

7.3 0.4

5.4 0.3

5.5 0.3

3.8 0.2

4.4 0.3

6.9 0.4

5.1 0.2

5.9 0.4

4.0 0.3

4.8 0.2

7.4 0.3

5.5 0.3

5.6 0.3

3.9 0.2

4.5 0.2

7.0 0.3

5.1 0.3

6.1 0.5

4.2 0.2

4.8 0.3

7.5 0.3

5.5 0.3

5.8 0.2

4.0 0.2

4.8 0.2

7.5 0.5

5.5 0.3

Source: Compiled from Parˇ ízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a.

Circumferences of the arm did not differ by sex, which was also manifested in circumferences of the forearm (Table 4.3f). On the other hand, circumferences of the thigh tended to be higher in girls. This was the only indicator of those used where it was the case. With regard to calf circumferences, there was a tendency toward higher values in 6–7-year-old girls. There were remarkable age-related changes in the relative increase of different morphological parameters during preschool age. Some increased much more than others; for example, the height of 6–7-year-old children was roughly 17–19% higher than in 3–4-year-old children. In the increase in height, the growth of the trunk participates less (increase of sitting height by 13–15%) than that of the lower extremities (by 21–22%). In the lower extremity, there is a relatively greater increase in the

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Nutrition, Physical Activity, and Health in Early Life

TABLE 4.3e Circumferential Measurements of the Head and Trunk (cm) of Children from Prague Aged 3–6 Years (n = 238; Survey A) Age (Years) 3–4

4–5

5–6

6–7

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

Head

Neck

Chest

Waist

50.4 1.1

25.5 1.0

54.2 2.4

50.8 3.6

49.3 1.7

24.3 1.0

52.6 2.6

49.7 3.3

51.3 1.3

25.9 1.3

57.0 3.5

53.0 3.5

49.5 1.3

24.6 1.2

54.2 2.7

51.5 4.4

51.4 1.5

25.9 1.4

57.3 2.7

54.3 3.4

50.4 1.2

24.9 1.1

55.3 2.6

51.8 2.8

52.3 1.5

26.2 0.9

58.1 3.1

54.0 3.5

51.3 1.4

25.2 1.2

57.2 3.3

53.7 4.5

Source: Modified from Parˇ ízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a.

length of the thigh (increase of iliospinale-tibiale by 31–38%) than of the calf (increase of tibiale-sphyrion by 19–23%). The length of the upper extremities increases relatively less than the length of the lower extremities, that is, by 20–22%. In this increase, the upper segment of the arm (acromion-radiale by 20–21%) as well as the lower segment of the arm (radiale-stylion by 20–26%; Table 4.3b) participate evenly. The width of the trunk changes less than the length dimensions. The relatively greatest increase occurs in the pelvic dimensions (bi-iliocristal breadth, by about 15–16%) and in the breadth of the shoulders (biacromial breadth, by about 13–14%). The breadth of the chest in 6–7-year-olds is about 12% greater than that in 3–4year-olds, while the depth of the chest changes relatively little during this period (see Table 4.3c).

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Growth and Somatic Development of Preschool Children

TABLE 4.3f Circumferential Measurements of the Extremities (cm) of Children Aged 3–6 Years in Prague (n = 238; Survey A) Age (Years) 3–4

4–5

5–6

6–7

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

Arm

Forearm

Thigh

Calf

17.0 1.1

16.8 0.8

32.0 2.3

21.9 1.3

16.6 1.3

16.5 1.1

32.2 2.5

21.7 1.6

17.2 1.2

17.2 0.9

33.5 3.4

23.4 1.2

16.9 1.4

16.7 1.2

34.1 3.2

22.9 2.2

17.5 1.2

17.5 1.0

34.8 2.6

23.7 1.6

17.4 1.2

16.9 1.0

35.2 3.2

23.0 1.2

17.7 1.1

17.6 0.8

35.4 2.5

24.1 1.1

17.7 1.2

17.4 0.9

36.3 2.5

24.5 1.6

Source: Adapted from Parˇ ízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Vol. 64, Charles University, Prague, 1984a.

The robusticity of the skeleton increased more on the upper extremity, that is, the breadth of the hand increases by 11–12%, the breadth of the wrist by 8–10%, and the breadth of the humeral condyles by about 9%. The breadth of the femoral condyles is, in the oldest group of 6–7-year-old children (compared to the youngest one), about 4–5% greater. The breadth of the ankle is greater by 5–6% (Table 4.3d). Improved bone health during growth was evidenced due to exercise and nutrition (Specker and Vukovich 2007), but has not yet been studied in preschoolers. The circumferential measures change little during this age period (see Table 4.3e) compared to other indicators, except for thigh circumference. Head circumference in our oldest age group (6–7 years) is only 3–4% greater than that in the youngest age group of 3–4-year-old children. Neck circumference differs even less, that is,

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TABLE 4.3g Indices of Body Build and Proportionality of Children Aged 3–6 Years in Prague (n = 238; Survey A)

Age (Years) 3–4

4–5

5–6

6–7

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

Sitt. ht. × 100/HT

Lgth l. extr. × 100/HT

Biacr. × 100/Hat

Bicr. × 100/HT

Bicr. × 100/biacr.

56.86 2.27

55.83 1.24

22.73 0.85

16.59 0.84

73.02 3.43

56.53 1.65

52.28 1.15

22.95 1.08

16.2 0.9

72.53 .93

56.88 1.26

56.97 1.89

22.56 0.69

16.51 0.73

73.17 3.47

55.56 1.52

56.68 1.64

22.58 1.13

16.39 0.86

72.67 3.62

56.34 1.82

57.70 2.04

22.62 1.04

16.39 0.65

72.56 3.70

55.49 1.69

57.64 1.18

22.68 0.76

16.00 1.72

70.59 5.40

54.98 0.97

57.99 1.07

22.02 0.66

16.26 0.64

73.95 3.88

54.52 1.08

58.12 1.80

22.02 0.68

16.20 0.67

73.64 3.41

Source: Adapted from Parˇ ízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a. Note: Sitt. ht., sitting height; Lgth l. extr., length of lower extremities; Biacr., biacromial breadth; Bicr., bi-iliocristal breadth.

by 2–4%. Chest circumference is 7–8% greater in the oldest age group, and the waist circumference by 10–12%. The same applies to the calf. When comparing the relative increase of bodily dimensions in our groups of children, it was shown that this increase is somewhat more marked in girls. The increase in total body weight during this period is 32–37% greater than the relative increase in height. BMI decreased slightly in both boys and girls (see Figure 4.1a and b), which corresponds to general trends of development assessed in Czech children as well as in other child populations.

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Growth and Somatic Development of Preschool Children

TABLE 4.3h Waist/Height Ratio Index of Preschool Children (Waist cm/Height cm × 100) Years 3–4 4–5 5–6 6–7

Boys

Girls

–x SD –x SD –x SD –x

49.2 2.0 48.6 2.6 47.9 0.9 45.3

49.9 1.6 47.8 1.4 45.9 0.6 45.3

SD

1.3

1.7

Source: Parˇízková, unpublished data, 2007

As is apparent, individual bodily dimensions of preschool children change in a different way. The greatest relative increase is that of total body mass, followed by the length of the thigh along with other longitudinal dimensions of the skeleton. The breadth of the trunk increases much less, and the same applies to the robusticity of the skeleton and the circumferences of the lower extremities. The relatively smallest increase is that of the head and neck circumferences. Proportionality also changes during preschool age. Young children have relatively shorter extremities than older ones. This was shown in our groups by examining the reduction of the values of the index (relative value that evaluates sitting height in relation to height; see Table 4.3g) and conversely by increasing the relative length of the lower extremities. The relatively smaller increase in the breadth of the trunk was also manifested by a decline in the relative shoulder breadth in relation to height (Table 4.3g). All these differences are statistically significant. The relative breadth of the pelvis in relation to height and shoulder breadth did not change markedly during the preschool period. As an important characteristic, the waist/height ratio was defined—an index that relates waist circumference to body height (McCarthy et al. 2003, 2005, McCarthy and Ashwell 2006). At present, waist (abdomen) circumference is considered and widely used as a characteristic of total and especially intra-abdominal fatness. It has great importance as a marker of health risks, especially when related to total body height. For adults, it is recommended that this value should not be greater than half the body height. In children, this parameter was evaluated more rarely (especially in preschool children; Table 4.3h). The Bogalusa Heart Study emphasized the importance of obtaining information on body fat distribution in children, waist circumference in particular. This parameter, which is easy to measure, may also help in identifying children with an adverse concentration of lipids and insulin (Freedman et al. 1999a,b, 2007). In adults of normal weight, the usual values of this index are around 40, in Miss World or Miss Universe participants it can be 32–35, and in the obese it is close to 100.

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Changes occur during puberty, and aging manifests with increasing values of this parameter. As is apparent from Table 4.3h, values of this index diminish as another marker of slenderization of the body during the period from 3 to 6–7 years, because of a relatively greater increase in length measures and a reduction (boys) and/or preservation of similar body fatness (girls). Gender differences were not revealed at this age. Along with the increase of obesity prevalence, this index markedly increased in U.S. children and adolescents, 2–19 years of age, that is, between 1988–1994 and 1999–2004 (Li et al. 2006). Unadjusted mean waist circumferences in boys 2–5 years old increased during the period 1999–2004 from 51.7 to 51.9 cm, and in girls from 51.0 to 51.8 cm. The changes in the index during this period showed similar values. Using the 90th percentile values of waist circumference for gender and age, the prevalence of abdominal obesity increased by 65.4% (from 10.5% to 17.4%) for boys and by 69.4% (from 10.5% to 17.8%) for girls. The Bogalusa Heart Study revealed a lack of difference between the ability of BMI-for-age and weight-to-height ratio to identify children with adverse health risk factors (blood pressure, lipids, fasting insulin, 5–17 years of age). The waist-to-height ratio is preferred because of its simplicity, but further longitudinal studies are needed to verify its importance with regard to health prognosis (Freedman et al. 2007). In preschool children, central obesity (in this study characterized by waist circumference/arm circumference, WC/AC) had a relationship with TG and HDL concentrations, which is independent of current height and BMI (Cowin and Emmett 2000). When measuring groups of children, a markedly different variability of individual morphological variables, characterized by the coefficient of variation (CV or z-score), was also found. The greatest interindividual variability was found in body weight, where CV varies from 11% to 14% in different age groups. Longitudinal dimensions, including height, have CV values of roughly 4–7%; breadths on the trunk and indicators of skeletal robusticity have values of 4–6%. The smallest variability at that age is found for head circumference (2–3%). It seems that children are born with very similar heads (which also changes the least during preschool years), but the rest varies much more due to the environment, mostly nutrition. The remaining circumferential measures have CVs within the range of 4–7%, similar to longitudinal measures and breadths. Apparently, body weight and volume are mainly influenced by environmental factors, particularly dietary intake, which applies to the earliest periods of life. Some of these morphological variables were also measured in a representative sample of children (age 6.4 years; sample B) from the whole of the Czech Republic. In this group of children only selected measurements could be made (Table 4.4). The average values from this larger sample were also higher than those of the same age category (i.e., 6–7 years of age) mentioned above (survey A), but the differences were mostly insignificant. This applied first of all to the values of height and weight. BMIs tended to be higher in girls only. The values of the waist (abdomen) circumference were higher in boys, and those of the arm were higher in both sexes. Otherwise the values from survey A were closer to the values of survey B for 6.4-year-old children (Table 4.4). After a 5-year interval, cross-sectional measurements of the same morphological characteristics in 1848 boys and in 1864 girls aged 4–6 years (survey C) were repeated (Table 4.5). The BMI values and other parameters mentioned above did not

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Growth and Somatic Development of Preschool Children

TABLE 4.4 Somatic Development of Preschool Children in the Czech Republic at the Age of 6.4 Years (All Regions: Boys n = 2587, Girls n = 2505; Survey B) x–

SD

Boys Girls Boys Girls Boys Girls

118.7 117.8 22.24 21.76 15.8 15.7

5.3 5.2 3.24 3.34 1.2 1.3

Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls

59.3 58.0 62.7 61.3 58.7 57.5 55.3 54.8 18.2 18.4 35.5 37.2

3.3 3.3 3.5 3.7 3.4 3.7 4.4 5.0 1.7 1.8 3.5 3.6

Measurement Height (cm) Weight (kg) Body mass index (BMI) (kg/m2) Circumferences Chest (cm) Rest Inspiration Expiration Abdomen (cm) Waist (cm) Arm (cm) Thigh (cm)

Source: Modified from Parˇ ízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a.

differ markedly from the previous measurements (Table 4.3a). Some variations were apparent, for example, a slight increase in the average values of height. Also, circumferences of the chest, abdomen, and arm tended to be greater when larger population samples from the whole of the Czech Republic, of boys and girls 6–7 years of age, were compared after the mentioned period of time. However, the values of body weight and thigh circumference were practically the same. BMI varied insignificantly in boys and was slightly higher in girls measured later (survey C). The average values of BMI for the whole group measured in the Czech Republic (survey B) corresponded to that ascertained earlier in girls in Prague (survey A), where most of the measurements always revealed higher values. The last cross-sectional measurements of similar parameters in the same age groups (4–6 years, survey D, Table 4.6a) in 1988–1989 were made in 9587 preschool children. A subsample of 1005 boys and girls was followed up in greater detail as in surveys A and E (see Table 4.6b). The average values of height and weight from this measurement did not differ significantly compared to the average values of height

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TABLE 4.5 Somatic Development of Preschool Boys (n = 1848) and Girls (n = 1864) in the Czech Republic (Height, Weight, and Circumference Measurements of the Chest, Abdomen, Arm, and Thigh) (Survey C)

Age (Years) 4–5 Boys, n = 630 –x SD Girls, n = 665 –x SD 5–6 Boys, n = 682 –x SD Girls, n = 653 –x SD 6–7 Boys, n = 536 –x SD Girls, n = 546 –x SD

Height (cm)

Weight (kg)

BMI (kg/m2)

Chest Circumference (cm)

Waist (cm)

Arm (cm)

Thigh (cm)

106.5 4.9

17.93 2.15

15.01 1.6

55.9 2.9

53.2 3.8

17.5 1.4

32.6 2.8

105.6 5.9

17.63 2.19

15.01 1.7

57.9 4.2

54.5 4.2

16.2 2.3

33.9 3.7

113.5 4.9

20.20 2.60

15.68 1.9

57.9 4.2

54.5 4.2

16.2 2.3

33.9 3.2

113.3 4.6

20.02 2.60

15.60 2.0

56.8 3.7

54.3 4.2

18.2 1.1

35.4 3.3

119.0 4.6

22.29 2.63

15.80 1.8

59.6 3.6

56.1 5.2

18.7 2.4

34.9 3.5

118.3 4.9

21.83 2.68

15.60 1.9

58.3 4.0

55.4 5.3

18.8 2.6

36.6 4.5

Source: Modified from Parˇízková, J., in Physical Fitness Assessment. Principles, Practices and Applications, R.J. Shephard and H. Lavallée, Eds, Charles C Thomas, Springfield, IL, p. 238, 1978b.

ascertained in surveys A and B (see Tables 4.3a–g and 4.4). During the 1970s and 1980s, the acceleration of growth in the Czech Republic was minimal, which was also apparent in our group of preschoolers. The average BMI values in the last survey (D) were, in some cases, slightly lower than those in previous surveys.

4.4 LONGITUDINAL STUDIES OF CHILDREN FROM 3 TO 6 YEARS OF AGE Growth trends during the preschool period were followed up in a longitudinal investigation of children (boys n = 36, girls n = 22, survey E) who were available for further measurements during the period from 3.5 up to 6.0 years (Table 4.7a–d and Figure 4.1a and b). The children were first measured in the autumn when they started

75

Growth and Somatic Development of Preschool Children

TABLE 4.6a Anthropometric Variables in Preschool Children (n = 9587; Survey D) Age (Years)

n Height (cm) Weight (kg) BMI (kg/m2) Birth weight (g)

4–5

–x SE –x SE –x SE –x SE

5–6

6–7

Boys

Girls

Boys

Girls

Boys

Girls

1637 108.0 0.13 18.7 0.05 16.12 0.04 3412 12

1607 107.4 0.13 17.92 0.06 15.54 0.04 3276 12

2521 114.2 0.11 20.28 0.06 15.55 0.03 3399 10

2514 113.2 0.11 19.77 0.05 15.42 0.03 3257 9

665 117.8 0.20 21.59 0.12 15.55 0.06 3354 20

643 117.5 0.23 21.34 0.12 15.46 0.07 3245 18

Source: Compiled from Parˇ ízková, J., unpublished data, 1986–96.

TABLE 4.6b Somatic Development of Preschool Children (n = 1005; Survey D) Age (Years)

n Height (cm) Weight (kg) BMI (kg/m2) Circumference measures Chest (cm) Waist (cm) Hips (cm) Waist/Hip

4–5

–x SD –x SD –x SD –x SD –x SD –x SD –x SD

5–6

6–7

Boys

Girls

Boys

Girls

Boys

Girls

138 107.6 5.7 18.1 2.6 14.6 1.8

158 107.1 5.0 17.7 2.3 15.43 1.5

301 114.1 5.8 20.2 2.9 15.52 1.5

267 113.1 5.1 19.8 3.0 15.48 1.8

67 118.2 4.8 22.0 4.2 15.74 2.0

74 116.6 4.4 21.2 2.9 15.6 1.7

55.2 3.4 51.9 3.5 58.6 3.7 0.88 0.15

57.7 3.0 53.7 3.6 60.4 4.1 0.88 0.20

56.6 3.8 52.5 4.2 60.9 4.2 0.86 0.18

59.2 4.9 54.3 5.5 62.0 5.0 0.87 0.14

56.0 4.1 52.7 4.7 58.4 4.5 0.90 0.18

57.4 3.3 52.4 3.7 62.7 3.9 0.83 0.21

Source: Modified from Parˇ ízková, J., in World-Wide Variation in Physical Fitness, A.L. Classens, J. Lefèvre, and B. Vanden Eynde, Eds, Institute of Physical Education, Katholieke Universiteit, Leuven, Belgium, 1993, p. 131; Parˇ ízková, J., in Nutrition in Pregnancy and Growth, M. Porrini and P. Walter, Eds, Biblthca Nutr. Dieta No. 53, S. Karger, Basel–Freiburg–Paris–London– NewYork, etc., p. 109, 1996.

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TABLE 4.7a Height, Weight, Body Mass Index (BMI), and Sitting Height in Preschool Boys (n = 36) and Girls (n = 22) Followed Longitudinally Five Times (1–5; Survey E) Age (Years)

Height (cm)

Weight (kg)

BMI (kg/m2)

Sitting Height (cm)

Boys –x

3.487

102.0

16.72

16.07

57.9

SD

0.299

1.96

1.2

2.9

Girls –x

3.534

15.70

15.95

56.1

Measurement 1

2

3

4

5

SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

4.42 99.2

0.364

5.72

2.28

1.1

3.1

3.934 0.349

104.5 4.65

17.70 2.34

16.20 1.4

59.3 2.0

3.928 0.358

101.7 5.14

16.4 1.90

15.8 1.4

57.7 2.5

4.548 0.339

109.0 3.96

19.18 2.86

16.14 1.2

62.0 2.3

4.486 0.372

106.4 5.15

18.2 3.27

16.07 1.3

60.0 2.7

5.102 0.348

112.7 4.32

20.13 2.90

15.85 1.3

63.4 2.6

5.021 0.351

109.8 5.29

19.53 3.71

16.19 1.2

61.8 2.9

6.025 0.338

119.8 4.21

23.1 3.52

16.09 1.4

66.3 2.5

6.016 0.369

116.37 5.34

21.58 3.97

15.93 1.2

63.9 4.1

to visit two kindergartens in the surroundings of our laboratory. The characteristics of the children’s family, age of parents, number of siblings, economic standard of the family, health record, etc., did not differ significantly from the characteristics obtained in a cross-sectional sample of a larger number of children as described above (see Table 4.3a–g).

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TABLE 4.7b Length Measures on the Extremities in Boys and Girls Followed Longitudinally Five Times (1–5; Survey E)

Measurement 1

2

3

4

5

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

Upper Extremities (Total)

Acromionradiale

Radialestylion

Lower Extremities (Total)

42.5 2.9

17.3 2.0

13.5 1.0

57.0 2.8

26.1 1.6

21.7 1.7

40.9 2.1

16.8 1.1

13.0 1.0

5.0 3.0

25.5 1.9

21.4 2.2

43.9 2.1

17.9 0.9

14.2 0.8

58.4 3.2

29.4 2.0

21.9 1.3

42.0 2.4

17.0 1.1

13.8 0.8

57.3 3.6

28.7 2.2

20.1 1.4

46.0 2.2

18.8 1.0

14.7 1.0

61.7 2.7

31.1 2.0

23.1 1.1

44.0 2.5

18.2 1.0

14.3 1.3

60.2 3.4

30.4 1.9

21.7 1.5

47.8 2.3

19.6 1.7

15.2 0.9

64.2 2.6

32.4 1.8

23.2 1.2

45.6 2.4

18.9 1.0

14.6 1.4

62.8 3.4

31.9 2.0

22.5 1.5

50.9 4.6

21.0 2.4

16.6 1.0

67.3 11.7

35.3 2.0

25.0 1.2

48.2 2.8

20.1 1.1

15.6 0.8

67.2 3.3

34.1 1.9

24.1 1.6

Iliospinaletibiale

Tibialesphyrion

In particular, attention was focused on the changes in body build and composition as related to the development of functional capacity and motor abilities. By investigating the same children we tried to confirm the conclusions of cross-sectional surveys, therefore reducing the impact of the selection of certain somatic and functional types that may interfere with the evaluation of growth trends in different age groups in cross-sectional studies.

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TABLE 4.7c Breadth Measurements of the Trunk and the Extremities (cm) of Boys and Girls Followed Longitudinally Five Times (1–5; Survey E) Measurement 1

2

3

4

5

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

Chest Biacromial Bi-iliocristal Depth

Hand

Wrist

Humeral Femoral Condyle Condyle Ankle

23.2 1.0

16.9 0.8

12.7 0.8

5.2 1.0

3.8 0.2

4.4 0.2

7.1 0.3

5.1 0.3

22.9 1.2

16.5 1.0

12.0 0.8

5.2 0.4

3.5 0.7

3.8 0.7

6.8 1.2

4.8 1.2

23.7 1.4

17.5 1.0

12.9 0.7

5.3 0.6

4.0 0.5

4.6 0.2

7.1 0.4

5.2 0.3

23.5 1.1

17.0 0.8

12.3 0.8

5.3 0.4

3.6 0.2

4.3 0.2

6.7 0.3

4.9 0.4

24.6 1.0

18.0 1.2

13.2 0.9

5.9 0.7

4.0 0.3

4.7 0.3

7.3 0.4

5.4 0.3

24.5 1.3

17.6 1.1

12.6 1.0

5.5 0.3

3.8 0.2

4.6 0.6

6.9 0.4

5.2 0.3

25.2 1.0

18.5 1.0

13.1 0.7

5.9 0.4

4.1 0.2

4.8 0.3

7.5 0.3

5.6 0.3

24.9 1.4

18.0 0.9

12.6 1.2

5.4 0.7

3.9 0.2

4.5 0.6

7.0 0.5

5.2 0.4

26.4 1.5

19.4 1.5

13.6 0.8

5.9 0.6

4.2 0.2

5.0 0.2

7.7 0.4

5.7 0.3

26.0 1.2

18.5 1.1

12.9 1.2

5.5 0.6

4.0 0.3

4.7 0.2

7.0 0.7

5.3 0.4

Table 4.7a–d shows the changes in anthropometric variables during the mentioned period of development. The changes in BMI were reported above. All measures increased significantly. As indicated by the results of the cross-sectional study, the increments of different bodily dimensions varied markedly. Body weight increased by 20–24% and height by only 9–10% as compared to initial values. The breadth measurements of the trunk-biacromial and bicristal breadth also increased approximately to an almost equal extent. Head circumference increased by 1–2%, similar to the femoral condyles, which was the smallest of all. The length of the trunk increased

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TABLE 4.7d Circumferential Measurements (cm) in Boys and Girls Followed Longitudinally Five Times (1–5; Survey E) Measurement 1

2

3

4

5

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

Head

Neck

Chest

Waist

Arm

Forearm

Thigh

Calf

50.5 1.1

25.6 1.0

54.4 2.4

50.9 3.6

17.1 1.2

16.7 0.9

32.0 2.4

21.7 1.4

49.3 1.7

24.3 1.0

52.8 2.6

49.8 3.3

16.5 1.1

16.7 1.4

32.3 2.5

21.3 1.6

50.9 1.1

25.4 1.2

55.7 3.2

52.8 4.7

17.2 1.5

17.0 0.9

33.1 3.1

22.7 1.4

49.5 1.0

24.2 0.8

53.6 3.2

51.3 3.2

16.8 1.1

17.0 1.6

33.5 3.5

22.5 1.9

51.3 1.3

25.9 1.3

57.0 3.5

53.5 5.0

17.6 1.6

17.4 1.0

33.5 3.4

23.5 1.6

49.8 1.2

24.8 1.1

55.6 3.6

52.3 3.5

17.3 1.3

17.0 4.1

34.7 3.6

23.4 1.9

51.7 1.2

25.9 1.4

58.0 3.2

54.2 4.4

17.7 1.6

17.7 1.0

34.3 2.9

23.5 1.4

50.2 1.7

25.0 1.6

57.0 4.0

53.5 4.6

17.6 1.3

18.1 1.8

35.5 3.7

24.0 2.1

52.2 1.2

26.7 1.2

60.3 4.6

56.7 5.5

18.3 1.7

18.0 1.1

35.9 3.4

25.9 3.4

50.6 1.0

25.3 1.1

58.3 4.3

53.5 3.3

17.8 1.2

18.4 1.6

36.9 3.6

24.7 1.9

relatively less than the length of the lower extremities. This influenced the proportionality of body build, as also shown in the cross-sectional study. The average values of BMI fluctuated slightly at the 55–70th percentiles. Sex-linked differences were apparent, especially regarding height and weight. However, in this smaller group they were not significant, obviously due to larger variability. The same applied to the breadth of shoulders and pelvis (biacromial and bicristal breadths). Apart from this, there were sex-linked differences in sitting height, length of the upper extremities, depth of the chest, and circumferences of the

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TABLE 4.8 Somatic Development in Preschool Boys (n = 367) and Girls (n = 397) Followed Longitudinally [First Measurement, 4.4 Years (Boys) and 4.6 Years (Girls); Second Measurement, 1 Year Later; Third Measurement, 5.9 Years (Boys) and/or 6 Years (Girls)] (Survey F) 1 x– Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls

Measurement Height (cm) Weight (kg) BMI (kg/m2) Circumferences Chest (cm) Waist (cm) Arm (cm) Thigh (cm)

2 SD

x–

107.7 107.2 18.32 17.78 15.8 15.47

4.6 5.1 2.11 2.41 1.4 1.3

55.0 54.4 52.6 52.0 17.2 17.4 32.9 33.8

2.7 3.2 3.5 3.3 1.4 1.7 2.9 3.2

3 SD

x–

SD

115.4 116.0 20.11 19.10 15.02 14.20

3.0 3.4 1.15 1.32 1.5 1.4

118.8 118.5 22.49 22.31 15.93 15.89

2.8 3.0 1.15 1.17 1.3 1.6

59.0 59.9 55.4 54.9 18.1 18.2 — —

2.3 2.1 2.1 2.2 1.0 1.0 — —

59.0 56.9 55.3 55.0 18.3 18.9 34.2 36.0

3.1 3.3 2.3 2.2 0.8 1.0 3.1 3.1

Sources: Modified from Parˇ ízková, J. and Kábele, J., Acta Univ. Carol. Gymnica, 21, 55, 1985; Coll. Anthrop., 12, 67, 1988.

head and neck, where the values in boys were higher. Chest circumference was significantly greater in boys only during the first measurement. The increments of individual parameters between measurements were also evaluated; this showed the dynamics of development in boys and girls (Parˇ ízková and Adamec 1980). In general, the conclusions from longitudinal measurements were in agreement with the results of cross-sectional investigations mentioned above (Tables 4.3–4.6b), thus confirming the developmental trends during this growth period. A longitudinal investigation (survey F) was also made in 367 boys and 397 girls (Table 4.8) who were measured in different districts of the Czech Republic. In this case, only height, weight, BMI, and circumferential measures were evaluated. The results of the longitudinal measurements in this larger sample during about 1½ years revealed slightly lower BMI values than those in other groups of children, fluctuating again at approximately the 55th percentile. The average values corresponded roughly to the results of other mentioned investigations. The results of the circumferential measurements also showed similar trends of development as in the above-mentioned surveys.

Growth and Somatic Development of Preschool Children

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4.5 BODY COMPOSITION AND FAT PATTERN Preschool age is characterized by a number of changes in physique. There is a trend toward increasing linearity, which is partly reflected by BMI development. Changes in circumferential measures also indicate variations in different body components, mainly fat depot. A more exact evaluation of body fatness in young children using advanced methods has been conducted recently using bioimpedance analysis (BIA), DEXA, magnetic resonance imaging (MRI), and other methods. Body composition—leanness and fatness during early childhood—is also dependent on parental characteristics. As shown, for example, by the study of Harvey et al. (2007), taller women and those with higher parity had offspring with increased birth weight. Mothers who were taller, of greater parity, fatter, or walked more slowly also had fatter offspring at birth. Mothers with higher prepregnant BMI or a larger midupper arm circumference during pregnancy tended to have children with greater adiposity at the age of 9 years (Gale et al. 2007). The results of the study of Okosun et al. (2000) revealed that fetal programming has an important influence on birth weight and subcutaneous fat, especially central fat accumulation. The data of Singhal et al. (2003) support the hypothesis that fetal growth, evaluated by birth weight, programs lean body mass later in life. The association of birth weight with later BMI may have an implication not only for obesity development but also for cardiovascular problems. This was shown, for example, in the study of Finnish children: irrespective of size at birth, low weight gain during infancy was associated with increased risk of coronary heart disease. After the age of 1 year, rapid weight gain was associated with further risk, but only among boys who were thin at birth. In these boys the adverse effects of rapid weight gain on later coronary heart disease at the age of 3 years were already apparent. Positive interventions in fetal, infant, and child growth and development could lead to substantial reductions in the incidence of coronary heart disease later in life (Eriksson et al. 2001). The highest death rates from coronary heart disease occurred in boys who were thin at birth, but whose weight caught up so that they had from 7 years an average or above BMI. It is assumed that death from coronary heart disease may be a consequence of poor prenatal nutrition followed by improved postnatal nutrition (Eriksson et al. 1999). Higher birth weight was shown to be associated with greater subsequent lean body mass rather than fat mass. In contrast, lower birth weight was associated with a subsequent higher ratio of fat mass to lean body mass, and greater central fat deposition and insulin resistance. This was partly explained by the growth restraint during the fetal period, and then the subsequent trend to gain weight more rapidly and catch up after birth. This also results in greater central fat deposition. With regard to the critical period for the risk of childhood obesity, this will be aided by the identification of maternal and fetal genes that regulate fetal nutrition and development, and postnatal genes that regulate appetite, energy expenditure, and the partitioning of EI into fat or lean tissue development (Ong 2008, Ong et al. 2000, 2002). In connection with weight gain during early infancy, among rapid growers full breast-feeding for longer than 4 months is protective against increased body fatness at the age of 2 years, whereas a lasting high fat intake in the second year of life

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interferes with the physiological decrease of body fatness between the second and fifth years of age (Karaolis-Danckert et al. 2006, 2007). Rapid growth during infancy and early childhood results in an increased BMI and fat ratio throughout childhood, and an increased risk of overweight at the age of 7 years. Rapid growth has a more pronounced effect on fat ratio than on BMI. Birth size also independently predicted abdominal fat. Children with the highest amount of abdominal fat were those who tended to be born lighter, and gained weight centiles (Garnett et al. 2001), which later could be associated with the development of cardiovascular diseases. The effect of other factors was also considered with regard to abdominal adiposity, for example, the short sleep duration of children (Chaput and Tremblay 2007). With regard to the role of breast-feeding, a longer period of breast-feeding has been considered as a protective factor against increased adiposity later in life, but has not always been confirmed; in this respect a positive influence of addition factors has been considered. Fuertez-Dominguez et al. (1990) showed the influence of breastfeeding versus formula feeding—children fed with adapted formula had higher sums of skinfold thicknesses and fat percentage than children who were breast-fed. All other anthropometric variables, that is, length, weight, Rohrer’s index, etc., were not affected. Neither breast-feeding nor the timing of the introduction of complementary foods was associated with adiposity in another study of children at the age of 5 years (Burdette et al. 2006).

4.5.1

STUDY OF CZECH PRESCHOOLERS

In our follow-up of preschool children, it was possible to use mostly anthropometric methods, which enabled measurements in large population samples all over the Czech Republic, of which some were representative samples of the whole national population at the age of 6 years. Body density measurements with the help of underwater weighing along with the simultaneous assessment of air in the lungs and respiratory passages (Parˇ ízková 1959, 1961a,b, 1963, 1977) were possible only during school age. Groups of children from 7 to 16 years were followed up using this method. The utilization of this method and others for body composition assessments was reviewed by Lohman (1992). Only some children who were 7 years old were able to cooperate with the underwater weighing and the simultaneous assessment of air in the lungs and respiratory passages. This procedure requires good cooperation, no fear about submerging the head under water, and breathing control as instructed by the researcher. Therefore, other methods such as anthropometry, mainly skinfold thickness measurements (which correlate significantly with the percentage of body fat and enable the derivation of regression equations for the estimation of fat depot [Parˇ ízková 1961b, 1977]), are recommended for younger schoolchildren. More recently these relationships were again validated, and the prediction of total body fat was made possible in children 7–10 years of age (Weststrate and Duerenberg 1989). We may assume significant correlations between skinfolds and total body fat assessed by densitometry in preschool children, as indicated by the correlations between skinfold thicknesses and body fat measured by body water measurements

Growth and Somatic Development of Preschool Children

83

(Brook 1975), even when the regression equation may be different. Other methods for body composition measurements are mentioned in Chapter 8. As shown by previous studies, body fat varies markedly since the very beginning of life; the CVs of the skinfolds, measured during the first 48 h after birth and during the first year of life, were the same as those during later growth and adulthood (Parˇ ízková 1963, 1977). At birth, there were already significant sex-linked differences (e.g., a significantly larger suprailiac skinfold in newborn girls) and marked differences among normal, full-term, and preterm children and/or children born from diabetic mothers (Parˇ ízková 1963, 1977). Subcutaneous fat varies markedly during the first year of life; there is first a significant increase and later a decrease, especially at the age of about 10 months and older. At that time, children start to walk independently and generally engage in more PA. A follow-up of the influence of breast-feeding in all our samples was difficult, as the weaning age was at that time generally earlier in our children than in those of other countries, and the transition to complementary solid food was gradual: children had mixed diets during various periods. Only in survey A did we obtain some information on the duration of breast-feeding. The transition to family food was mostly mixed and gradual, that is, children were breast-fed and they also consumed partly beikost food. Breast-feeding has been recently changing in the Czech Republic as elsewhere, because more mothers are presently involved in breastfeeding than before. The influence of early weaning in our child population (about 30% of infants are breast-fed at the age of 3 months and about 10% at the age of 6 months) may also be manifested in both BMI and fatness. The development of fat was followed up in our study by measurements of 10 skinfold thicknesses using two types of calipers. First, we used a modified caliper designed by Best (1954), which varies from other calipers in the size of contact surfaces and the pressure exerted on the measured skinfold (Parˇ ízková 1961b, 1977). This type of caliper was selected because it is the only one that makes it possible to check and adjust the pressure exerted on the measured skinfold. This is important when measuring very young children, especially newborns, because the pressure of other calipers continues, the read value decreases for a longer period, and it is difficult to assess when to read the decisive value. The modified caliper is easy to set and rectify after longer measurements; it also has a greater range of measured values, making it possible to measure grossly obese subjects where the range of other calipers is not sufficient. The Harpenden caliper (Tanner 1962, Parˇ ízková 1977), which has similar characteristics and therefore gives values comparable to the Lange caliper, was also used for measurements of five skinfolds on the right and left sides. The selection of skinfolds was meant to characterize the development of subcutaneous fat on the cheek, neck, trunk, and extremities. In selected surveys (A and C), the percentage of fat depot was also evaluated using Brook’s formula and Harpenden caliper values. BIA was available for our research from the beginning of the 1990s. Without validation for children 3–6 years old, we preferred to continue body composition estimations using skinfold thickness measurements. As shown by Bláha and Vignerová (2004) and Bláha et al. (2001, 2003), usual regression equations for the evaluation of fat from BIA do not give reliable results for younger children (see Chapter 8).

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Changes in individual skinfolds (as measured by the modified Best caliper [1954]) with increasing age are presented in Figure 4.2a–d. This overall trend is characterized by a decrease in the subcutaneous fat layer in boys. This is most apparent when we compare the values associated with the sum of skinfolds measured using both calipers in the youngest and oldest boys. In girls there is a stagnation in the sum of all skinfolds. At certain sites (under the chin, on the chest, in the abdomen, and in the suprailiac) there is a slight increase, but at other sites the skinfolds diminish (cheek, chest, triceps, subscapular skinfolds). The deposition of subcutaneous fat is greater in the cheek and in the extremities than in the trunk, which differs from the older age categories starting with puberty. When estimating the fat ratio from skinfolds (Parˇ ízková 1977), its value decreased from about 14–13% to 11–10% in boys, remaining at about 16% in girls. There is always more subcutaneous fat in girls, that is, in practically all cases the values of skinfolds are higher (Figure 4.2a–d). The differences are more apparent in the trunk. The sex-linked difference in the amount of subcutaneous fat is, however, manifested immediately after birth, increasing later. (The relatively greatest differences between sexes appear at the time of puberty; Parˇ ízková 1961a,b, 1963, 1977.) Skinfold thicknesses measured by the Harpenden caliper (Table 4.9a) vary from the values ascertained by the modified Best caliper, which results from different parameters of the calipers. (It is possible to convert the results assessed by one caliper to the results corresponding to measurements by another caliper; Parˇ ízková 1977.) This gives the researcher an opportunity to compare data assessed by different calipers. Measurements by an Harpenden caliper give higher values on the left side as compared to the right side. In our group the number of left-sided children was low and laterality was not accomplished; nevertheless, the more loaded side of the body had a smaller layer of subcutaneous fat (Table 4.9b). The fat pattern and distribution was evaluated with the help of indices relating skinfolds on the trunk to those on the extremities—that is, the subscapular/triceps skinfold ratio (centrality index), including all skinfolds on the trunk to all skinfolds on the extreities (cheek + chin + triceps + thigh + calf/chest 1 + 2, subscapular + abdomen + suprailiac skinfolds). As is evident from the average values (Figure 4.3a–c), the fat pattern does not change markedly during the period of preschool age. The centrality index decreased slightly from 3 to 5 years and then increased again at the age of 6 in boys and in girls when the skinfolds were measured using a modified Best caliper. The trend in the changes of the same index, calculated from the values of skinfolds measured by the Harpenden caliper, is the same in girls, but there is a decrease in boys. The evaluation of the second index (relating all skinfolds measured on the trunk and on the extremities) revealed a small fluctuation in boys and an increase in girls (Figure 4.3a–c). When we measured five skinfolds by the Harpenden caliper in the longitudinal study (survey E), covering a similar growth period, a decrease in the sum of all skinfolds was again found for boys and a stagnation of values for girls (Table 4.10). Repeated measurements of skinfolds in the same children confirmed the conclusions based on cross-sectional measurements of subcutaneous fat. The centrality index changed very slightly in both boys and girls, that is, the fat pattern remained more or

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Growth and Somatic Development of Preschool Children

TABLE 4.9a Skinfold Thicknesses (mm) Measured by the Harpenden Caliper at Five Sites (Right, Left Sides) in Preschool Children (Survey A) Triceps

Age (Years) 3–4 4–5 5–6 6–7

x– Right Boys

Subscapular

SD

x–

9.2

2.9

Girls

10.3

Boys

8.8

Girls

Suprailiac

SD

x–

4.2

1.9

3.1

4.6

2.0

3.2

10.0

2.9

Boys

8.6

Girls

Calf

SD

x–

2.6

1.9

2.3

3.4

0.6

2.1

3.7

1.2

2.5

3.3

8.9

2.7

Boys

6.3

Girls

Biceps SD

x–

SD

3.8

2.0

3.0

1.8

3.0

4.7

2.0

2.9

1.7

1.5

3.3

1.2

2.7

1.0

3.1

1.8

4.3

1.7

2.7

1.4

1.5

2.5

1.9

3.9

2.2

2.4

0.9

3.3

1.0

2.0

0.8

2.7

1.1

2.3

0.9

1.9

2.8

0.3

1.7

0.3

2.5

1.1

1.8

0.9

9.5

2.6

4.2

2.3

3.8

3.6

4.0

2.2

2.8

1.6

Boys

9.5

2.6

5.7

2.1

4.2

1.7

5.1

1.7

4.6

1.5

Girls

10.0

2.4

6.0

2.0

5.2

2.5

5.9

1.8

4.5

1.2

Boys

9.2

1.9

4.6

0.6

3.6

1.2

4.6

1.0

4.4

1.1

Girls

10.1

2.4

5.2

1.1

4.7

1.7

5.7

1.5

4.5

1.0

Boys

8.9

1.9

4.8

1.6

4.0

1.7

5.2

2.1

3.9

0.7

Girls

8.8

2.1

4.8

0.8

3.5

0.9

4.4

0.8

4.0

1.0

Boys

7.2

1.7

4.0

0.4

3.0

0.6

4.0

1.0

2.9

0.6

Girls

9.4

2.0

5.6

2.3

4.9

3.2

5.0

1.8

4.2

1.2

Left 3–4 4–5 5–6 6–7

less the same during preschool years. As mentioned above, genetic factors have an impact on fat distribution, as shown by longitudinal studies (Kaplowitz et al. 1988, Parˇ ízková 1977). A comparison of the average values of the individual skinfold thicknesses measured in the late 1950s (Parˇ ízková 1961a,b, 1963, 1977) and in the present studies did not show an increase of subcutaneous fat in preschool children. An increase, however, was seen for children between the ages of 4.5 and 11.99 years in the United Kingdom measured in 1972, 1982, and 1990; these changes were associated with an increase in parental BMIs and a decrease in family size (Boyd 1962).

4.6 SOMATOTYPES The somatotype is a description of the morphological state of an individual at a given moment. It is expressed using a three-digit evaluation comprised of three consecutive numbers always listed in the same order. Each number represents the evaluation of one of the three basic components of the figure and expresses individual variations

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Nutrition, Physical Activity, and Health in Early Life

TABLE 4.9b Sum of Skinfolds (n = 10, 11, 5 mm) Measured by Different Calipers (Modified Best, Harpenden) in Preschool Children (Survey A) Skinfolds (mm)

Age (Years) 3–4

4–5

5–6

6–7

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

10

11

5

5

Best Right

Best Right

Harpenden Right

Harpenden Left

47.1 17.5

50.5 19.2

23.0 9.5

29.2 8.7

53.3 18.8

56.5 20.1

26.0 10.9

31.8 9.0

41.6 9.6

44.6 10.3

20.4 4.1

26.6 4.4

50.1 11.9

53.3 12.7

24.6 7.8

30.3 6.7

43.1 17.0

46.1 18.3

20.7 8.1

26.6 7.0

46.6 15.0

49.8 16.3

19.4 5.1

25.7 5.0

38.3 10.1

40.9 10.7

15.9 3.6

20.9 3.7

49.3 18.1

52.7 18.9

24.5 11.1

29.1 9.6

Note: 1, cheek; 2, under the chin; 3 and 4, thorax (1 and 2); 5, triceps; 6, subscapular; 7, abdomen; 8, suprailiac; 9, thigh above the knee; 10, calf; 11, biceps. Sum of 10 skinfolds: 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10. Sum of 11 skinfolds: sum of 10 + 11. Sum of 5 skinfolds: 5 + 6 + 8 + 10 + 11.

in the morphology and composition of the human body. The procedure by Heath and Carter (1967, 1990) was used. The first component, endomorphy, relates to the relative adiposity of subjects; it also relates to thinness. This means that endomorphy expresses the amount of subcutaneous fat on a continuum from the lowest to the highest values.

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Growth and Somatic Development of Preschool Children

TABLE 4.10 Skinfold Thicknesses (mm) Measured Longitudinally Five Times by the Harpenden Caliper in Preschool Children (Survey E) Measurement 1

2

3

4

5

Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD Boys –x SD Girls –x SD

Triceps

Subscapular

Suprailiac

Calf

9.5 2.6

5.6 2.0

4.3 1.7

5.1 1.8

10.0 2.4

6.1 1.9

5.2 2.5

6.0 1.8

9.3 3.5

5.3 1.9

4.5 3.4

4.9 2.2

10.0 2.8

5.9 1.9

4.5 3.4

4.9 2.2

8.9 3.2

5.5 2.7

4.6 3.4

4.8 2.3

9.7 2.7

6.3 3.7

4.9 3.0

5.5 2.1

8.2 2.7

5.0 2.3

4.1 3.5

4.3 2.2

9.8 3.1

6.5 4.6

4.1 3.0

5.2 2.1

8.3 3.3

5.5 3.2

4.4 3.3

4.3 2.1

10.0 3.3

6.4 4.6

5.0 3.8

5.3 2.3

Note: See also Table 4.7a–c.

The second component, mesomorphy, relates to the relative skeletal muscle development in relation to height. It appraises skeletal muscle development on a continuum from the lowest to the highest values. Mesomorphy may be considered as lean body mass in relation to height. The third component, ectomorphy, relates to the relative length of parts of the body. Assessment of the third component is based mainly on the index of the ratio of height to the cubic root of body weight. This index and the assessment of the ectomorphic component are closely related. The lower end of the range implies

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Nutrition, Physical Activity, and Health in Early Life

the relative shortness of various bodily dimensions and the upper end implies the relative length of various bodily dimensions. The extreme values are at the end of each series (a continuum). This means that a low value of the endomorphic component describes an individual with a small amount of body fat, while a high value describes an individual with a large amount of fat. A low value of the mesomorphic component describes an individual with a small frame and poorly developed musculature, while a high value of this component implies marked muscular development. A low value of the ectomorphic component describes an individual with relatively short extremities and a low ratio of height divided by cube root of weight (HWR), while a high value of this component describes an individual with relatively long extremities and relatively long segments of the whole body with a high index. The following data are needed for ratings: height, weight, four skinfolds (triceps, subscapular, suprailiac, and calf), two bone diameters (humerus and femur), two muscle ______circumferences (calf and flexed arm), age, and revised HWR table (height 3 √weight ). The usual form for the evaluation of somatotype, as presented by Heath and Carter, was used for preschool children, that is, for our longitudinal study (boys n = 38, girls n = 22, survey E; see Table 4.7a–d), and then also on the occasion of the second measurement of 367 boys and 397 girls measured in different districts of the Czech Republic (survey F; see Table 4.8). There was no experience with the somatotype method in preschool children. The mean values of somatotypes evaluated in our longitudinal survey E are given in Table 4.11a. The dominant component in preschool age is the mesomorphic one. From 3 to 6 years there is a slight declining trend as regards the mesomorphic

TABLE 4.11a Somatotypes Measured Longitudinally Five Times in Preschool Children (Survey E) Components Endomorphy Measurement 1 2 3 4 5

Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls

x– 1.50 2.31 1.37 2.12 1.39 2.20 1.21 2.06 1.28 2.11

Mesomorphy

Ectomorphy

SD

x–

SD

x–

SD

0.60 0.87 0.86 1.04 1.05 1.03 1.02 1.18 1.30 1.08

5.64 5.50 5.45 5.59 5.33 5.43 5.08 5.19 5.03 4.88

0.49 0.79 0.66 0.66 0.71 0.79 0.78 0.83 0.74 0.54

1.22 1.06 1.37 1.19 1.74 1.47 2.09 1.62 2.25 2.15

0.56 0.57 0.53 0.54 0.78 0.79 0.73 0.82 0.94 0.82

Source: Compiled from Parˇ ízková, J. et al., Humanbiol. Budapest, 16, 113, 1985.

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TABLE 4.11b Somatotypes Evaluated on the Occasion of the Second Measurement of a Longitudinal Study of 367 Boys and 397 Girls, at the Age of 5.4 Years (Boys) and 5.6 Years (Girls) (Survey F) Components Endomorphy Measurement 2

Boys Girls

x– 1.74 1.81

Mesomorphy

Ectomorphy

SD

x–

SD

x–

SD

0.23 0.37

5.06 5.15

0.64 0.79

2.54 2.67

0.31 0.41

Sources: Modified from Parˇ ízková, J. and Kábele, J., Acta Univ. Carol. Gymnica, 21, 55, 1985; Coll. Anthrop., 12, 67, 1988. Note: See Table 4.8.

component. The ectomorphic one is slightly increasing. This is more evident in some subjects compared to others. The endomorphic component from 3 to 6 years changed relatively little in both boys and girls. With regard to sex-linked differences, the values of the endomorphic component in girls were, on average, higher (see Table 4.11a). The values of ectomorphic and mesomorphic components were higher in boys. Sex-linked differences in mesomorphic and ectomorphic components were small and insignificant; in endomorphic components, they were significant in all measurements. Table 4.11b shows the mean values of somatotypes in children 5 years and 4 months old (survey F) who could be assessed at only the second measurement. As the age of these children was just between the age of the fourth and fifth measurements of the previous follow-up (study E), it is difficult to compare the results directly. However, the values of the mesomorphic component did not differ markedly. The endomorphic component was lower in study F, made later than study E, and the reverse applies to the ectomorphic component, which seemed to be higher. These results correspond to other trends evaluated when comparing children measured in our country earlier (beginning of the 1970s) and more recently (end of the 1980s), as a slightly higher level of ectomorphy runs parallel to slenderization of our children from 3 to 6 years.

4.7 BODY POSTURE Body posture is one of the most important morphological characteristics and can become quite a health problem in all age categories in industrially developed countries. Back pain in middle-aged subjects or even in younger adolesent ones is often observed. It is probably one of the most common complaints in the majority of any population, especially in industrially developed countries. Generally, it is assumed that deterioration of body posture starts to develop during school age when children have to sit for hours on school benches; however, even the

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level of spontaneous activity of children is decreasing. This was also revealed with an evaluation of the level of spontaneous PA assessed in the same children, which decreased just around entering primary school. Surprisingly, this reduction in PA concerned not only the daytime spent at school but also the leisure time during afternoons and during weekends (Parˇ ízková and Hainer 1990, Sigmund et al. 2008). For the evaluation of body posture, a simple scale was chosen that enabled assessment in larger population samples under field conditions. This procedure was developed by Jaroš and Lomíˇcek (see Parˇ ízková et al. 1984). During the evaluation, we first asked the child, “Show how you can stand up before the start of exercise!” The child’s posture was evaluated from the profile and from the back. If the child stood up in a stiff manner, he/she was asked to perform some simple exercises or to say something about his/her family, etc. During the evaluation, different signs were marked on the record card in three grades (1–3; see Appendix 1). The depth of cervical and lumbar lordosis was given in centimeters of the deviation from a plummet dropped from the back of the child’s nape. In some instances, evaluation of the abdominal wall was facilitated by dropping a plummet from the breastbone. The lowest score (1) was the best, and the highest score (3) was the poorest. Not only was the ratio of different grades in boys and girls in individual age groups used, but also average values that made the statistical evaluation easier. First we evaluated body posture in the cross-sectional study of 3–6-year-old children in Prague (n = 238, survey A). The position of the neck (Table 4.12) was most frequently evaluated by grade 1 followed by grade 2; the worst score was only observed exceptionally. There was a trend toward somewhat poorer results in girls, but a significant difference was only recorded in 5–6-year-old children. The position of the back and the evaluation of the outline of the abdomen were worse; grade 2 predominated. There was a somewhat poorer trend in girls. Score 3 was again observed exceptionally. The depth of cervical and lumbar lordosis was evaluated in centimeters. Mean values are given in Table 4.12. There was a trend toward higher values in girls. The position of the shoulders and back was expressed by grades 1–3, with the average value expressing the mean grade. No marked sex-linked differences were found. An evaluation of the shape of the spine from the back view in a standing position and when bent forward shows markedly better results in girls when evaluated bent forward. These results are, in almost every age group, statistically significant. In both types of evaluations, spine grade 1 predominates, which demonstrates the most favorable result. Worst results were recorded when evaluating the position of the back (view from profile) where grade 2 was most frequent. The same applied to the outline of the abdomen. The average evaluation of the position of the shoulders (view from back) was not favorable either: grade 2 was less frequent than in the case of the back and spine. The frequency of grade 3 was a total of 7.4% of all cases, which implies a markedly impaired position of the shoulders. At this young age, the impaired position of the spine was not yet associated with the impaired shape of the spine; however, from the prognostic aspect, it is possible that the development of mild and later more severe scoliosis may be foreseen unless a marked improvement occurred soon.

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TABLE 4.12 Body Posture in Preschool Children (Survey A) Age (Years) 3–4

Neck Back Abdomen Cervical lordosis Lumbar lordosis Shoulders Scapulae Spine 1 Spine 2

–x SD –x SD –x SD –x SD –x SD –x SD –x SD –x SD –x SD

4–5

5–6

6–7

Boys

Girls

Boys

Girls

Boys

Girls

Boys

Girls

1.06 0.4 1.79 0.48 1.56 0.61 2.69 0.62 2.62 0.78 1.53 0.56 1.62 0.55 1.24 0.43 1.03 0.17

1.13 0.34 1.65 0.45 1.74 0.45 2.87 0.07 2.97 0.68 1.35 0.48 1.43 0.50 1.00 0.00 1.00 0.00

1.48 0.51 1.74 0.45 1.96 0.36 2.91 0.75 2.2 0.76 1.91 0.59 1.73 0.45 1.30 0.47 1.13 0.34

1.54 0.51 1.88 0.34 1.67 0.48 3.10 0.66 2.33 0.54 1.71 0.62 1.63 0.57 1.08 0.28 1.00 0.00

1.50 0.51 0.77 0.50 1.77 0.43 3.25 0.66 2.37 0.78 1.73 0.52 1.60 0.50 1.17 0.38 1.13 0.34

1.80 0.50 2.00 0.29 1.8 0.50 3.50 0.94 2.56 1.04 1.88 0.72 1.72 0.68 1.44 0.58 1.08 0.27

1.60 0.50 2.07 0.46 1.80 0.41 3.30 0.75 3.0 0.50 1.60 0.50 1.73 0.59 1.07 0.26 1.13 0.35

1.75 0.44 2.19 0.40 1.94 0.44 3.31 0.47 3.06 0.77 1.88 0.62 1.56 0.51 1.13 0.34 1.00 0.00

Note: 1, best; 3, poorest level; depth of cervical and lumbar lordosis in cm; spine 1, evaluated in erect position; spine 2, when bent forward.

The above-mentioned deviations are obviously due to an impaired and inadequate muscular tonus, as also indicated by the outline of the abdominal wall, suggesting general marked flabbiness of the musculature. Protruding scapulae and an increased lumbar lordosis are other consequences of an inadequate muscular tonus, resulting from inadequate and reduced PA. A comparison of different age groups indicates that posture further deteriorates with advancing age from 3 to 6 years. The depth of cervical and lumbar lordosis increases significantly and persists, based on a comparison of the youngest age group (3–4 years) and the oldest one (6–7 years). This increase in the depth of lordosis is associated not only with the generally increasing bodily dimensions, but also with further deterioration of body posture with age. This is apparent in particular from the comparison of the youngest and oldest children regarding the position of the neck and the outline of the back, shoulders, and abdomen. The older the child, the poorer the posture. This applies to both girls and boys. It may be assumed that during school years body posture deteriorates even more, especially in children who do not take part in regular exercise.

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TABLE 4.13 Body Posture in 5598 Preschool Boys and Girls (Survey B) Boys

Neck (grade) Back (grade) Abdomen (grade) Cervical lordosis (cm) Lumbar lordosis (cm) Shoulders (grade) Scapulae (grade) Spine 1 (grade) Spine 2 (grade)

x– 1.28 1.55 1.68 2.0 3.0 1.28 1.40 1.24 1.28

Girls SD

x–

SD

0.47 0.54 0.51 1.00 0.90 0.49 0.45 0.45 0.47

1.34 1.47 1.69 2.00 3.00 1.26 1.31 1.17 1.23

0.49 0.54 0.52 1.00 1.00 0.49 0.49 0.44 0.44

Note: See Table 4.4.

In a large sample of 2839 boys and 2759 girls aged 6.4 years (survey B), body posture was also evaluated (Table 4.13). The results varied: in some items the results were better in boys (neck, abdomen); in others there were no differences (e.g., depth of cervical and lumbar lordosis). In some instances girls had better results (outline of the scapulae, shoulders, shape of the spine). There were also some differences related to environmental conditions (see Chapter 9). A comparison of the results from our study with those assembled in the 1950s revealed that the mean value of cervical and lumbar lordosis increased and that new standards must be elaborated (Parˇ ízková et al. 1984). The changes were partly due to accelerated somatic development and to the increase in bodily dimensions of children equal in age, then and now; however, the generally greater weakness of skeletal muscles resulting from lifestyle changes—especially from a reduced opportunity for spontaneous games and outdoor exercise—is considered as the main cause of poor body posture. This is more marked in larger urban agglomerations than in smaller communities (see Chapter 9). We wanted to validate findings on the deterioration of body posture during preschool years by longitudinal observations of the same groups of children. Therefore, some of the children were followed up further (survey E, n = 58; see Tables 4.7a–d, 4.10, and 4.11a). Body posture was evaluated using the procedure of Jaroš and Lomíˇcek (see Parˇ ízková et al. 1984). Longitudinal observations confirmed the above-mentioned results and conclusions: with advancing age, body posture deteriorated in the same children in all the items mentioned above. An unequal level of the shoulders and protruding scapulae and abdominal wall, as compared to the thorax, were found in a greater proportion of children during the last measurement at the age of 6 years and more frequently than during the first measurement, that is, at the age of 3 years (Parˇ ízková et al. 1986). Deteriorated body posture, due mainly to inadequate muscle tone, resulting from insufficient motor stimulation and a lack of exercise during preschool years, deserves

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much greater attention than it has had up to now. Deterioration of the position of the vertebral column, inadequate position of the thorax, etc., influence the function of the lungs, heart, etc., and may have an effect, inter alia, on cardiorespiratory efficiency. Adequate measures for the prevention of poor body posture, or at least a reduction in its deterioration, have to start sooner than was originally assumed, as it very probably accentuates further during school years and later on. For this reason, a proper system of motor stimulation and exercise should be introduced as early as possible.

4.8 RELATIONSHIP BETWEEN HEIGHTS AND WEIGHTS OF PARENTS AND ANTHROPOMETRIC VARIABLES OF PRESCHOOL CHILDREN In survey A, the heights and weights of parents of children from day-care centers were also assessed. In both parents, significant relationships between the total height of the father and mother, on the one hand, and the total and sitting height and length measures of the extremities (acromion-radiale and iliospinale-tibiale) of boys and girls from 3 to 6 years, on the other hand, were most often found. Correlations were much more frequent between the anthropometric variables of children and the height and weight of the mother than between those of the father. The height of the father correlated significantly with the child’s total and sitting height, weight, and waist circumference. The weight of the father correlated significantly with the child’s total and sitting height, waist circumference, and bi-iliocristal and femoral condyle breadths. The height of the mother correlated significantly with the child’s total and sitting height, weight, circumferences of the head, neck, abdomen, forearm, thigh, and calf, and biacromial, bi-iliocristal, hand, femoral condyle, and ankle breadths. The weight of the mother correlated significantly with total and sitting height, weight, circumferences of the neck, chest, abdomen, arm, forearm, thigh, and calf, and biacromial, bi-iliocristal, hand, femoral condyle, and ankle breadths. The relationships were weak (r = 0.2–0.39) but significant (mostly p < 0.01) and consistent, both in the whole sample and in individual age groups of boys and girls. In age and sex subgroups these relationships were similar, except for lower significance due to the smaller number of analyzed individuals (Parˇ ízková et al. 1984). Fat patterning also correlated significantly between mothers and children 2–5 years old (see Chapter 3, Table 3.6) along with other morphological parameters.

4.9 OTHER SURVEYS As mentioned above, surveys on growth and development have been conducted in many populations, especially in the United States and Europe (e.g., Rolland-Cachera et al., 1984, 1988, 1991; National Center for Health Statistics, National Center for Chronic Disease Prevention and Health Promotion 2000, USA). Efforts for developing local growth standards continue in more countries. Numerous longitudinal studies revealed that the earlier a child develops a certain degree of fat depot ratio, the more possible that he/she will be fat later on in life; for

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example, Siervogel et al. (1991) showed that weight/stature2 at an early age correlates significantly with that at the age of 18 years. Rolland-Cachera (1995) and RollandCachera et al. (1984, 1986, 1988, 1990, 1991, 1995) concluded the same on the basis of evaluations in her longitudinal studies of BMI. As reviewed by Kuczmarski et al. (1994), the increasing prevalence of obesity among U.S. adolescents and adults shown in the National Health and Nutrition Examination Surveys 1960–1991 indicates that the prevention of obesity early in life has become even more urgent than before. This trend was also confirmed by the following studies during later years. Wilson et al. (1991) found no relationships between nutritional indicators (BMI, skinfolds, waist/hip ratio, height, weight) and dietary intake (energy, protein, fat, carbohydrates) in adolescents; the possible effect of the level of PA was not analyzed. However, children within normal nutritional status were followed up in this study, so there is a question of how these relationships would manifest when malnourished and/or obese children were included. Preschool children were not followed up in other studies. As mentioned before (Chapter 3), longitudinal studies of French children led to the conclusion that the early production of IGF-1 triggering cell multiplication in all tissues precociously shows a positive association with an increased intake of protein in early childhood (Rolland-Cachera et al. 1995). This is consistent with the acceleration of maturity in obese children, in which early rebound of BMI and adiposity (AR) were observed. On the other hand, when dietary intake is reduced, the plasma concentration of growth hormones is increased while IGF-1 is decreased. Excess protein intake in early childhood causes obvious chronic increases in IGF-1, which reduces growth hormone levels and slows down growth in the obese (RollandCachera 1995, Rolland-Cachera et al. 1995). However, some other studies that were arranged differently in some respects did not confirm the role of relatively increased protein intake at the beginning of life with regard to adiposity at the age of 10 years (Hainer et al. 2004).

4.10 GENERAL CONSIDERATIONS Growth and development during preschool age are characterized by differentiated changes in individual anthropometric variables, which are related to parental characteristics, early dietary intake and its composition resulting from various environments, and size of early weight gains especially during the period of AR. Greatest changes from 3–4 to 6–7 years occur in length dimensions and in body weight. Breadth and circumferential measurements on the trunk and extremities change relatively less. The smallest change occurs in head circumference, which also shows smallest interindividual variability. Body proportionality also changes significantly. Body fat is the only variable that stagnates (in girls) or decreases (in boys); fat patterns remain nearly the same, similar to the somatotype. All these morphological changes are related to variations of functional development during that period. Sex-linked differences are already evident in a number of variables. Body posture already starts to deteriorate during the preschool period. This was confirmed by both cross-sectional and longitudinal measurements. Anthropometric

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variables of children are significantly related to the height and weight of parents, showing genetic predispositions in preschool children similar to the fat pattern mentioned in Chapter 3. When comparing the results of the measurements at the beginning of the 1970s and at the end of the 1980s, there was a trend toward slight growth acceleration and the slenderization of preschoolers. Skinfold thicknesses did not change markedly. BMI values, especially those from the beginning of the 1970s, were higher than those evaluated in Czech children in 1895, or than BMI values of French or U.S. children. As mentioned above, all these findings refer to the population of young children living under stable social, nutritional, and lifestyle conditions. More detailed data enabling complex evaluation of the somatic development of preschool children as related to their functional capacity are still needed.

5

Nutritional Status and Dietary Intake in Early Life

5.1 INTRODUCTION Food intake corresponding to one’s needs is a prerequisite for adequate growth and development as well as for desirable nutritional status, a condition for an adequate level of functional capacity and fitness. All of this applies even more to early childhood. Food intake in all age categories has been recommended mainly using dietary guidelines, which have undergone quite an evolution during history. Already over the ages, advice on eating behavior, food choices, and food preparation has been incorporated into philosophical and religious writings. Over the past 150 years, recommended dietary allowances (RDAs) have been based on scientific knowledge related to public health. During the first half of the last century, the focus was on prevention of nutrition deficiency diseases, but during the second half the attention shifted to prevention of chronic diseases and excess intakes that increase disease risks. Current guidelines also consider lifestyle (including PA) and food choices and preferences (including saturated fat, individual nutrients, and fiber). Recommendations have become more food based, as elaborated by the Food and Agricultural Organization (FAO) and the World Health Organization (WHO). A framework for food-based dietary guidelines in the European Union (EU) was also prepared (Sandström 2001). Considerable development with regard to dietary recommendations has occurred (Mertz 2000, Meacham et al. 2002, Millward 2004). The scope of RDAs has markedly expanded since their first edition in 1941, and their re-evaluation has had far-reaching applications to human health and agricultural practices. The American Dietetic Association suggested dietary guidance for healthy children also at the age of 2–11 years (Nicklas et al. 2004). Dietary reference intakes (DRIs) as resulting documents have been released over a number of years from 1997 to 2003, and later (Nestle Pediatric Nutrition Workshop 2006), for both North America and the EU. Another version of DRI was last modified in 2008. However, the evaluation of dietary intakes and individual nutritional surveys, and their comparison among different groups and nations over time are still problematic and not quite reliable. An analysis of 79 surveys from 23 countries, for example, showed that collection methods, representativeness of samples, use of different food composition and conversion tables, and other additional differences showed a lack of standardization. This can make comparisons and conclusions difficult and inaccurate (Lambert et al. 2004). Local studies in well-defined population groups that use 97

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validated local methods, food composition tables based on local food composition data analysis, etc., can give some information on the adequacy of diet. “How much is enough” (Widdowson 1983, Waterlow et al. 1992, Waterlow and Schu˝rch 1993) (too little and/or too much) is difficult to define. From the beginning of life, “nutritional individuality” (Widdowson 1962a,b) is manifested in newborns and infants. Pediatricians claim that newborns already behave in a different way during the first breast-feeding (the same applies to motor activity, crying, etc.). Some newborns accept the mother’s breast quietly, drinking enough milk, while others often refuse an adequate amount. These characteristics often persist and are manifested even more markedly later in life. During the first year of life, variability in both absolute and relative energy intake (EI) in infants was shown. Black et al. (1983) showed that the variation coefficients in the EI of infants from 2 to 18 months were between 16.9–23.3% (between subjects) and 10.6–18.1% (within subjects). Bellu et al. (1995) also showed a great variability of EI in Italian infants. Intra- and interindividual variability ratios were found to be even greater than 1. “Sensitive or critical periods” (Dietz 1994) exist in the first 2 or 3 years of life, during which humans acquire a basic knowledge of foods that are safe to eat. Cashdan (1994) showed that the willingness to eat a variety of foods is greatest between the ages of 1 and 2 years, declining to lower levels at 4 years of age. As shown in a longitudinal follow-up of twins from 4 to 10 years, eating behaviors, including those associated with a tendency to over-eat, emerge early in life, and show levels of individual continuity comparable to stable personality traits. Appetitive traits related to higher satiety tended to decrease later with maturation, while those associated with food responsiveness tended to increase. This pattern is consistent with strong tracking of BMI simultaneously with increasing obesity risk (Ashcroft et al. 2008). These observations imply the possibility of positively affecting the food choice early in life, with desirable delayed consequences and advantages. But also, the reverse can occur, with negative eating behavior in later life. The requirements for energy and protein of children are similarly specified for all other age categories; adhering to the RDAs, which correspond to the actual needs of the growing organism, is also essential in light of the future development of health. Presented information on RDAs for energy, macrocomponents, minerals, and vitamins was selected with respect to early age (WHO 1985, 1990a,b, 1997a,b, Nutrient and Energy Intakes for the European Community 1993).

5.2 ENERGY REQUIREMENTS The energy requirement of an individual relates to the level of EI from food, which will balance energy expenditure when the individual has body size and composition, and the level of PA consistent with long-term good health. This will allow for the maintenance of necessary and socially desirable PA. In children and in pregnant and lactating women, the energy requirement includes the energy needs associated with the deposition of tissues or with the secretion of milk at rates consistent with good health. This is a definition that the WHO presented in the Report of a Joint FAO/ WHO/UNU (Food and Agricultural Organization and United Nations University)

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Expert Committee, which met at FAO in Rome in 1981, and was then published by WHO in Geneva in 1985. It was also confirmed in the Report of the Scientific Committee for Food, Nutrient, and Energy Intakes for the European Community (EC) (1993). Very few important modifications of the mentioned principles have been presented since then. James and Schofield (1990) elaborated further on the principles of defining the recommended energy allowances, especially with respect to PA, resulting energy output, and its balance with EI. DRIs for the macronutrients and energy, which are the North American reference standards for nutrients in the diets of healthy individuals, were considered for PA (Zello 2006). For example, South African pediatric food-based guidelines for children younger than 7 years strive to facilitate the education of carers of young children in the adoption of healthy eating practices (Bowley et al. 2007). All requirement estimates refer to needs persisting over moderate periods of time. The corresponding intakes may be referred to as “habitual” or “usual” in order to distinguish them from intakes on a particular day. However, as a matter of convention and convenience, they are expressed on an intake basis. There is no implication, though, that these amounts must be consumed each day (WHO 1985). Energy requirements should be defined so as to correspond to the real needs of the individual (Widdowson 1983). Once the level of body weight and PA has been fixed and the appropriate growth rate defined, there is only one level of intake at which energy balance can be achieved. As a result, this becomes that individual’s requirement for energy. Even some degree of adaptation is possible, but it is assumed that such a range is fairly narrow (WHO 1985). Therefore, it is desirable to define, as exactly as possible, individual recommended energy allowances. In case the intake is either above or below the requirement, a change in body energy stores should be expected unless energy expenditure is correspondingly altered. If such changes in expenditure do not occur, the energy store, mainly in the form of adipose tissue, will increase when the intake exceeds the requirement and decrease when it is below the requirement. It would be contradictory to general experience to suppose that for each individual there is one fixed set point for body weight and adipose tissue mass compatible with adequate health. In fact, for any individual there is probably a range of acceptable body weights. However, if the imbalance is too great or continues over very long periods, the resulting changes in body weight and composition can be detrimental to function and health. In conjunction with this, risks that are associated with intakes either above or below the actual requirements may appear. This applies to all age categories, including the preschool one. Body size is the major determinant of the absolute requirements for energy. Variations in size are probably more significant quantitatively than metabolic adaptations. Acceptable ranges in body size have already been discussed; tables of weight, height, and BMI standards as established in different parts of the world are presented (see Tables 4.1, 5.1a and b). Although the energy and protein requirements for the process of growth are relatively small compared to those for maintenance (except in the young infant), satisfactory growth is nevertheless a sensitive criterion for whether the energy and protein needs are being met or not. Therefore, the definition of satisfactory growth is

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TABLE 5.1a Body Weight for Children Boys Age (Years) 3 4 5 6 7

Girls

−2 SD

x–

+2 SD

−2 SD

x–

+2 SD

11.4 12.9 14.4 16.0 17.6

14.6 16.7 18.7 20.7 22.9

18.3 20.8 23.5 26.6 30.2

11.2 12.6 13.8 15.0 16.3

14.1 16.0 17.7 19.5 21.8

18.0 20.7 23.2 26.2 30.2

Source: Adapted from the World Health Organization, Diet, Nutrition and the Prevention of Chronic Diseases, Technical Report Ser., No. 797, World Health Organization, Geneva, 1990a.

the first and most important step (WHO 1985). Presented tables were used as a criterion for RDAs and generally agree with the criteria for growth evaluation (BMI; see Chapter 4). As mentioned above, there is a dilemma as to whether reference standards for the growth of children in industrialized countries should be accepted universally as relevant, or whether local standards should be used. Differences were found even in the framework of an industrially developed country—children from larger urban agglomerations are usually bigger and more advanced in growth and development (Parˇ ízková 1978b, 1980, 1987) and mostly also fatter. In addition, increasing average and/or 50th percentile values during recent periods might not correspond to optimal, desirable values from the point of view of health and overall fitness. As mentioned in Chapter 4, Cole et al. (2000, 2005, 2007) defined standard cut-off values for child overweight and obesity as well as for thinness. BMI, BMI%, BMI z-scores, or BMI

TABLE 5.1b Mean Values for Height and Weight in European Children Height (cm) Age (Years) 3.5 4.5 5.5 6.5 7.5

Boys 96.0 106.5 112.5 119.0 124.5

Girls 95.0 105.5 111.5 118.0 123.5

Weight (kg) Boys

Girls

15.0 17.5 19.5 22.0 24.5

14.0 17.0 19.5 21.5 24.0

Source: Modified from Nutrient and Energy Intakes for the European Community, Report of the Scientific Committee for Food, 31st Series, Directorate-General, Industry, Office for Official Publications, Luxemburg, 1993.

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centiles were also discussed as related to dietary intake. However, it was also considered whether all present standards—with regard to recent changes in adiposity and aerobic fitness—are optimal when evaluating the adequacy of BMI development. Estimates of requirements based on body size are, however, an approximation because they do not take body composition into account more exactly, which may finally determine the requirements. In recent decades, the emergence of numerous methods for the estimation of body composition in living subjects (see Chapter 8) has resulted in observations on several thousand people, ranging from newborn infants to the elderly. The neonate averages 14% of depot fat, which gradually accumulates during the last stage of pregnancy. Children of diabetic mothers were not only larger but also with a greater amount of body fat (Parˇ ízková 1963, 1977). During the first year of life, depot fat rises to about 23% and then declines to 18% at 6 years of age (Haschke et al. 1981). This applies to both total and subcutaneous fat, measured as skinfold thickness using a caliper (Parˇ ízková 1963, 1977). Girls always have larger absolute and relative amounts of depot fat and this difference increases with advancing age. Individual differences in body composition may cause different energy and protein requirements in spite of the same body size. The proportion of internal organs, which have a much higher metabolic level, is considerably greater in early childhood than later on (Table 5.2).

TABLE 5.2 Metabolic Rates (MR) of Organs and Tissues in Man Newborn Organ Liver Brain Heart Kidney Muscle Rest (by difference) Total

Adult

Weight (kg)

MR/day kcal (kJ)

% of Whole Body MR

Weight (kg)

MR/day kcal (kJ)

% of Whole Body MR

0.14 0.35 0.02 0.024 0.8 —

42 (176) 84 (325) 8 (33) 15 (63) 9 (38) —

20 44 4 7 5 20

1.6 1.4 0.32 0.29 30.00 —

482 (2017) 338 (1414) 122 (510) 187 (782) 324 (1356) —

27 19 7 10 18 19

197 (824)

100

70.00

1800 (7530)

100

3.5

Sources: Adapted from Boyd, E., in Growth, Including Reproduction and Morphological Development, P.L. Altman and D.S. Dittmer, Eds, Washington, DC, Publ. Federation of American Societies for Experimental Biology, 1962, 346; Benedict, F.G. and Talbot, F.B., Metabolism and Growth from Birth to Puberty. Washington, DC, Carnegie Institute, Publication No. 302, 1921. Note: Organ weights are taken from Boyd (1962). Metabolic rates for the neonate are estimated by assuming that the metabolic rate of each organ per unit weight is the same as in the adult. The total activities of the tissues listed are expressed as fractions of the total basal energy expenditure in the adult and the neonate. The total BMR in the neonate approximates that measured by Benedict and Talbot; no data on children 3–6 years of age are available.

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The impact of fat-free body mass and gender on the resting energy expenditures (REEs) of children was found to be similar to that in adult age, that is, the evaluation of body composition contributes substantially to the definition of energy requirement in childhood (Goran et al. 1993a,b, 1995). The assessment of energy needs is based on energy expenditure (James and Schofield 1990). Therefore, estimates of energy requirements should be based on measurements of energy expenditure during different periods of time and during various activities. Under conditions of dynamically changing PA (which is usual in small children; Parˇ ízková and Hainer 1990, Goran et al. 1993), it is very difficult to obtain exact data even when sophisticated methods (such as doubly labeled water (DLW)—2H218O) are available. The only feasible approach, then, is to estimate requirements from measurements of intake, provided the usual growth rate of height and weight is preserved (Gobedzhishvili et al. 1990). Detailed questionnaires on PA for parents and caretakers (for example, teachers from day-care centers) help in differentiating and categorizing children when used for longer periods of time (Parˇ ízková et al. 1986); however, they should be validated when such a method is available. Usually, the intensity and character of PA are not registered; so it is necessary to consider that only a certain threshold of the character and intensity of PA can change EI and body composition significantly. It cannot be assumed that the observed expenditure or intake levels always represent, under any conditions, what is desirable for the maintenance of health (Chavez and Martinez 1984). In developing countries, actual intakes may be too low to allow for what has been previously described as “leisure time” activity or “discretionary” activity. On the other hand, in industrially developed countries the actual intake is usually excessive and the same applies to the recommended energy allowances (Prentice et al. 1988). Moreover, in affluent societies many individuals, including young children, may be less physically active than what is considered desirable for ensuring cardiovascular health. The basal metabolic rate (BMR) is the metabolic rate measured at optimal mental and physical rest conditions, at a comfortable temperature, 12–14 h after the last meal. The metabolic rate during sleep or just after waking up (which is difficult to assess in healthy, non-institutionalized normal subjects) is even lower; hence the metabolic rate measured under these conditions is also defined as the resting metabolic rate (RMR). The energy requirement per kilogram of body weight varies markedly during the lifespan. In children, the change of BMR per kilogram of body weight with age is much greater than that in adults, that is, about 5% per year between 3 and 10 years. Presently, we do not know to what extent this reflects an age-related change per se or age-related changes in body composition and relative weights of vital organs. The BMR per unit of weight also varies with weight and BMI: within a given age range, the BMR per kilogram of body weight is higher in short, light, and lean individuals and lower in taller, heavier individuals. For practical purposes, then, the most useful index is body weight. Until recently, many regression equations have been used for the estimation of RMR, the results of which are indirect calorimetry assessments made 70–80 years ago. These equations were validated with new measurements of resting energy

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metabolism in children 5–16 years old and compared: the Harris–Benedict and new equations were elaborated due to the WHO/FAO/UNU Expert Committee (WHO 1985). Those published by James and Schofield were in best agreement with the recent measurements of many authors, including, for example, Firouzbakhsh et al. (1993). Numerous mathematical analyses were tested; for example, the conventional use of surface area or inclusion of height made no significant difference to the accuracy of prediction. Different types of equations were tested (linear, quadratic, logarithmic, etc.). The more complex functions added nothing to the accuracy of prediction. Therefore, in each age–sex group the BMR was estimated from the body weight by the following simple linear equations: Boys 3-10 years: kcal/day = 22.7 weight - 495 (SD = ±62). Girls 3-10 years: kcal/day = 22.5 weight - 499 (SD = ±63). These equations were also used for the estimation of BMR and for the evaluation of total energy output (adding multiples of BMR for various activities) in our studies of small children (WHO 1985). The changes in body composition with age markedly affect energy requirements because some organs are metabolically more active than others. Table 5.2 shows a comparison between a newborn and an adult; for example, the neonate brain comprises about 10% of the total body weight and may account for 44% of the total energy needs of the child under basal conditions (Benedict and Talbot 1921). On the other hand, the energy needs for muscle metabolism at this time are very low because of the relatively small muscle mass (see Table 5.2). Data on preschool children are not available. Some studies attempt to assess possible ethnic differences in BMR: for example, Spurr et al. (1992) measured BMR in both control and undernourished boys and girls in underprivileged areas of Cali, Colombia, but these failed to reveal any differences that could not be related to nutritional status or climatic conditions. Another item in the estimation of energy requirement is the energy cost of growth, which includes two components: the energy value of the tissue or product formed and the energy cost of synthesizing it. The total cost will, therefore, depend on the composition of such a tissue. The energy value is the heat of combustion without the deductions for losses in urine and feces, which are allowed for by the Atwater factors. The average values for protein, fat, and carbohydrate are 5.7, 9.3, and 4.3 kcal (24, 39, and 18 kJ) per gram, respectively (WHO 1985). In young children, a rounded-off value of energy cost of 5 kcal (21 kJ) per gram of tissue increment has been widely accepted (Spady and Payne 1976). In contrast, a higher figure is obtained in adults for the energy cost of weight gain under different conditions. This may be because relatively more fat is laid down. However, even during growth the weight increments may have quite a different composition in children living under various conditions of dietary intake, PA, etc. In the case of growth spurts, very little or no fat is laid down. This also applies to preschool age. As described in Chapter 4, skinfold thickness decreases in boys and remains stable in girls, which mainly indicates the development of lean body mass (Parˇ ízková 1977).

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Energy output resulting from PA and work varies according to age. In children, it is determined by habitual physical tasks and play. The degree of energy output depends on the intensity and duration of such activities. This may be estimated using multiples of BMR. Calculations in children and youth are more difficult because during the same physical task, growing subjects increase their energy output in relation to BMR relatively less than adults. Studies concerning age differences in the relative increase of energy output during the same workload started at the age of 12 years. It was shown that during a workload of 2 w/kg body weight on a bicycle ergometer with an 11.8-year-old boy the energy output was 5.91 BMR and in a 17.8-year-old boy it was 7.18 BMR, which is 21% higher. When we compare the youngest boys with a 25.1year-old man, where the BMR multiple during the same workload equals 7.76, the difference is 31%. These differences may be part of the reason for the decreasing level of spontaneous PA with advancing age: the strain during the same workload is relatively greater in older subjects due to a relatively greater increase of energy output in relation to BMR. This also imposes a greater demand on all systems engaged during increased workload and higher PA in older subjects, and vice versa in children (Parˇ ízková 1985). There are no comparable data in preschool children, who display even higher spontaneous PA compared to older children and youth, and in which such workload testing and comparisons would not be possible. However, it may be assumed that especially during spontaneous dynamic activity such as running and playing, the relative increase in energy output as related to BMR is correspondingly lower than that in older children and/or in adults. During spontaneous play, telemetric measurements reveal an increase in heart rate of up to 220 heart beats/min (Kucˇera et al. 1975, 1994). In adults, a heart rate of 200 or more is considered the maximal value during a maximal workload. When we compare these maximal values with basal values at rest in children (i.e., about 100–115 beats/min), we again see that the difference between them is much smaller than that in older subjects. From these observations, it may be deduced that in small children the values of multiples of BMR, which characterize the energy output during various activities, will probably be different, that is, lower than that in older age categories. The validation of these multiples, however, has not yet been made in preschoolers. An example of the estimate of energy output is presented by WHO (1985) for the energy requirement of a 4–5-year-old child (Table 5.3). Recommendations for the EI established for the EC (1993) are based on the same principle and procedure. The EC document gives direct estimates for an average EI of preschool children (Table 5.4). Recently, more data on energy expenditure measured with the help of DLW (2H218O) are available (Davies et al. 1994, 1995a, Prentice 1990). In our studies, we used BMR multiples estimated from the increments of heart rate at rest, during moderate activity, and maximal values during spontaneous play (Kucˇera et al. 1975, Parˇ ízková 1977, Parˇ ízková et al. 1984). Children can manage with considerably lower EI compared to the actual RDAs for this age category without growth deficits (Prentice 1990). On the other hand, a higher energy intake (EI) does not cause most actual cases of overweight. Another

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TABLE 5.3 Example of the Estimation of the Daily Energy Expenditure of a 4.5-Year-Old Boy (Body Weight 18 kg) Activity

Hours

kcal

kJ

Sleep at 1.0 ¥ BMR Kindergarten

12

456

1884

Light activity at 1.2 ¥ BMR

3.0

137

565

Moderate activity at 1.9 ¥ BMR

3.5

253

1044

High activity at 5.0 ¥ BMR Home

0.5

95

392

Light activity at 1.3 ¥ BMR

2.5

123

510

Moderate activity at 2.0 ¥ BMR

2.0

152

628

0.5

95

395

— 24.0

80 1391

334 5752

High activity at 5.0 ¥ BMR Growth Total requirement per 24 h at 1.31 ¥ BMR

Note: BMR was estimated to be 913 kcal/day, 38 kcal/hod (3.82 MJ/day, i.e., 157 kJ/hod) using the regression equation of BMR of the EC (1993). The multiples of BMR were roughly estimated from the ratio of heart rate at rest (BMR) and maximal levels achieved in preschool children, and from the comparison with similar ratios in older subjects (this ratio is much lower in children (Parˇízková 1985) but is not yet known for preschoolers). The total energy requirement depends on the level and duration of PA per day, and thus varies considerably among individual children.

question remains, however: how will such discrepancies between EI and output be manifested in the long run? It is also known that children with insufficient EI decrease their PA, an action that is considered the “first line of defence” against malnutrition in childhood (Kraut 1972, Waterlow et al. 1992). TABLE 5.4 EARs of Energy for Children 3–7 Years Old Average Weight (kg)

EI (kcal/kg)

EI (kJ/day)

Age (Years)

Boys

Girls

Boys

Girls

Boys

Girls

3.5 4.5 5.5 6.5 7.5

15.5 17.5 19.5 22.0 24.5

15.0 17.0 19.5 21.5 24.0

395 375 365 350 330

375 354 330 330 305

6100 6550 7100 7700 8100

5650 6200 6800 7100 7300

Source: Adapted from Nutrient and Energy Intakes for the European Community, Report of the Scientific Committee for Food, 31st Series, Directorate-General, Industry, Office for Official Publications, Luxemburg, 1993.

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Under the usual physiological conditions, the physical activity level (PAL) in preschool children varies markedly in the same way as in older children; that is, under the same conditions one child could be several times more active than another one. This was confirmed by pedometer measurements or direct observations in preschool children. Therefore, it is very difficult to estimate more exactly the energy output and thus the energy requirements in individual children. It can also vary considerably from day to day in the same children (Parˇ ízková et al. 1986a,b). Estimation of energy output used the most common approach as the assessment of spontaneous food intake; Birch et al. (1991) showed that in children 2–5 years old the intake of individual children was relatively constant during 6 days in spite of a great variability in each meal during the day. There were also marked differences between each child. The spontaneous intake of individual meals, though, depends significantly on food choice and preference. With very appetizing meals with a high energy density (ED), self-control may fail. Then, the intake of protein, fat, sugar, and other components may be excessive and may not be compatible with optimal development of weight, BMI, and body composition in the present or future. Thus, parents should respect the real energy needs of the developing child, supplying an adequate and individually defined dietary allowance of energy. Nutrient intakes were followed, for example, in a national random sample of infants and toddlers until 2 years of age. The mean EI exceeded the estimated energy requirements by 10–31%, which was higher for children fed solid foods than breastfed, which might be, inter alia, due to the overreporting of parents (Devaney et al. 2004). The Genesis Study in Greek toddlers and preschoolers showed that a substantial percentage of children had usual intakes outside the acceptable macronutrient distribution range, whereas protein was less than this range. Subjects at risk of overweight, and overweight subjects had higher intakes of energy, protein, and fat than normal-weight children (Manios et al. 2008). A survey in Cape Town metropolitan area in 1990 revealed low intakes as compared to RDAs; nearly half of the children had only two meals per day, which resulted in stunting, underweight, and wasting. But, 20.1% of children were simultaneously obese (Bourne et al. 1994), indicating a higher EI than needed.

5.3

PROTEIN REQUIREMENTS

Protein requirements are defined as the lowest level of dietary protein intake that a person will need to balance nitrogen losses from the body in persons maintaining an energy balance at modest levels of PA. In growing children and pregnant or lactating women, this requirement includes the needs associated with the deposition of tissues or the secretion of milk at rates consistent with good health. During growth and development, more protein is necessary to build up the body; that is, about 2 g/kg body weight at the first through third months is recommended. The period from 6 to 12 months is clearly most critical because of the rapid growth that occurs during this time, and because the child increasingly relies on supplementary foods. The mean rate of nitrogen accretion during growth can be estimated using the expected daily rate of weight gain, which corresponds to the 50th percentile of usual growth standards (Bláha 1991, Prokopec 1976, 1986, Prokopec et al. 1986,

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Prokopec and Bellisle 1992, Rolland-Cachera et al. 1988, 1990) and to the nitrogen (N) concentration in the body. This is low at birth and increases to the adult value by the age of 5 years or sooner. The extent of the increase is important between 6 and 12 months when growth is rapid. Reported values for body N concentration at different ages were obtained using three different methods (Fomon et al. 1982, WHO 1985). At some ages, the values were not in agreement. It should not be assumed that growth always proceeds at exactly the same rate from day to day, even in normal healthy children with adequate and regular food intake. The cause, extent, and significance of these fluctuations in growth rate are difficult to assess. The variability of gain is much greater than the variability of intake. These differences may also represent day-to-day differences in the proportions of deposited fat and lean tissue, which depends on both nutritional and PA regimens. This applies even more to periods of recovery from malnutrition and/or from a disease, etc. In order to maintain a satisfactory overall growth rate, any failure to take in protein on one day must be compensated for on a subsequent day. The human body has a very limited capacity for storing amino acids or for drawing on the free amino acid pool for protein synthesis. Even during short periods such as 12 h without food, the nitrogen balance becomes negative (Clugston and Garlic 1982). It follows that since it is impossible to foretell on which days the growth rate will be lower or higher, it is necessary to provide enough energy and protein everyday for the possible extra demand even when some sparing mechanisms under conditions of malnutrition may appear. The estimated safe levels of N and protein calculated in this way are shown in Table 5.5 (WHO 1985). These values are given for a joint group of boys and girls. This RDA refers to high-quality protein (from sources such as egg white, milk, beef, fish, and the like). Proteins should account for 12–13% of the EI. This applies to all age categories. In very young children, this proportion is higher: in a 4-year-old boy with a body weight of 18 kg about 18% of energy is covered by protein, as follows from the calculations of the intake of protein in grams per kilograms of body weight and total energy RDA.

TABLE 5.5 Safe Level of Protein Intake (Milk or White of Egg Protein) of Small Children (Genders Combined)

Age (Years) 3–4 4–5 5–6 6–7

Maintenance Growth Total + 2 SD (mg N/kg per day) 117 116 115 114

24 21 17 17

141 137 132 131

175 170 164 163

% CV

Safe Level (g prot./kg BW)

12.0 12.0 12.0 12.0

1.09 1.06 1.02 1.01

Source: Modified from the World Health Organization, Energy and Protein Requirements, Report of a Joint FAO/WHO/UNU Meeting, World Health Organization, Tech. Rep. Ser., 724, Geneva, 1985.

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Habitual home diets of some population groups may provide the same foods in different proportions, and their constituent proteins may not supply an adequate combination of essential amino acids. In such a case, when the quality is poor, a higher intake of protein is required. The safety margin is narrower for children than for adults. Energy and protein are the two main components of foods that cannot be substituted with anything else. Energy is also derived from fat and carbohydrate and, when the EI is not sufficient, from protein. This is especially detrimental during growth, and sufficient amounts of both energy and protein are, therefore, essential. However, as mentioned in Chapters 3 and 4, a higher protein intake at the beginning of life, exceeding 16% of EI, can influence AR, which occurs earlier than usual (normal age 5.5–6 years), and thus increases the risk of easier development of obesity later during growth (Rolland-Cachera et al. 1995). Even though this was not proved in all studies, it is necessary to adhere to adequate protein intake, which has to be balanced and adjusted as exactly as possible to the needs of the growing organism. This can guarantee adequate development of the child at present and also later on.

5.4

FATS

Another source of energy is fat, which has the highest energy content. Moreover, it contains essential fatty acids, which are essential for adequate growth and development. TGs are the principal lipid component of foods and the most concentrated source of energy among the macrocomponents of a diet (9.3 kcal/g, 38 kJ/g). They can enhance palatability by absorbing and retaining flavors and by influencing the texture of foods. When fats are digested, they facilitate intestinal absorption (and perhaps also the transport) of the fat-soluble vitamins A, D, and E. Actual RDAs specify the intake of saturated, and mono- and polyunsaturated fatty acids. The RDAs of the EC specify servings for PUFAs (Table 5.6a). The most important PUFAs are linoleic acid and linolenic acid (containing more than one double bond). The major PUFAs in fish are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). All these fatty acids are essential for healthy development, while also playing a role in the prevention of cardiovascular diseases. Fatty acids can be utilized directly as a source of energy by most body cells, with the exception of erythrocytes and cells of the central nervous system (CNS), cells that normally use glucose as the major energy source. Excess energy is stored principally as TGs in adipose tissue, the percentage of which varies markedly in the organism with age, sex, nutritional status, and PA regimen. The RDA for fat is defined as 30% of the total EI or less. The usual consumption of fats is mostly higher, which was found for different population groups in most of the industrially developed countries. Children who had different ratios of their dietary energy covered by fats did not show differences in growth (Shea et al. 1993). Linoleic acid should account for 1–2% of total dietary calories: that is, for infants consuming 100 kcal/kg body weight per day, only 0.2 g/kg body weight. For adults, a minimal adequate intake (AI) of linoleic acid is 3–6 g/day; RDAs for young

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Nutritional Status and Dietary Intake in Early Life

TABLE 5.6a Population Reference Intakes for all Healthy Preschool Children Age Group (Years) 4–6 Protein (g/kg BW) n-6 PUFA (% dietary energy) n-3 PUFA (% dietary energy)

1.0 2 0.5

Source: Adapted from Nutrient and Energy Intakes for the European Community, Report of the Scientific Committee for Food, 31st Series, Directorate-General, Industry, Office for Official Publications, Luxemburg, 1993.

children are intrapolated from RDAs for older subjects (WHO 1991; RDAs, USA 1989, EC 1993). Essential fatty acids are especially important during pregnancy (Chapters 2 and 3). The strongest dietary determinant of blood cholesterol is the level of saturated fatty acid intake. The cholesterol concentration of the diet has an appreciable, but usually smaller, influence. In the past decade, considerable attention was also given to the potential role of dietary factors in the etiology and prevention of not only cardiovascular diseases but also cancer. Increased consumption of fats is considered a risk factor. Regarding the influence of diet and its composition on the development of these diseases, there has already been evidence that these factors influence the human organism from the very beginning of life (WHO 1985, 1991). Therefore, not only during childhood, but also during pregnancy, an adequate diet can play an important role in health development and in the prevention of these diseases later in life. The findings of the study of Tucker et al. (1997) indicated that the macronutrient intake of children, especially fats but also carbohydrates, may play a role in excess adiposity independent of the influence of total EI, gender, physical fitness, and parental BMI. On the other hand, the fat intake of children should not be lower than 22% of energy and should contain animal fats. Lower intake could restrict growth and adequate development, especially of the CNS (Widhalm 1996, Uauy et al. 2000). Koletzko et al. (2007) recommended the range of acceptable fat intakes for infants and children. Satiety is significantly influenced by fat intake: fat supplements in breakfast produced no detectable effect on the expression of appetite, which could lead to passive overconsumption of energy. Supplements of breakfast carbohydrates, on the other hand, can suppress the appetite (Cotton et al. 2007). At present, children as well as the whole population are negatively influenced by commercials and marketing, which promote fat and sugar intake. The majority of food advertising in TV is counter to nutritional guidelines, especially for fat and carbohydrate (Taras and Gage 1995, Wilson et al. 2006, Neville et al. 2005, Page and Brewster 2007, Kelly et al. 2007, Thompson et al. 2008, Batada et al. 2008).

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5.5 CARBOHYDRATES Carbohydrates, an important source of energy, should account for more than half the EI. This follows from the recommendations for protein and fat. However, in small children, where the percentage of energy covered by protein is higher due to higher amounts of protein per kilogram of body weight, at least 52–54% of energy should be covered by carbohydrate. The intake of sugar should not exceed 10% (according to WHO, 1985: larger amounts involve the risk of, e.g., elevated blood cholesterol and TG level, dental cavities, etc.), and the percentage of fiber ought to amount to 20% of the total EI. The latter is hygroscopic, promoting normal elimination. A fiber-rich diet may also promote satiety. Some fiber components, including oat bran and pectin, lower plasma cholesterol levels, either by binding bile acids or by other mechanisms. Diets rich in plant foods with an increased amount of fiber are inversely related to the incidence of cardiovascular diseases, colon cancer, and diabetes. In the RDAs of the United States (1989), the percentage of energy covered by various macrocomponents of diet did not generally correspond to these standards, that is, carbohydrates covered only 45.3% of energy in adult men, 46.4% in adult women, and 52% in children 1–5 years of age. Similar conclusions also apply to the dietary intake in the Czech Republic (Paˇrízková 1993a). This situation has been changing in some population groups, but not always in a positive way. As mentioned above, most promoted simple sugar intake in children is due to the increased sweetened-beverage consumption (Bellisle and Drewnowski 2007), which has been considered as a possible cause of obesity development. Regular sugarsweetened beverage consumption between meals may put some young children at a greater risk of overweight (Dubois et al. 2007). However, the Bogalusa Heart Study, which compared this consumption over a 21-year period (1973–1994) in Bogalusa, LA, showed a decrease in the consumption of such beverages. There was no linear relationship between sweetened-beverage consumption and BMI and total EI (Rajeshwari et al. 2005). This regional finding has to be confirmed in other populations; increased beverage consumption usually increased EI, but not BMI (O’Connor et al. 2006). Further findings are not consistent with any specific role of non-milk extrinsic sugars or caloric soft drinks in obesity in British children and adolescents, but point instead to a general risk of over-eating (absolute and relative) and physical inactivity (Gibson and Neate 2007). As shown by studies in Australian preschool children, their food preferences align with dietary guidelines and RDAs only in some respects (e.g., cereals and extra food groups higher in sugar and more energy dense) but not in others (especially vegetables; Russel and Worsley 2007, 2008). This seems to be a comparable situation in other countries.

5.6 MINERALS AND TRACE ELEMENTS A positive calcium balance is required for bone formation until peak bone mass is achieved. The mineralization of bone continues for some years after longitudinal bone growth has ceased. Most of the accumulation of bone minerals occurs in

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humans by the age of about 20 years, but some mineral is added during the third decade. Bone growth needs in 1–4-year-old children following American diets are met by a daily calcium intake of approximately 470 mg/day, which suggests that the current AI of 500 mg/day is close to the estimated average requirement (EAR) (Lynch et al. 2007). But African-Americans, an at-risk population of public health concern in the United States in all age categories, did not meet dairy recommendations according to the 2005 US Dietary Guidelines and the 2004 National Medical Association Consensus Report (Fulgoni et al. 2007). Inadequate dairy and calcium intakes in 4–18-year-olds were also revealed in other groups of children in the United States (Fiorito et al. 2006, Kranz et al. 2007). Meta-analysis of randomized controlled trials did not show any effect of calcium supplementation on bone mineral density at the femoral neck or lumbar spine in healthy children (Winzenberg et al. 2006), and is very unlikely to result in a clinically significant decrease in fracture risk. Already during pregnancy maternal calcium intake can have a certain effect on the offspring: a systematic review of the literature revealed an association between maternal calcium intake during pregnancy and offspring blood pressure (Bergel and Barros 2007). The fat mass is lower in calcium-supplemented than in unsupplemented preschool children with low dietary calcium intakes (DeJongh et al. 2006). Calcium and exercise have a more positive combined bone-stimulating effect (Welch and Weaver 2005, Specker and Vukovic 2007). The preliminary results of Ambroszkiewicz et al. (2007) suggest that an inadequate dietary intake of calcium and vitamin D may impair the bone turnover rate in vegetarian children. The parameters of bone metabolism should be monitored in these children in order to prevent bone abnormalities. A high-calcium food consumption pattern from milk and its products established in childhood may be related to bone density in postmenopausal women (Garn 1970). The most promising nutritional approach to reducing the risk of osteoporosis in later life is to ensure a calcium intake that allows the development of each individual’s genetically programmed peak bone mass during the formative years, especially during childhood (Schramm et al. 1985; RDAs, USA 1989, EC 1993) (Tables 5.5 and 5.6b). Regarding the growth period, calcium accretion averages 140–165 mg/day and may be as high as 400–500 mg/day during puberty (Garn 1970). An intake of 800 mg/day is recommended for both sexes from ages 4 to 10 years and of 1200 mg/day later on (RDAs, USA 1997). The RDAs of the EC (1993) are lower. These amounts can easily be obtained if dairy products are included in the diet (see Table 5.6b). Another essential component of bone is phosphorus, where it is present at a mass ratio of one phosphorus to two calcium. Children and adults absorb 50–70% of the phosphorus in normal diets and as much as 90% when the intake is low (LSRO 1981). Phosphorus is present in nearly all foods. Major contributors of phosphorus are protein-rich foods and cereal grains, milk, meat, poultry, and fish. Cow’s milk contains more calcium and phosphorus than human milk, and the ratios of the elements differ widely. The RDAs of the EC are lower than those of the United States (Table 5.6b).

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TABLE 5.6b Comparison of RDAs of Minerals for Preschool Children (4–6 Years) Mineral Calcium (mg) Phosphorus (mg) Magnesium (mg) Iron (mg) Zinc (mg) Iodine (μg) Selenium (μg) Copper (mg) Manganese (mg) Fluoride (mg) Chromium (μg) Molybdenum (μg) Potassium (mg)

NRC

EC

800 800 120 10 10 90 20 1.0–1.5 1.5–2.0 1.0–2.5 30–120 30–75 —

450 350 — 4 6 90 15 0.6 — — — — 1100

Sources: Adapted from Nutrient and Energy Intakes for the European Community, Report of the Scientific Committee for Food, 31st Series, Directorate-General, Industry, Office for Official Publications, Luxemburg, 1993; also compiled from Recommended Dietary Allowances, 10th edition, National Research Council, National Academy Press, Washington, DC, 20416, 1989.

The requirement for phosphorus is usually set equal to calcium RDAs for all age groups except the young infant. It was accepted that a 1:1 ratio of calcium to phosphorus will provide sufficient phosphorus for most age groups, but if the calcium intake is adequate, the precise ratio of these minerals is unimportant. The RDA for phosphorus is 800 mg, and/or 350 mg for children 1–10 years of age (RDAs, USA 1989, EU 1993) (Table 5.6b). Magnesium modulates many biochemical and physiological processes and is indispensable to them as the Mg–ATP complex. The highest concentrations of magnesium are found in whole seeds such as nuts, legumes, and unmilled grains. More than 80% of the magnesium is lost by removal of the germ and outer layers of cereal grains. No data exist on the magnesium requirements of young children; however, 80–170 mg/day is recommended for children from 1 to 10 years of age (Table 5.6b), that is, about 6 mg/ kg body weight. The RDA of the EC (1993) is 7–4.2 mg/kg weight from 6 months up to 15–17 years; that is, from 4 to 6 years the RDA is 120 mg/day (Table 5.6b). Iron, a constituent of hemoglobin, myoglobin, and a number of enzymes, plays an important role in ensuring an optimal level of overall functional capacity and an adequate aerobic power during all periods of life, starting with early childhood. When the iron supply in food is sufficient, its absorption is regulated to keep the body iron content constant. Iron absorption increases under conditions of its

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deficiency. However, this response may not be sufficient to prevent anemia in subjects whose intake of available iron is marginal. Impaired iron status is manifested in three stages: 1. Diminished stores manifested by a fall in plasma ferritin, and no functional deterioration evident 2. Iron-deficient erythropoiesis in which the hemoglobin level is within 95% of the reference range for age and sex, and the working performance may be impaired 3. Iron deficiency anemia in which total blood hemoglobin levels are reduced below normal values and severe iron deficiency anemia is characterized by microcytosis and hypochromia The mentioned deficiency resulting in anemia is most common in developing countries, and has a deteriorating effect on overall physical and mental fitness. However, due to inadequate diets, milder forms can appear even in developed countries. For males and females over 4 years of age, anemia is defined as a hemoglobin level below 13 and 12 g/dL, respectively. In children, iron deficiency is associated with apathy, reduced attention, irritability, and the reduced ability to learn. Milder forms of anemia may be connected with poor school performance; this situation may be found even in countries with adequate and/or abundant availability of food and nutrition. Breast-fed children get enough iron from mother’s milk but later from about 6 months to 4 years, iron deficiency may be due to a low iron content of milk while the body is growing rapidly, and iron reserves are low. Iron availability may be enhanced by simultaneously consuming foodstuffs containing vitamin C. Increased consumption of bran can limit the absorption of iron. From birth to the age of 3 years, infants not breast-fed should have an iron intake of approximately 1 mg/kg body weight per day. Children and adolescents need iron, not only to maintain hemoglobin concentrations but also to increase their total iron mass during the growth period. The iron requirements of children and adolescents are considered to be slightly higher than those of adults. A dose of 10 mg/day is recommended for children. RDAs of the EC are lower (see Table 5.6b). Zinc is an essential element for humans as a component of some enzymes. Its deficiency is manifested by loss of appetite, growth retardation, skin changes, and immunological abnormalities. Experiments in laboratory and domestic animals have shown that zinc deficiency during pregnancy may lead to developmental disorders in the offspring. Pronounced zinc deficiency in men, resulting in hypogonadism and dwarfism, has been found in the Middle East. Marginal zinc deficiency was also observed in a survey of apparently healthy children who exhibited suboptimal growth, poor appetite, and impaired taste acuity, along with a low hair zinc level (Hambidge et al. 1972). Increasing the zinc intake by 0.4–0.8 mg/kg brought about marked improvement. Supplementation of infant formulas to increase zinc levels resulted in increased growth rates in males, but not in females (Walravens and Hambidge 1976). Animal products provide about 70% of the zinc intake, followed by zinc from cereals. The bioavailability varies in different foodstuffs. The recommended U.S. allowance for children is 10 mg/day and the EC allowance is 6 mg/day (see Table 5.6b).

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Lower intakes in preadolescent children resulted in lower hair and plasma zinc levels along with retarded growth (10th percentile). The rate of linear growth improved as a result of supplementation with zinc to the level of the RDA. Excessive intakes of zinc can cause the impairment of various immune responses, a decrease in HDLcholesterol, etc. Iodine is an integral part of the thyroid hormones thyroxine and triiodothyronine. Its deficiency can lead to a wide spectrum of diseases, ranging from severe cretinism with mental retardation to barely visible enlargement of the thyroid. Endemic goiter continues to be a worldwide problem. Iodine deficiency disorders can be prevented, but not cured, by providing adequate iodine intake. The prevalence of goiter decreased considerably in all countries where iodized salt was introduced. Natural goitrogen sources are cabbage or cassava (RDAs, USA 1989). In coastal areas, seafood, water, and iodine-containing mist from the ocean are important sources of iodine, whereas further inland, the iodine content of plants and animal products is variable, depending on geochemical environment, fertilizing practices, feeding practices, and food processing. In these areas, iodized table salt is a reliable source, providing 76 mg of iodine per gram of salt. For example, in former Czechoslovakia, iodized salt eliminated goiter completely in the 1950s. The RDAs for children are 70–90 μg/day in both the United States and the EC (see Table 5.6b). Excess intake of iodine, that is, 1 mg/day, did not produce indications of physiological abnormalities in children (RDAs, USA 1989, EC 1993). The role of selenium in human nutrition was demonstrated by the association of low selenium status and Keshan disease, a cardiomyopathy that primarily affects young children and women of childbearing age in China. A large-scale intervention trial involving several thousand Chinese children showed the value of selenium in preventing this disease. The most important sources of selenium are liver, kidneys, and seafood. The content of selenium in grains and seeds depends on the content of this trace element in the soil. Small amounts are also seen in vegetables and fruit. RDAs for the United States for selenium were extrapolated from the values of adults, that is, 10–15 μg/day because little is known about the selenium requirements for children (Table 5.6b). Other essential trace elements are copper, manganese, fluoride, chromium, and molybdenum. Their function, bioavailability, RDAs, etc., are described in Table 5.6b.

5.7 5.7.1

VITAMINS FAT-SOLUBLE VITAMINS

Vitamin A comprises a group of compounds essential for vision, growth, cellular differentiation and proliferation, reproduction, and integrity of the immune system. Vitamin A deficiency is found most commonly in children under 5 years of age, mainly in the Third World countries, and is usually due to insufficient dietary intake. Deficiency also occurs as a result of chronic fat malabsorption. The RDAs for children (400–500 μg/day) were extrapolated from infant values to the adult level on the basis of body weight. No differentiation between genders is necessary (RDAs, USA 1989).

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TABLE 5.6c Comparison of RDAs of Vitamins for Preschool Children (4–6 Years) Vitamin A (μg RE) D (μg) E (mg alfa TE) K (μg) C (mg) Thiamin (mg) Riboflavin (mg) Niacin (mg NE) B6 (mg) Folate (μg) B12 (μg) Biotin (μg) Pantothenic acid (mg)

NRC 500 10 7 20 45 0.9 1.1 12 1.1 75 1.0 25 3–4

EC 400 10 0.4 (/g PUFA) — 25 100 (μg/MJ) 1.0 — 15 (μg/g protein) 130 0.9 — —

Sources: Modified from Recommended Dietary Allowances, 10th edition, National Research Council, National Academy Press, Washington, DC, 20416, 1989, and from Nutrient Energy Intakes for the European Community, Report of the Scientific Committee for Food, 31st Series, DirectorateGeneral, Industry, Office for Official Publications, Luxemburg, 1993.

The RDAs of the United States and the EC are given in Table 5.6c. A single dose of 60 mg of retinol in oil (60,000 RE or 200,000 IU) has been successfully used prophylactically in Asian preschool children. About 1–3% of children have transient toxic symptoms without lasting effects. Vitamin D (calciferol) is essential for proper skeletal formation and mineral homeostasis. Vitamin D deficiency in children causes deformation of the skeleton, resulting from the inadequate mineralization of bones. In industrially developed countries, milk and other foods are fortified with vitamin D, and hence rickets are very rare in these countries. When the skin is sufficiently exposed to sunlight, the amount of vitamin D synthesized can meet the requirements. The amount depends on area of skin exposed, time of exposure, and wavelength of ultraviolet light. The allowance for children older than 6 months has been set at 10 mg (400 IU)/ day (Table 5.6c). Because the complete maturation of the skeleton is not achieved until the third decade, this allowance is recommended through 24 years. There is a problem as to whether the usual sources of vitamin D are sufficient (milk, eggs, butter, etc.) without enough exposure to sunlight. However, in many industrialized countries, such as the United States, these foodstuffs are fortified by sufficient amounts of vitamin D (RDAs, USA 1989, EU 1993). Vitamin E (or tocopherols) is known biochemically as an antioxidant, that is, it prevents propagation of the oxidation of unsaturated fatty acids by trapping peroxyl

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free radicals. In vitamin E deficiency, the oxidation of PUFAs is more readily propagated along the cellular membrane, leading to cell damage and eventual symptoms, mainly neurological. During steady growth in early childhood, an intake increasing from 6 mg for the reference child of 13 kg body weight at 1–3 years of age to 7 mg at 10 years should be satisfactory for the average diet (Table 5.6c). The RDAs of the EC (1993) give a value of 0.4 mg a-tocopherol equivalents per gram of PUFA. In children, vitamin E deficiency occurs mostly in those with congenital disorders. The vitamin K content of commonly consumed foods is not known exactly and therefore is not given in food composition tables. Green leafy vegetables are the best source. Small but significant amounts of vitamin K are also present in milk and dairy products, meats, eggs, cereals, fruits, and vegetables. Another potentially important source of vitamin K is the bacterial flora in the jejunum and ileum. In the absence of specific information about the vitamin K requirement of children, RDA values for them are set at about 1 mg/kg body weight for both the United States and the EC (see Table 5.6c). The toxic effects of excessive amounts ingested are not known (RDAs, USA 1989, EC 1993).

5.7.2

WATER-SOLUBLE VITAMINS

Vitamin C (l-ascorbic acid) cannot be synthesized by humans; it affects the functions of leukocytes and macrophages, immune responses, wound healing, and allergic reactions. It also increases the absorption of inorganic iron (RDA, USA 1989). The major sources are vegetables and fruits. Vitamin C status is usually evaluated from clinical deficiency, plasma (or blood) levels (<0.2 mg/dL), or leukocyte concentrations. Vitamin C must be continuously supplied in the food. The RDAs for children are 25–45 mg/day (see Table 5.6c). Thiamin (B1) deficiency is associated with abnormalities of carbohydrate metabolism related to the decrease in oxidative decarboxylation. Dietary sources of thiamin include unrefined cereal grains, brewer’s yeast, organ meats, lean cuts of pork, legumes, seeds, and nuts. The daily RDAs for children were approximated at 0.5 mg/1000 kcal (or 100 mg/MJ), which provides for variability in requirements (see Table 5.6c). Riboflavin (B2) functions primarily as a component of two flavin coenzymes: flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) catalyze many oxidation–reduction reactions. Clinical signs of ariboflavinosis are rare. Nevertheless, children’s diets must contain adequate amounts of riboflavin: 0.8–1.2 mg/day of riboflavin is recommended (see Table 5.6c). No cases of toxicity are known. Niacin is used here in a generic sense for both nicotinic acid and nicotinamide, and the PP factor. Nicotinamide functions in the body as a component of two coenzymes: nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). The best source of niacin is meat. Tryptophan in the diet can contribute to the niacin supply due to possible conversion. No data exist on the niacin requirements of children. The RDAs are set at 6.6 NE/1000 cal (NE—niacin equivalent) or at 9–13 mg NE/day (1.6 mg/MJ; see Table 5.6c). Vitamin B6 comprises three chemically, metabolically, and functionally related forms: pyridoxine (pyridoxol PN), pyridoxal (PL), and pyridoxamine (PM). The

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richest sources are chicken, fish, kidney, liver, pork, eggs, unmilled rice, soy beans, oats, whole-wheat products, peanuts, and walnuts. Information on the requirements of children are scarce. The RDA is 1.0–1.4 mg/day or 15 μg/g protein (see Table 5.6c; RDAs, USA 1989, EC 1993). Folate and folacin include compounds that have nutritional properties and a chemical structure similar to those of folic acid (pteroylglutamic acid—PGA). Folates function metabolically as coenzymes that transport single carbon fragments from one compound to another in amino acid metabolism and nucleic acid synthesis. Deficiency of this vitamin leads to impaired cell division and to alterations of protein synthesis, which manifest most markedly in idly growing tissues. Folate is widely distributed in foods. Evidence of defective DNA synthesis is seen as the hypersegmentation of cells and abnormality in the sensitive deoxyuridine suppression test. Megaloblastic bone marrow and macrocytic anemia are late consequences of deficiency. The folate RDAs for healthy children between 1 and 10 years are interpolated from allowances for infants and adolescents, that is, 50–130 μg/day (see Table 5.6c). There is no evidence about the benefit of excess folate intake, but some potential for toxicity may exist (RDAs, USA 1989). Vitamin B12 (cobalamin) stimulates erythropoiesis and acts as a coenzyme in amino acid metabolism. Cyanocobalamin is commercially available as vitamin B12 in pills. This form is water soluble and heat stable. Animal and dairy products (where they accumulate from bacterial synthesis) are the primary dietary source of vitamin B12 in different forms. The RDAs for children 1–5 years of age are about 0.05 μg/kg body weight/day, that is, 1 μg/day (see Table 5.6c). The real intake of the child population is usually higher. An additional non-dietary source of small amounts of absorbable vitamin B12 may be bacteria in the small intestine of humans. An insufficient supply of vitamin B12 results in macrocytic anemia, megaloblastic anemia, and neurological symptoms, due to demyelination of the spinal cord and brain and the optic and peripheral nerves. In others, less specific symptoms also occur (e.g., a sore tongue, weakness). The cause of this deficiency in industrially developed countries may mostly be malabsorption. Biotin contains sulfur, and is essential for humans and other species. It is contained in different foods and is synthesized in the lower gastrointestinal tract by microorganisms and some fungi. Biotin is an integral part of enzymes, transporting carboxyl units and fixing carbon dioxide in animal tissue. The conversion of biotin to the active enzyme is dependent on magnesium and adenosine triphosphate (ATP). The RDAs for children and adolescents gradually increase from infant values (10–15 μg/day) to adult values (see Table 5.6c). No toxicity was reported in conjunction with intakes as high as 10 mg daily. Pantothenic acid, a vitamin of the B-complex, is a component of the coenzyme A molecule. It is important in the release of energy from carbohydrates, in the degradation and synthesis of fatty acids, in gluconeogenesis, in the synthesis of vital compounds such as sterols, steroid hormones, porphyrins, and acetylcholine, and finally in acylation reactions in general. In children of younger school age (7–9 years), diets that met the recommended allowances for all the other nutrients provided 4–5 mg of pantothenic acid daily. The RDAs (USA 1989) for children are extrapolated from infant values (2–3 mg/day) to adult ones (see Table 5.6c).

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5.8 METHODS FOR THE EVALUATION OF DIETARY INTAKE The goal of nutrition surveys is to define a population and/or an individual in terms of a specific factor, that is, dietary intake and resulting nutritional status, related to a number of characteristics of the human organism. These comprise morphological, functional, biochemical, and psychological variables. Most often, it is designed to identify malnutrition, which can vary in character. Quite often a diet that seems to correspond to the rules of rational nutrition may be unsatisfactory because it does not meet the real needs of the subject in question. This happens most frequently in hypokinetic individuals, who have a very low energy output and who need not only to reduce the amount of food ingested but also to pay increased attention and great care to what they eat, in order to ensure a well-balanced and satisfactory diet without any deficiencies. For normal individuals, this is quite difficult and time consuming. On the other hand, active individuals with a high level of energy output do not need to care so much about the composition of their diets because they can eat more than others, even abundantly; in a larger amount of food, a deficient intake of some essential nutritional items is less likely to occur. The classic approach for the determination of nutritional status can provide dietary, biochemical, and clinical data. It is generally agreed that dietary surveys evaluate current food intake, biochemical characteristics, present nutritional status, and clinical evaluations of long-term nutritional history. The results of these three approaches do not necessarily correlate with each other (Hunt and Groff 1990, Pike and Brown 1984). Generally, information on the nutrition of a population can be supplemented by agricultural data, vital and health statistics, anthropometric studies, and others, such as various dietary surveys. But most often summary average data on the food consumption of a population and/or per one inhabitant of any age are given. The most commonly used methods are household food consumption, food lists, food records, weighed household consumption, and individual food consumption assessment. Estimation by recall is generally used for a 24-h period only. Food records must be kept by the individual (i.e., of food eaten during varying lengths of time, usually 3–7 days). Weighed intake may be obtained by having a subject or a trained person weigh all the food consumed during a given period of time. In spite of the accuracy of actual data, there are some limitations: subjects are prone to try and find shortcuts and thus to change from their usual eating patterns. It is used mostly in laboratory and metabolic ward studies (Pike and Brown 1984). Diet history is designed to uncover the usual food intake and dietary habits over a longer period of time. Most often, it is obtained with an interview. Needless to say, in small children only direct observation and an interview with parent, caretaker, etc., have to be conducted. Biochemical evaluation is mostly limited to blood and excreta in human metabolic studies in nutrition surveys. Clinical evaluations include physical examination of the subjects, which was the earliest means of evaluating nutritional status since the knowledge of nutrients evolved from the observation of deficiency syndromes. Signs used in nutrition surveys are found on the hair, face, eyes, lips, tongue, teeth, gums, glands, skin, nails, subcutaneous tissue, muscular and skeletal system, and internal systems (gastrointestinal, nervous, cardiovascular) (Pike and Brown 1984).

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All the mentioned methods were repeatedly analyzed by numerous expert committees of the WHO (1985, 1990a,b, 1991), EU, etc. Regarding mutual relationships, dietary and biochemical data correlate more closely than either criterion correlates with clinical examination (Pike and Brown 1984, Hunt and Groff 1990). As mentioned above, it is very difficult to compare the results of individual studies from different countries, and draw reliable conclusions (Lambert et al. 2004). The compositions of individual foodstuffs vary, and so do the composition and conversion tables. More and more computer methods that make the evaluation easier are being used; however, basic predispositions for comparisons still vary. Moreover, the results of food diaries or interviews cannot be completely trusted as over- or underreporting is not rare, especially in younger subjects, or in their parents or caretakers. Hence, resulting and also future nutritional, morphological, functional, health, etc., status of the subjects in question is probably the most reliable criterion of the adequacy and/or acceptability of their dietary intake. This could again vary considerably according to the adaptive abilities of the human organism, which is able to function satisfactorily even under conditions that do not always correspond to the RDAs. Again, delayed effects have to be considered. Generally, studies of the dietary intake of children starting with preschool age show an inadequate intake of most items as compared to the RDAs. For example, a Swedish study revealed that preschool children from well-educated urban families ate too much junk food and sucrose, and 18% were found to be overweight or obese. The total EI was above the present Nordic Nutrition Recommendations (NNR), but lower than that 20 years ago, when overweight was rare. Fat intake was negatively associated with BMI, and low n-3 fatty acid intake was associated with higher body weight. Dietary intake was not optimal in more aspects in children (Geremo et al. 2007). Even though children in Canada may also consume an excess of energy, they may not be meeting all their micronutrient needs (Gillis and Gillis 2005). This concerned also, for example, iron intake in some preschool groups of children. School meals typically failed to meet the guidelines in the 4–18-year-old UK subjects (Nelson et al. 2007). A prevalence of erosive tooth wear and associated risk factors was found in German kindergarten children (Wiegand et al. 2006). Studies in a French population 4–92 years old showed vitamin and mineral inadequacy as compared to the EARs (Touvier et al. 2006).

5.9 DIETARY INTAKE AND ENERGY OUTPUT IN CZECH PRESCHOOLERS: RESULTS OF CROSS-SECTIONAL AND LONGITUDINAL SURVEYS Food intake studies in the preschool period have been relatively rare. Most studies of this sort were performed in infants, mostly during their stay at some institution. The evaluation of food intake in preschoolers and young children is a much more demanding task than for older children and youth, as it requires the cooperation of numerous staff, nutritionists, pedagogues, caretakers, and parents (hence, such studies are costlier). Direct measurements may be more easily conducted in infants and

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institutionalized subjects, and of course in older subjects who are able to cooperate personally (we succeeded mostly with subjects during prepuberty and puberty, who were specially instructed and overlooked). UK children from 1.5 to 4.5 years of age were followed up (Griffiths et al. 1990, Gregory et al. 1995). Previous measurements of this sort in UK children were conducted in 1967. Otherwise, mainly schoolchildren were followed up. Our initial measurements were made in a day-care center in Prague, where it was possible to cooperate with the director and all the staff members, that is, teachers, cooks, and other employees, as well as parents. In the first survey (G; n = 84), we recorded the food ingested by individual children, entered daily for 1 week on food record forms by teachers and cooks in the kindergarten for all individual children followed up. In the second study (H; n = 52), the overall dietary intake in individual children during the whole day and weekend and also at home was recorded, including the food ingested at the center, as in survey G. This was supplemented by data from the parents, who recorded all the foods ingested by the child during the rest of the day and during the weekend. Also, measurements of anthropometric variables, skinfolds, step test, and motor and sensomotor development were evaluated with the help of these procedures and tests. The dietary intake of individual children was assessed with an analysis of the amount and composition of meals and foods ingested. The composition of the food was evaluated using a computer program based on the composition of local foods, which is used widely for other population groups in the Czech Republic (National Institute of Public Health, Prague, Ing. Z Roth). The results were compared with national and other (WHO, EC) RDAs. The recommended allowance (RDA) for EI in children 4–6 years old in the Czech Republic (Kajaba et al. 1992) was 1550 kcal, that is, 7120 kJ. The diet should contain 60 g of protein, 50 g of fat, and 234 g of carbohydrate. These RDAs (which were previously even higher) differ markedly from the RDAs of WHO (1985), the United States (1989), and the EC (1993) (i.e., energy is either adjusted according to energy output assessed individually or taken from tables). There is also a differentiation according to individual years (i.e., the energy recommendation for 4-year-old children is lower and that for 6-year-olds is higher than those in the Czech Republic) and gender (i.e., the RDAs for energy are lower for girls). The RDA for protein in the EC is 1 g/kg body weight/day, which is lower than the Czech RDA; the same approach is applied in the United States. The recommended value for U.S. children 4–6 years old is 24 g/day, contrasting with 60 g/day for Czech children. At the time of our measurements, the daily menus for children in kindergarten were prepared centrally (Parˇ ízková et al. 1984). The results of a 5-day follow-up (survey G) in 84 day-care center children showed that 85% of our daily recommended allowance for energy was already met during the day in the day-care centers (where children spent, on an average, 7.3 h/day). The children ate, as a rule, three meals (unless they went home earlier, which was not the case during our observations). Carbohydrates accounted for 49.3% of the EI, fats for 39.3%, and proteins for 14.4%. When we evaluated nutrient intake in relation to Czech dietary allowances at that time (Kajaba et al. 1992), fat intake corresponded to 98.5% of the allowance, and

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protein and carbohydrate intake corresponded to roughly 80%. When the diet of the children was investigated at home, it was found that they had breakfast, an afternoon snack (in case they left the kindergarten earlier), and a complete, balanced supper. These data indicate that, on average, the EIs of investigated children were excessive as compared to the RDAs. Although there was always a considerable variability in the EIs of different children, the teachers tried to ensure that the children ate all their helpings of meat, fruit, etc.; hence the variability of EIs was due to carbohydrates or possibly fats (Parˇ ízková 1982, Parˇ ízková et al. 1984). The assessments of food intake were repeated in several studies, cross-sectional and longitudinal, again along with other measurements (morphological, functional, biochemical, motor performance, etc.). In the following group of preschool children (survey H; boys n = 31, girls n = 21), it was possible to measure food intake not only in the day-care centers, where teachers and cooks recorded the food intake of individual children, but also at home, with the help of parents who were involved in the study and cooperated by recording data on food consumption at home during the whole week. The results are shown in Table 5.7a and b, which confirm observations on the excessive food intake of preschool children. The results of this comparison concern Czech RDAs; if we compare these data with other RDAs, the relative intake in Czech preschoolers would be even higher. The EI was higher by about 31% in boys and by about 30% in girls. The intake of the absolute amount of protein (g) was higher by 23–24% in boys and by 18–19% in girls. If we compare the intake of protein with the EC or the U.S. RDAs, the intake will be about three times higher than those recommended in these countries for preschool children. When we compare the average intake of fat with actual Czech RDAs (Kajaba et al. 1992), it was 53% higher in boys and about 46% higher in girls. The intake of carbohydrate was higher by about 25% in boys and by about 28–29% in girls.

TABLE 5.7a Dietary Intake/Day of Czech Preschool Children, Aged 4–5 Years (Boys, n = 31; Girls, n = 15; Survey H) Protein (g)

Boys Girls

x– SD x– SD

RDAa

Fat (g)

Energy (kJ)

Total

Animal

Plant

Total

Animal

Plant

9190 2380 9140 2450 7120

74.0 20.7 71.2 19.6 60.0

50.8 17.9 46.9 18.2 40.0

23.3 6.9 24.3 6.5 20.0

84.3 26.5 80.4 36.3 55.0

67.5 21.9 64.7 35.0 —

16.9 16.1 15.8 13.8 —

Carbohydrate (g) 294.8 82.7 301.7 87.6 234.0

Sources: Adapted from Parˇízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a; Kajaba, I. et al., Cˇas. Lék. Cˇes., 131, 198, 1992 (in Czech). a RDA used in the Czech Republic (Kajaba et al. 1992).

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TABLE 5.7b Intake of Minerals and Vitamins/Day in Preschool Children, Aged 4–5 Years (Survey H) Mineral

Boys Girls

x– SD x– SD

RDAa

Vitamin

Ca

Fe

B1

B2

PP

C

1122 568 1076 678 900

10.7 5.7 9.9 4.1 12.0

1.1 0.4 1.1 0.4 0.7

1.4 0.9 1.2 0.4 1.0

12.8 5.6 12.0 4.3 11.0

63.5 30.6 63.3 34.1 55.0

Sources: Modified from Parˇízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a; Kajaba, I. et al., Cˇas. Lék. Cˇes., 131, 198, 1992 (in Czech). a RDA used in the Czech Republic.

Neither the EC nor the U.S. RDAs give special values for fat and carbohydrate intake; hence Czech data cannot be compared. Again, though, an excess could be assumed. In survey H the intake of calcium was higher by 24–25% in boys and by 19–20% in girls, in comparison to the Czech RDAs. When compared with the RDAs for calcium, it was nearly 2.5 times as high for the EC (1993) and 1.4 times as high for the United States (1989). This applies to boys, although the difference will be slightly lower for girls. The intake of iron was lower by about 11% in boys and by about 16–17% in girls compared to the Czech RDAs (Kajaba et al. 1992). The intake of iron corresponds to the United States RDAs (1989), and will be more than double the EC RDAs (1993). The intake of vitamin B1 was higher than recommended by 15–16% in both boys and girls. [The RDAs for thiamin for U.S. (1989) preschool children are slightly lower compared to the EC (1993); it is expressed in relation to EI in MJ; see Table 5.6c.] The intake of vitamin B2 was about 40% higher in boys and 20% higher in girls. Because the RDAs of the EC and the United States are higher, the consumption of this vitamin by our group of children would have corresponded better to these RDAs than to Czech ones. The intake of niacin was about 16% higher in boys and about 9% higher in girls, and the intake of vitamin C was higher than recommended by about 15%, in both boys and girls. The EC (1993) and U.S. RDAs (1989) for vitamin C are lower (see Table 5.6c); hence excess intake of this vitamin would be even more marked when compared with these RDAs. Regarding the sex-linked differences, the intake of energy and all other items was almost always slightly higher in boys than in girls (with the exception of vegetable protein and carbohydrate), but the differences were not significant because of great interindividual variability, that is, high values of CV (see Table 5.7a and b).

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The trend toward higher EI in preschool boys can be explained by a slightly higher weight and leanness; in addition, practical experience and evaluation by the teachers in day-care centers showed, almost regularly, slightly higher levels of spontaneous PA in boys, which could be responsible for the trend of increased EI. This was also proved by DuRant et al. (1993a,b) when using the Children’s Activity Rating Scale (CARS). These measurements showed, moreover, a higher level of activity in summer and in spring than during the winter and ethnic differences in activity levels in Anglo-, African-, and Mexican-American children aged 3 or 4 years. When we evaluated the ratio of macrocomponents, that is, the percentage of energy provided by protein, fat, and carbohydrate, the results were not satisfactory. In boys the energy ratio of protein was about 13%, of fat was about 34%, and of carbohydrate was 53%. In girls the energy ratio of individual nutrients was about 13:32:55. This indicates once more that the amount and percentage of fat was too high; recommendations of the WHO (1985) emphasize that less than 30% of energy should be provided by fat and more than 50% by carbohydrate. The practical outcomes of these assessments are individual recommendations and counseling for parents on how to improve the diet of their children, mainly by decreasing the amount of fat and protein and by increasing the consumption of carbohydrates (especially of complex carbohydrates). Girls had a slightly better composition of diet, but the differences in our groups were not significant. General instructions also included increased vegetable and fruit consumption and reduced sugar consumption. An increased intake of total and saturated fat was also shown in U.S. children: in 80% of children, this intake was higher than the recommended levels (Johnson et al. 1994, Thompson and Dennison 1994). The level of urbanization affected most of the nutrient intake variables, followed by race. Living in a rural area and being black were significant predictors for higher intakes of total and saturated fat, cholesterol, and sodium. By introducing meals containing a smaller amount of fat, a significant reduction of fat intake was achieved (Thompson and Dennison 1994). Until recently, the computer program used in the Czech Republic did not permit the evaluation of saturated and polyunsaturated fats, cholesterol, sugar, fiber, etc.; the use of foreign programs cannot always give exact results (International Union of Nutritional Sciences (IUNS), Federation of European Nutritional Sciences (FENS), European Academy of Nutritional Sciences (EANS), etc., do not permit the use of programs with different databases). Analysis of the intake of individual foodstuffs showed that children consumed more sugar (especially as sweets) and less fruit and vegetables than generally recommended. Although there was no vitamin C deficiency in the whole group, in a number of children the intake of this vitamin was quite low (but not as low as the RDAs of the EC 1993), as indicated by the values of CV. The same also applied to some other dietary components, especially to calcium and iron intake. The values of somatic development—height, weight, and BMI—did not reveal markedly elevated values and/or obesity. However, the delayed effects of such a diet with too much protein and fat in preschool age may appear later in school age and/or during adolescence. This was shown by higher BMI values in the upper percentiles, starting with 7 years of age in Czech children (Prokopec and Bellisle

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1993). All this may be related to increased health risks later on in life as mentioned above. Large interindividual variability of food intake (as an average value for 1 week) was also shown, that is, excessive intake was recorded only in some children. For example, the values of CV of the intake of energy were 24–26, of proteins 27–28, of fats 31–32 in boys and about 45 in girls, and of carbohydrates about 28–29. Variability was even greater regarding the intake of minerals and vitamins (see Table 5.7b), that is, the values of CV were 41–63 for calcium and iron intake, about 36 for vitamin B1, 64–65 for vitamin B2, 35–43 for niacin, and around 50 for vitamin C. These values indicate that in some cases the intakes were not only excessive but also occasionally deficient. This was found when evaluating between child and day-to-day variability of children who spent most time in the kindergarten, that is, under the same conditions and offered meals. However, on a long-term basis and even within 1 week, the variations were usually compensated for and, on average, no real deficiencies were found. However, some intakes were lower than desirable. Correlation analysis among individual components showed the closest relationship between intake of energy and that of carbohydrate (r = 0.92), then of fat (r = 0.85), and finally of protein (r = 0.82). Correlation coefficients r were always higher for animal than for plant fat and protein. There were no marked relationships between diet and somatic growth, which was also influenced by the age range of our groups. A lack of relationship was also found between dietary intake of total energy, protein, fat, carbohydrate, and percentage of fat in U.S. preschool children (Atkin and Davies 2000). It may be speculated that the present energy disbalance may be rectified, for example, by increased PA, but also may not. The relation of fat intake and body fat may develop later on. It could be assumed that an increased food intake during this period of development accelerates the overall development, but does not result in overweight and/or obesity yet. Food intake was also assessed in our longitudinal measurements of children mentioned in Chapter 4 (study E). At the time of the first measurement of 36 boys and 22 girls, dietary intake was examined using the same procedure as mentioned above. However, due to a greater need for cooperation, at the time of the second and third measurements we were only able to assess the dietary intake in a smaller number of children. Therefore, they were not always the same children in all measurements. On the whole, the conclusions based on the sort of diets ingested by preschool children revealed that composition, mutual relationships of various components, inter- and intraindividual variability, etc., were nearly identical, as described above by crosssectional assessments. The results of both cross-sectional and longitudinal measurements of dietary intake made during the same growth period, that is, 4–6 years (G, H, E), revealed the following: 1. There was approximately the same dietary intake in both genders, with a trend toward higher intake in boys; this applied to both cross-sectional and longitudinal surveys (see Table 5.7a and b). The differences between boys and girls were not significant, and interindividual variability was great.

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g

200 150 100

Total Animal Plant

50 0 Protein

Fat

Carbohydrates

FIGURE 5.1 Intake of protein, fat, and carbohydrate in preschool boys and girls (survey I).

2. During repeated measurements, dietary intake showed a slightly increasing trend that was not significant during the period from 4 to 6 years, mainly due to great variability (Parˇ ízková et al. 1980, 1984). All these studies were made in Prague, where the economic level has always been the highest in the Czech Republic. When we compared the results with the data assessed in other parts of the country, we found different results: Prague children had a higher dietary intake than children from a small town (16,000 inhabitants) about 60 km from Prague (survey I). These children also had smaller body sizes and different motor abilities (Chapter 9; Figure 5.1). When evaluating the dietary intake of children followed up on different occasions, we obtain the reason for elevated BMI: dietary intake, especially that of fat, but also that of protein, was too high (Parˇ ízková et al. 1984). The intake of energy obviously did not correspond to the needs of the organism as in other studies (Kisteneva et al. 1990). This was also confirmed by the estimation of energy output using the abovedescribed approach for the analysis of energy requirements recommended by WHO (see Table 5.3). These evaluations could not be made in all children, but only in a subsample, using questionnaires where the activities of children (specified activities, duration) were entered by kindergarten teachers and parents. The results showed that the estimated energy output was lower than the EI, by about 20% (see the example). We had no opportunity to use the DLW method in normal healthy Czech preschoolers.

5.10 FOOD INTAKE AND ENERGY OUTPUT IN OTHER PRESCHOOL CHILD POPULATIONS A great variability in food and nutrient intake was also observed in other studies of child populations, for example, in Asian children in Sheffield (Harbottle and Duggan 1994). The between-person variation, as measured over a period by weight

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intake data, was high and comparatively larger than the within-subject variability. For energy, the between-subject variability was 26% at 4–12 months and 36% at 12–24 months. Variability of a similar sort already appears, however, at the beginning of life, similar to the variability in infants (Bellu et al. 1995). Johnson et al. (1994) showed that in U.S. children aged 1–10 years, nutrient intake was mostly affected by the level of urbanization; this was followed by the impact of race. Living in a rural area was a significant predictor for a higher intake of total fat, saturated fatty acids, cholesterol, and sodium. Mean annual household income had no significant effect on any of the diet quality measures. In an average diet, vitamin E, vitamin C, iron, and zinc intakes were below the recommended levels. The percentage of calories from total and saturated fats and mean sodium intakes was above the recommended levels. In the United Kingdom, the intake of fats increased up to 40% of the levels of energy in the late 1950s, with little change until the late 1970s (Stephen and Sieber 1994). Trends were similar in all age groups. These results differ from the pattern in the United States, where a decline in mortality from coronary heart disease can be seen. In preschoolers in the United Kingdom, fat intake was found to be 35.9% of energy (Gregory et al. 1995). A low intake of vitamin C was shown even in a country where fruit is cheap; in Latino children in the United States, it was lower than recommended levels (Basch et al. 1994). There is a problem with alternative diets for young children (macrobiotic, vegetarian, etc.; Leung et al. 2001). The long-term consequences of all the diets mentioned above concerning nutritional, metabolic, and functional status of children have not yet been reported, which would be a decisive factor in the evaluation of their longitudinal impact during the growth period. Because it is very difficult to ensure an adequate composition of alternative diets in line with the RDAs for young children, it is necessary to be very careful; perfect nutritional knowledge on the required composition and/or supplementation of such diets is limited, so it is better to choose normal diets (however, even such diets can have inadequate composition and deficient amounts of certain items!). Measurements of dietary intake (during 4 days) in 1657 UK children (Gregory et al. 1995) from 1.5 to 4.5 years of age showed, in the oldest subgroup (3.5–4.5 years), markedly lower energy, nutrient, vitamin, and mineral contents compared to those in Czech children, which cannot be explained by the slightly different ages of the groups compared. Although the dietary intake of UK preschool children was also higher than local RDAs, a considerable difference in the dietary intake of Czech and UK children was obvious. Actual values of BMI in Czech and UK children, however, do not differ significantly. Energy expenditure has a significant effect on dietary intake in all age categories, including young children. Data on this have been sparse up to now, especially in industrially developed countries. However, the method of DLW made a number of important measurements under field conditions possible (Prentice 1990, Livingstone et al. 1991). Data on EI correspond much better to data on energy output in young children, especially infants, than in older subjects. However, in children 3.5–4.5 years old, the weighed dietary record gave an EI greater than the expenditure measured by DLW (Davies et al. 1994, Gregory et al. 1995), which confirmed the

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conclusions from our observations. Similar results have been reported in slightly older children (Livingstone et al. 1991). There may be a significant bias that could ultimately lead to obesity (provided the measurements are exact), the elevated prevalence of which was reported recently in the United States (Kuczmarski et al. 1994) and elsewhere during adolescence. Goran et al. (1994) examined the components of daily energy expenditure in children 4–6 years old, characterized for body weight, height, heart rate, and body composition from bioelectrical resistance. The total energy expenditure (TEE) was measured over 14 days under free living conditions using DLW. REE was estimated using indirect calorimetry, and activity energy expenditure (AEE) was calculated from the difference between TEE and REE. The mean value of the assessed TEE was markedly lower than the RDA for energy for this age group. Activity-related energy expenditure was estimated to be 267 kcal, that is, 1117 kJ/day. TEE was most closely related to FFM, body weight, and REE. When TEE was adjusted for FFM, a significant correlation with heart rate was observed. When evaluated collectively, 86% of interindividual variations in the TEE were accounted for by FFM, heart rate, and REE. The results of this study also indicate that the present RDAs for energy are unnecessarily high (Prentice 1990), which could be one of the reasons for an increasing prevalence of obesity later on. This applies even more to Czech children. In another study, Dauncey (1990) showed that the evidence from direct and indirect calorimetry suggests the possibility of the alteration of 24-h energy expenditure by 20% by altering the differences in minor spontaneous activity. This compares with values in the order of 10% from moderate overfeeding and somewhat less than this during mild cold exposure. Individual variability in 24-h energy expenditure can, therefore, be accounted for not only by the differences in resting metabolism and the thermic responses to EI and temperature, but also by the differences in minor activity. Even fidgeting can contribute significantly to energy expenditure in restless children. Davies et al. (1995a) measured TEE using the DLW technique and compared it with the 1991 UK recommendations for EI. These results add to the growing literature (Durnin et al. 1974, Durnin 1984, Livingstone et al. 1991, Prentice et al. 1988), which indicates that energy expenditure in young children is significantly below previous estimates, that is, by 10–12%. Secular changes in habitual levels of PA might be responsible for reduced energy output, as shown previously by Durnin et al. (1974) and recently by Schlicker et al. (1994). Davies et al. (1994, 1995a) assessed TEE/ BMR and TEE minus BMR in 77 preschool children. TEE was measured using the DLW technique, and BMR was predicted from body weight. Body fat was assessed by measuring total body water via stable isotope dilution. Correlation analysis of the results showed that a low PAL was associated with a high level of body fat. This was also demonstrated in previous surveys of Czech children (Parˇ ízková et al. 1986a,b) and in other populations of children (see also Chapter 8). The estimates of energy expenditure for children published by the FAO/WHO in 1973 gave much higher values than the actually measured values. Since a dramatic decrease in the BMR of children during the last decade could hardly be assumed, only changes in behavioral patterns, that is, an overall lowering of PAL, may explain the discrepancies between the assessed energy expenditure of children and the

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previous RDAs for energy (Durnin 1984, WHO 1985, Gregory et al. 1995). The differences found between these RDAs for energy and the level of energy expenditure measured by Griffiths and Payne (1976) were of the same range as the differences in energy expenditure of children from obese and normal-weight children (Griffiths et al. 1990). PA and motor development level, which display such a large variability, can be influenced by a number of factors (Wolanski and Parˇ ízková 1976). The results of Wolanski et al. (1992) showed that, parallel to genetic and maternal factors, cultural factors in a particular society (traditional customs, social practices, etc.) determine motor traits in children. Genetic factors obviously play an important role in the development of PA and energy expenditure (Roberts et al. 1988; see Chapter 8). The level of spontaneous PA in 24-h cycles during 1 week was assessed in monozygotic and dizygotic twins (Gapon 1972, Ledovskaya 1972). Under physiological conditions, the level of PA was quite stable over a certain period of time, as also observed for EI (Birch et al. 1991). Days with a high level of spontaneous PA were alternated with days in which the activity level was low. The resulting value for 1 week was a relatively stable characteristic for a particular child. There was more resemblance in the level of spontaneous activity during the same period in monozygotic than in dizygotic twins (Ledovskaya 1972), which might have obviously had an effect on EI. Another study using a film recording method showed that monozygotic twins resembled each other more regarding biomechanical stereotype when performing the same physical task (e.g., running, jumping, etc.) than normal siblings or non-related children of the same age (Sklad 1972). Griffiths and Payne (1976) assessed energy expenditure in 4–5-year-old children born to either normal or obese parents, in whom a different level of PA may be assumed. The values of integrated pulse rate for the day were measured and individually calibrated for oxygen consumption (measured with a continuous- flow diaferometer). The energy expenditure was significantly lower in children of obese parents. Birch et al. (1991) recorded a lower EI in 2–5-year-old U.S. children comparable in weight (and obviously also in age) than in Czech children. The composition of the diet in U.S. children was quite different (see Table 5.7a and b). U.S. diets were lighter, with more fruit and less fat. A great variability in the food intake of children was also found; in this study, however, the age and weight range was much wider than in our study, so it is difficult to compare the results. These authors also found a great variability in individual meals and a negative correlation between the EI of one meal to the next. Negative correlations predominated. This indicates the existence of some orderly control mechanism, which is regulated over a longer period of time, under conditions when a child is free to consume meals according to spontaneous choice. Genetic similarities in response to a negative energy balance caused by exercise in adult identical twins with constant EI were observed. Intrapair resemblance in the changes of body weight, fat mass, skinfolds, abdominal visceral fat, fasting plasma TGs and cholesterol, maximal oxygen uptake, and respiratory exchange ratio was found (Bouchard et al. 1994). Regarding relationships between dietary intake and energy output, measurements using DLW during a 7-day period showed, in another study of 5-year-old

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children, that the total free-living energy expenditure (TEE), including PA (assessed by questionnaires), was considerably lower than the RDAs (1370 ± 222 vs. 1807 ± 310 kcal/day, p < 0.001). The RMR was slightly higher than the predicted RMR. PA accounted for only 7% of the TEE. The index of activity, assessed as the difference between measured TEE and predicted TEE, correlated positively with sports leisure activity assessed in the questionnaire. It was concluded that the TEE in 5-year-old children yields lower values of energy expenditure by about 400 kcal/ day compared to current estimates. This might be due to lower than expected levels of PA (Fontvieille et al. 1993). However, it is necessary to be cautious regarding the interpretation of data using various methods—for example, the use of the foodfrequency questionnaires significantly overestimates the EI measured in children (Kaskoun et al. 1994). The influence of parental practices on children’s food intake is important (Koivisto et al. 1994), and the same applies to general lifestyle (Birch et al. 2001). In addition, the effect of commercials in mass media, especially TV, promotes sedentary activities such as playing videogames, watching TV programs, etc., which concerns at present even preschool children. The imbalance between EI and output (Durnin 1984), the impact of which might not be manifested immediately, is obviously a serious risk for later obesity and other health risk factors. This was also indicated by some experiments on laboratory animals (Hiremagalur et al. 1993). Food intake and behavior are significantly influenced by TV viewing: food advertisements shown during children’s viewing times involve foods that are high in fat, sodium, or added sugars, and low in nutrients (Batada et al. 2008). Foods most advertised during children’s viewing hours are not those foods that contribute to a healthy diet for children (Taras and Gage 1995, Neville et al. 2005, Wilson et al. 2006, Kelly et al. 2007, Page and Brewster 2007, Thompson et al. 2008). Food advertising regulation is required, especially for children. But in spite of this effort, no significant change has been achieved up to now. Such advertising has even spread to other countries. One of the reasons for low fat deposition is a high level of spontaneous PA, a common characteristic of preschool age. Later on, when the level of activity is diminished (as occurs at the beginning of primary school both at school and during leisure time; Parˇ ízková and Hainer 1990, Sigmund et al. 2008), the excess intake may already manifest itself gradually in apparent overweight or even obesity. This starts to manifest itself in younger schoolchildren and worsens later, especially if the overall dietary regimen and PA do not improve.

5.11

FOOD HABITS, PREFERENCES, AND AVERSIONS IN PRESCHOOL AGE

Early food preferences have an important role in the dietary intake of children. As was shown in a study in 70 child/mother pairs, mothers influence their children through their own preferences, which may limit the foods offered to children (Skinner et al. 2002). A study in English children 4–16 years old revealed healthier food preferences in girls (fruit, vegetables) than in boys (sugary and fatty foods, processed meat products, eggs). Across ages and genders, children rated fatty and sugary foods

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most highly, although ratings for fruit were also high. Children’s food preferences overall were not consistent with a healthy diet (Cooke and Wardle 2005). For healthy eating patterns, breakfast is very important; the breakfast glycemic index affects the subsequent daily EI in free living children 2 years old. A low glycemic index of the first meal results in the intake of more calories throughout the remainder of the day (Donald Study; Buyken et al. 2007). Portion size and energy density (ED; Astrup 1998) act additively to promote EI at meals among preschool children (Fisher et al. 2007). Reducing the ED of an entree decreases children’s EI at lunch (Leahy et al. 2008). The effect of bite size and intake of an entree are greater with large portions than with age—appropriate or self-selected portions. Large entree portions may constitute an obesogenic environmental influence in preschool age, resulting in excessive dietary intake. Children with satiety deficits may be most susceptible to large portions (Orlet Fisher et al. 2003). Preference of beverages can influence significantly EI and turnover. In a followup, O’Connor et al. (2006) found that preschool children drank less milk than recommended; only 8% drank low-fat and/or skim milk, which is recommended after 2 years of age. On average, preschool children drank less than 6 oz/day of 100% fruit juice. An increased beverage intake was associated with an increased EI, but not with BMI. Water as a neglected nutrient is suggested—provided it is hygienically safe—as a healthy alternative to calorie-dense, non-nutritive beverages, such as artificial fruit drinks and soda (Bourne et al. 2007). Neophobia can play an important role in food preferences, and a strategy to influence it should be considered when educating children on a healthy diet at an early age (Russel and Worsley 2007, 2008). Branding of foods and beverages influences children’s taste perceptions. Marketing for children should be regulated; suitable marketing and commercials may be a useful strategy for improving children’s eating behavior (Robinson et al. 2007). An intake of unsuitable beverages can contribute to an increased incidence of dental caries in young children (Marshall et al. 2003). The availability of adequate food and PA in school neighborhoods was considered with regard to obesity risks in children in Los Angeles. It was found that the location of food establishments, the availability and quality of fruit and vegetables in local grocery shops, and the quality of local parks can have a significant effect in this respect. Nearly half the food outlets were fast food restaurants, most of them within walking distance from schools. In contrast, only 18% of grocery shops sold fresh fruits, etc., and only a minority of them was within walking distance from schools. Only approximately half an acre of parks per 1000 inhabitants was available for PA and exercise. Easy access to fast food and limited access to both healthy food options and parks in areas around schools can contribute to overweight and obesity development in children (Kipke et al. 2007). The fast food industry continues to increase nearly everywhere; scientific findings and corresponding public health implications of the association between fast food consumption and increasing weight and BMI (Rosenbeck 2008), also in children, deserve special attention. Some sections of the society (children from low-income groups or homeless, minority subjects of all age groups, seniors, etc.) appear to rely on fast food as an important source of meals (Rice et al. 2007). Health-care

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professionals should be alerted to the fact that fast food should not be forbidden, but should be—when necessary—prepared and offered in a form more compatible with the RDAs. It would be possible to present a fast food menu that provides a reasonable level of essential nutrients without exceeding the caloric and essential macro- and micronutrient recommendations. The effort to introduce healthy eating behaviors since early childhood has had a long tradition (Comenius 1632): education has an essential role starting with adequate nutritional status of the mother before pregnancy, her optimal dietary intake and PA regimen during pregnancy, family model and lifestyle, and educational interventions since early childhood. All these early influences help in nurturing proper nutritional and PA habits in children during subsequent preschool years (Parˇ ízková 2008). Inter alia, it is a good start for adequate health status and prognosis for later life, which generally has a dimension of public health and immense economic significance (James 2006). Proper food habits and adequate food preferences have an essential importance, and should be started as early as possible: continuity and stability of eating behavior traits were revealed in a longitudinal study starting at 4 years of age, with a control 7 years later. As mentioned before, eating behaviors, including those associated with a tendency to over-eat, emerge early in life, and show levels of individual continuity comparable to personality traits (Ashcroft et al. 2008). Rectification of improper eating behavior is therefore needed as early as possible.

5.12 RDAS FOR PRESCHOOL CHILDREN: IS THERE A NEED FOR FURTHER REVISION? With increasing frequency, we encounter the opinion that not only the actual food intake but primarily the recommended energy allowances for children are too high. The effort to feed the child abundantly is certainly well motivated, and is the result of experiences from previous centuries where a bigger and fatter child survived more often or was in better shape than a smaller, leaner, or skinny child. Old painting masters presented the “little angels” as an ideal who are today considered obese. Energy reserves were good for coping with gastrointestinal, respiratory, and other illnesses, especially in early childhood. This may still apply to some Third World countries. However, under the present conditions in industrially developed countries, such a situation is not necessary because of the development of medical care. The delayed consequences of an imbalance between EI and output since the beginning of life have been considered. As shown by our previous studies, the percentage of depot fat correlated significantly positively with total serum cholesterol and TGs, that is, the fatter the preschool child, the higher the serum level of cholesterol and TGs (Parˇ ízková 1989). Donker et al. (1993) found a significant positive correlation between the Quetelet index (which is the same as the BMI) and cholesterol in children and youth aged 4–19 years. However, such a relationship was not proved in child populations in Spain, which may be due to the Mediterranean diet (ElcarteLopez et al. 1993). Dietary intake was also followed in preschool children in Yugoslavia and intervention was made according to the level of their serum lipids (Pavlovicˇ 1995).

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These relationships indicate that excess dietary intakes resulting in actual or delayed fatness are risk factors that enhance the development of atherosclerosis and/ or ischemic heart disease, diabetes, and other health problems later on in life. Atherosclerosis has been defined as a “pediatric problem” (Kannel and Dawber 1972). Obese children generally become obese adults (DiPietro et al. 1994), accompanied by comorbidities. Nutritional data from the Second National Health and Nutrition Examination Survey (NHANES II) were analyzed in order to assess the dietary patterns of a representative sample of children, starting with the first year of life. The results showed that the average U.S. child’s diet is relatively high in total and saturated fat and low in the ratio of polyunsaturated and saturated fat. These dietary patterns deviate from current dietary recommendations of the WHO (1985), among other organizations (RDAs, USA 1989, EC 1993). The percentage contributions of specific macronutrients to the total EI in the U.S. study were as follows: total fat, 35–36%; total carbohydrate, 49–51%; protein, 15–16%. This is in contrast to current expert recommendation for the period of growth, that is, up to 30% of energy covered by fat, 15% by protein, and 55% by carbohydrate. The observed intake of saturated fats in U.S. children was 13% of energy, in contrast to a recommended level of 10%. There were also some racial differences—white children ingested more carbohydrate and less fat than black children, who had more cholesterol in their diet. The amount of protein did not differ. More wholesome dietary intake patterns were suggested for U.S. children (Kimm et al. 1990). Another previous comparative analysis by Albertson et al. (1992) showed trends after a 10-year interval, that is, 1978 and 1988 in U.S. 2–10-year-old children: 14-day food consumption diaries showed that the intake of most dietary macrocomponents of food remained constant. However, daily vitamin and mineral intakes were lower in 1988 than 10 years before. The intake of most nutrients remained higher than the U.S. RDAs. For more than half of the children, the intakes of calcium, zinc, and vitamin B6 were below the RDAs. These results also indicate the necessity for the permanent monitoring of food consumption patterns in children, as unfavorable changes have continued until the present. Surveys by Gregory et al. (1995) showed a higher than necessary energy and macrocomponent intake in preschool children in the United Kingdom, confirming previous conclusions on the necessary revision of RDAs (Prentice et al. 1988). Measurements in children of the Czech Republic revealed, as mentioned above, much higher dietary intakes, especially of fat and protein, which may be one of the reasons for the numerous health problems in the Czech population later on in life (Uemura and Píša 1988). Due to recent positive changes in Czech diets (less saturated fats and simple sugars, more fruits and vegetables), improvements in morbidity and mortality appeared during the last two decades. However, the RDAs for fat must be adhered to, especially for the essential, longchain fatty acids. Their deficiency may affect the maturation of the CNS, including visual development and intelligence. The intake of fat should not be restricted to under 30% of EI until the age of 2 years (Hardy and Kleinmann 1994, Uauy et al. 2000). The same applies to many other essential items of children’s diets.

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As shown by Shea et al. (1994) higher amounts of fat are not absolutely necessary for normal growth; the statures of children with different fat intakes, that is, 27.1% versus 38.4% of energy (i.e., lowest and highest quintiles), were compared. Children who consumed a lower percentage of energy provided by fat also consumed significantly less total calories, saturated fat, cholesterol, calcium and phosphorus, carbohydrates, thiamin, niacin, vitamin A, and vitamin C. No differences were evident in growth stature across quintiles, in spite of all the differences in dietary intake mentioned. However, possible later changes in growth were not followed up.

5.13 GENERAL CONSIDERATIONS AND RECOMMENDATIONS Adequate energy balance and turnover have to be considered—individuals with higher energy output can eat more without the risk of enhanced fatness or possible marginal deficiencies due to reduced food intake. It is therefore, especially for children, more plausible to return to former behavioral patterns with increased PA than to adapt dietary intake to reduced energy output with lowered food intake. It is also highly desirable to introduce a healthy composition, that is, the ratio of macrocomponents of diet early in life when nutritional habits are established (Cashdan 1994), and an adequate and/or inadequate food choice may be taught and practically introduced. This includes an adequate amount and mutual ratio of foods ingested, with a satisfactory amount of fiber, a limited amount of sugar and saturated fats, and adequate amounts of other food items. Because of recent changes in lifestyle, it is important to correct energy output and overall energy balance with increased energy output, that is, exercise—this may be a more natural and physiological way of improving fitness and health. Even when no substantial modifications of dietary recommendations are suggested, more recent information is available. Nutrition has an effect on cognition and behavior of children (Bellisle 2004, Kramer et al. 2008). Reference values for nutrient intakes for the EU (German and Austrian Nutrition Societies—DGE, OGE, and Swiss Nutrition Societies, 1st ed., German Nutrition Society 2002) suggest 6.4 and 5.5 MJ/day (2500 and 1400 kcal/day) for 4–7-yearold boys and girls. EI was recommended according to PAL, which varies (340– 330 kJ/kg body weight for moderate PA; no measurements for high PA are available). With regard to protein, 0.9 g/kg/day, or 18 and 17 g/day, and/or 2.8 and 2.9 g/MJ for boys and girls of the same age are given. Fat should be 30–35% of EI per day. Carbohydrate should be more than 50% of the daily EI. The intake of disaccharides (lactose included) is between 8.9% and 19%, and that of monosaccharides is between 4.7% and 6.4% of dietary energy. The proportion of added sucrose (isolated cane/beet sugar) accounts for 6.3–13.2% of energy; sugar intake should be moderate. For infants and children no guiding values for dietary fiber are available. Water intake is 940 mL/day from beverages, 480 mL/day from solid food, and 75 mL/kg/day from beverages and solid food together for both boys and girls of preschool age. DRIs (Barr 2006) give dietary guidelines on individual macronutrients, phytonutrients, vitamins, and minerals (USDA, National Agricutural Library). DRI Reports on the internet also give essential guidelines on nutrient requirements, and define the needs for all individual items of dietary intake for individual age groups.

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They were last modified in spring 2008 (DRI Reports, see www/nap.edu). DRIs for energy are differentiated according to PAL (WHO 1985). Estimated average requirement (EAR) do not differ markedly from DRIs. However, further effort for a more exact definition of dietary recommendations with regard to age, gender, permanently changing lifestyle and environment, PAL and/or increasing inactivity, and changing character of foodstuffs and their marketing can be expected in the near future.

6

Functional Development and Physical Activity during Early Childhood

The weaker the body, the more it gives orders; the stronger it is, the more it obeys. —Jean Jacques Rousseau

6.1

INTRODUCTION

During early growth, attention has mainly been focused on body size development and much less on the functioning of the organism, which may be more important. New standardization was introduced, enabling the use of functional testing and comparisons between groups and/or along various periods of growth, and its larger application is considered for future studies. This was apparent especially when considering the effect of different types of nutrition and PA. Actual and delayed consequences of early dietary intake and PA regimen levels manifested during later life have been considered in greater detail only more recently, and studies on PA and related energy expenditure (EE) and nutrition in this respect are rarer. Habitual PA, functional capacity, and motor performance are due not only to genetic factors but also, on a large scale, to early environment (Marisi 1977, Franks et al. 2005)—for example, family models, availability of spontaneous PA and exercise, food behavior of parents, etc. The role of genetic factors in physical performance, aerobic fitness, and muscle strength was found to be very important, but has been studied mostly in adults (Missitzi et al. 2004, 2008). It is possible to assume that they may already appear at an earlier age. It was mentioned above that in adolescents the amount of PA during a certain time interval (a week; Ledovskaya 1972) and the character of movement during certain motor tasks (Sklad 1972) more closely resemble each other in identical twins than in non-identical twins, or brothers and/or sisters in one family. Genetic variation also concerns maximal velocity and EMG activity as found in mono- and dizygotic twins (Missitzi et al. 2008). The same applied to physical fitness as characterized by aerobic power and cardiorespiratory efficiency. In addition, education and stimulation in this respect have an essential role in achieving optimal functional level at an early age (Parˇízková 1977, 2008), especially when based on proper genetic predisposition. An adequate level of PA results in a desirable level of physical and aerobic fitness, and has been recommended since preschool years (American Academy of Pediatrics 1992, Timmons et al. 2007).

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Adequate development of cardiorespiratory fitness, endurance, skill resulting from an optimal example and stimulation in the family, or day-care centers, and/or anywhere else are a good predisposition for the development of necessary functional capacity, and thus also the willingness to continue with a desirable level of PA along with further development of physical fitness. Stimulation for the development of these faculties should be adequate according to age, gender, and developmental level, based on individual testing, so as to avoid undesirable loading during early life (Timmons et al. 2007). Improper stimulation and loading could have undesirable consequences, and also result in a refusal of any PA and exercise, which should anyway be performed in a relaxed state. This would involve a subject characterized by a low, understimulated level of functional capacity, resulting in unpleasant strain during most physical activities. Children with poorer motor skill performance were found to be less active than children with better-developed motor skills. The relationship between motor skill performance and PA could be important to health during early growth, especially as related to obesity prevention (Williams et al. 2008). The importance of adequate education and stimulation at an early age is evident, especially when PA, aerobic fitness, and performance in children and adolescents have been deteriorating during the last decades (Ekeland et al. 1999, Tomkinson et al., 2003, 2007, Tomkinson and Olds 2007a,b, Olds et al. 2006, Tomkinson 2007, Malina 2007) accompanied by increasing adiposity (James 2002, 2006, 2008a,b, James et al. 2004).

6.2

PA, EE, AND PHYSICAL FITNESS IN YOUNG CHILDREN

EE is composed of a number of components. TEE includes the following: Basal metabolic rate (BMR)—the minimal rate of EE compatible with life (under conditions of sleep). It is higher in children than in older subjects. Resting metabolic rate (RMR)—the rate of EE usually measured under resting conditions, and the most commonly used measure. Thermic effect of food (TEF) or diet-induced thermogenesis (DIT)—the energy used for digesting, absorbing, storing, and disposing of ingested nutrients. It is usually estimated as 10% of total energy expenditure (TEE). AEE—the energy spent for activity—PA, exercise, etc. PA generally means any body movement produced by muscles that results in an increased EE. PAL expresses the ratio between BMR and TEE: TEE during 24 h/ BMR during 24 h. Physical activity ratio (PAR) = TEE min/BMR min (WHO 1985). Exercise is a PA that is planned, structured, repetitive, and purposeful. Physical fitness is a set of attributes that relate to the ability of people to perform PA and exercise; health-related physical fitness includes components of physical fitness that are associated with aspects of health (McArdle et al. 1991)—a status of full mental, physical, and social well-being (WHO 1985). Physical fitness is also defined as a complex of prerequisites that allows an organism to react in an optimal way to various environmental stimuli. As mentioned above, this is an essential component of health. Therefore, its examination is also essential for the evaluation of the health status of any human being generally, and of

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course not only in relation to eventual sports activity and performance (Tomkinson et al. 2007a,b). The human being was born as an active subject, so he/she should be examined as such—during activity. This applies to all age categories, including preschool age. The level and character of PA belong to the individual characteristics of any human subject, and are usually higher during growth—especially during preschool age— than during later periods of development, and were shown to be related to many other characteristics, for example, EE (Montgomery et al. 2004, 2005), body composition, and aerobic fitness (Parˇízková 1977). Step count recommendations for children based on body adiposity were prepared (Duncan et al. 2006, 2007, 2008). Movement assessment batteries for preschool children in, for example, Australia were suggested (Livesey et al. 2007). Significant relationships between PA, physical fitness, muscle strength, and nutritional state were found in children 5–11 years old (Grund et al. 2000). A lower PA was found to be related to SES in some growing populations (Lampert et al. 2007, Opper et al. 2007, Starker et al. 2007), but not in others such as Scottish children (Kelly et al. 2006). New estimates for energy requirements even for children 0–3 years old have been derived with respect to TEE, by combining the measurements of EE for growth and energy output using DLW, which may result in the need to reappraise dietary guidelines for young children (Prentice et al. 1988). This is essential so as to avoid the possibility of early overnutrition and the risk of overweight and obesity. A longitudinal study in a group of the same children using pedometers revealed a decrease of spontaneous PA when comparing preschool age periods and after starting primary school, when evaluating activity not only during weekdays, but also during free time weekend days (Parˇízková and Hainer 1990, Sigmund et al. 2008). Crosssectional assessments of PA using accelerometers were conducted in U.S. Hispanic children from 4 to 19 years, along with BMI, body composition, fitness (VO2 max), and metabolic risk factors. A decline of PA with age was also found, especially in heavier, older, and sedentary subjects (Butte et al. 2007). PALs were weakly but significantly associated with percent fat mass, aerobic power (characterized by VO2 max), fasting serum insulin, and waist circumference. PAL and activity-related energy expenditure (AEE) decreased when following subjects from 3 up to 16 years (i.e., after puberty), as measured by the DLW method (Hoos et al. 2003). In this respect, these conclusions are due to the influence of body size and weight. The DLW method was also used for rural preschoolers in Cuba (Hernandez-Triana et al. 2002). As measured by DLW, AEE and PAL are negatively associated with body fat in non-obese preschool children and in 6–8-year-old children (Davies et al. 1994, 1995a,b, Rennie et al. 2005). Also, muscle strength can be significantly negatively influenced by reduced TEE, AEE, and PAL levels (Grund et al. 2000, 2001), which resulted from TV viewing. PAL was not influenced by moderate and vigorous PA [which was not high, but was influenced by the time spent in both sedentary activities and light-intensity activities (Montgomery et al. 2004, 2005)]. This shows the importance of exercise, which should be arranged specifically for young children. PAL was shown to be related to body composition (Abbott et al. 2002, Abbott and Davies 2004); this study revealed that there may be a threshold of intensity of PA

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that influences body fatness. This was also seen before in other studies of adolescents (Parˇízková 1977), which stressed the significant and decisive importance of character, intensity, and duration and frequency of PA and exercise, which should achieve a certain significant level. A balance between EI and EE was shown to be achieved during 1 week in adolescent gymnasts, but not when comparing both EE and EI on a daily basis. However, this applied under conditions of a relatively high level of both EE and EI (Parˇízková and Heller 1991), when balance can be more adequately achieved. Measurements of EI in preschoolers can be inaccurate, which can influence the conclusion on energy balance; this improves with age. However, the assessments of EI must be conducted by adults—parents, caretakers, teachers in kindergartens, and the like. Methods comparing TEE (DLW) and EI (by weighed record) proved the reliability of these methods (Davies et al. 1994). More recently, EE in young children has been considered to be significantly below previous estimates (Davies et al. 1995a,b), and secular changes in habitual levels of PA might be responsible for reduced levels of PA and the prevalence of sedentary activities, especially TV viewing. More recently, a sedentary lifestyle has been established even during preschool age as assessed, for example, in Scottish children (Reilly et al. 2004). Sedentary behavior can be evaluated by objective methods published by Reilly et al. (2003). Lower PA and more TV viewing were associated with overweight and obesity in young children 4.8–11.4 years old; however, TEE, AEE, and PAL were not related to fat mass at an early age but only later in older children (Grund et al. 2000), when a longer-lasting reduction of EE and lower PA were also manifested by a higher deposition of fat. A marked variability in body composition, food intake, and functional testing was found in children 3–5 years old; cardiorespiratory fitness, evaluated by the results of the step test, creatine kinase (CK) activity, and fat intake correlated significantly with the index relating lean body mass (LBM) kg/10 cm height (Parˇízková et al. 1986a,b). PA as well as dietary patterns in preschool children were closely associated with home environment, as shown by a cross-sectional study of Spurrier et al. (2008), using direct observations and parent interviews. Parental PA, size of the backyard, and amount of outdoor play equipment were associated with more outdoor play. Fewer rules about TV viewing and the presence of a playstation were associated with more sedentary time. This was also related to other items of lifestyle. A higher fruit and vegetable intake was associated with restricting children’s access to fruit juices, carbonated drinks, and high-fat/sugar snacks. A lower fruit and vegetable intake was associated with reminding the child to “eat up” and offering food rewards to eat the main meal. The availability of food groups at home was associated with children’s intake of these foods (fruit and vegetables), fat in dairy products, sweetened beverages, and non-core foods. Early PA as related to dietary intake habits and behavior is significantly influenced by the parent’s example and the home environment, which plays a decisive role at an early age. Therefore, for example, Amish youth, due to the example of the family and overall lifestyle in this community, are physically more active and also have a lower rate of obesity than children living in modern, industrially developed societies (Basset et al. 2007).

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How much and how with regard to PA in preschool age has been discussed, and its determinants, including the role of a child’s environment (family, child care, SES, ethnicity, etc.), have also been considered (Timmons et al. 2007). The role of the association of PA and healthy weight maintenance from childhood to adulthood as related to personal, social, and environmental factors was further analyzed by Cleland et al. (2008). How much PA is enough to prevent unhealthy weight gain during growth and development was the topic of the IASO 1st Stock Conference and consensus statement (Saris et al. 2003). Due to a high level of spontaneous PA as a natural characteristic of small children, it is understandable that limitation of activity was induced as a sensible punishment for some bad deed in previous times—standing in a corner, being closed in a small room, and the like, with no possibility of playing. However, this sedentarism has at present become the lifestyle for nearly all, including children.

6.3

EVALUATION OF PA AND PHYSICAL FITNESS

Physical fitness can be evaluated by assessing the functional capacity of various body systems involved during physical workloads of different degree and character. Fitness implies optimal reactions to demanding situations—both heavy workloads and accompanying environmental stress. The mentioned characteristics are related to age, gender, BMI, and other parameters during growth (Butterfield et al. 2002). Impaired PA and fitness often appears as a result of either a markedly reduced or an overabundant food supply. Inadequate diet has a significant impact on functional development as well as on the level of spontaneous PA of the human organism. All this can cause deviations from normal growth and development. In addition, lack of PA, which contributes to an inadequate energy balance and has an undesirable impact on lipid metabolism, plays a role in the pathogenesis of diseases manifested in later life. The assessment of physical fitness has been frequently restricted to the evaluation of only one system—mostly cardiorespiratory and/or motor fitness—or to the determination of total work output, which under special situations may depend primarily on muscular strength, endurance, or skill. Thus, the interpretation of nutritional and other environmental stimuli varies considerably, depending on the approach used. The comprehensive and well-integrated evaluation of physical fitness still needs substantial methodological development. There appeared also the question—“Are we measuring the right thing?”—when considering cardiorespiratory fitness, exercise capacity, and PA (Ekelund 2008). Up to now the usual evaluation methods mentioned here have been used, which gave some valuable results. When correlations are sought between diet, PA, and physical fitness, individual aspects must be differentiated and specified. Along with morphological prerequisites, physical performance is determined by the summation of aerobic and anaerobic processes, depending largely on the cardiorespiratory system, with a contribution from neuromuscular function and psychological factors. All of this varies during different periods of life, especially during childhood. Even a small child may develop a strain during different physical tasks and workloads, which can be quite intense. As mentioned above, telemetric measurements

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during a game, running round, fighting, etc., showed that the heart rate reached a frequency of 200–220 beats/min (Kucˇ era et al. 1975). This of course never lasts very long, and a child spontaneously interrupts demanding activity. We may assume that all systems necessary for performing such tasks are mobilized and function at a high level. All of this may be markedly influenced by diet and by adaptation processes to different regimens of PA early in life, starting with the possibility of spontaneous play. This has been followed up and analyzed in greater detail during more recent times; however, with regard to the effect of PA as associated with growth, body composition, and overall physical fitness development, data are still rare. This means that the effect of regular and structured PA and exercise during early growth is still insufficiently known (see Chapter 10). As mentioned before, the role of parents, who mostly do not recognize the importance of establishing desirable PA from the beginning of life for their children (i.e., >30–90 min/day), is essential (Irwin et al. 2005). PA is significantly related to EE, as found in a mixed longitudinal study in 5-year-old Scottish children (Reilly et al. 2004). Developmental functions of activity play were therefore reviewed, which were potentially important for children’s education, health, and development (Pellegrini and Smith 1998). The level of PA can be assessed by an actiwatch accelerometer (Lopez-Alarcon et al. 2004) or by pedometers (Duncan et al. 2008); a comparison of the results showed the association (Cardon and De Bourdeaudhuij 2007) and the possibility of evaluating EE. Simplification of the method of assessing daily and nightly EE, using heart rate monitoring calibrated against open-circuit indirect calorimetry, was validated by the DLW method and used for children 8.9 ± 3 years old (Beghin et al. 2000). Accelerometry-measured activity was evaluated in rural boys and girls, and lower adiposity was found in girls who were more active (Treuth et al. 2005). Pedometer-determined PA and body composition (i.e., body fatness) were strongly associated in children 5–12 years old in New Zealand. Mean counts in this sample were 16,133 ± 3864 (boys) and 14,124 ± 3286 (girls) on weekdays, and 12,702 ± 5048 (boys) and 11,158 ± 4309 (girls) on weekends. The range of values and variability was found to be quite large because of gender, weekdays or weekends, and SES. Analysis of variance revealed a stronger association between step counts and body fatness than between fatness and BMI or waist circumference (Duncan et al. 2006). Obese boys were significantly less active than their non-overweight peers 3 – 5 years old (Trost et al. 2003). PA should achieve a certain threshold level to be influential with regard to body composition as mentioned above (Abbott and Davies 2004). Body fatness has been usually found to be associated with the level of PA; however, cut-off points applied to define its intensity have to be validated to develop a firm evidence base for the establishment of more exact PA recommendations (Rennie et al. 2006). This applies especially for individual age and gender groups starting with preschool age. A longitudinal study of preadolescent children over 4 years did not show any effect of EE (DLW method) on the change in fat mass adjusted for fat-free mass (Goran et al. 1998). However, the range of EE and/or intensity of exercise was not considered; results might have appeared after a longer time and at older age. Habitual PALs also correlate with flow-mediated dilation of the brachial artery in 5–10-year-old children, indicating a positive impact of PA on cardiovascular health in childhood (Abbott et al. 2002).

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Measurements in German children and adolescents underlined the importance of exercise-promoting measures; involvement in exercise was lower in subjects of low SES, especially girls and immigrants (Lampert et al. 2007, Opper et al. 2007, Starker et al. 2007). Recommendations for BMI-referenced standards for pedometerdetermined steps/day for children were prepared (Tudor-Locke et al. 2004), and similar recommendations were also based on body fat (Duncan et al. 2007). The role of sedentarism and reduced PA has been analyzed especially with regard to the changes of lifestyle in many countries; there is a general consensus, for example, among pedagogues in schools of all sorts that PA in youth has been decreasing, along with skill and endurance (Parˇízková 1977). This runs parallel to the above-mentioned decline of aerobic fitness in youth, etc. (Tomkinson et al. 2003, 2007). There appeared to be significant and important associations between performance of locomotor skills and weight status among children and adolescents (Okely et al. 2004). Increased fatness due to insufficient development of fundamental movement skills, caused by reduced EE and PA, is another factor in circulus vitiosus, resulting finally in obesity and comorbidities in children. Evidence on the effects of sedentarism, which is against the natural tendencies of children, has been increasing significantly (Gorely et al. 2004, Hancox et al. 2004, Hancox and Poulton 2006). However, when considering, for example, TV viewing, it is important to also know what children were doing during their remaining free time; this is lacking in the majority of studies. Information about all the other discretionary activities should be known and evaluated in mutual relationships; this also concerns diet. The time spent in TV viewing (Parson et al. 2005), especially when the TV was in the children’s bedroom (Dennison et al. 2002), was considered as a reason for BMI and body fatness increase during preschool years (Jago et al. 2005, Gorely et al. 2004). Longitudinal studies, for example, the Framingham Children’s Study (Proctor et al. 2003) and the Iowa Bone Development Study (Janz et al. 2002), revealed this phenomenon with greater variety; this has an impact especially when inactivity has an influence during the AR period. TV viewing during growth and development was found to be associated with adult health, as shown in the birth cohort study of Hancox et al. (2004). Education and stimulation in this respect play an important role in achieving the optimal functional level (Parˇízková 2008), especially when based on favorable genetic predisposition. As compared to morphological and nutritional data, there have been much less complex data available up to now on functional capacity, cardiorespiratory fitness, and gross and fine motorics in preschool children, which could serve as standards.

6.4 CARDIORESPIRATORY FITNESS The ability to carry oxygen to working tissues—particularly to active muscles (aerobic power)—depends on the efficiency of the cardiorespiratory system. It can be evaluated by measuring the oxygen consumption at a given power output, along with necessary factors such as heart and ventilation rate, respiratory volume, carbon dioxide output, or the respiratory gas exchange ratio (R).

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6.4.1 METHODS OF TESTING The maximal oxygen uptake characterizing aerobic fitness is usually measured during a workload on a treadmill, on a bicycle ergometer, or while mounting steps (single, double, triple—step test; McArdle et al. 1991, Parˇízková 1987, Skinner 1987). The maximal oxygen uptake during a load may be expressed in either absolute or relative terms (e.g., per kg body weight and/or LBM or per heart beat). The selection of the tests depends on the aim of the study and on the character of subjects evaluated (age, sex, degree of adaptation to a workload, environmental conditions, financial resources, etc.). With preschool children, testing on a veloergometer would be difficult, because adhering to a regular rhythm and number of rounds in a certain period of time (as an essential condition for testing and comparing individuals) is practically impossible for very young children. Methodical experiments with a specially constructed veloergometer for our laboratory proved that 4–6-year-old children were able to tread on the veloergometer, although irregularly, with intervals of different duration, and so on. Adherence to the conditions of veloergometer testing was only possible in 6-year-old children. With younger children, cooperation was more difficult, in spite of their enthusiasm to use the bicycle ergometer. (There are also special veloergometers that display an attractive picture only when a certain frequency of pedaling is achieved and maintained; we did not have such equipment.) Using a treadmill was only possible for children older than 5 years. At that age they were able to run on it with a safety belt inserted through a pulley. A maximal workload, though, was not used for both ethical and physiological reasons, even in children this age. As shown by our methodical experiments, 3- and 4-year-old children were, on the whole, unable to accept the running carpet below their feet; hence this workload could not be generally used for our studies of cardiorespiratory fitness when we wanted to compare age changes during the whole preschool period, that is, from 3 to 6 years (Cˇ ermák 1969, Cˇ ermák et al. 1973, Parˇízková et al. 1984a,b). We succeeded in testing and evaluating only some children at the age of 6 years, but not all the younger ones. Children of this age were also tested in other studies, for example, by means of track running along with the 25- and 50-m run, the 5-min endurance run, muscle strength, skinfolds, and standing broad jump (Yoshizawa et al. 1977); gender differences were seen in muscle strength, aerobic work capacity, endurance, and agility. Using a mask for measuring oxygen intake and carbon dioxide output was not feasible. The only exception was children at least 5–6 years old, who were able to tolerate the mask and breathe normally with it, not only at rest but also during a workload. The same applied to cooperation with the experimental worker, so as to gain reliable and comparable data. Hoods can hardly be used during different workloads for reliable measurements in young children. A standardized treadmill walking test was used to test the exercise capacity of children 4–6 years of age, which showed good feasibility, safety, and repeatability (Waffler-Kammermann et al. 2008). The distance walked during 6 min was also used as a measure of exercise capacity in children 4–11 years old; normal values

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were established, which decreased with age (4 years—383 ± 41 m, up to 7 years— 488 ± 35 m). Gender differences at this age were not found (Lammers et al. 2008). The 6-min walk test was also used in other groups of children (Geiger et al. 2007). It is recommended that we choose a test that is natural for all children, guarantees homogeneous conditions for all subjects 3–6 years of age, and gives reliable results in all the age categories mentioned. Considering the peculiarities of preschool age as well as the accessibility of equipment, we fi nally chose, after long testing, a modified step test with a submaximal workload of aerobic character. This test was carried out in accordance with the modification of Cˇ ermák et al. (1973) (Appendix 2). The rate was 30 steps per minute; the height of the step was 25 cm, which was adequate, on average, for all the children tested (it was, of course, not possible to adjust the height of the step to everybody’s body height, or better yet to everybody’s distance from the center of gravity and/or length of lower extremities from the ground), and 30 cm for the oldest children. In kindergartens, small benches were used, and the height was adjusted with the help of mats. The use of CE1,2 indices made it possible to compare the results in children who differed in height, weight, etc. This test can also be used under very simple field conditions. A preschool child is unable to climb a step with regular rhythm and rate. Hence an experimental worker always climbed the step along with two children, whom she held lightly by the hand, thus regulating the rhythm throughout the test but without actually assisting the child to climb the step. The heart rate was recorded using leads from the chest. Initial experiments were carried out with the help of a multichannel recorder (Alvar and Co.), and the heart rate was then obtained from the records. Later on, a specially constructed calculator, which alternatively gave the values after 30 s for one child and after another 30 s for the other child (who were tested simultaneously), was used (Parˇízková et al. 1984a,b). As shown by methodical measurements, heart beat totalizers, sports testers, and other apparatuses constructed for the registration of heart rate in older subjects and/or adults were not usable for preschool children. Before the examination, the child rested for about 15 min. Then the heart rate was assessed during 3 min of rest, in the course of 5 min while climbing the step, and finally in the course of 5 min of recovery. In total, the heart rate was recorded during 13 min. We also evaluated whether a steady state (i.e., stabilization of the heart rate during a workload, without permanently increasing until the end of the climbing) was established or not, and, if so, during which minute of the workload. In addition to the shape of the curves of heart rate during the above-mentioned intervals, other indicators were investigated to characterize the general response to a load and to indicate the economy of this reaction. Cardiac efficiency indices 1 and 2 (CEI1 and CEI2; see Appendix 2), described previously by Cˇ ermák (1969), were used for this purpose. These indices render general characterization of the capacity of the cardiovascular system possible (e.g., how much work is performed per heart beat), thus also rendering the evaluation and comparison of different age groups of boys and girls from 3 to 8 years possible, where marked morphological and functional changes during the preschool period of their development occur. New standardization was introduced, enabling the use of functional testing and comparisons between groups and/or along various periods of growth, and its larger application is considered for future studies (Parˇízková 2008).

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6.4.2 RESULTS OF CROSS-SECTIONAL AND LONGITUDINAL SURVEYS Average values at rest, as measured in survey A, corresponded to standards given in pediatric textbooks in all the age categories examined. Mean rest values declined significantly with increasing age and did not differ (except in two cases) in boys and girls (Figure 6.1a and b). The heart rate while climbing a step increased on average by about 30–45%. In younger children (i.e., 3–4 years), in light of the higher rest values, the relative increase during a workload was somewhat smaller than that in older children (6–7 years). Similar to heart rates during rest, the mean values of the heart rate also declined while climbing the step with advancing age. Sex-linked differences were only recorded in exceptional instances (Figure 6.1a and b). Evaluation of the steady state revealed that it was established in all children approximately during the second minute of the step test. The establishment of the steady state was more rapid in older children (Figure 6.1a and b).

(a)

Step test—Boys

160

Age (years) 3 to 4 4 to 5 5 to 6 6 to 7

Heart rate/min

150 140 130 120 110 100 Load

Rest

90 1

2

3

1

Recovery 2

3

4 5 Minutes

1

2

Step test—Girls

(b)

3

5

Age (years)

160

3 to 4 4 to 5 5 to 6 6 to 7

150 Heart rate/min

4

140 130 120 110 100

Load

Rest

90 1

2

3

1

Recovery 2

3

4 5 Minutes

1

2

3

4

5

FIGURE 6.1 Heart rate during the step test, that is, 3-min rest, 5-min workload (climbing a step), and during 5-min recovery in boys (a) and girls (b) of different ages (survey A) (Parˇ ízková et al. 1977, 1984a,b).

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During the recovery period, the values of the heart rate returned relatively rapidly to the values at rest. The values of the heart rate during the fifth minute of recovery did not differ significantly from the values recorded during the first 3 min of rest. In older children the values of the heart rate during recovery were again lower than those in younger ones (Figure 6.1a and b). An evaluation of the total values of the heart rate at rest, during a workload, and during recovery supplemented the evaluation from previous experiments (Figure 6.1a and b). A marked decrease in the values of all indicators was observed with advancing age, that is, of the mean heart rate after 3 min of the initial rest period, the sum of heart beats during 5 min of workload (A) and 5 min of recovery (B, Appendix 2). In spite of slightly higher average values of heart rate in girls, no significant sex-linked differences were observed. In line with the calculation of the indices (see Appendix 2), that is, net heart rate increase during workload, CEI1 and CEI 2 (Figure 6.2a and b), net heart rate during recovery, and Brouha’s step test index (STI) (Table 6.1) indicate an improved economy of cardiac work during a workload in older children. An increased (a) 0.8 0.7 0.6 CEI1

0.5 0.4 0.3 0.2 0.1 0

3–4

4–5

5–6

6–7

5–6

6–7

Years

CEI2

(b) 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 3–4

4–5 Years Boys

Girls

FIGURE 6.2 CEI1 (a) and CEI2 (b) in boys and girls 3–6 years of age (survey A) (Parˇ ízková et al. 1984a,b).

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TABLE 6.1 Results of Brouha’s STI in Children from 3 to 4 and 6 to 7 Years of Age (Survey A) Boys Age (Years) 3–4 4–5 5–6 6–7

x– 87.1 91.4 92.2 99.9

Girls SD

x–

SD

8.0 9.2 10.2 9.9

82.8 90.6 92.7 98.3

6.5 7.4 10.4 10.9

Source: Modified from Parˇízková J. et al., Growth, Fitness, and Nutrition in Preschool Children, Charles University, Prague, 1984a. Note: SD, standard deviation.

effectiveness of cardiac work in relation to performed physical work is also evident. This is manifested in particular by the CEI (which relates the total number of heart beats during workload and recovery to the amount of performed work; Appendix 2 for formula; Figure 6.2a and b) and by other indicators. Brouha’s index also increased markedly (Table 6.1), indicating an improvement in cardiac efficiency during a load and a better economy of cardiac activity during the step test. In older children, the increased amount of circulating blood, and thus a more ample oxygen supply to the tissues during a load, was obviously due to the increase in stroke volume. This is a functional advantage for the organism during PA. It coincides with the increasing level of spontaneous PA during the preschool period and with improving motor performance (Parˇízková et al. 1984a,b). As mentioned above, sex-linked differences were sporadic. Girls tended to have somewhat higher values of heart rate during load and during recovery. These differences were significant, however, in rare instances only. In the economy of cardiac activity, marked sexual differences were not observed. It is expected that such differences might have appeared during maximal workloads, which were not used in our studies. With regard to the relationships of anthropometric variables and response of the circulation during the step test, the absolute values of heart rate during the step test and recovery correlated significantly negatively, that is, the older and bigger the child, the lower the heart rate during workload and recovery. In relation to the indices of cardiorespiratory efficiency, that is, CEI1, CEI2, and Brouha’s STI, the situation is the reverse (Table 6.2). The same applies to bone age, which characterizes the level of maturation of the child. All indicators concerning the development of the child from 3 to 6 years, including the increasing circumferential and breadth measurements, correlated positively with the characteristics of the economy of work of the cardiorespiratory system. In our sample, which did not include malnourished and/or overweight children, this

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TABLE 6.2 Correlation Coefficients of the Relationship between Anthropometric Variables and Indices of Cardiorespiratory Efficiency (CEI1, CEI2, and Brouha’s STI) in Preschool Children (Survey A) Height Weight Length of lower extremities Breadths Biacromial Bi-iliocristal Circumferences Chest Abdomen Arm Forearm Thigh Calf Skinfolds Sum of 10 (modified Best) Sum of 5 (modified Best right) Sum of 5 (Harpenden right) Sum of 5 (Harpenden left) Bone age

CEI1

CEI2

Brouha’s Index

0.752** 0.884** 0.718**

0.254* 0.353** 0.222*

0.399** 0.334** 0.376**

0.773** 0.631**

0.287** 0.238*

0.357** 0.274**

0.793** 0.637** 0.704** 0.737** 0.732** 0.7526**

0.322** 0.254* 0.259* 0.236* — 0.228*

— — — 0.241* — 0.252*

0.239* 0.238* 0.223* 0.578** 0.462**

— — 0.276** 0.257** —

— — 0.262** 0.202* —

Source: Modified from Parˇízková, J. et al., Growth, Fitness, and Nutrition in Preschool Children, Charles University, Prague, 1984a. Note: CEI1, CEI2, Brouha’s STI—see Appendix 2; *p < 0.05, **p < 0.01.

also concerned skinfold thicknesses that decreased during this age period—slightly in girls and more markedly in boys. Therefore, the correlation coefficients for CEI1, CEI2 (Figure 6.2a and b), and Brouha’s STI with skinfolds are much lower than those for the other anthropometric variables and/or bone age (Table 6.2). Only skinfolds measured on the left side correlated more closely with the indices of cardiorespiratory efficiency (Parˇízková et al. 1984a,b). This correlation analysis was also made in individual age groups where these relationships were rarely apparent; however, even within the framework of one age subgroup, the age was not exactly the same. As marked changes occur in preschool children even within trimesters, the impact of age was always significant. When the group was homogeneous with respect to age, relationships between body size and cardiorespiratory efficiency (and also some motor tests) were not obvious; this was most marked in older children.

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Measurements of heart rate during the step test were also made repeatedly in longitudinal studies of the same children followed up five times from 3.3 to 6.0 years along with morphological, motor, and other characteristics (survey E; Table 6.3) using the same protocol as in cross-sectional investigations. Although the total work performed (expressed in kpm) increased significantly during the step test, the heart rate during all stages of the step test decreased. The heart rate also decreased in older children at rest, similar to those in our cross-sectional measurements of study A (see Figure 6.1a and b). In the course of workload during each subsequent examination, the heart rate was lower; the same applied to the heart rate during recovery. With advancing age, the workload was performed more economically and efficiently. This was proved when comparing the average values of CEI (CEI1, STI; see Table 6.3) during the first and fifth measurements (Parˇízková et al. 1984a,b). In this respect, the results of longitudinal survey E confirmed the trends of development in the response of the cardiovascular system to a workload as assessed in cross-sectional survey A. During the period from 3 to 6 years, important functional changes in the cardiovascular system obviously occur, implying less strain for the child because of improved cardiorespiratory efficiency (Table 6.3). The above-mentioned changes render a gradual increase of the workload possible and, in particular, its prolongation, which is impossible at a younger age. Children 5–6 years old were able to tolerate a defined workload without major fatigue. This applies to an aerobic workload of medium intensity, which partly has an endurance character.

TABLE 6.3 Changes in CEI1 and Brouha’s STI in Preschool Children Followed Up Repeatedly (Five Measurements 1–5; Survey E) Measurement CEI1 Boys x– SD Girls x– SD STI Boys x– SD Girls x– SD

1

2

3

4

5

0.47 0.07

0.53 0.09

0.57 0.08

0.64 0.08

0.85 0.08

0.43 0.07

0.47 0.07

0.51 0.10

0.59 0.10

0.80 0.10

87.2 8.0

92.5 8.7

91.1 6.0

99.1 9.0

103.3 8.9

82.9 6.3

88.2 10.5

90.5 9.7

92.8 10.56

98.0 10.1

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6.4.3 SURVEYS IN OTHER CHILD POPULATIONS Cardiovascular functions (heart rate and blood pressure at rest, heart rate response) were tested by Baranowski et al. (1992) in 3–4-year-old children with varying infant nutrition, along with different heights, BMIs, and seven skinfolds. Infant feeding practices were not related to cardiovascular functioning. DuRant et al. (1993a,b) followed up on cardiovascular fitness along with somatic characteristics and blood lipids. Cardiorespiratory responses to locomotor activities were studied in those 4.1 ± 0.8 years old during several workloads (rest, slow and brisk walking, running, 5 min each); a steady state was always achieved after 2 min. Significant differences in cardiorespiratory responses were found with regard to different activities (Almeida 2004). In the available literature we did not find results of a comparable study. More recently, Italian (Ferro-Luzzi 1985), Turkish (Türnagöl et al. 1995), and Senegalese (Bénéfice 1990, 1995) preschool children were examined; Prista et al. (2003) examined schoolchildren in Mozambique (see Chapter 7).

6.5

MOTOR AND SENSOMOTOR DEVELOPMENT: GROSS AND FINE MOTORICS

Gross and fine motor development was followed in preschool children using a number of tests that varied markedly. A review of three tests of motor proficiency for children was prepared (Yoon et al. 2006) to enable clinicians, therapists, educators, etc., to assess the motor skills of children with possible delays. Researchers mostly used approaches and methods that were available and used before. Some studies concerned children with some developmental delays in motor development and handicaps. The predictive validity of the test of infant motor performance (TIMP) was examined with regard to motor ability at school age as measured by the Bruininks– Osseretski test (Flegel and Kolobe 2002). The reliability and validity of qualitative and quantitative motor tests for young children were examined with regard to the specificity of this age period (Kroes et al. 2004). The relationship of PA to motor ability and school readiness was analyzed in 6-year-old Finnish children, and it was shown that these tests appear to be related to the chosen measures of school readiness (Oja and Ju˝rimae 1998, 2002). Laterality and motor skills were also followed up in 4-year-old children (Tan 1985), which could serve for comparison with the present results of comparable tests. Basic motor faculties were followed in children 4–11 years old, that is, development of coordination during reaching. During age ranges in which stable patterns emerge, children reached from the seated position with the dominant arm and grasped a cone placed at three distances in the forward sagittal plane in front of the body. Kinematic data from markers placed on the arm, head, and trunk were recorded at 100 Hz (Oprotrak Motion Analysis System). Immature patterns of reaching were characterized by increased variability in younger compared to older children. Hand trajectories became smoother and less variable with increasing age; only children between 8 and 11 years had variability comparable to adults.

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Gender and age differences in motor performance were also followed up in boys and girls, for example, in Nigeria (Toriola and Imbokwe 1986). Generally, children in Third World countries seem to be more advanced in motor development at the beginning of life than children in industrially developed countries, but later this difference disappears and/or becomes just the reverse. Similarities and differences may also appear between countries like the United States and the Netherlands, as shown by the movement assessment battery for children (Van Waelwelde et al. 2008). Different aspects of movement kinematics seem to mature at different ages (Schneiberg et al. 2002). A longitudinal study in children from the fifth month up to 3 years showed that the development toward adult forms of multijoint coordination in goal-directed reaching requires a longer time during early age than was assumed previously (Konczak and Dichgans 1997). Another study followed rhythmic bimanual coordination as related to hand preference (right-handed, left-handed, and ambidextrous). A significant difference was noted in the right-handed, who had higher accuracy and stability in bimanual coordination. The influence of handedness might also be related to the development of interspheric communication (Mori et al. 2007). Changes along with age and the contribution of variables such as age, gender, and BMI were followed up in 6-year-old children. Sex was associated with the step test and sit and reach performance (girls were better). BMI was related to increased grip strength and fewer timed sit-ups. Running, skipping, and leaping improved with increasing age (Butterfield et al. 2002). Age and sex differences and the impact of nutrition with regard to motor performance were also followed in preschool Nigerian (Toriola and Igbokwe 1986) and Senegalese children (Bénéfice et al. 1999). The approaches and methods for the evaluation of gross and fine motor development varied widely (Reeves et al. 1999, Deitz et al. 2007, Norris et al. 2008), and the results could be hardly compared (with respect to the differing age categories of children followed up). In cross-sectional and longitudinal studies of Czech children, several tests were selected to characterize different aspects of motor development during preschool age in a more comprehensive way. The tests were selected with regard to their characteristic validity of certain motor faculties that would have been adequate and natural regarding the stage of development, easy to perform under laboratory and/or field conditions, and reproducible. Numerous methodical measurements were performed and validated; last but not least, there was also an attempt to use tests that are usually a part of children’s usual play activities (Parˇízková 1977, 1978a,b, 1987, 1993b, 1994, Parˇízková and Adamec 1980, Parˇízková et al. 1984a,b).

6.5.1

METHODS OF TESTING

6.5.1.1 Speed The 20-m dash was evaluated mostly outdoors in a playground or on a pathway in a park, not on a pavement or on concrete. The child stands ready at the starting line, in suitable light clothing and gym shoes. At the starting line one person gives the order: “Ready, set, go!” The second person is at the finish line, recording the time in seconds and tenths of seconds with a stopwatch. After a 10-min rest, the run is repeated,

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and both times are recorded for each child. Two children run simultaneously, but the time is only recorded for one child (Appendix 3). 6.5.1.2 Endurance Endurance was tested in 4-year-old (and older) children (survey E) using a 500-m run-and-walk test. This test was performed in a stadium or on a road. Ahead of the children, an instructor ran in order to set a suitable speed for both running and alternative walking, according to the capabilities of the children tested. This arrangement was indispensable as in the case of the step test. These activities are usually monotonous and uninteresting for children in this age group; hence it was necessary to guide them and adjust their running speeds so that they would be able to complete the test. Endurance time was also tested in young children using the Bruce walking treadmill protocol to voluntary exhaustion. This method, however, is too demanding for some young children at, for example, 3 years of age. In addition, such a method requires certain laboratory equipment and requires the children to visit a particular institution. 6.5.1.3 Muscle Strength and Skill Muscle strength in Czech preschoolers has already been measured by Matiegka (1927). Hand grip strength was included in our surveys, assessed by a special dynamometer designed for the hands of small children in our laboratory (Parˇízková 1977) based on a tensometric principle. Instruction and demonstration by an experimental worker preceded the experimental measurements. Two attempts were always made; the better result was finally evaluated, as in other performance tests. Standing broad jump tests the explosive strength of the lower extremities and is partly a test of skill. The experimental worker demonstrates the jump and instructs the child: “swing your arms and then jump as far as possible!” The child makes two attempts; both performances are recorded in centimeters, from the toes to the last foot mark of the child as in tests for older subjects. Care must be taken to ensure that the child does not start the jump while standing on the mat, but when standing on the floor. He/she then jumps onto a low mat. Throwing a tennis ball characterizes both the explosive strength of the upper extremities and the skill of the child. The child stands at the line and throws the ball with an upper arch. Two attempts with each arm are made. This is preceded by a demonstration by the experimental worker. The result of this performance is measured by a tape measure with an accuracy of a tenth of a meter. 6.5.1.4 Balance Walking on a beam (at a height of about 25–30 cm) unassisted (but supervised) is a test of audacity as well as of skill and balance. The task is considered fulfilled (grade 1) when the child has walked over the whole beam without touching the floor. When he/she touches the floor, even with just the tip of the foot, the task is considered not fulfilled (grade 2). This test is carefully followed as with all others, and the experimental worker is ready to assist in the case of marked imbalance of the child.

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Standing on one leg is also a test of the ability to balance one’s own body. It is demonstrated once by the experimental worker, and then one attempt (the first attempt of the child) is evaluated. The task is fulfilled when the child does not touch the floor for a period of 10 sec (recorded using a stopwatch). The other leg may be bent. The forward roll (one attempt) is evaluated according to a detailed scale from one to five (see Appendix 3). The best performance is the highest score, of five. Instructions are as follows: “Stand on the mat (not on the floor), make a ‘window’ with your legs wide apart, and do a forward roll as best as you can!” After doing the forward roll the child should sit on a mat. 6.5.1.5 Rhythm, Response, and Coordination Walking at a given rate (one attempt), the experimental worker beats a drum at a rate suitable for a preschool child’s gait. The child adheres to the rate set by the drum and marches about 20 steps in the desired direction. The standard of walking is also evaluated under the heading “body posture.” The rate is given by the drum (fulfilled, 1; not fulfilled, 2). This test shows the child’s ability to adhere to a given rhythm. The task of catching a ball (8-cm diameter) is a test of prompt response, anticipation, and skill as detailed in Appendix 3. Each task is only performed after a demonstration by the experimental worker. The thrusting requires throwing the ball two to three times above the child so that he/she can catch it. Only one attempt is evaluated (however, if the experimental worker throws the ball badly, the procedure is repeated; see Appendix 3). Opening and closing the hands is an important indicator of sensomotor development and psychomotor coordination, as well as of the observing ability of the child (Appendix 4). The experimental worker demonstrates each procedure five times. Before doing so, he/she says: “Watch what I am doing carefully and then you will do it yourself!” The demonstration is not commented on verbally so that the child can watch attentively. When the child performs, we again abstain from any comments, verbal or otherwise. The first attempt (1) is evaluated (see Appendix 4). This test includes six items, each gradually becoming more difficult. We evaluate whether the child fulfills the task (score 1) or does not fulfill the task (score 2). Orientation in space and in one’s body scheme is also evaluated after the first trial (see Appendix 4; fulfilled, 1; not fulfilled, 2). In addition, testing of laterality renders the evaluation of the dominant hand, leg, and eye possible (Appendix 4) (Parˇízková et al. 1984a,b).

6.5.2

RESULTS OF MOTOR AND SENSOMOTOR TESTING

Speed, that is, performance in the 20-m dash (survey A), increased with advancing age, that is, the time for covering this distance was lower in older children than in younger ones. The performance level was better in boys than in girls in all age categories (Figure 6.3a). This was also seen in survey B (Table 6.4). The same applied to the results of broad jump: a longer jump in older children, and better results in boys (study A, Figure 6.3b; survey B, Table 6.4). Throwing a ball with both hands was also better in older children, and in boys compared to girls. In this case, the sex-linked differences were usually significant (Figure 6.3c and d).

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s

(a) 9 8 7 6 5 4 3 2 1 0

153

3–4

4–5

5–6

6–7

Years (b) 140 120

cm

100 80 60 40 20 0

3–4

4–5

5–6

6–7

5–6

6–7

Years (c) 1400 1200

cm

1000 800 600 400 200 0

4–5

3–4

4–5

Years

cm

(d)1000 900 800 700 600 500 400 300 200 100 0

3–4

5–6 Years Boys Girls

6–7

FIGURE 6.3 Performance in the 20-m dash (a), broad jump (b), and ball throw with the right (c) and left hand (d) in boys and girls 3–6 years of age (survey A) (Parˇízková et al. 1977, 1984a,b).

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TABLE 6.4 Motor Performance in Boys and Girls 6.4 Years Old (Survey B) Boys Test 20-m dash (s) Broad jump (cm) Throwing ball/right hand (cm) Throwing ball/left hand (cm)

x– 5.43 108.5 1068.6 681.8

Girls SD

x–

SD

1.13 20.8 386.8 237.5

5.69 101.7 688.8 528.3

1.27 20.4 218.8 159.8

Source: Adapted from Parˇízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a.

During preschool years there are remarkable improvements in performance each year. This is most apparent when we compare children 3–4 and 6–7 years old: average values for the time in the 20-m dash are significantly shorter; the results for the jump and the ball throw are significantly better (Figure 6.3a–d). The results of survey B (children 6.4 years old; Table 6.4) showed very similar results compared with the oldest age category of survey A (Figure 6.3a–d). Sex-linked differences in this larger sample were always statistically significant (Parˇ ízková et al. 1984a,b). Physical performance in age groups from 4–5 up to 6–7 years was tested several years later in another cross-sectional study of 1848 boys and 1864 girls (survey C) and in 506 boys and 499 girls (survey D). The conclusions of these measurements were similar, that is, improvement of motor performance with increasing age, with significantly better results in boys (Figure 6.4a–c). Performance in the 20-m dash tended to be worse than that in survey A which was conducted earlier, and in boys as compared to survey C. The results of the broad jump and ball throw were almost the same. Tests of motor performance correlated significantly positively with the results of the step test, that is, the reaction of the cardiorespiratory system to this workload was closely related to the performance in the above-mentioned tests (Table 6.5). CEI1 correlated most closely with the performance in the 20-m dash, broad jump, and ball throw. The results of hand grip strength (right and left) in our study of Czech children were significantly better in boys of all ages. Average values were also significantly higher for the right hand, for both boys and girls (survey A, Figure 6.5). In this case the results also improved significantly from 3 to 6 years (Parˇízková 1980). The data of Matiegka from 1927 gave the maximal strength of the right hand of 5-year-old children as 2.5 kp, that is, 24.5 N, and of 6-year-old children as 9.0 kp, that is, 88.3 N—much lower values than measured in our recent studies. These secular changes in hand grip strength appeared along with the increase in body size and BMI. Trunk flexion in healthy children aged 3–7 years was followed using two exercises of isometric trunk flexor muscle strength (half-hook-lying position and supine

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155

(a) 8 7 6 s

5 4 3 2 1 0

4–5

5–6 Years

6–7

(b) 160 140 120 cm

100 80 60 40 20 0

5–6 Years

4–5

5–6 Years

6–7

cm

(c) 1800 1600 1400 1200 1000 800 600 400 200 0

4–5

6–7

cm

(d) 1000 900 800 700 600 500 400 300 200 100 0

4–5

5–6 Years Boys

6–7 Girls

FIGURE 6.4 Performance in the 20-m dash (a), broad jump (b), and ball throw with the right (c) and left hand (d) in boys and girls 4–6 years of age (survey C) (Parˇ ízková et al. 1984a,b).

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TABLE 6.5 Relationships (Correlation Coefficients r) between the Results of the Step Test and Motor Performance in Preschool Children (Survey A) Ball Throw Tests CEI1 CEI2 Step test (Brouha)

20-m Dash

Broad Jump

Right

Left

–0.568** –0.215* –0.330**

0.566** — 0.362**

0.502** 0.258** 0.273**

0.463** 0.231* 0.298**

Source: Adapted from Parˇízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a. *p < 0; ** p < 0.01.

(a) 18 16 14

kp

12 10 8 6 4 2 0

3–4

4–5

5–6

6–7

5–6

6–7

Years (b) 16 14 12 kp

10 8 6 4 2 0

3–4

4–5 Years Boys

Girls

FIGURE 6.5 Hand grip strength of the right and left hands in boys and girls 3–6 years of age (survey A; Parˇ ízková et al. 1984a, b).

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flexion position) and one exercise of isotonic trunk muscle strength (hook-lying situps) to establish normative data (Lefkof 1986). Norms for hand grip strength for children aged 5–18 years showed lower values for girls; handedness influenced grip strength. Correlations with height and weight were also found (Newman et al. 1984). Other norms for 4–16-year-old subjects (Hager-Ross and Rossblad 2002) were found to be slightly lower than those from 1980 from United States and Australia, which may be due to the divergences in age groupings and the instruments used. In tests of skill (survey A), girls tended to perform better, which was manifested, in particular, in standing on one leg (lower average values mean a better result; see methods) or in the forward roll (higher values mean a better result). There were no marked differences in walking at a given rate and catching a ball in different modifications (study A; Table 6.6) (Parˇízková et al. 1984a,b).

TABLE 6.6 Results of Skill Tests in Preschool Children (Survey A) Age (Years) 3–4 Skill *Crossing a horizontal beam *Standing on one leg **Forward roll *Walking in rhythm *Catching Ball 1 Ball 2 Ball 3 Ball 4

4–5

5–6

6–7

Boys

Girls

Boys

Girls

Boys

Girls

Boys

Girls

x–

1.38

1.43

1.17

1.17

1.03

1.08

1.13

1.00

SD x– SD x– SD x– SD

0.49 1.56 0.50 2.50 1.33 1.68 0.47

0.50 1.26 0.45 2.70 1.71 1.52 0.51

0.38 1.25 0.44 3.54 1.25 1.17 0.38

0.38 1.04 0.20 3.38 1.47 1.25 0.44

0.18 1.13 0.34 3.97 0.76 1.10 0.30

0.27 1.04 0.20 4.52 0.92 1.08 0.27

0.35 1.07 0.26 3.67 1.34 1.27 0.46

0.00 1.13 0.34 4.13 1.15 1.25 0.44

x– SD x– SD x– SD x–

1.85 0.36 1.65 0.49 1.97 0.17 1.71 0.46

1.65 0.48 1.61 0.50 1.91 0.29 1.78 0.42

1.25 0.44 1.17 0.38 1.79 0.41 1.46 0.51

1.29 0.46 1.17 0.38 1.88 0.34 1.29 0.46

1.07 0.25 1.03 0.18 1.53 0.50 1.23 0.43

1.08 0.27 1.08 0.27 1.48 0.51 1.24 0.43

1.07 0.26 1.00 0.00 1.53 0.51 1.33 0.49

1.06 0.25 1.06 0.25 1.50 0.51 1.25 0.44

SD

Source: Adapted from Parˇízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a. Note: *Evaluation by 2 grades, 1—fulfilled, 2—not fulfilled. **Evaluation by 5 grades, 5—best, 1—worst. Mean values are given for the group. Values above 1.0 indicate the percentage of children with grade 2.

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In survey B with a greater number of children, girls had better results in tests characterizing skill, that is, walking on a beam, standing on one leg, forward roll, walking at a certain rate, etc. Only in the last variety of catching a ball (i.e., throwing it vertically above the child who then catches it from the air; Table 6.7) were the results slightly better in boys. All sex-linked differences, although not very great, were statistically significant in this large sample (Table 6.7; Parˇízková et al. 1984a,b). The results of the evaluation of sensomotor development, that is, the “open- and close-hands test,” in Prague children (survey A) did not show any significant sexlinked differences in any of the six items of the test. The same applied to the testing of spatial orientation and laterality (Table 6.8a). The level of sensomotor development improved with advancing age, similar to the results of other motor tests. In more simple parts of the test requiring the opening and closing of hands, these age differences were not apparent. All the children were able to perform the test successfully from the beginning of our measurements. Even 3-year-old children were able to imitate without making mistakes on the more simple actions. More marked differences with advancing age were found as in the separate opening and closing of either the right or the left hand (item 6), where differences between the youngest and oldest children were greater. The more complicated the test, the poorer the result in the youngest age group. The relatively greatest improvement with age was observed in items 4 and 5 of the test (Table 6.8a). The last item (the most difficult) improved the least with age, that is, the level of sensomotor development still remained at a relatively low level (approximately like the results from items 2 and 3 of this test at the age of 3–4 years). Evidently, sensomotor development before entering primary school still remains at a low level and is only finished during school years.

TABLE 6.7 Skill Development in Preschool Children 6.4 Years Old (Survey B) Boys Skill *Crossing a horizontal beam (grade 1–2) *Standing on one leg (grade 1–2) **Forward roll (grade 5–1) *Walking in rhythm (grade 1–2) *Catching a ball 1 (grade 1–2) Ball 2* Ball 3* Ball 4*

Girls

x–

SD

x–

SD

1.08 1.15 4.15 1.21 1.17 1.13 1.34 1.28

0.27 0.36 1.10 0.40 0.38 0.33 0.48 0.49

1.06 1.12 4.36 1.15 1.13 1.11 1.34 1.29

0.23 0.33 1.01 0.36 0.34 0.31 0.47 0.45

Source: Adapted from Parˇízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a. Note: *grade 1 (fulfilled); **grade 5 (best score); *grade 2 (failed); **grade 1 (worst score).

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TABLE 6.8a Sensomotor Development of Preschool Children of Survey A Age (Years) 3–4

Boys Girls

4–5

Boys Girls

5–6

Boys Girls

6–7

Boys Girls

x– SD x– SD x– SD x– SD x– SD x– SD x– SD x– SD

1

2

3

4

5

6

1.06 0.23 1.04 0.20 1.00 0.00 1.00 0.00 1.00 0.00 1.00 0.00 1.00 0.00 1.00 0.00

1.44 0.50 1.43 0.50 1.08 0.28 1.08 0.28 1.00 0.00 1.08 0.27 1.00 0.00 1.00 0.00

1.47 0.50 1.39 0.49 1.04 0.20 1.03 0.18 1.03 0.18 1.08 0.27 1.00 0.00 1.00 0.00

1.76 0.43 1.87 0.34 1.25 0.44 1.21 0.41 1.10 0.30 1.20 0.40 1.07 0.25 1.13 0.34

1.88 0.32 1.87 0.34 1.38 0.49 1.33 0.48 1.17 0.37 1.28 0.45 1.20 0.41 1.38 0.50

1.97 0.1 1.91 0.28 1.54 0.50 1.67 0.48 1.50 0.50 1.60 0.50 1.47 0.51 1.44 0.51

Source: Modified from Parˇízková, J. et al. Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a. Note: Lower average values mean better results. Results of “opening and closing hands”; see Appendix 4; grade 1, fulfilled; grade 2, failed.

High levels of performance in spatial orientation were attained in the youngest children. There were no errors in the 6–7-year-old children (Table 6.8b). The results of the laterality test were poorer, although they improved significantly with advancing age (Table 6.8b). Similar to the test of “opening and closing the hands,” this test still found a fairly low level of performance even in the oldest category of preschool children. This may be due to unfinished development of leftand right-handedness in preschool children. As indicated by the observations of Keogh (see Parˇízková et al. 1984a,b) at the age of 7 years, California schoolchildren did not still completely master the “openand close-hands” test. Sensomotor development evaluated by means of this test improves during younger school age and reaches real maturity only later. Data in older children have not been obtained so far, and there are no available data on the same test in the literature. These trends do not differ significantly according to sex with increasing age. The test of “opening and closing the hands” in children 6.4 years old (survey B; Table 6.9) shows higher levels of concentration, attention, and imitating capacity as well as a well-coordinated, more refined activity of the upper extremities in girls. This was apparent, in particular, in the more complicated parts of this test (see items 3–6 in Appendix 4). The percentage of girls who completed these tests was well above the percentage of boys. The same applied to spatial orientation (Table 6.9; see

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TABLE 6.8b Results of Testing of Spatial Orientation and Laterality in Preschool Children of Survey A Spatial Orientation Age (Years) 3–4

Boys Girls

4–5

Boys Girls

5–6

Boys Girls

6–7

Boys Girls

x– SD x– SD x– SD x– SD x– SD x– SD x– SD x– SD

Laterality

1

2

1

2

1.06 0.23 1.09 0.28 1.13 0.33 1.04 0.20 1.03 0.18 1.00 0.00 1.00 0.00 1.00 0.00

1.03 0.17 1.09 0.28 1.04 0.20 1.04 0.20 1.00 0.00 1.00 0.00 1.00 0.00 1.00 0.00

1.59 0.50 1.74 0.44 1.38 0.49 1.54 0.50 1.23 0.43 1.40 0.50 1.20 0.41 1.31 0.47

1.88 0.32 1.96 0.20 1.58 0.50 1.67 0.48 1.40 0.49 1.56 0.50 1.20 0.41 1.63 0.50

Source: Modified from Parˇízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a. Note: See Appendix 4; grade 1, fulfilled; grade 2, failed.

TABLE 6.9 Sensomotor Development in Preschool Children 6.4 Years Old (Survey B; Grades 1 and 2) Boys Sensomotor Test Opening and closing hands Opening and closing hands Opening and closing hands Opening and closing hands Opening and closing hands Opening and closing hands Spatial orientation Spatial orientation Laterality Laterality

Item 1 2 3 4 5 6 1 2 1 2

x– 1.03 1.09 1.10 1.34 1.33 1.72 1.02 1.02 1.29 1.33

Girls SD

x–

SD

0.16 0.28 0.30 0.47 0.47 0.45 0.10 0.10 0.45 0.48

1.02 1.09 1.09 1.30 1.30 1.67 1.02 1.01 1.28 1.36

0.15 0.29 0.28 0.46 0.46 0.47 0.14 0.10 0.45 0.48

Source: Adapted from Parˇízková, J., et al. Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a.

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item 2 in Appendix 4) and laterality test 1. The remaining tests characterizing sensomotor development in survey B did not differ in 6.4-year-old boys and girls. The relationship between the results of individual motor and sensomotor tests was also analyzed. Figure 6.6 shows the results of the tests of independence in 3712 boys and girls aged 4–6 years (survey C). There were mostly very close relationships between the results of individual performance and skill tests. Therefore, for practical purposes it is possible to use only fewer selected motor and sensomotor tests in order to obtain more general information on the development of motor abilities. As in the testing of cardiorespiratory efficiency by the modified step test, children were followed up in longitudinal studies from 3.5 to 6.0 years with respect to their motor development (study E). Repeated measurements of the same children again confirmed the results of cross-sectional examinations: the level of performance in running, jumping, and throwing improved significantly with advancing age, and the results were always better in boys. Hand grip strength increased with age and was also greater in boys (Parˇízková and Adamec 1980). This was in contrast to the results of the step test; apparently, sex-linked differentiation is only manifested in tests motivated toward maximum performance and not in those of medium intensity. All the above-mentioned sensomotor tests were repeatedly performed. As mentioned in conjunction with cross-sectional comparisons, a marked improvement with increasing age was found. Individual stability of motor development was shown by intercorrelations of the results measured in individual children at the first and second, the first and third, and the second and third measurements in survey E (Table 6.10), that is, from about 3.5 to 6.0 years. The closest relationships were found for speed (20-m dash) and in the broad jump at the beginning and end of our measurements (Parˇízková et al. 1985).

1 20m dash Broad jump 2 Throw—right hand 3 4 Throw—left hand Walking a beam 5 Standing on one leg 6 7 Forward roll Walking in tempo 8 9 Walking posture 10 Catching a ball I. Catching a ball II. 11 Open–close hands test 1. 12 Open–close hands test 2. 13 Open–close hands test 3. 14 Open–close hands test 4. 15 Open–close hands test 5. 16 Open–close hands test 6. 17 Space orientation 1. 18 Space orientation 2. 19 Laterality 1. 20 Laterality 2. 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

c2<1000 700–1000 400–700 100–400 <100 0

FIGURE 6.6 Relationships among the results of motor performance and skill tests in preschool children (survey C).

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TABLE 6.10 Correlation Coefficients between the Results of Performance Tests Measured Three Times at Different Ages in Preschool Children (Survey E) Measurement Discipline Boys 20-m dash Broad jump Throwing a ball (right) Throwing a ball (left) Hand grip strength (right) Hand grip strength (left) Girls 20-m dash Broad jump Throwing a ball (right) Throwing a ball (left) Hand grip strength (right) Hand grip strength (left)

1st–2nd

1st–3rd

2nd–3rd

0.677** 0.709** 0.321 0.356 0.533** 0.488**

0.714** 0.422* 0.516** 0.634** 0.477* 0.532**

0.857** 0.661** 0.374 0.450* 0.424* 0.336

0.647** 0.554* 0.655** 0.390 0.515* 0.587**

0.633** 0.750** 0.714** 0.495* 0.462* 0.379

0.598** 0.204 0.678** 0.461* 0.479* 0.365

Sources: Compiled from Parˇízková, J., Wld. Rev. Nutr. Diet., 51, 1, 1987; Parˇízková, J. et al., Humanbiol. Budapest, 16, 113, 1985. *p < 0.05; **p < 0.01.

Further analyses of the results in motor tests in the individual years did not always show more favorable results in larger children in the same age category. In some cases, performance was better in larger peers, but quite often smaller children of comparable age were more fit, especially in running and in skill tests. Another longitudinal study, made several years later along with morphological measurements (survey F) from about 4.5 years up to 5.9–6.0 years, also confirmed, in three consecutive measurements, a significant improvement in motor performance with age and better results in boys (Figure 6.7a–d). Mutual comparison of the results of the same tests in studies E and F was complicated because of the slightly different average age of the individual groups of children followed in these particular surveys; it was not possible to keep our measurements completely identical to homogeneous samples in relation to age. In study F, the evaluation of performance in the 500-m run-and-walk (Figure 6.7d) was also evaluated, but only starting at the age of 5 years and 4 months in boys and 5 years and 6 months in girls. In this endurance test, there were significant improvements again with advancing age and significantly better results in boys. Girls in survey F performed better in skill tests as in the other groups mentioned above (Parˇízková 1987).

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(a) 7

s

6

5

4

1

2 Measurement

3

(b) 130 120 cm

110 100 90 80 70

(c)

1

2 Measurement

3

1100 1000

cm

900 800 700 600 500 400

1

2 Measurement

3

2 Measurement

3

min

(d) 3.5

3

2.5

1

Boys

Girls

FIGURE 6.7 Changes in the performance in the 20-m dash (a), broad jump (b), ball throw with the right hand (c), and 500-m run-and-walk (d) in boys and girls followed up longitudinally from 4.4 years (boys) and 4.6 years (girls; survey F), then 1 year later, and finally at the age of 5.9 years (boys) and 6 years (girls) (Parˇ ízková et al. 1984, Parˇ ízková and Kabele 1985).

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Performances in tests of fine motorics and coordination of the hands (open- and close-hands test) improved significantly between the first and second measurements of survey F in both girls and boys. On the other hand, the results of the third and last measurement were significantly worse in both boys and girls. However, girls always had better results compared to boys, especially during the second and third measurements. Performance in the test of copying pictures improved in boys and girls during all measurements. Girls had significantly better results than boys during the first and third measurements (see Parˇízková and Kábele 1985, 1988). Orientation in space and in relation to one’s own body was tested during the first and third measurements of study F. The results were significantly better in the last measurement. In both cases, girls had markedly poorer results than boys. Laterality was tested only during the first and third measurements. The results were worse during the third measurement compared to the results of the first one. This shows a shift toward ambivalence in the development of preschool children (Parˇízková 1987). In this case, sex-linked differences were not observed. Laterality and motor skills were also followed up in another study of 4-year-old children, and no differences between left-handers and right-handers were observed. Only children lacking hand preference had lower scores of McCarthy Motor Scales and fine motor scale than right-handers (Tan 1985). Association of the strength of hand preference with rhythmic bimanual coordination was studied in preschool children 4–6 years of age. A significant difference was noted among three groups, with right-handers having higher accuracy and stability. This finding suggests that bimanual coordination in young children may be influenced by handedness, which may be related to the development of interspheric communication (Mori et al. 2007). Worse results in left-handers in two motor (gross and fine) subscales could result from poorer performance of left-handed boys on fine motor tasks. This could cause learning difficulties in left-handed children later on in school (Giagazoglou et al. 2001).

6.5.3

MOTOR DEVELOPMENT IN OTHER SURVEYS OF PRESCHOOL CHILDREN

Various fitness components (½-mile run, the prudential PACER test, body composition, shoulder stretch, trunk lift, sit-and-reach, curl-up, and flex arm-hang) related to motor performance on the Bruininks–Osseretski test battery, including running, speed, agility, balance, bilateral coordination, and strength, were compared in another study of kindergarten children. Half-mile-run performance was associated significantly with body weight and relative body fat, showing less time in subjects with higher weight or relative body fat. Half-mile-run performance was negatively correlated with measure of balance, bilateral coordination, and strength while the prudential PACER test was positively correlated with strength. During continuous walk–jog movements (½-mile run) in a relatively homogeneous sample, increases in body size improved balance, bilateral coordination, and strength, but negatively affected running during the ½-mile fitness test (Reeves et al. 1999). Norms for hand grip strength for children aged 5–18 years showed lower values for girls; handedness influenced grip strength. Correlations with height and weight were also found (Newman et al. 1984). Other norms for 4–16-year-old subjects (Hager-Ross and Rosblad 2002) showed slightly lower results than those from United States and Australia in 1980, which may be due to the divergences in age groupings

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and the instruments used. Reference values of maximum isometric muscle force for similar age groups were given by Beenakker et al. (2001). Grip strength was followed up in another group of growing subjects 5–15 years old, and a striking parallelism between boys and girls was found up to the age of 12 years, along with a great variability of results. A trend for better results in right-handers was also revealed (De Smet and Vercammen 2001). Normative data for isometric muscle torque in children 5–15 years of age showed an increase with age and weight, and a strong correlation with both age and weight (Eck et al. 2006); in this study few gender differences were found. Trunk muscle strength correlated significantly with age in children 5–18 years old (Sinaki et al. 1996). Measurements in a group of Indian subjects with a wide age range (4–67 years) showed that prediction for hand grip strength on the basis of gender and age gives relatively reliable results (Vaz et al. 2002). The vigorimeter used for the measurement of spherical grip strength enabled one to assess grip strength in children with rheumatic disorders without excessive pressure on the joints (Link et al. 1995). Oja and Ju˝rimae (1998, 2002) measured preschool children in Tartu, Estonia. The goal of their investigation was to develop a battery of tests for measuring motor abilities in preschool children and to validate the tests used elsewhere for Estonian children of preschool age, which have never been followed up in this respect before. Somatic development is shown in Table 6.11, that is, the values of height, weight, and BMI of children measured in various kindergartens in Tartu. The average values

TABLE 6.11 Anthropometric and Motor Performance Variables of Preschool Children in Tartu, Estonia (n = 932) Age (months) Height (cm) Weight (kg) BMI (kg/m2) 3-min run (m) Broad jump (cm) Bag throw—right (cm) Bag throw—left (cm)

x– SD x– SD x– SD x– SD x– SD x– SD x– SD x– SD

Boys

Girls

Boys

Girls

54.2 3.8 107.0 4.4 18.0 2.0 15.7 1.2 333.9 37.4 88.2 17.3 472.8 144.1 337.0 90.6

53.5 3.7 106.4 5.3 17.5 2.2 15.4 1.4 324.5 36.0 84.7 16.1 359.6 93.4 300.9 74.8

65.9 3.6 114.2 5.0 20.1 2.4 15.4 1.2 366.7 38.1 105.4 17.5 609.1 172.7 433.8 114.3

65.7 3.4 112.8 5.1 19.5 2.6 15.2 1.3 349.3 34.8 100.1 14.6 439.7 110.3 363.6 83.4

Source: Modified from Oja, L. and Jürimae, T., Assessment of motor ability in 4- to 5-year-old children, 1998.

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do not differ significantly from international standards and/or from the values measured in Prague children. Regarding motor abilities, the standing long jump, the two-handed sand bag throw (150 g), the 4 by 10 m shuttle-run, the 3-min run, sit-ups, and the sit-and-reach were used to test children 4–5 and 5–6 years old. As shown in previous studies, the performance of children improved significantly with age. Motor performance was better in boys (Table 6.11) while girls had better results in flexibility tests. Correlation analyses showed that the results of motor ability testing were often dependent on body height and weight, but not on BMI. Tests of fine motorics were not made. The results of Tartu children were somewhat better than the results of surveys A, B, and E (Parˇízková et al. 1984a,b) made in the 1970s, but they were lower when comparing newer data from surveys D and F. In this case, Czech children were also more advanced in somatic development. In other tests used in the Estonian survey, only the previous data of Cratty et al. (1973) and Cratty (1986) were available for comparison. Generally, the results of the same tests applied in both Tartu and Prague children did not differ markedly, because the conditions of life and daily regimens of the children were quite similar.

6.6 METABOLIC AND BIOCHEMICAL CHARACTERISTICS Most often, it is of interest to gather data on blood lipids for the early screening of possible at-risk subjects. The document of the WHO on Prevention in Childhood and Youth of Adult Cardiovascular Diseases (WHO 1990b) focuses on the earliest periods of life, including preschool age, regarding the necessary measures for the prevention of the development of risk factors (Akerblom et al. 1984, Ginzburg and Zetterstrom 1980, Gregory et al. 1995). Therefore, in additional surveys H, I, and J, serum lipid levels were measured. In conjunction with the evaluation of body composition, CK activity was also assessed as an indicator of muscle mass in children. Only selected smaller groups of healthy non-institutionalized children could be examined taking blood samples.

6.6.1

METHODS AND SUBJECTS

Serum lipids were estimated in the morning after an overnight (12–14 h) fast. Only a light breakfast was permitted, that is, a cup of herbal tea, half a roll, and no fats. Total cholesterol, HDLs (HDL-C), and low-density lipoproteins (LDL-C) were estimated using Boehringer tests. TGs were assessed using Lachema tests in the WHO Regional Lipid Reference Center in the Institute of Clinical and Experimental Medicine (IKEM) in Prague (Parˇízková et al. 1986a,b). CK activity in the blood was assessed in our laboratory using Boehringer tests (Sylvén et al. 1983). The average measurement error of all the biochemical methods used was 2–4%. The mentioned assessments were performed in a smaller group of Prague children in day-care centers (n = 22; subgroup of survey H, i.e., group l, age 3–5 years). Preliminary analyses did not show any significant sex-linked difference in the

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biochemical variables in this sample. Further measurements were repeated in groups of children from other localities and will be discussed later. Along with the assessment of serum lipids, cardiorespiratory efficiency was tested, using the modified step test as described above (see Chapter 10). Simultaneously, dietary intake and skinfold thicknesses were measured, and body composition was evaluated using the formulas of Brook (1975). Mutual relationships of all the variables followed were also analyzed.

6.6.2

RESULTS: BLOOD LIPIDS AS RELATED TO SOMATIC DEVELOPMENT, DIETARY INTAKE, AND CARDIORESPIRATORY EFFICIENCY

mmol/L

The mean values of height and weight did not differ significantly from standard values for this particular age category with an average age of 4.9 ± 0.52 years (Prokopec 1976, Bláha 1991). The average value of BMI was 16.2 ± 0.3, which was close to the 70th percentile of Czech standards (Bláha 1991); that is, similar to other samples of Prague children, it was slightly higher than the corresponding 50th percentile. The percentage of body fat was 16.0 ± 4.0%; the absolute amount of LBM was 16.1 ± 1.8 kg. Regarding somatic development, children in this particular group did not differ significantly from the average child population of the Czech Republic. A special index expressing the robusticity of LBM development was also evaluated, that is, LBM kg/10 cm body height. The value of this index was 1.46 ± 0.10 kg (Parˇízková et al. 1986b). With sex-linked differences, only body weight was significantly higher in boys who were slightly, but insignificantly, older than girls. There was a higher absolute amount of LBM as well as a higher index LBM kg/10 cm height in boys. These sex-linked differences, however, were not statistically significant in this group of preschool children. Therefore, mean values for all children together were given. There were no significant sex-linked differences in the serum level of serum lipids, as in UK children (Gregory et al. 1995). The average values of serum lipids are given in Figure 6.8. These values did not differ significantly from those given by other authors. However, the comparison with 9 8 7 6 5 4 3 2 1 0 TC

HDL

LDL

TG

FIGURE 6.8 Blood lipid level (total, HDL, LDL cholesterol, TGs) in a group of preschool boys and girls (survey I).

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recent data on serum lipids in children in the United Kingdom showed significantly lower values of total cholesterol, significantly higher values of TGs, and the same values of HDL in slightly younger UK children (3.5–4.5 years old). As in other variables, there was a marked interindividual variability apparent, which was greatest for TGs (0.34–0.89 mmol/L, CV = 30.8%) and smallest for total cholesterol (3.6–6.2 mmol/L, CV = 15.6%). HDL values varied from 0.6 to 1.6 mmol/L (CV = 20.1%) and LDL values from 2.1 to 5.0 mmol/L (CV = 23.3%) (Parˇízková et al. 1986a,b). Values also did not differ markedly from those ascertained for older Czech children (Pistulková et al. 1991). No significant relationship of blood lipids, above all HDL, to the level of physical fitness was found. Our data indicate that the CEI in preschool children varied more on a constitutional basis and was not significantly related to HDL. In Czech schoolchildren (11–12 years old) extreme values of total cholesterol ranging from 2.6 to 7.4 mmol/L in boys, with an average value of 4.32 mmol/L, were found. For girls the values ranged from 2.6 to 8.2 mmol/L, with a mean value of 4.4 mmol/L. The EIs in these children were also higher than the RDAs of the Czech Republic (Kajaba et al. 1992) and of the EC (1993), mostly due to a high ratio of energy derived from fat (Pistulková et al. 1991). The resting values for CK as an indicator of muscle mass were 42.2 ± 14.4 U/L, which varied from 26.6 to 85.6 U/L (CV = 34.1%). The CK activity was approximately half the value normally assessed in adults (Parˇízková et al. 1986b). We did not find any values for children of this age in the literature. In other variables assessed, the intake of energy and other dietary components (see Figure 5.1) corresponded roughly to the RDAs for Czech preschool children and was slightly, but not significantly, higher in boys. The fat intake was approximately 35% higher than the RDAs for Czech children. The difference from the U.S. and EC RDAs (Tables 5.6a and 5.6b) is much greater, that is, the intake of energy and macrocomponents was again much higher in Czech children (Parˇízková et al. 1986b). The variability of food intake was marked as usual. The values of CV were about 28% for total energy, about 34% for protein, 34% for fat, and 35% for carbohydrate. The average value for 1 week’s EI for individual children varied from 5.9 to 9.32 MJ/day. The results of the step test again showed that the workload used was not excessive. The steady state was established during the second and third minutes of climbing, and the heart rate returned to rest values during the second to fourth minutes of recovery. The curves of heart rate during the step test were comparable to previous results (survey A; Figure 6.1a and b). The calculation of the step test and cardiac efficiency indices showed marked variability (CV about 10%). With sex-linked differences, boys tended to have better results (i.e., a smaller increase in the pulse rate during the workload and higher values of both indices), but these differences were not statistically significant. Generally, the reactions of the heart rate to this workload did not differ from those found previously in larger groups of children. There were no significant mutual relationships between somatic variables, percentage of depot fat, dietary intake, and blood lipid values in this group of 22

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children. (Significant positive relationships were found, however, in a larger sample of 54 preschool children for the percentage of body fat, on the one hand, and both total cholesterol and TGs, on the other hand.) However, the index LBM kg/10 cm height correlated significantly in this group with CEI (r = 0.696, p < 0.001), CK activity (r = 0.436, p < 0.05), and fat intake (r = 0.489, p < 0.05), thus revealing the importance of the development of LBM in cardiorespiratory efficiency (Parˇízková 1989, Parˇízková et al. 1986b). At this age, the consumption of fat seems to have an influence on the development of LBM. CK activity as an indicator of muscle mass was also significantly related to the development of LBM, as already characterized by the above-mentioned index at this growth period. The influence of fat intake, which was increased as compared to RDA, did not yet cause obesity, but rather caused an accelerated development of LBM. We had no opportunity to assess similar characteristics in parents; hence the relationships between parent and child could not be analyzed.

6.7

STUDIES OF BIOCHEMICAL VARIABLES, BLOOD PRESSURE, AND FATNESS IN OTHER POPULATIONS

DuRant et al. (1993a) examined somatic variables, blood lipids, and activity in 4–5year-old children followed up during 2 years. The waist/hip ratio assessed during the first year was inversely correlated with total body cholesterol (TCH) and LDL levels. On the basis of multiple correlation analysis, the sum of seven skinfolds, height, and gender explained the 15.4% variation in the TG levels. The sum of seven skinfold measurements was inversely correlated with the HDL level. The sum of seven skinfolds measured during the second year correlated positively with the LDL/HDL and TCH/HDL ratios. These results indicate, as in our previous study (Parˇízková et al. 1986b), a significant relationship between the accumulation of body fat and blood lipids at a young age. Higginbotham et al. (1988) considered the association between Type A behavior patterns (TABP) and serum cholesterol levels. The effects of TABP may be related to the usual coronary heart risk factors (CHRF) early in life. However, no significant differences in serum cholesterol were found among young children (5–6 years old) differing in ethnicity, gender, and/or TABP. LDLC and TGs differed significantly according to gender and ethnicity. Blood pressure was investigated by Gutin et al. (1990), along with fat distribution and fitness (submaximal treadmill test), in children 5–6 years old. Diastolic blood pressure was inversely related to the level of fitness in boys and girls and positively related to fatness in boys. Systolic blood pressure was positively related to fatness in both boys and girls. When using multiple regression including parental blood pressure, fatness indicated a significant variance in systolic blood pressure for both boys and girls. The variance in diastolic blood pressure applied only to boys. Central deposition of fat had the greatest influence, that is, large values of skinfold thicknesses on the trunk and less on the extremities, again applying only to boys. Fitness and fatness were inversely related in both sexes. Even in small children, then, it is possible to find the same risk factors for increased blood pressure as in older individuals.

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6.8 GENERAL CONSIDERATIONS Cardiorespiratory and motor development was followed up less in preschool children than in older children, and numerous motor tests were used. Not only the tests, but also age ranges and other characteristics vary; hence comparisons are not possible. However, the conclusions on gender differences and age changes generally agree. Studies in Czech preschoolers were conducted on the basis of the same or similar methodology as in, for example, Estonian children. Cross-sectional and longitudinal measurements revealed the following on the functional development of preschool children: • A significant improvement performance occurs in all age categories during preschool age, that is, from 3 to 6 years (Parˇízková 1994, 1995a,b, Parˇ ízková and Douglas 1995). • In testing cardiorespiratory fitness by the modified step test, exceptionally significant sex-linked differences appeared in spite of a slight trend for higher values of heart rate during workload in girls when a medium aerobic workload is induced. • Boys have significantly better results in performance tests such as the 20-m run, the 500-m run-and-walk, and jumping and throwing a ball, that is, in tests where a competitive aspect for maximal effort is involved. Boys also tended to have better results in orientation tests in space and in relation to one’s own body. • Girls normally have better results in skill tests such as walking on a beam, walking at a given pace, forward roll, and standing on one leg as well as in relation to indicators for sensomotor development, that is, the “open- and close-hands test.” The same applies to the “draw-a-man test” and other tests for fine motorics. • In all the parameters measured, there appeared a marked variability, that is, children showed characteristic individual features in the level of performance in various tests as well as in the attitude toward performing different types of exercise and PA. This indicates that some of the children were enthusiastic to participate in our testing (and also in exercise and physical education at the day-care centers in general), while others had to be stimulated to take part in these activities. The combination of various favorable predispositions and/or handicaps for PA and performance characterized the above-mentioned “motor individuality.” • Motor individuality had a stable trend of development as shown by significant correlations between the results in various disciplines measured in individual years of longitudinal survey E. • Significant relationships were found between the results of individual motor and sensomotor tests as shown by analysis: when a child shows a good level of performance in one physical task, it can be assumed that he/she will have a similarly good result in another task and vice versa. For practical purposes, a battery of selected tests will be sufficient (see Chapter 12). • As shown by the better performance of children from survey A in, for example, the 20-m dash, compared to other Prague children measured

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during the same period (B), the role of optimal pedagogical guidance in the physical education of children is essential to achieving adequate motor development at preschool age (see Chapter 10). A battery of tests was selected to characterize the natural motor abilities of children. The simplicity of tests enabled their use under field conditions and in large, often representative samples of subjects. Taking blood samples from healthy children was very difficult, and possible only under hospital conditions (outpatient pediatric departments) and in smaller groups. The conclusions of these measurements reveal the remarkable dynamics of functional development during preschool age, that is, the motor stimulation and physical education of children should be differentiated by age. The same applies to sex-linked differences (Cratty 1986), which require a different approach to the physical education of boys and girls at preschool age (Parˇízková 1994, Parˇízková et al. 1984a,b). BMI did not correlate with the level of performance in preschool children of the same age and with the level of serum lipids. This also concerned dietary intake; for example, fat intake correlated positively only with the LBM kg/height cm index, that is, only with the more robust development of LBM. This seems to confirm the conclusion that at that time the development of obvious obesity did not appear so often at preschool age, in spite of more supporting factors. Along with increasing adiposity in children and adolescents during the last decades, aerobic power and physical fitness level in mutual relationships have been decreasing: declining physical fitness and skill since early childhood results in a reduced interest in exercise. Inadequate diets resulting from unfavorably changing lifestyles since the beginning of life, further contribute to an undesirable fitness and health status. Not enough data on preschool children are available from the last and present centuries, so the comparison is difficult. However, a deterioration in all the mentioned functional parameters can be assumed starting with early age; improvement of this situation is therefore urgent.

7

Influence of Varying Nutrition and Environment on Somatic Development and Physical Fitness

Everyone has the right to a standard of living adequate for health and well-being of himself and his family, including food. —Universal Declaration of Human Rights, 1948

7.1

INTRODUCTION

There is a long-standing ideal that adequate food should be a fundamental human right. After 1948, when the Universal Declaration of Human Rights was proclaimed, other such declarations followed. The International Covenant of Economic, Social and Cultural Rights (1976) states that “The State Parties to the present Covenant recognize the right of everyone to an adequate standard of living for himself and his family, including adequate food, clothing and housing, and also recognize the fundamental right of everyone to be free from hunger.” In the Convention on the Right of the Child (1991), two articles address the issue of nutrition. Article 24 proclaims that “State Parties recognize the right of the child to their enjoyment of the highest attainable standard of health,” and thus they “shall take appropriate measures to combat disease and malnutrition” through the provision of adequate nutritious foods, clean drinking water, and health care. Article 27 indicates that State Parties “shall in case of need provide material assistance and support programmes, particularly with regards to nutrition, clothing and housing” (Kent 1993). There might have been some progress with these ideals (Scrimshaw 1990) in some parts of the world, but the situation of those who are most vulnerable and defenseless in society—children and youth—is still unsatisfactory in many parts of the world due to war conflicts, migration, and further deteriorating conditions. As a result, a call to action was given by the Commission on Global Governance in 1995, because in some parts of the world the situation is not improving significantly (SCN News, UN 1995, Labadarios et al. 2005) and health status, especially during growth, is deteriorating. This is accompanied by reduced functional capacity and reduced physical fitness, and

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the socioeconomic cost of malnutrition during growth is too high, resulting finally in lower cognitive outcomes and reduced adult productivity (Khor 2003). The overlasting paradox thus refers to the parallel existence of malnutrition along with physical overloading due to child labor, and/or overnutrition and inadequate diet composition along with reduction of PA, resulting in overweight and obesity.. There exist populations, especially those in transition, where acute and chronically undernourished children coexist with those who are obese (Bourne et al. 1994). Even in countries during transition, obesity in children may be related to cardiovascular risks, as shown in the Bogalusa Heart Study (Freedman et al. 1999a). Health risks may also be higher, for example, in Asia: it was shown that South Asian children have higher BMI adjusted blood pressure levels than children in the United States (Jafar et al. 2005). The disease risks of childhood obesity, including nonalcoholic steatohepatitis in obese children, have also been appearing in China (Li et al. 2005, Fu et al. 2006), already existing in the United States (Must et al. 1999). Enough knowledge is available to rectify this contrasting situation, but realization still seems far away.

7.2 GROWTH AND DEVELOPMENT Malnutrition has remained the most serious problem in growing children, in spite of the fact that overweight and obesity have been simultaneously increasing in many parts of the world. Stunting and wasting have been recognized in many populations suffering from malnutrition. Stunting, that is, small body size due to deficits in linear growth, is still common in some countries of the Third World, where energy and protein requirements cannot be met. In some countries, almost 50% of children have been recently classified as stunted (Waterlow 1989, 1994, Waterlow et al. 1992), so its significance in relation to public health care cannot be ignored. Signs of severe malnutrition, including stunting, may be observed even in industrially developed countries. The most common causes of such a phenomenon are poverty and accompanying ignorance (Brown 1966, Pollitt et al. 1986), unfortunately quite common even in places where it is avoidable. Serious malnutrition is mostly accompanied by functional and health deterioration. The Expert Committee of a Joint FAO/WHO/UNU Consultation (1985) accepted the view that children of different ethnic groups basically have the same growth potential, and that the cause of widespread growth retardation is principally environmental. Satisfactory growth is a sensitive criterion, that is, whether the energy and protein needs of the child are met (Waterlow et al. 1977, Schürch and Scrimshaw 1987). The definition of satisfactory growth is also the fi rst step in estimating the requirements of infants and children (Chavez and Martinez 1981, 1984). For this reason, evaluation of the growth level holds an important place in many scientific disciplines. Early onset of stunting has different etiologies among populations of varying biological, environmental, and cultural circumstances. Powerful determinants of an infant’s size at birth and during the first 6 months of life are maternal size at the beginning of pregnancy and weight and fat gain during pregnancy and lactation (Neumann and Harrison 1994).

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As mentioned above, a dilemma has materialized as to whether reference standards for the growth of children in industrialized countries should be accepted as universally relevant or whether local standards should be used (Cole et al. 2000, 2007). Children in many developing countries are already smaller at birth compared to those born in industrialized countries, and they then grow at a slower rate during infancy and early childhood. Accordingly, critical cut-off points of BMI have to be adapted, for example, for Asian subjects. In some discussions, stunting has been classified as a sort of adaptation to adverse environmental conditions and lack of food. A small child needs less food, and thus survival is promoted when food is in short supply (Seckler 1982). This is the concept of costless adaptation (FAO 1973), which has aroused a great deal of emotional discussion (Beaton 1989, Gopalan 1983, 1985, Martorell 1989, Waterlow 1989, Waterlow et al. 1992). “Small but healthy” was postulated by Seckler (1982) when body size was at least above a certain limit. This concerns more cases of marginal malnutrition than truly severe malnutrition. But many authors, for example, Satyaranayana et al. (1979, 1980, 1991), claim that this justifies a certain degree of malnutrition and poverty and does not correspond to human rights, which should be the same for all human beings, including sufficient food and the development of one’s own genetic potential. We may only comment that “small but healthy” is better than “small, sick, and unfit.” This general hypothesis may be rephrased in the following way: stunting is a compromise with environmental stress, perhaps the best that can be achieved under the circumstances (Waterlow et al. 1992). With preschool children, in places where nutrition problems are coming under control, such as in Latin America, the 1990s have brought about continued improvement. In the following two worst-affected regions in terms of numbers and prevalence, the situation is worrisome: sub-Saharan Africa is still deteriorating, but South Asia has been improving slowly (ACC/SCN Summary, SCN News 1995). The coming years will be decisive in resolving this problem. The effort to improve the nutritional situation due to the urbanization of Africans in the North West Province has often been accompanied by increases in overweight, obesity, and several factors for noncommunicable diseases (Vorster et al. 2005). The intervention programs for promoting health status should be aimed at improving the quality of dietary intake, especially with regard to micronutrients.

7.3 INFLUENCE OF DIFFERENT TYPES OF NUTRITION AND DIETARY INTAKE Wasting is associated with a low weight for height, which, especially in young children, is associated with an increased risk of morbidity and mortality (WHO 1985). This type of severe weight deficit is generally found in a small proportion of children who survive. A higher incidence of this type of malnutrition is found during famines. The extra amount of energy and protein needed for catch-up growth has been calculated in some detail in studies on the rehabilitation of malnourished children. The role of urea salvage in adaptation to a low intake of protein and energy has been described (Jackson and Forrester 1993). Representative values for the

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energy cost are about 5 kcal, that is, 21 kJ/1 g of tissue laid down. The protein cost is 0.23 g/1 g of deposited tissue (0.16 g deposited at 70% efficiency of metabolic processes). Waterlow et al. (1992) summarized data on the influence of malnutrition on somatic growth, especially on height and weight. Data on other anthropometric variables are still rare. Some data for circumferential measurements and skinfolds are available. Arm circumference was selected, along with height, as a representative measure of wasting, using the “Quack stick” (i.e., a stick for measuring total body height with a mark for critical values of arm circumference) used by Quakers under field conditions in developing countries (Broz´ek 1974). Arm muscle circumference (AMC) is another variable that can be used in a formula to evaluate the degree of malnutrition (Imbembo et al. 1984). Similar formulas have also been derived by other authors (Amador et al. 1990). Body composition in relation to body water was simultaneously followed up by Field et al. (1990) in malnourished children using 18O and BIA. Regression equations for the assessment of body composition were derived from BIA measurements. Vettorazzi et al. (1990) also used BIA for the estimation of total body water in malnourished children. However, observations in Czech children showed some inaccuracies when evaluating body composition using BIA during various periods of growth (Bláha and Parˇízková 2007). Some observations indicate that the effort to achieve larger body size does not always coincide with fulfilling the potential for other factors such as high levels of cardiorespiratory fitness (Parˇízková 1977), positive health, and long life expectancy (Hejda 1967, Ross 1964, Ross et al. 1976). Experience with long-surviving populations (e.g., in Abkhasia, where an increased number of individuals live up to the ninth decade) indicates that they mostly had very modest, even austere diets during growth, and also later in life. Children also did not grow as fast as elsewhere, were smaller and leaner (Miklashevskaya 1994), and did not achieve large body size in adulthood as a result of modest natural nutrition and a high level of PA. All this contrasted with the situation in the Tbilisi population with comparable ethnic characteristics, where long-living individuals were very rare (Kozlov 1987). This study was conducted with the cooperation of Russian and U.S. researchers in the 1960s and 1970s, and could not be repeated later due to changed life conditions. In a previously mentioned experimental model with laboratory animals, Ross (1964) and Ross et al. (1976) showed that restriction of dietary intake had a significant impact on duration of life. Restriction of the protein component had a small but significant effect in two dietary groups allotted rations on an isocaloric basis. A restricted carbohydrate intake with resultant restriction of EI enhanced life expectancy. Restricting the intake of both protein and carbohydrate with restriction of EI, although showing no pronounced effect early in life, enhanced life expectancy to the greatest degree because of the beneficial effects later on in life. Under ad libitum conditions of feeding, the mortality patterns were considerably different from those under restricted conditions. When the identical diets used earlier were employed in all groups except the one fed a relatively low protein ratio (8%) and a high carbohydrate ratio, the lifespan was one-half to one-third that of the

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groups of rats fed a restricted diet (Ross 1964). Rats ingesting ad libitum a diet with 30% protein (casein) also started to die much earlier than rats on a diet of normal composition. Data concerning life tables and national food balance sheets (Stephen and Sieber 1994) for populations from 96 countries (Gage and O’Connor 1994) indicate that life expectancy at birth increases with total calories, with the overall quality and quantity of the diet, and with the ratio of fat to protein. The ratio of carbohydrate to fat is negatively associated with the level of mortality. However, evidence indicates that the main effect of the ratio of fat to protein is reversed when diets are high in quality, and that all the effects tend to saturate at high nutrient availability. Variation in nutrition is also strongly associated with the international variation in age patterns of mortality. When life expectancy is held constant, populations with higher quality diets tend to have lower childhood mortality but higher adult mortality (Gage and O’Connor 1994). The definition of the limit of dietary intake for acceptable and/or satisfactory functional development, along with a desirable body size, also considering the genetic potential, is surely a very difficult task. Even in a healthy privileged population, a wide range of variation exists in the size of children. The reasons for this are mostly of genetic character, and the size of the mother seems to be of great importance. In developing countries, a body weight of 40 kg is considered a risk factor for reduced birth weights (Galloway and Anderson 1994): children born with very low birth weights are usually unable to catch up completely, remaining smaller until adulthood. In the United States only 1% of women have a body weight lower than 40 kg (Gopalan 1985); therefore, the risk of babies with reduced birth weights is very small in this country. In industrially developed countries, the wide range of variation in body size is not related to health, well-being, or physiological function per se. However, in communities where children’s growth is limited by environmental factors, especially marked, serious malnutrition, there is evidence of an association between functional impairment and deficiencies in linear growth. In such situations, it is very difficult to differentiate the effects of malnutrition from those of other aspects of social deprivation (Cravioto and Arrieta 1985). Further research is, therefore, necessary for the elucidation of the main mechanism resulting in small body size—whether it is only a handicap or a result of meaningful adaptation—because minor limitations of genetic potential might not be harmful. Eventually, nonmaximal realization of one potential may render possible more marked realization of another potential—especially of a functional one—such as skill, speed, endurance, etc., as markers of a higher level of physical fitness. These characteristic faculties, especially cardiorespiratory fitness, are significantly deteriorated in overweight and/or obese subjects. Full realization of all human potentials would be the optimal goal of health and nutritional care. However, environmental conditions do not always permit this. It is then necessary to decide what is primary and preferable: the functional potential of an organism might be, especially under special conditions, more important than maximal body size; satisfactory function may exist even in a smaller organism. Take the example of the Sherpas in the Himalayan mountains, characterized by low height and BMI. They are very efficient at carrying heavy loads (which might even be

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heavier than their own body weights) and climb with these loads up to very high above sea levels. Their dietary intake and food quality are more limited as compared to bigger Western subjects, who cannot even compete with them with respect to physical performance. This fitness status is a result of selection and long adaptation for many generations in the Himalayan mountains. As mentioned above, children in developing countries of the Third World start with lower birth weights, which is an additional risk factor. In epidemiological studies of childhood undernutrition, it is conventional to accept –2 SD from the median of weight as the cut-off point between “normal” and “malnourished.” This corresponds approximately to the third percentile (or 80%) of the median for weight and 90% for height. However, inadequate dietary intake resulting in low body weights is also a risk for low-income children elsewhere (Brown and Tieman 1986, Pollit 1994). This was defined with regard to BMI; the cut-off points have not changed more markedly during the last time, and the third percentile remained mostly unchanged as a criterion for malnutrition. BMI cut-offs to define thinness in children and adolescents were defined, based on international surveys (Cole et al. 2007). But this might still be different in other countries with different ethnic, social, and economic conditions. The effect of dietary intake concerns the quality and composition of food, especially with respect to protein and energy, and also some micronutrients such as, for example, iron, which has a special effect on functional parameters. Bioavailability of iron in the diet was shown to be associated with hemoglobin concentration in Mexican children (Rodriguez et al. 2007). Prevailing legumes and cereal-based diets reduce iron availability, and can cause iron deficiency and iron deficiency anemia, as shown in Moroccan children (Zimmermann et al. 2005). Increasing iron stores can prevent iron deficiency and improve children’s well-being, including health status and physical fitness. Fortification of drinking water with iron and vitamin C was shown to be effective in Brazilian preschool children: decreasing anemia and increasing hemoglobin levels associated with height increase were found (de Almeida et al. 2005). The physical performance of children from 0 to 18 years improved significantly due to iron supplementation, as evaluated through the postexercise heart rate in anemic subjects, blood lactate levels, and treadmill endurance time. However, in view of limited functional data availability, these findings cannot be considered, with regard to systematic reviews of randomized controlled trials, as conclusive yet (Gera et al. 2007). Supplementation has been shown to be mostly effective in initially deficient subjects. Even in developed countries, iron deficiency can occur, for example, in British toddlers with an overdependence on milk, which displaces iron-rich or ironenhancing foods (Thane et al. 2000). Education can play a role in this respect— recommending regular fruit juice intake rich in vitamin C at least five times per week can significantly increase iron stores, as followed in iron-deficient preschool children in Teheran (Khoshnevisan et al. 2004). The functional capacity of a growing organism is an important characteristic of nutrition status, and should also be taken into account when evaluating the impact of diet. Conclusions on changes in body size, BMI, and body composition can be different when comparing changes in functional capacity—especially changes in

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cardiorespiratory efficiency, skill, muscle strength, etc. There is very little precise information on the age up to which the capacity for catch-up of various parameters is retained. It is probable that this is possible until the end of the adolescent growth spurt (WHO 1985).

7.4 SURVEYS IN POPULATIONS VARYING IN ENVIRONMENT AND DIETARY INTAKE The follow-up of healthy normal Czech children provided only a limited opportunity to analyze the influence of markedly differentiated dietary intakes, since the situation was relatively uniform and cases of markedly reduced food intake were exceptional (mostly due to disease of children). The opposite situation, abundant nutrition and obesity, has become much more usual. During the last decades of the previous century, obesity was rare, even exceptional, in preschool children, that is, at the time of our previous studies. Surveys on the functional capacity and motor development of children with severe and/or marginal malnutrition are still very rare, because such measurements in extremely malnourished populations are considered inappropriate. The influence of nutrition was mainly analyzed and compared in selected surveys of subjects with different levels of food intake, that is, in marginally malnourished and normally and/or abundantly nourished preschoolers. With regard to different nutritional status, there has been more focus on somatic development than on functional development and physical fitness, and related to health parameters. For example, a decrease in BMI and an increase in the level of aerobic fitness reduce the rate of the age-related increase in blood pressure (Shea et al. 1994). These results may have implications for positive intervention concerning the primary prevention of hypertension during growth. A high fat content in the diet can result in a greater prevalence of obesity; however, in preschool British children less than 2 years, this is not yet apparent. A high-fat diet resulted in higher cholesterol levels in boys, and was mostly accompanied by lower iron intake (Rogers et al. 2001), which could be relevant from the functional point of view. When analyzing the database and references, more complex studies simultaneously following nutritional status, dietary intake, somatic, functional, and other aspects, and especially those concerning physical fitness as a possible characteristic of “positive health” in young children, have remained still rare. Therefore, studies with agreed-on aims using comparable methods were conducted in cooperation with several countries.

7.4.1

SOMATIC DEVELOPMENT

7.4.1.1 Italian Survey Preschool children with reduced rather than ample energy and protein intake were followed by Ferro-Luzzi (1977, 1985). This study included data not only on growth, but also on dietary intake along with functional capacity and performance using the modified step test (see Chapter 6).

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A sample of 2241 children was obtained by selecting representative numbers of children from two areas, central and southern Italy, characterized by contrasting conditions of life. This concerns, inter alia, dietary intake and the level of PA. Dietary intake was followed in a subsample of 550 children. Analysis of the composition of the diet showed marginal malnutrition in preschool children from southern Italy, characterized by lower SES, compared to children of the same age from central Italy and Rome who had a higher intake of energy and macrocomponents and a better diet. Growth retardation, that is, smaller body size, was obvious in a greater proportion of children from southern Italy. The values of BMI were generally slightly higher in children from central Italy. Skinfold thicknesses and the calculated amount of total fat were significantly higher in children from central Italy than in those from the poorer sections of the population in the south, suggesting that at least part of the extra energy available for children was deposited as fat (Ferro-Luzzi et al. 1977). The values of individual skinfold thicknesses and fat patterns could not be compared with those of Czech or other children because only values from the sum of four skinfolds were given. 7.4.1.2 Turkish Survey Türnagöl et al. (1995) measured children younger and older than 4.5 years in Ankara. These children could not be classified as malnourished; nevertheless, their food intake was somewhat different as compared to Czech and Italian children, making a comparison of morphological and functional variables related to dietary intake possible. The energy and macrocomponent intake in children from Ankara was lower than that in children of similar age from Prague and/or children from central Italy (Table 7.1a and b). The intake of protein was similar to that in children from southern Italy and lower than that in children from Rome or Prague. (The highest intake of protein was found in children from Rome from the highest social strata, i.e., about 63–67 g/day, who also had the highest values of height and weight. On the other hand, children from Prague had the highest fat intake. The intake of total energy did not differ in children from Rome and Prague, similar to the values of height and weight.) The vitamin and mineral intakes of Turkish children (see Table 7.1b) varied; for example, the intake of Ca and Fe was lower than the U.S. RDAs (1989) and higher than the EC population reference intakes (1993), and the intake of vitamin C was higher than the U.S. RDAs or the EC population reference intakes. Height and weight did not seem to be different in children from an Ankara day-care center. However, when we compare breadth measurements, the values were significantly lower in children from Ankara compared to those from Prague, except for biacromial and femoral breadths. Circumferential measurements did not seem to differ significantly. The comparison was rendered difficult because the exact age of children before and after 4.5 years was not given, and the measured group from Ankara included a small number of children. According to the values of CV, important differences do not seem to exist. With skinfolds, it was possible to compare Prague and Ankara children. Ankara children had slightly higher values of individual skinfolds, measured by a Harpenden caliper, compared to Prague children, which was the case only when a morphological variable had a higher value in Ankara children.

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TABLE 7.1a Dietary Intake of Preschool Children in Ankara, Turkey, Aged < 54 or > 54 Months at the First and Second Measurements (M) 4 Months Later

Boys

Age (Months)

M

<54

1 2

>54

1 2

Girls

<54

1 2

>54

1 2

x– SD x– SD x– SD x– SD x– SD x– SD x– SD x– SD

Energy (kJ)

Protein (g)

Fat (g)

Carbohydrate (g)

6397 1074 6422 940 7134 955 7142 841 6177 1079 6417 852 6814 938 6885 825

49.2 6.6 49.2 7.0 56.4 12.1 55.0 10.1 47.2 8.4 51.3 8.4 52.7 10.2 59.0 11.3

66.0 15.0 58.7 11.6 71.2 14.2 68.9 10.6 60.7 13.5 60.1 10.1 66.5 10.7 58.7 11.6

189.7 31.5 201.1 46.8 213.6 39.7 221.7 42.8 189.7 47.2 201.7 44.3 209.7 32.7 209.5 36.3

Source: Adapted from Türnagöl, H.H. et al., in Proc. Symp. Human Growth, Dietary Intake and Other Environmental Influences, J. Parˇízková and P.D. Douglas, Eds, 13th ICAES, Mexico City, 1993, Danone, Paris, p. 8, 1995. Note: SD, standard deviation.

Age differences and developmental changes proceeded as in Prague children. Sex-linked differences in Ankara children had the same characteristics as those in Prague children, that is, girls were slightly smaller, their bodies were less robust, and the deposition of subcutaneous fat was greater (Türnagöl et al. 1995). Somatotype was also evaluated in Ankara children. Mesomorphy was a dominant component in Ankara children as in the case of Prague children of corresponding age. The endomorphic component was slightly higher in Turkish girls, and the mesomorphic and ectomorphic components were higher in boys. Somatotypes changed much less with advancing age during the preschool growth period than any other morphological characteristics given in absolute values (kg, cm) (Türnagöl et al. 1995). 7.4.1.3 Senegalese Survey Bénéfice (1990, 1995, Bénéfice et al. 1996, 1999, 2007, Bénéfice and Malina 1996, Bénéfice and Ndiaye 2005) followed mild-malnourished children in Senegal and compared them to their normally nourished peers. The children came from two villages in west-central Senegal (Diokhane and Ndandol in Bambey county) and from

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TABLE 7.1b Intake of Minerals and Vitamins in Preschool Children (<54 and >54 Months Old) at the First and Second Measurements (M) in Ankara, Turkey Minerals

Boys

Age (Months)

M

<54

1 2

>54

1 2

Girls

<54

1 2

>54

1 2

x– SD x– SD x– SD x– SD x– SD x– SD x– SD x– SD

Vitamins

Ca (mg)

Fe (mg)

A (IU)

B1 (mg)

B2 (mg)

PP (mg)

C (mg)

691 267 575 259 651 342 709 306 650 209 671 306 678 347 828 257

8.7 1.5 9.1 2.5 10.1 1.9 10.1 1.5 8.1 1.9 8.7 2.6 10.2 1.7 8.8 1.9

4970 2492 5443 4581 6209 3935 5491 4797 4746 2627 4323 3086 6492 3650 4582 2197

0.83 0.13 0.85 0.17 0.95 0.13 0.92 0.18 0.80 0.05 0.79 0.13 0.96 0.13 0.97 0.11

1.12 0.33 1.00 0.31 1.15 0.44 1.21 0.46 1.05 0.30 1.12 0.36 1.20 0.49 1.28 0.31

8.1 1.5 10.0 3.7 10.0 3.0 9.8 2.1 8.5 2.6 9.4 2.6 9.7 1.6 10.8 27

95.0 40.6 100.0 47.9 94.0 47.1 100.4 51.8 105.4 52.7 83.2 40.4 97.7 42.6 102.6 51.8

Source: Adapted from Türnagöl, H.H. et al., in Proc. Symp. Human Growth, Dietary Intake and Other Environmental Influences, J. Parˇízková and P.D. Douglas, Eds, 13th ICAES, Mexico City, 1993, Danone, Paris, p. 8, 1995.

a small coastal town, Mbour. The inhabitants of this region are Muslims, ethnic Wolofs, or in the case of Mbour, Lebous fishermen, a related tribe. Their basic diet is the same: rice and fish at mid-day and millet or sorghum gruel in the evening. A study of food consumption showed more than half these families to be short of food calories during the rainy season. Protein energy malnutrition in this region ranks highest in Senegal. Forty-four boys and 44 girls were divided into three cohorts according to their year of birth (1983–1985), that is, the children were 3.4, 4.5, and 5.5 years old at the beginning of the follow-up. These children were then examined longitudinally, that is, three times between October 1988 and November 1989. The interval between the first and second examination (5 ± 1.5 months) was shorter than that between the second and third examination (6.4 ± 0.5 months). Only healthy children were recruited for the study. The heights of these children at the beginning of the study were close to the National Center for Health Statistics (NCHS) median, but the children were delayed in weight growth. A total of 18% of the children had a height-for-age deficit between –1 and –2 from the NCHS distribution and 36% had a weight-for-height deficit of the same order. Only 19 children attained the median for height and for

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weight-for-height. There were no significant sex-linked differences, and the proportion of wasted or stunted children did not change during the study. Repeated measurements showed regular growth, but they were still deficient compared to NCHS. On average, Senegalese children were 1.5 years behind in weight development and 3–6 months behind in height compared to the mentioned standards. Bénéfice and Ndiaye (2005) showed in a later study that Senegalese children show PA that is less dependent upon physiological characteristics than it is in adults. 7.4.1.4 Zapotec Survey Malina and colleagues (Malina and Bushang 1985, Malina et al. 1991, 1995) followed somatic development in children 6–14 years old with different degrees of malnutrition in Mexico. Smaller body size was mostly apparent in malnourished children; the deficit in growth was relatively greater in older children.

7.4.2

FUNCTIONAL DEVELOPMENT: CARDIORESPIRATORY FITNESS

7.4.2.1 Italian Survey Ferro-Luzzi (1977, 1985) followed a subsample of 326 Italian preschool children from the above-mentioned study with different degrees of dietary intake, examining the response of the respiratory system to a constant medium-intensity workload, that is, the modified step test, as described in Chapter 6. In this study, sex-linked differences were observed, that is, boys had better results than girls in this functional test (in smaller samples of Czech children, a trend for better results in boys did not reach a level of statistical significance). The work efficiency of the cardiovascular system also improved with advancing age, obviously due to the increase of stroke volume in older children. The results of the step test, especially of the CEI, correlated significantly with a number of characteristics of body composition, that is, with arm and thigh muscle area (cm2) and with fat-free body mass (kg) (r values were from 0.568 to 0.872, all highly significant). The closest relationship was found for the absolute amount of fat-free body mass and CEI. No relationship was found for dietary intake and CEI. When the groups were compared on the basis of belonging to high- and lowincome families or to rural versus urban environments, and on the basis of their level of spontaneous PA, as described by parents and teachers in the questionnaire (specially designed for this purpose), no significant differences were found. However, grouping the children by the usual geographic criteria, south and central, and on the basis of their dietary intake and nutritional status, the cardiorespiratory efficiency was much better in the marginally undernourished children from the south. In these children EI was significantly lower, and the values of skinfold thicknesses were also lower in relation to the calculated total amount of body fat. However, fat-free body mass and arm and thigh muscle areas were the same or only very slightly smaller in boys and girls from the south compared to children from the central part of Italy (Ferro-Luzzi et al. 1977). Evidently, marginal malnutrition did not markedly reduce fat-free LBM and also did not interfere with a good level of performance during a step test in preschool children. The response to workload was better than that in bigger and fatter children

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with higher food intakes from central Italy. Because burdening the organism by a greater amount of fat may be a disadvantage during a dynamic workload (includes weight bearing), it is understandable that smaller and leaner children performed at a higher level during a workload of this sort. The situation would, no doubt, be different during a workload requiring muscle strength (static workload) or even during the same workload in children with a more serious degree of malnutrition. Similar results were found previously in prepubertal children, differentiated in a similar way, examined in Tunisia (Parˇízková 1977). 7.4.2.2 Turkish Survey The step test was also used for the follow-up of preschool children in Ankara. The average values of the heart rate at rest, during workload, and during recovery did not differ significantly from the values assessed in Prague children (see Figure 6.1). Türnagöl et al. (1995) gave only average values of the heart rate during rest, during a 5-min workload, and finally during recovery (Table 7.1c), that is, it was not possible to compare the course of a steady state and/or the speed of recovery by minutes during workload and recovery. In addition, the average age of the individual groups of Ankara children did not correspond exactly to the average age of the group of Prague children. Therefore, only values of the CEI were compared in several cases when the ages of the children were comparable. This concerned the CEI evaluated for the second time in Ankara girls less than 54 months old and Czech girls 4–5 years old or the CEI in boys

TABLE 7.1c Results of the Step Test in Preschool Children from Ankara, Turkey, at the First and Second Measurements, 4 Months Later Boys

Girls

Age (Months)

<54

<54

>54

>54

<54

<54

>54

>54

Measurement

1st 14 110.5 5.9 149.3 14.5 115.9 6.7 0.44 0.04 87.4 5.3

2nd 14 111.4 9.3 152.3 15.6 118.0 10.1 0.45 0.06 86.0 8.3

1st 15 104.2 9.3 150.2 13.0 115.2 10.8 0.57 0.06 88.6 10.10

2nd 15 107.7 10.2 152.6 16.2 115.0 9.4 0.58 0.06 88.1 7.5

1st 16 109.6 12.4 156.8 9.0 117.1 9.5 0.45 0.9 88.0 7.3

2nd 16 113.7 10.2 164.2 10.6 123.2 11.9 0.45 0.8 83.0 8.4

1st 10 108.0 11.3 156.7 12.2 121.3 12.0 0.51 0.09 88.3 7.7

2nd 10 112.3 10.7 162.3 16.9 121.6 12.4 0.52 0.08 84.1 8.2

Rest Workload Recovery CEI 1 Brouha’s index

n x– SD x– SD x– SD x– SD x– SD

Source: Modified from Türnagöl, H.H. et al., in Proc. Symp. Human Growth, Dietary Intake and Other Environmental Influences, J. Parˇízková and P.D. Douglas, Eds, 13th ICAES, Mexico City, 1993, Danone, Paris, p. 8, 1995. Note: Average values of heart rate at rest, during 5-min workload, and during 5-min recovery.

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less than 54 months old measured for the second time compared to Prague boys 4–5 years old. The average values of CEI were significantly higher in Prague children (see Tables 7.1c, 6.1, and 6.3; Figure 6.2a and b). As mentioned above, the values of height, weight, and BMI were not different, but there were variations in breadth measures, skinfolds, and dietary intake. In these cases, the average values were higher in Prague children. This may indicate more accelerated development in Prague children, which was, in some cases, accompanied by slightly better results in cardiorespiratory fitness. This comparison concerned children from larger cities. The comparison of preschool children with different dietary intakes and different physical regimens in Italy (i.e., those from the central and from the south) concerned children from large and small communities (Ferro-Luzzi et al. 1977). All these data seem to indicate that, as in older age categories (Parˇízková 1977), the higher level of cardiorespiratory fitness at an early age is related to more modest nutrition to prevent the deposition of excess body fat, but not reducing LBM that also contributed to the involvement in PA. Also the opportunity for exercise is usually better in smaller communities than in larger urban agglomerations. 7.4.2.3 Senegalese Survey Bénéfice (1990, 1995) followed the reaction of the heart rate in the modified step test carried out as described before (Appendix 2). The results (Figure 7.1) indicate that the heart rates at rest, during exercise, and during the recovery period were higher in Senegalese children than in Czech children. The reaction of the cardiorespiratory system to this type of workload was less efficient than the one in Czech boys. The reaction to workload, that is, the change of heart rate during climbing the step, was similar to that of Czech girls, who increased their heart rates more slightly than boys. However, heart rates during recovery decreased more slowly in Senegalese children as compared to both Czech boys and girls (Figure 7.1), which indicates slower, that is, less efficient, recovery after workload and thus a lower level of cardiorespiratory efficiency in this particular test. 160

Heart rate/min

150 140 130 120 Senegal boys, girls Czech girls Czech boys

110

min

100 0

1

2 Rest

3

1

2

3 4 Work load

5

1

2

3 4 Recovery

5

FIGURE 7.1 Comparison of heart rate during the step test, that is, during 3-min rest, 5-min climbing the step, and 5-min recovery, in Senegalese and Czech children.

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This difference might be partly due to the influence of varying habits resulting from different conditions of life. Children in a Senegalese village are obviously less adapted to climbing steps for 5 min than children in industrially developed countries. Differences in cardiorespiratory fitness between children in different countries, that is, different ethnic and cultural settings, may require other types of tests.

7.4.3

MOTOR DEVELOPMENT

Some differences may appear when more marked chronic nutritional deficiencies are manifested. Although in this case it is also necessary to differentiate between the degrees of malnutrition and various aspects of physical fitness characterized by various motor tests, it seems obvious that speed running and skill tests (and not only those that were used in our studies) do not depend on body size, and the status of marginal malnutrition does not interfere. This may also manifest itself in adulthood; for example, Ethiopian long-distance runners, who are shorter and skinnier than most runners, do not seem to have an abundant or even a satisfactory diet from the beginning of life and sometimes even later. Even so, they are still able to win gold medals just like the bigger and better-fed American, Scandinavian, and other athletes from different countries. The excellent working efficiency of the Sherpas under conditions of high above sea levels in the Himalayas is another convincing example of the mentioned long-term adaptation and selection of extremely fit individuals, in spite of smaller body sizes. Another example is gymnasts, who are mainly within the 25th to 23rd percentile for height, weight, and BMI and are still capable of a physical performance far beyond that of their peers with better nutrition and larger body size (Parˇízková 1986). Of course, adaptation processes and training started early in life (even in preschool age; this is also specific for this sports discipline) are essential for such a performance level. On the whole, this example shows that ample nutrition and body size are not decisive factors for the intense training and achievement of top performances of this sort, that is, gymnastics, which requires perfect neuromuscular coordination and skill. According to growth standards, gymnasts display a sort of marginal malnutrition, sometimes accompanied by deficiencies of some vitamins and minerals (Parˇízková 1977, 1986), which must be supplemented. Not all can endure such conditions of diet and training, but some still achieve best performance on a world scale, due not only to selection and early training but also to special psychological and behavioral preparation. A similar situation can be found in other sports disciplines: adaptation to highly specialized exercise may result in an extraordinary, often onesided performance (moreover during a very short part of the lifespan) in spite of a questionable nutritional status and diet. However, this is surely not the aim for the optimal development of a normal population. 7.4.3.1 Turkish Survey There are very few data on motor skill and physical performance testing of small children with different degrees of nutrition. Türnagöl et al. (1995) assessed some of the mentioned faculties, for example, performances in the 20-m dash and broad jump (Table 7.1d). Again, the exact comparison with Prague children is difficult

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TABLE 7.1d Motor Performance in Preschool Children (<54 and >54 Months Old) at the First and Second Measurements (M) in Ankara, Turkey

Boys

Girls

Age (Months)

M

<54

1

<54

2

>54

1

>54

2

<54

1

<54

2

>54

1

>54

2

x– SD x– SD x– SD x– SD x– SD x– SD x– SD x– SD

20-m Run (s)

Broad Jump (cm)

Hand Right (kp)

Grip Left (kp)

7.15 0.89 6.37 0.84 5.65 0.71 5.36 0.61 7.54 1.0 6.79 0.78 6.04 0.83 5.69 0.06

59.1 13.7 66.2 13.45 66.4 14.6 81.3 17.1 60.3 14.0 63.5 15.7 64.2 15.5 76.8 11.45

5.1 2.3 6.4 2.3 8.6 2.9 8.8 2.9 4.1 1.2 5.4 1.5 6.9 1.9 7.7 1.9

4.7 1.9 5.9 2.5 8.6 2.9 8.3 2.9 4.0 1.1 5.0 1.6 6.4 2.0 6.3 1.5

Source: Adapted from Türnagöl, H. et al., in Proc. Symp. Human Growth, Dietary Intake and Other Environmental Influences, J. Parˇízková and P.D. Douglas, Eds, 13th ICAES, Mexico City, 1993, Danone, Paris, p. 8, 1995. Note: Average values of heart rate at rest, during 5-min workload, and during 5-min recovery.

according to age, although the average values indicate markedly better results in Prague children than in Ankara children. This includes both boys and girls. Türnagöl (1993) followed longitudinally other parameters of motor development, for example, squat jump, counteractive jump, and sit-and-reach. There was an improvement in motor performance with increasing age, with better results in boys, similar to other groups of preschool children measured before (Parˇízková 1978c, 1980, 1987, 1993b, Parˇízková et al. 1984). In the results of the comparison between Ankara and Prague children, it seems that besides slight differences in dietary intake and some parameters of body size, some of the differences in motor skill may be conditioned by cultural characteristics and by kindergarten teaching programs. Prague children were obviously more adapted to running mentioned distances and/or jumping than Ankara children. Therefore, the difference does not seem to be due to some functional handicaps; this is also indicated by the very few differences in the results of the step test. It would be interesting to find out whether these discrete differences increase further and become significant later on in life. This would depend not only on

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dietary intake and way of life, but also on the ability to adapt to physical workloads of this type, which may follow during later growth periods. Further measurements in the same subjects would be necessary to define the role of genetic and constitutional factors in these ethnic differences already manifested during preschool age. 7.4.3.2 Senegalese Survey Bénéfice (1990, 1995) followed in several studies the results in the 20-m dash, broad jump, ball throw, and muscle strength in Senegalese children (Table 7.2) by repeating them three times. These children suffered from mild malnutrition and somatic deficiencies in growth and development as mentioned above (Bénéfice et al. 1996, 1999, 2007, Bénéfice and Malina 1996, Bénéfice and Ndiaye 2005). After dividing the children into four nutritional groups according to their heightfor-age and weight-for-height deficiencies, it was found that normal and thin children scored higher in the various tests than children who were underweight or who were both underheight and underweight. In this study, the contrasts in nutritional status were more marked than in the other above-mentioned studies. Senegalese performance in three motor tasks (Table 7.2) was well below those of Czech children who weighed 2–3 kg more. When the performance was adjusted for a unit of body weight, Czech children still ran faster than Senegalese children, but the differences tended to diminish. When the performance in jumping was adjusted TABLE 7.2 Motor Performance and Abilities in Preschool Children in Senegal Age Group (Years)

3–4 18

N

20-m dash—1 (s) 20-m dash—2 (s) 20-m dash—3 (s) Broad jump—1 (cm) Broad jump—2 (cm) Broad jump—3 (cm) Throwing ball—1 (m) Throwing ball—2 (m) Throwing ball—3 (m)

4–5

x– 8.01 7.10 6.55 42.5 59.9 66.4 2.6 3.0 3.6

5–6

34 SD

x–

1.33 0.75 0.90 16.3 19.0 21.6 0.7 1.2 0.9

7.05 6.47 5.76 56.3 62.4 85.7 3.9 4.5 5.7

36 SD

x–

SD

0.83 0.69 0.52 16.5 24.3 19.2 1.2 1.6 2.0

6.27 5.80 5.24 78.5 89.4 103.5 5.9 6.9 7.8

0.95 0.59 0.61 10.8 19.9 18.1 1.4 1.8 1.8

Sources: Adapted from Bénéfice, E., Early Child Dev. Care, 61, 81, 1990, and from Bénéfice, E., in Proc. Symp. Human Growth, Dietary Intake and Other Environmental Influences, J. Parˇízková and P.D. Douglas, Eds, 13th ICAES, Mexico City, 1993, Danone, Paris, p. 32, 1995. Note: 1, 2, 3—number of visits (interval between 1st and 2nd visit = 5 ± 1.5 months, 2nd and 3rd visit = 6.4 ± 0.5 months). The differences between average values of different age groups, and between average values measured during the individual visits 1–3 were all statistically significant.

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for body weight, Senegalese children jumped farther than Czech children. Finally, smaller Senegalese children, after adjusting for body weight, were quite equal to Czech children in throwing performance (Bénéfice 1990, 1995). To our knowledge no other available similar measurements of motor skill as related to the nutritional status of preschool children in countries or regions with differentiated dietary intake, especially Third World countries, have been conducted up to now.

7.4.4

MUSCLE STRENGTH

Measurement of muscle strength has been more common than testing of other motor faculties. Strength has been a more interesting parameter from the point of view of not only actual but also future work performance level. This is connected with the economic impact of the possibility of child labor and/or the future development of a labor force in adulthood in Third World countries, where malnutrition is usual. Muscle strength is more closely related to body size than to any other parameter of motor development. This applies to the relationship to fat-free LBM and especially to muscles. Muscle force is also higher in obese children, in contrast to most other motor abilities. Therefore, muscle strength is more influenced by malnutrition than, for example, speed or skill. In this case, even mild malnutrition, which still does not interfere with speed, skill, or even endurance development, can reduce muscle strength significantly. 7.4.4.1 Turkish Survey Türnagöl et al. (1995) measured the hand grip strength of preschool children (see Table 7.1d). In this case, too, the average values of hand grip strength were markedly lower in Ankara children than in Prague children. The exact evaluation of the differences is difficult due to various age groupings in the two samples. There was, however, quite a contrast in muscle strength between preschool children in Turkey and the Czech Republic along with relatively small differences regarding other morphological and functional parameters. Also, in this case, it would be interesting to measure the strength of other muscle groups of the body, which may be more important for daily activities than hand grip. This study of Ankara children continues, and further data will reveal more on the possible differences between children with different types of nutrition. 7.4.4.2 First Senegalese Survey Bénéfice (1990, 1995, 2007) measured the muscle strength in the above-mentioned groups of Senegalese children longitudinally. A comparison of the results in Senegalese and other children is not directly possible because a different method was used: a special dynamometer, in fact a manometer (Vigorimeter Martin R, Tuttlingen, Germany), was used. The children had to press on a bulb, adjusted to the size of the palm and connected to a manometer; pressure, not force, was assessed. Units were expressed in bars. Recalculation of the data using different methods could give inexact results; however, we can assume lower values of hand grip strength in Senegalese children.

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A comparison of different measurements showed the usual increase in muscle strength with age. The results were evaluated in a combined group of both boys and girls; hence sex-linked differences could not be evaluated. Insufficient muscle mass available for motor performance seemed to be the principal factor limiting adequate physical achievement in malnourished children. There are also other hypotheses—reduction in children’s habitual PA and neuromotor consequences resulting from preceding severe malnutrition. Therefore, the measurements in Senegalese children from 3 to 6 years of age showed that even a slight degree of malnutrition can affect a child’s ability to perform physical work, thus hindering his/her future work output (Bénéfice and Malina 1996, Bénéfice and Ndiaye 2005, Bénéfice et al. 1996, 1999, 2007). 7.4.4.3 Tunisian Survey When muscle strength was tested in youth from poor and well-off families in Tunisia and compared with Prague children (11–12 years), it was shown that smaller, poor children had significantly less LBM, but the strength of the extensors of the trunk, the flexors and extensors of the elbow, and the extensors of the knee joints was higher than that of their bigger and fatter peers from well-off families. (These results are mentioned in spite of age because as far as we know no other study in an African country has focused simultaneously on numerous functional variables, i.e., the step test, strength of seven muscle groups, vital capacity, forced expiration, performance in the 50-m dash, 300-m run, and broad jump, along with numerous morphological characteristics, including body composition.) Hand grip strength and the strength of the plantar and knee flexors were the same in bigger and smaller Tunisian boys. When muscle strength was related to both total body mass and LBM, the differences in favor of smaller boys with poorer nutrition were even more apparent: they always had a relatively greater strength compared to bigger Tunisian boys (Parˇízková 1977). The same applies for the comparison with bigger Czech boys of the same age. Parallel to that, smaller Tunisian boys had better results in the step test, similar to smaller south Italian children compared to bigger central Italian children (FerroLuzzi et al. 1977). The results in sports disciplines, testing of vital capacity, maximum voluntary ventilation, forced expiration, etc., were also better in smaller Tunisian boys compared to bigger ones. These results indicate that (1) hand grip strength might not give exact information on the strength of other muscle groups and (2) even in smaller and obviously marginally malnourished children, the absolute values of the muscle strength of the most important muscle groups on the trunk and on the extremities may be higher than those in their bigger peers (in most of the above-mentioned surveys, other muscle groups were not followed). This applies even more when we evaluate muscle strength in relation to total body mass or LBM. Last but not least, it is necessary to consider that the smaller children were from poor families, had to do more physical work, and thus may have become more efficient due to adaptation. All these results refer to children with marginal malnutrition (which is characterized by normal or only slightly reduced lean, fat-free body mass and an obviously unchanged size of vital organs) in the prepubertal period, a condition that did not interfere with their spontaneous PA and games. This also contributed to the higher

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level of their physical fitness when compared to the bigger (obviously overnourished) Tunisians and their Czech peers. Moreover, the results of the measurements of muscle strength correlated significantly with other physical performance tests (Parˇ ízková 1977). 7.4.4.4 Second Senegalese Survey Bénéfice (1995) carried out another complex study in Senegalese schoolchildren (10–12 years of age). Measurements were repeated every 6 months for 2 years. There were no sex-linked differences in height and weight. The average values of height for age at the beginning of the study decreased from a –1.3 z-score to a –1.5 z-score. The weight also deteriorated significantly from a –1.5 z-score to a –1.7 z-score. The motor performance of Senegalese children was compared with that of African-American children from Philadelphia (Malina and Roche 1983). In the 33-m run, standing broad jump, and softball throw, African-American children had a better level of performance. Senegalese children were lighter than American or Czech children; when performance was adjusted for body weight, Senegalese children were still slower at running, but they were significantly superior at the broad jump. No differences in throwing were found (Bénéfice 1995). This might be related to the adaptation to different PAs under different environmental conditions. The average heart rates at rest and during exercise (another modification of the step test for older children) showed significantly lower values in 12-year-old boys as compared to girls: the cardiorespiratory efficiency at this age was significantly differentiated regarding gender. There were also sex-linked differences in PA (Bénéfice 1995). 7.4.4.5 Zapotec Survey Malina et al. (1991, 1993) measured the hand grip strengths in chronically mild-tomoderately undernourished rural boys in southern Mexico (Zapotec) aged 9.5–14.5 years. Their heights, weights, skinfolds, calculated LBMs, and hand grip strengths (average of the right and left hands) were always lower than those of MexicanAmerican boys of the same age. When hand grip strength was related to total body weight, there was no significant difference between Zapotec and Mexican-American boys. However, when related to lean, fat-free body mass, the difference was always significant, with the exception of the age group of 12.5-year-old boys. Perhaps, this suggests qualitative changes in muscle tissue due to chronic malnutrition in this particular population group, which also reduces LBM (Malina et al. 1991). In another study, the hand grip strengths in Zapotec boys and girls at the age of 6 and 7 years were also investigated. Heights and weights were lower in Zapotec children in comparison to Prague children (Parˇízková et al. 1984). The BMI was only slightly lower in Zapotec children. Hand grip was, however, markedly lower in Zapotec children. In this case, hand grip strength was the average of the right and left hands. However, even the values of the left hand grip strength in Prague children were much higher than the average value of both hands in Zapotec children. Moreover, in Prague children there were more marked sex-linked differences at this age period than in

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Zapotec children where hand grip strength was uniform on a lower level in both boys and girls. Similar values of the average hand grip strengths of Zapotec children compared to 6–7-year-old boys and girls in Prague were found only about 3–4 years later in Zapotec boys (i.e., only when they were 3 years older than Prague boys) and slightly sooner in Zapotec girls. In these children, the relative differences in the values of height and weight were greater than those of strength and other functional characteristics of well-off and poor Tunisian and Czech boys (Parˇízková 1977), that is, the difference in dietary intake and degree of malnutrition was also much greater. However, it would be interesting to compare the strength of other muscle groups, which could not be measured in Zapotec children. As mentioned above, hand grip strength might not be a representative indicator of muscle strength for other muscle groups of the organism. However, all mentioned motor changes may play an important role in following development and economic productivity in adulthood. 7.4.4.6 Other Functional and/or Motor Development Surveys Regarding the level of functional development related to reduced dietary intake, most studies were carried out in schoolchildren and adolescents. Eventually, 6-yearold children were also examined; for example, among Ethiopian boys who varied in body weight, physical working capacity (W) at the level of a 170 heart rate per minute (PWC170) was related significantly to body size or nutritional status (Areskog et al. 1969). In 6-year-old children, the maximal oxygen uptake (mL min−1 kg−1) was lower in severely malnourished children with reduced body mass in comparison to well-fed children (Barac-Nieto et al. 1984). The low level of physical performance and fitness in malnourished children results from reduced body mass, especially from a reduction of skeletal muscles (Davies 1973). The functional consequences of marginal malnutrition in children and youth 6–16 years of age were evaluated during a maximal workload on a treadmill. The absolute values of maximal oxygen consumption were reduced in the marginally malnourished boys, who had lower weight for age and height and who were recruited from lower urban and rural social groups in Colombia. However, when comparing the values of maximal oxygen uptake per kg body weight, boys with lower SES and lower body weight for height had higher aerobic power. This was obviously the reflection of various body compositions, that is, a higher proportion of LBM as indicated by smaller skinfold thicknesses (Spurr et al. 1982, 1983). Urban boys always had higher values of maximal oxygen uptake per kg body weight, seemingly due to active sports programs and government sports facilities in the capital of Cali (enabling a higher level of adaptation to workloads), which was lacking in rural areas. It has been suggested that the urban–rural differences in recreational facilities could have contributed to the lower values of predicted maximal oxygen uptake of rural compared to urban children. This indicates the great importance of early motor stimulation and of an adequate PA regimen, which can (because of adaptation) compensate for certain functional inadequacies of dietary intake and body size. Another study showed that marginal malnutrition did not limit the level of PA (Spurr 1988, Spurr et al. 1984). The total daily energy expenditure and EE in PA

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were estimated, in free-ranging nutritionally normal and undernourished boys, 6–16 years of age, by measuring basal and resting metabolic rates and average heart rates while they were awake during the day. TEE increased less with increasing age in undernourished boys, but the increase in EE due to PA was the same in both groups. These observations indicate that the nutritional differences between groups concerning TEEs were due to different body sizes, and that the reduced growth and associated economy of EE in motor activity is sufficient physiological adaptation under conditions of marginal malnutrition, but only up to a certain limit (Spurr et al. 1983). The same results were observed in a study with normal and undernourished girls. The total daily energy expenditure measured by means of the sum of the heart rate during a certain period of time (calibrated individually) and the energy expended in PA did not differ significantly in the two groups characterized by various nutritional status (Spurr 1988, Spurr et al. 1982, 1983, 1984, 1992, Spurr and Reina 1989). Davies (1973) did not find any urban–rural differences in East African children, but he pointed out that the dividing line between urban and rural areas is often unclear in most areas, not only in Africa. The mentioned values of maximal oxygen uptake in Colombian children were not different from those in European children, but were slightly lower than those in Scandinavian children. Prista et al. (2003) followed up subjects aged 6–18 years, divided into five subgroups according to nutritional status, with regard to cut-offs set by WHO in Maputo, Mozambique. Compared with the group with normal nutrition, three undernourished groups performed significantly worse in absolute strength tasks, better in endurance tasks, and equally in flexibility and agility. Very few differences were found in the PA scores. The three undernourished groups had scores for the biochemical indicators that were similar to those of the normal group, and had more favorable profiles for blood pressure and cholesterol. Also in this population, the cut-offs to classify overweight appear to identify potential health problems approximately. No relevance for health was found for the lower cut-offs, identifying undernourished children. The majority of other data on the influence of nutrition concern body size (Eveleth and Tanner 1990). Body size may correlate with some of the functional variables (Ghesquiere and D’Hulst 1988), but not with others in children of the same age. Fatness and overweight coexist in children in Bolivian Amazon (Bénéfice et al. 2007). Physiological reasons for that still remain to be resolved by further research.

7.5 INFLUENCE OF SEVERE MALNUTRITION Many authors followed the impact of extreme malnutrition in children of all ages, including the preschool growth period. The data were summarized in an excellent monograph by Waterlow et al. (1992). Health status and basic anthropological variables were analyzed. Functional variables were however followed mainly under rest conditions, a state that does not render possible an evaluation of the reaction of the malnourished organism to some degrees of workload. Even if it is hardly feasible to test starving children in this way, we must bear in mind that their life often requires larger physical loads; thus, more information about their reactions would be certainly desirable. Obviously, very severe malnutrition interferes substantially with the normal development of the child and leads to deterioration of most systems and functions.

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The line drawn between marginal, mild-to-moderate, and severe malnutrition may be transient and is not always clear, which can influence various functional systems differently. However, when food intake is severely restricted during longer periods of development, significant functional, metabolic, and biochemical changes occur in all organs and systems (see Waterlow et al. 1992). Children with severe malnutrition usually have a lower metabolic rate than normally nourished children. There are problems on how to express the metabolic rate because the composition of the whole body and of individual tissues is changed. Under conditions of severe malnutrition, wasting also occurs in the heart muscle as shown by autopsy, chest x-rays, and echocardiography. Previous histological studies of the heart showed only nonspecific changes (Waterlow et al. 1992). Characteristics of the heart muscle in children aged 9.6–54 months, who suffered from severe protein energy malnutrition, were studied by various authors (Tanman 1971, Viart 1978). The initial heart rate at rest, stroke volume, and cardiac output were low. After treatment and recovery, all these variables increased. Cardiac output increased due to the increase in both heart rate and cardiac volume. Systemic and pulmonary artery pressure (by cardiac catheterization) was found to be significantly reduced. Peripheral resistance was increased (Viteri et al. 1979). The relationship between heart rate and EE (kcal/min) is different in severely malnourished children: the heart rate is much higher when EE is not as increased before than after realimentation. As the child recovers, the slope of the regression line becomes steeper, implying a more efficient utilization of energy per heart beat (Spady and Payne 1976, Waterlow et al. 1992). Malnutrition also causes changes in blood volume and hemodynamics, which can be positively changed by realimentation (Viart 1977, 1978). Although smaller body size does not always interfere with the dynamic performance of aerobic character and although small individuals may be quite fit during dynamic, weight-bearing activities, small individuals are at a disadvantage when considering the total work output in physical terms. Such a workload mainly demands strength (depending on muscle mass and therefore on body size) and endurance. This aspect is mostly important in light of the working efficiency and economic productivity of a population. Spurr (1988) and Spurr et al. (1984) showed that the working capacity related to the body weight of Colombian boys who were small for their age was normal, that is, their cardiorespiratory fitness was unimpaired. However, no task could be performed continuously at a rate greater than about 40% of their aerobic power (VO2 max). As also shown by Satyaranayana et al. (1979, 1980), in India, where boys were mostly employed as agricultural laborers, small individuals were always at a functional disadvantage. A longitudinal study of the same author showed that subjects who were small at the age of 5 years were also small adults (Satyaranayana et al. 1991). Hence, the problem perpetuates itself. Small, undernourished women also have smaller babies, and the infant mortality rate is higher than that of larger babies from larger mothers (Martorell 1989). Overall, then, the problem of low working capacity and productivity starts from the beginning of life. Another manifestation of severe malnutrition concerning both energy and protein is mild anemia (see Chapter 5). The hemoglobin concentration is usually 8–10 g/dL. Red cells are of normal size and have a normal or somewhat lower hemoglobin content.

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This might be related to reduced iron intake (Chapter 5). The bone marrow may show normal erythropoiesis, or it may be fatty and hypoplastic (Viart 1977, 1978). Thus, anemia is another factor that limits work performance and physical fitness, causes early fatigue, and limits the level of PA. According to the WHO, about half of the children under 5 years of age in developing countries are anemic, that is, the hemoglobin level is less than 11 g/dL (DeMayer and Adiels-Tegman 1985). The principal cause of anemia is iron deficiency, which is not always present in protein-energy malnutrition. More important, the connection is indirect, that is, iron deficiency is a result of blood loss due to malaria and intestinal parasites. Increased morbidity from these diseases is caused, in part, by suppressed immunoresistance resulting from the lack of energy and high-quality protein intake, that is, this status is finally also the result of malnutrition. Regarding the nervous system, children of undernourished mothers may be born with smaller brains, as shown in Uganda (1966). Protein-energy malnutrition is very dangerous between the 10th and 20th week of pregnancy, an especially vulnerable period due to rapid growth and multiplication of neuronal cells. This phase is followed by one of slower growth, resulting in the multiplication of glial cells, a phase that extends through the third trimester of pregnancy up to about 6 months of postnatal life (Dobbing and Sands 1973, Dobbing 1990). This development varies in different species. According to the theory on vulnerable periods, protein-energy malnutrition that develops postnatally should have its greatest effect during the second period. Since glial cells are responsible for the production of myelin, it is not surprising that there is evidence of delayed myelin formation in protein-energy malnutrition. In severely malnourished children, some researchers observed a reduction in conduction velocity in peripheral nerves, both sensory and motor (Chopra et al. 1986, Waterlow et al. 1992). Perhaps the strongest evidence pertains to a decrease in the density of neuronal synapses. A lower synapse to neuron ratio in some regions of the brain is a result of early severe postnatal malnutrition, as described by Bedi (1987). Dobbing (1990) concluded that the nerve cell number, which, in any case, may not be significant for mental function, is “out of the reach of malnutrition” in humans, since almost all the adult nerve cells are produced before mid-pregnancy. An adequate quantity and quality of dietary intake during pregnancy is highly desirable, even if there is evidence that the fetus takes all that is necessary from the mother. Dobbing claims that not all negative changes are irreversible, and some may be completely reversible, provided adequate realimentation in time is possible (which is not always the case). However, it is not yet known which of these changes caused by dietary intake are significant for higher mental functions, as mental achievements must be followed up later on in life in the same subjects, who were rarely available. In addition, how the effect of malnutrition may cumulate and persist during more generations (still usual in many developing countries) has to be studied. One of the most important associations of stunting that is well documented in school-age children is impaired mental development (Cravioto and Arieta 1985, Cravioto and De Licardie 1976, Cravioto and Cravioto 1990). This association is not found in children from well-off families, where differences in the heights of individual children may be explained by genetic influences. Cravioto and Cravioto (1990) have also shown that by the age of 10, children who have survived an earlier episode

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of malnutrition did not reach the same level of competence as those who had not been malnourished. The level of spontaneous PA is, as a rule, reduced to save energy. This low PA could be the “first line of defence” for severely undernourished children (Spurr et al. 1982, 1983, 1884, 1992, Spurr and Reina 1989). Kraut (1972) stated that the spontaneous activity of small children can serve as an indicator of the level of nutrition in the particular country: when children are generally inert and inactive, it shows a lack of energy and malnutrition of the population. Some studies in Ugandan children compare their low activity levels to those in European children. These children, in spite of low EI, grew normally, that is, activity was sacrificed in order to maintain growth (Ratishouser and Whitehouse 1972, Waterlow et al. 1992). Similar conclusions were formulated in studies concerning children in Jamaica and Gambia (Lawrence and Lawrence 1991). In Mexico, Chavez and Martinez (1981, 1984) showed that children who received food supplements became more active than those who did not. Their activity was measured using a method that records the number of times the child’s foot touches the ground. In a study in Guatemala, reduction of the EI of preschool children from 100 to 80 kcal/kg/day was accompanied by a reduction of expenditure without a change in nitrogen balance or in weight gain (Torun 1984). It seems, therefore, that faced with an inadequate EI, the child preserved weight at the expense of PA. This behavior contrasts with that of adults. In young children, PA plays a key role in psychological and social development. There is also evidence that it influences the rate of linear growth (Torun 1986, Torun and Viteri 1994). If so, expenditure on activity should be the key criterion of adequate EI at this age, particularly since more activity may be demanded of children in Third World countries than in most industrially developed affluent countries. Malnourished children admitted to a hospital were much less active even with toys than later after realimentation. The activity and exploration ratings tested in these children were reduced a lot at the beginning of the treatment for malnutrition than later after rehabilitation. In children over 2 years of age, improvement was usually observed in performance tests of specific cognitive functions and in school achievements. Pollitt et al. (1986) have suggested that these improvements are mediated through changes in the child’s level of arousal and attention. As mentioned above, the level of functional deterioration depends on the degree, sort, and duration of malnutrition. Many functions of children were studied, but, in the case of very severe malnutrition, performance tests were usually not applied for obvious reasons. The transition point where malnutrition is no longer marginal, but severe and eventually irreversible, is interesting with regard to not only the actual functional and working capacity, but also the future one. Unfit children most often become unfit adults with a lower level of productivity, which is disastrous for the whole population or community. When the real optimum of dietary intake cannot be ensured, at least the “minimal optimum” or the “optimal minimum” should be provided. This may be favored by certain types of adequate PAs that can enable, in realimented children, faster rehabilitation after a malnutrition period (Torun 1984, 1986, Torun et al. 1983, Torun and Viteri 1994).

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The effect of exercise on linear growth during nutritional recovery was investigated in experimental models with laboratory rats and in preschool children recovering from protein-energy malnutrition. Physically active animals grew more in length and weight than their inactive counterparts. Groups of preschoolers recovering from malnutrition were assigned to either an active group (encouraged, but not forced, to participate in games and activities such as walking uphill, climbing, running, etc.; 2.0 BMR) or a control group (1.7 BMR). With almost identical dietary intakes, the weight gains in both groups were practically the same, but the active group grew more in length and in LBM (Torun and Viteri 1994). Malina and Bushang (1985) followed up not only marginally but also severely undernourished children. The absolute values of hand grip strength and motor performance were significantly below those of better-nourished Philadelphia schoolchildren. When corrected for body size differences, that is, when relating various parameters per unit body height and weight, rural Zapotec children performed commensurate with their smaller body size in the dash and jump at early ages, but less than expected for their size at older ages. The strength per unit body size was slightly, but consistently, smaller in Zapotec children, while their throwing distance per unit body weight was greater. The estimated energy, protein, vitamin, and mineral intakes were considerably lower than the recommended dietary intakes for Mexican children. A marked reduction in body size, compared to national standards, was the result. High crude death rates and infant mortalities were also apparent in this Zapotec locality, where no change in growth status and no secular change in size and sexual maturation over the past 80 years were recorded. In this case excessive malnutrition markedly impaired most of the items of functional capacity and physical performance. Nevertheless, the throwing performance was better in relation to body size in Zapotec children. This however be due to a skill development that is not mainly dependent on body size and body mass. Some skill tasks may sometimes be performed even better by children with smaller body size, as shown in 11-year-old Tunisian boys with lower values of height and weight (Parˇízková 1977). This, however, is an exceptional case in severely malnourished children. However, the transition from marginal to mild-to-moderate to severe malnutrition in functional parameters is not always clear. As mentioned above, individual items of physical fitness and performance may be influenced to a different degree. Deterioration of health and function is an unavoidable consequence of extreme malnutrition, which is manifested in all systems; this mainly affects children from Third World countries. However, the results of two surveys, HANES I and HANES II (Jones et al. 1985), showed lower mean values for growth measures assessed in children living below the poverty threshold. The magnitude of these poverty-associated differences tended to decrease between the times of the HANES I and HANES II surveys, although not sufficiently enough to be statistically significant. These differences in growth were not consistently associated with differences in the dietary intake of energy between poverty groups or surveys. Functional consequences were not followed up. As mentioned above, in severely malnourished children muscle weakness results in very limited muscle strength. Cardiorespiratory efficiency is also severely limited, especially during PA demanding endurance. Sensomotor development, along with

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psychological development, is always severely reduced. However, in some cases (even in severely malnourished children), certain skills can be sufficiently developed— especially those concerning small muscle groups of the hand. With this faculty, children can achieve quite a high level of ability because of adaptation and also because it is not very demanding with respect to energy needs. Hence many malnourished children are used as laborers in some types of manufacturing industries, for domestic work, etc.

7.6 PROBLEMS OF CHILD LABOR The poorer the country, the larger the number of children who have to perform activities representing inadequate workloads for their ages. However, child labor also exists illegally in some developed countries, for economic reasons. The age limit for the term “child labor” varies officially in many countries, but the criterion is normally 15 years. Nevertheless, this age limit is not respected, and many children below this age work (Shah 1985). It is obvious that this is unacceptable. Quite often, though, if the children do not work, they die of hunger—not only themselves, but their families, for whom (under the conditions of certain countries) this is the only income available. Different cultures and states define the state of childhood in different ways. The International Labor Office (ILO) sets out the minimum age for work as 14 or 15 years. These limits may be higher for work conditions that jeopardize the health, safety, or morals of the young worker. It was noted that some Asian children under 5 years of age were involved in rolling cigarettes, wrapping bonbons and sweets, carrying bricks, and the like. Clearly, then, child labor includes the age group of 5–15 years. The problem of child labor also concerns very early periods of life. Child labor is generally forbidden; nevertheless, it continues to exist for obvious reasons. It is necessary to point out, however, that children in villages or even in cities have always helped their parents by participating in the economic activities of the family, by helping with domestic work, by watching over younger brothers or sisters, by running errands, and so on. When such activities do not surpass certain limits of workload or duration, they may be tolerable, or when appropriately used, they may even be useful for the education and development of the child, as in exercise. However, there are some types of child labor that have been defined as exploitative. Exploitative child labor has been defined by the ILO as any labor that deprives children of any basic need, including health. Such a definition may be too wide, including most children in developing countries, whether they work officially or not. Some jobs for children have obvious health-related problems; while not intrinsically unhealthy, they are simply part of the general environment of poverty (Shah 1985). Certainly, it is necessary to focus on the problems of child labor. Classical epidemiological methods will follow up on the morbidity and mortality associated with the various industries where children work. Perhaps, most child labor is illegal, so exact information on the extent and sort of child labor is very difficult to obtain. Even preschool children sometimes have to participate in economic activities in order to earn money for themselves or for their families. The influence of these activities is both direct and indirect. Growth and development may be affected by continuous, and thus too demanding, rather than unhealthy

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labor. The health effects are also of long-term nature. This mainly concerns labor in sweatshops or even an involvement in criminal activities. When such activities affect older children, it should be noted that these children have started very young, especially street children who have been abandoned by their parents. The member states of the WHO, at the historic WHO/UNICEF conference in Alma Ata in 1978, adopted an approach to primary health care through a program called “Health for All by the Year 2000.” Although exploitative child labor is not mentioned here, the First World Health Assembly in 1948 adopted a wide-ranging resolution condemning child labor. To date, very little has happened to prevent this shameful phenomenon (Naidu and Kapadia 1985). The roots of this problem are of a social, economic, and political nature, and as such they must be solved (Onyango and Kayongo-Male 1983). Scientific research may eventually help in compensating for the harmful consequences affecting children and in ensuring health and fitness in adulthood, provided there are better living conditions. According to the available literature, except for somatic and possibly psychological assessment, the influence of child labor has not been systematically investigated, and there was not even an opportunity to do so. (Anybody who could approach such children would, of course, help and not just do research.) In general, it is well known that the development of such children is retarded, their health is impaired, their immunoresistance is reduced, and many die very young when the situation is extreme. In spite of the fact that children may achieve a relatively high level of ability in some activities (e.g., carpet weaving, where the skill and performance of small muscle groups of the hand are mainly involved), the overall result on the health and functional capacity of these children is negative and deteriorating. Even considering the Convention on Children’s Rights (1991), much remains to be realized, not only for the children of today but especially for those of future generations.

7.7 GENERAL CONSIDERATIONS Most functional measurements were made in older children (schoolchildren, adolescents), who are not the focus of this volume. Some studies included the oldest age category of children (6–7 years old). We may only speculate that some of the conclusions based on measurements of older children might also apply to preschool age; this, however, remains to be validated by future research, which is still lacking. This seems to result from the difficulty in obtaining preschool children for functional and motor studies, that is, normal and healthy children who do not yet need any medical or institutional assistance. Therefore, there still remains the problem of how marginal malnutrition is manifested in preschool children regarding the functional variables mentioned above, and whether the symptoms will be similar to those in older children. We assume that early diagnosis of functional impairment is of utmost importance because the earlier the intervention, the more feasible and successful any compensation and rehabilitation, including physical working capacity. In addition, there is still the question of whether marginal malnutrition is a proper definition of nutrition, which may be more modest than has been usual up to the present, but optimal from the point of view of the development of all potentials of the human organism, including the functional one.

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In general, marked negative functional consequences especially manifest themselves when the reduction of energy and individual nutrient intake reaches a certain critical level. It may not be clear as to what conditions the degree of marginal nutrition still remains within the adaptation limits of the organism. When lean, fat-free body mass, vital organs, and especially important muscle groups are not reduced markedly and mostly fat is decreased, the functional status can be satisfactory or at least acceptable. Dynamic activities, cardiorespiratory fitness, skill performance, and flexibility seem to be much less affected (if at all) than performances demanding strength, which require larger muscle mass and are more dependent on total body mass and LBM. A question remains as to whether such a status can be defined as malnutrition. Performance levels in certain tasks (i.e., jumping or strength testing) are equal or even better when adjusted to body weight, as shown in many studies, for example, in Senegalese or Tunisian children. As shown by the Italian study, the results of the step test, which characterize cardiorespiratory fitness, were generally better in smaller, marginally malnourished children. Even in industrially developed countries, we find a number of children who could be defined as marginally malnourished according to a number of morphological parameters mentioned above, yet they do not have any functional or health problems. Even though a mention of animal models might not seem appropriate here, it is worth mentioning that smaller body size does not mean smaller vital organs; the running performance of smaller animals was at a high level, proving that function was not affected (Chapter 2). The manifestations of malnutrition are modified by possible simultaneous vitamin and mineral deficiencies of a different degree, concerning, for example, iron. There is also evidence that individual functional systems are not impaired by different degrees and different characters of malnutrition in an identical way. Mild-to-moderate malnutrition, however, is always a health risk for preschool children. The character of functional deterioration depends on degree, sort, duration, timing during ontogenesis, and severity of malnutrition. The critical limit between marginal, mild, and/or more marked, severe malnutrition must be defined as exactly as possible, as mild malnutrition is already a serious survival risk in preschool children in developing countries (e.g., Malawi; Pelletier 1994, Pelletier et al. 1994) associated with reduced immunoresistance, etc. Many other studies proved the disastrous effect that serious malnutrition had on all aspects of child development, including functional and motor capacity. This is more applicable to excessive malnutrition during early growth. The consequences of malnutrition always depend on degree, character, timing during ontogeny, and duration of impaired nutrition, and also on predispositions—including genetic ones, adaptation capability, and psychological factors—of the subject in question. The effect of the opposite extreme such as overweight and/or obesity is a significant problem not only from the point of view of physical fitness and performance, which vary with regard to cardiorespiratory characteristics, endurance, motor performance, and skill, but also with respect to health status and its prognosis for later life periods. This problem will be analyzed and discussed in Chapter 8.

8

Development of Obesity and Its Influence on the Functional Capacity of Children and Youth

8.1 OBESITY IN YOUNG CHILDREN During recent decades, obesity during growth has developed into a growing global epidemic, with a large variation in secular trends across countries (Walker et al. 2001, James 2002, James et al. 2004). More recently, an increasing number of children of preschool age are becoming obese; the main reasons for this phenomenon have been proposed (Hawkins and Law 2006) and also with regard to public perceptions (Evans et al. 2005). Our understanding of this problem in children is limited because of unsatisfactory comparable representative data from different countries. However, a combination of predictors, which could be assessed during the initial years of life, could improve the predictability and evaluation of overweight especially at school entry; a classification and regression tree analysis approach was suggested (Toschke et al. 2005). For example, in German kindergartens recently, each tenth child was found to be overweight. This situation can be expected in other countries too, and may only worsen in the future. Macro-environmental and socio-demographic determinants of childhood obesity were also analyzed (Moreno et al. 2004). The most serious problem is that childhood obesity usually predisposes to obesity later on in life: the BMI in childhood was found to be related to adult adiposity (Bogalusa Heart Study; Friedman et al. 2005), with accompanying health risks. In this connection, international child overweight guidelines can also be utilized for the prediction of coronary heart disease factors (Katzmarczyk et al. 2003). Comorbidities of obesity were already found in preschoolers (Wake et al. 2008). Moreover, the quality of life of obese children may not be advantageous (Williams et al. 2005). Racial/ethnic disparities were found in 4-years old U.S. children— highest prevalence in U.S./Indian Alaskan children (Anderson and Whitaker 2009). Obesity is mainly characterized by the disproportionate accumulation of depot fat in the organism in relation to all other tissues, with due consideration to age and sex. Functional capacity and metabolic and biochemical variables also differ in obese subjects, including children and youth (Parˇ ízková 1961a,b,c, 1977, 1993a, Parˇ ízková et al. 2002, Parˇ ízková and Hills 2001, 2005). One of the most important and simplest characteristics of overweight and obesity is the increased BMI value, which correlates significantly with the percentage of 201

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body fat in all age categories of males and females (Parˇ ízková 1989a,b). In adults, a BMI higher than 25 in males and 24 in females is a criterion for being overweight and a BMI of 30 for being obese (Chapter 4). As mentioned in Chapter 4, the evaluation of obesity in children is in more difficult because of the marked changes body proportionality during growth, and because the absolute BMI values considered as critical for obesity can change throughout the whole period of development (RollandCachera 1995, Rolland-Cachera et al. 1984, 1987, 1988). More recent studies showed, however, that especially the critical cut-off point for overweight and obesity can be different for various child populations, for example, Asian subjects compared to other populations (Cole et al. 2000, 2005, Pan et al. 2004). It was interesting to find that in Chinese adolescents more subcutaneous adipose tissue (biceps, triceps, subscapular, suprailiac skinfold thicknesses) was found than in Dutch Caucasians of the same BMI and age (Deurenberg et al. 2003). This further indicates that the criteria established for a Western population are not always valid for exact evaluation of especially Asian subjects. Long-term experience also showed that the criteria for overweight have changed with time: adoption of the WHO 2006 growth charts would set markedly lower standards of weight gain beyond 4 months of age for UK infants (Wright et al. 2008). As mentioned in previous chapters, a rapid and more marked weight gain at the beginning of life can predispose to later overweight and obesity, and lowering the standards could support efforts to prevent future childhood obesity. In spite of the changes in the criteria for overweight and obesity (Wang and Wang 2002), it is obvious that their prevalence has increased in almost all countries from which data are available (Wang and Lobstein 2008, James et al. 2004). As the genetic pool cannot change so quickly, environmental and lifestyle changes are considered as the main cause. However, genetic factors also have an important role in the sensitivity to environmental changes. Stagnation and/or a decrease of overweight was reported in primary school children in Scotland (Mitchell et al. 2007), and there has been no evidence of a major increase in BMI values and no prevalence of obesity in children in Japan since 1948 (Hermanussen et al. 2007). However, whether to take the present cut-off points and centiles as criteria of adequacy is questionable: as shown, for example, in Dutch children (Cole and Roede 1999), previous data from the 1980s better correspond to criteria for adequate BMI development because of a lower prevalence of overweight and obesity at that time. The recent and present shift to higher values does not correspond to the desirable growth and development of children. Differences between males and females in exposure and vulnerability to obesogenic environments were found; the consequences of child obesity and responses for the condition were also considered (Sweeting 2008), which are probably not so marked earlier in life. Many studies were conducted in groups of children of preschool age, and continued until pre-adolescent and adolescent age; at any age, increased PA reduces body fat (Rennie et al. 2005, 2006). Data on obesity at an early age and in preschoolers are rarer as compared to subsequent age periods, not only because the prevalence until recently seemed to be lower, but also because the follow-ups are more difficult than at school age.

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8.2

203

CHANGES OF OBESITY PREVALENCE WITH TIME IN DIFFERENT COUNTRIES

Geographical comparisons of obesity prevalence were conducted mainly in schoolaged children. Obesity was found to vary markedly across countries with different socioeconomic conditions and developmental levels (Wang 2001). The global epidemic of obesity concerns at present all age categories in most countries of the world (Lissau 2004, Li et al. 2005, Ogden et al. 2008, Wang and Lobstein 2008). In the United States, mean body weight, height, and BMI increased at any age from 1960 to 2002 (Ogden et al. 2004). SES was previously found to be inconsistently related to children’s adiposity— associations were found to be negative, positive, and/or not associated (Stunkard et al. 1986). Findings on this relationship, however, have been changing with time, and were also different in various parts of the world or even in the same continent or country (Wang and Zhang 2006). More recent studies within the past 15 years found that associations between SES and adiposity were predominantly inverse in UK children, and positive associations disappeared (Shrewsbury and Wardle 2008). Further research is needed to elucidate the mechanisms through which parental social class affects adiposity during childhood; this could also vary in different countries depending on various economic, social, and cultural conditions, and their range and variability. Different SES groups seem to be at different risks, and the relationship between obesity and SES varies across countries (Wang 2001). In Scottish children aged 4–10 years, a greater prevalence of obesity was shown in those with lower SES, but as their heights were slightly lower, height-growth limitation in the absence of overall growth restriction could be one of the causes of increased obesity in this group (Cecil et al. 2005). For example, in 3-year-old Belgian children, there was no association between SES and excess weight. AR before the age of 5 years was inversely related to body mass at the age of 3 years and was independent of SES (De Spigelaere et al. 1998). Perhaps in an industrially developed country the range of SES has not been large enough to prove a significant effect. This applies especially to industrially developed countries with the highest average SES and those that changed their economic and social conditions more recently. Overweight is the most common health problem facing children in the United States, which has been increasing rapidly from 1986 to 1998, especially among Hispanics and African-Americans (Strauss and Pollack 2001). During subsequent years, obesity in growing children increased even more (Margellos-Anast et al. 2008, Haas et al. 2003). This increase also applies to preschool children starting with the age of 2 years (Warner et al. 2006, Kimbro et al. 2007, Turner and Hagin 2007). The national survey of children’s health in the United States thus gave data that can provide clinicians and public health professionals with useful instructions indispensable for medical care, prevention, policy, and planning related to child health (Tudor-Locke et al. 2007). The estimation of pediatric obesity in Europe, as compared to other continents, is hampered by methodological problems (Livingstone 2000, Lissau 2004) as

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mentioned above: criteria, cut-off points, lack of homogeneity even on the European scale, etc. (Lobstein and Frelut 2003). Generally, childhood obesity has been increasing (Jackson-Leach and Lobstein 2006, Lobstein and Jackson-Leach 2003, 2006). Until recently, Western and Eastern Europe varied in a number of respects; even when this started to change from the late 1980s and the beginning of the 1990s, the differences have not yet definitely disappeared. Moreover, these changes had a different character, and concerned not only political, economic, and social but also cultural and fashion aspects. This was best documented by the consequences of the reunification of Germany, which was accompanied by marked changes in child growth and development and also changes in obesity prevalence (see below). There was a dramatic general increase in upper BMI percentiles and in the prevalence of overweight and obesity, for example, in the Belgian province of Limburg (Massa 2002) similar to UK children at an early age, that is, 4 years (Bundred et al. 2001). Overweight and obesity in UK children increased from 1979 to 2003, more in subjects of lower SES (Stamatakis et al. 2005), which was revealed in other analyses (Lobstein et al. 2003, Chinn and Rona 2001, 2002, Jebb et al. 2004). The prevalence of obesity in children and in individuals up to the age of 20 years, who were of different ethnic origin (Pakistani, British Afro-Caribbean, Indian), was found in the United Kingdom, but not with regard to SES (Saxena et al. 2004). Maternal employment, rather than lack of money, was found to be associated with overweight in 3-year-old English children, which might impede young children’s access to healthy food and exercise (Hawkins and Law 2006, Hawkins et al. 2008). The BMI of French children was assessed and the frequency of obesity, overweight, and thinness was evaluated. An increasing prevalence of overweight in comparison with previous French data was found. The IOTF-based prevalence of overweight including obesity in 2000 in France was similar to the prevalence recorded in the late 1980s in the United States, and the prevalence of obesity in 2000 in France was similar to the prevalence of obesity in the late 1970s in the United States. Data in France are comparable to those reported in other studies conducted in Western Europe (Rolland-Cachera et al. 2002). Multilevel analysis of weight problems in early childhood in France revealed that the prevalence of obesity was significantly higher in girls, only children, children who had not attended day care before nursery school, children whose mothers were not employed, or children whose fathers were not white-collar workers. Independently of these variables, it was also significantly higher among children who lived in urban areas or deprived municipalities. Moreover, none of these factors were found to be associated with overweight alone (Verger et al. 2007). Another survey in French children 3–7 years old revealed the association between SES, snacking, sedentary behavior, and childhood overweight. Since 1999 to 2007, the rates of overweight and obesity in French children 3–14 years old are currently stabilizing along with the reduction of EI and increase of sedentary behavior (Lioret et al. 2009). Comparable results were found in Germany, where a change in life conditions took place during the decade after its reunification. Rapid adoption of Western lifestyle in East Germany increased the prevalence of obesity; although prevalences of obesity were generally higher in Western Germany, there was no evidence that the increase was leveling off, and overall trends were similar in the East and West German samples of children (Apfelbacher et al. 2008). Children from some ethnic

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minorities were more frequently overweight or obese compared to German children. Social class and family duration of stay after immigration influenced the pattern of overweight and obesity in children at school entry (Will et al. 2005, Kuepper-Nybelen et al. 2005). An increase in overweight also concerns preschool children—every 13th child in kindergarten is overweight, every eighth child with the school enrolment medical checkup is overweight, and almost half of them are obese, for example, in Karlsruhe (Bauer and Rosemeier 2004). The prevalence of obesity increased in adults during the period from 1985 to 2000 (Helmert and Strube 2004). But secular changes seem to level off with regard to height, weight, and BMI in 7–14-year-olds during the period from 1975 to 2001 (Zellner et al. 2004). Obesity in Spain and Portugal has also increased (Perez et al. 2004, Padez et al. 2004, Perez-Rodrigo et al. 2006), and higher peaks of the problem were identified between 9 and 13 years among boys of low SES. Similar causes as elsewhere were considered to be responsible for obesity development (lack of breast-feeding, a low consumption of fruit and vegetables, a high consumption of cakes and buns, soft drinks, and butchery products, low PA, and increased TV viewing). The prevalence of overweight and obesity in 2–6-year-old Italian children was close to that reported in children living in the United States (32% vs. 32.7%, respectively), and is rapidly increasing (Maffeis et al. 1998, 2006). When the prevalence of obesity in Italian children was evaluated with the use of different criteria (Center for Disease Control and Prevention (CDC) criteria, IOTF by WHO criteria, and curves published in Italy), similar, but not identical, results were obtained. The use of CDC growth curves leads to an increase in the prevalence of obesity when evaluating children under 5 years of age; this makes earlier identification of subjects at risk and timely intervention possible (Vidal et al. 2006). In northern Italy, parental obesity and birth weight represented major risk factors for obesity among children, including those of preschool age (Maffeis et al. 1994). A significant increase in the prevalence of obesity in Danish children, including those of preschool age of both genders, was reported between 1992 and 2000–2002 (Matthiessen et al. 2008). Centiles for the BMI in Dutch children were evaluated in 1980 when they were free of obesity, and it was suggested that they could better serve as a baseline to monitor international trends in obesity (Cole and Roede 1999). The same could be suggested for BMI centiles assessed previously in other countries. Dutch national reference values allow monitoring the growth and development of overweight or obesity in special groups, for example, asylum seekers (StellingaBoelen et al. 2007). Similar trends for obesity prevalence were found in Ireland, starting with preschool age (McMaster et al. 2005, Whelton et al. 2007). Different results on prevalence were found when using different approaches (IOTF and UK criteria); however, increased obesity prevalence was proved in all cases (O’Neill et al. 2007). The need for a single definition of obesity was again defined. The prevalence of overweight and obesity in children 4–12 years old was for the first time estimated using IOTF criteria in Gibraltar (Kirk and McLeod 2003), which does not seem to vary markedly from other European countries. Overweight and obesity were detected in a national sample of 6–12-year-old Swiss children in whom BMI and percentage of body fat were defined from skinfold

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thicknesses. According to the criteria of the US CDC, 19.1% of boys and 20.3% of girls were overweight, and BMI and fat percentage correlated significantly as in other samples of growing children. However, BMI was an excellent proxy measure for adiposity, especially using CDC criteria but not the criteria set by IOTF by WHO (Zimmermann et al. 2004). Transition, despite some benefits, has also conferred problems on Eastern Europe as shown above in the example of reunited Germany. Collateral damage involves fast-growing obesity in general (Knai et al. 2007) and also in young children. A similar situation occured in the Czech Republic (Parˇ ízková et al. 1995, Bláha and Vignerová 2007, Kobzová et al. 2004, Kunešová et al. 2007), the Russian Federation (Abrosimova et al. 1998, Jahns et al. 2003), and Poland (Malecka-Tendera et al. 2005). A significant increase in overweight was observed among 6-year-old girls from the 2006 study in comparison with the 1986 study in Lithuania. The prevalence of obesity among preschool children was low (i.e., 0.8–3.7% in boys and 0–1.9% in girls) and did not change significantly during 1986–2006 (Jakimaviciene and Tutkuviene 2006). As follows, studies have shown a high prevalence of overweight and obesity even before the start of compulsory schooling when spontaneous PA decreases significantly: approximately 51% of overweight 6-year-olds were still overweight after puberty, as found by tracking overweight from early childhood to adolescence (Johansson et al. 2006). Even when knowledge is relatively limited with regard to preschool children, it is obvious that early overweight prevention, based on adequate information, testing, and analysis, is of utmost importance (Parˇ ízková 1996, 2008). Individualized dietary and lifestyle counseling given at regular intervals since infancy can decrease the prevalence of overweight later on, also with regard to other comorbidities, for example, atherosclerosis, without great energy restriction (Hakanen et al. 2006). Under the present conditions, lifestyle counseling is very important (Moodie et al. 2006), especially when considering the marketing of unsuitable diets and reduced PA due to TV and videogame programs. The latter is extremely attractive for children, but results in reduced physical fitness due to sedentarism. It was concluded that unless action is taken to counteract the mentioned trends in obesity development, by the year 2010 the EU can expect to see the number of overweight and obese children rising by approximately 1.3 million children per year, of which the number of obese children will be rising by over 0.3 million per year (Jackson-Leach and Lobstein 2006). Similar risk, or even greater, concerns the United States. Studies in New Zealand (Gordon et al. 2003) and Australia (Sanigorski et al. 2007) also revealed obesity development during childhood. As mentioned above, the estimated burden of pediatric obesity is due to comorbidities, as the number of children with indicators of obesity-related health problems and diseases—impaired glucose tolerance, hyperinsulinemia, type 2 diabetes (T2D), some cardiovascular risk factors, hyperlipoproteinemia, nonalcoholic fatty liver disease, and metabolic disease syndrome (MS)—has also increased (Lobstein and Jackson-Leach 2006). Obesity has also developed in countries of South/Latin America, the Caribbean, the Middle East, and Northern Africa, where more than 30% of the population are

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obese. Populations living in the Pacific and Indian Ocean Islands have the highest prevalence of obesity in the world (Hainer et al. 2003). Growth and obesity prevalence have changed along with fitness, for example, in Inuits (Shephard and Rode 1995). In Asia and Black Africa, the overall prevalence of overweight is still low, but the incidence is high in urban areas. In most of these countries, there are both underweight and overweight people. The increase in obesity prevalence has occurred within recent years: earlier in the affluent and later in the low-income classes, including young children and adolescents. The prevalence of overweight and obesity among preschool children was also found in developing countries (Martorell et al. 2000, de Onis and Blossner 2000), and can vary according to the degree of development and local conditions. An energy-dense diet (Astrup 2000) and reduced PA were considered along with fetal and early life malnutrition, which can predispose to overweight (Delpeuch and Maire 1997) due to improved nutrition during later growth periods. There is evidence on childhood obesity from many other parts of the world in recent years, for example, South Africa (Monyeki et al. 1999, Kruger et al. 2004, 2006, Armstrong et al. 2006), Burkina-Faso (Ye et al. 2001), Nigeria (Senbanjo 2007, Senbanjo and Adejuyigbe 2007), Cameroon (Pasquet et al. 1999, SaidMohamed et al. 2009), Morocco (2007), Saudi Arabia (El-Hazmi and Warsy 2002, Al-Hazzaa 2007), Qatar (Bener and Kamal 2005), Iran (Mirmaran et al. 2002, Dorosty et al. 2002), United Arab Emirates (Al Haddad et al. 2005, Malik and Bakir 2007), Algeria (Mekhancha-Dahel et al. 2006), Egypt (Galal 2002), Lebanon (Jabre et al. 2005), Sri Lanka (Wickramasinghe et al. 2005), Trinidad and Tobago (children of African and Indian descent; Gulliford et al. 2001), South India (Kumar et al. 2008), Chile (Uauy et al. 2006, Stonojevic et al. 2007, Kain et al. 2007, Vio et al. 2008), Hawai (Barufi et al. 2004), Argentina (Orden and Oyhenart 2006), Venezuela (Viso Gonzales et al. 2005), and others. In many countries both under- and over nutrition exist simultaneously (Jinabhai et al. 2005); however, this has been changing recently, and increased overweight has been seen. In most studies, groups of growing individuals, including preschool children, were followed. There was no evidence of a major increase in the prevalence of obesity in Japan (Hermanussen et al. 2007) and also in Scotland (Mitchell et al. 2007) and/or Lithuania (Jakimaviciene and Tutkuviene 2006) as mentioned above. In China, where initially the prevalence was lower, the trend of obesity during the past decades also increased in young children (Ji and Sun 2004a,b, Lobstein et al. 2003, Ji et al. 2007, Liu et al. 2007, Luo and Fu 2002, Ji 2006), especially in urban ones (Iwata et al. 2003). Differences in BMI during growth are related to various geographic regions (Ji and Sun 2004, Ji et al. 2004). Nutrition transition has had an important role (Zhai et al. 2005). BMI was found to be associated with blood pressure (Wang et al. 2004) and comorbidities such as nonalcoholic fatty liver (Shen et al. 2003) and others (Wang et al. 2006). Overweight and obesity in Chinese children in 2000 were similar to the situation in the United Kingdom or the United States in the 1980s or earlier. The age at AR as measured by BMI for Chinese children was more than 6.5 years (Liu et al. 2007), that is, later than in other Western countries, indicating a smaller obesity risk. Relevant associations were found for the new stage of nutrition transition

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(Du et al. 2002) and fat intake (Wang et al. 2007, Cunming 2000). A similar situation was found in Hong Kong (Leung et al. 2000, Wong et al. 2005). Attention was paid to psychological factors and weight perception (Xie et al. 2003), PA and inactivity, snacking, etc. (Tudor-Locke et al. 2003, Waller et al. 2003). In China, special attention was paid to the prevention of obesity in preschool children (Ma et al. 2006) and of MS (Fu et al. 2006). Studies in Singapore showed significantly more severe grades of obesity in Malay preschool children compared to Chinese and Indian children (Ray et al. 1994). Ethnicity seems to play an important role in the early development of obesity in the same environment. Lower social class, lower expressive social support, and unmarried status of the caretaker were associated with higher calorie intakes and higher weight-for-height scores in children aged 2.5–5 years (Gerald et al. 1994). Changing life conditions have a significant impact on child growth and obesity prevalence not only in different parts of the world (Popkin 2001), but also when moving from one country to another. BMI increased during the last 20 years in children 0–4 years of age born to Maghrebian immigrants in a Parisian area (Rovillée-Sausse 1999). Similar changes evaluated by international standards were observed for children of Turkish, Moroccan, and Dutch origin in the Netherlands (Fredrics et al. 2005). Obesity and undernutrition in sub-Saharan African immigrant and refugee children were seen in Victoria, Australia (Renzaho et al. 2006). The prevalence rates of obesity within Latino male children are higher than in other major gender-ethnic groups in the United States and are accompanied, on a larger scale, by comorbidities (Stovitz et al. 2008, Flegal et al. 2004, McArthur et al. 2004). There is a relationship between fetal and early life malnutrition, resulting in the initial stunting of children but associated with later overweight, which is usual in developing countries. Measurements of children of four nations where nutrition transition occurred (Russia, Brazil, Republic of South Africa, and China) showed that where large changes in dietary and activity patterns took place, other problems, including obesity, may be faced in the not too distant future (Popkin et al. 1996, 2006). This was found later in preschool age in Latin American and Caribbean (Duran et al. 2006), Mexican (Fernald and Neufeld 2007), and South African children (Mamabolo et al. 2005). Assessments of BMI in African urban children showed, however, that a greater BMI in stunted infants does not show a trend for overweight and obesity, but is a reflection of a greater reduction in height rather than weight (Cameron et al. 2005). A special kind of obesity as a consequence of early malnutrition results in the stunting of girls, who have the potential to catch up in growth during puberty. The greater accumulation of subcutaneous fat on the upper parts of the body in stunted girls may be a consequence of complex hormonal adjustments at the onset of puberty (Bénéfice et al. 2001). Environmental factors do not influence children in the same manner, and there is the question of why some children become obese and others do not, and also why some children remain obese whereas others do not. During significant transition in China, many factors were considered, especially the composition of nutrition and dietary patterns along with reduced energy output (Wang et al. 2003), as also observed elsewhere. For example, small changes in dietary sugar and PA can be

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responsible, and their rectification can be a suitable approach for preventing obesity in U.S. children (Rodearmel et al. 2007). Most of the studies to date gave epidemiological data about the changing prevalence of overweight and obesity. Fewer of them followed and analyzed the causing factors—for example, diet and PA—exactly, in greater detail, and during longer periods, and also with regard to accompanying pathological traits and comorbidities. A large number of new studies have been appearing, but most of them have not brought any definite results that could resolve the obesity problem and prevent it, starting during early and later growth. Most studies confirmed well-known conclusions on previous research and empiric experiences from the past concerning the causes and effect of more modest adequate diets, and enough of PA necessary for growth and development. However, because of the continuing changes in environment and lifestyle, it is still necessary to increase our efforts to find solutions under any conditions for this urgent and costly health problem.

8.3

GENETIC AND HEREDITARY FACTORS IN EARLY CHILDHOOD OBESITY

Growth and its programming, and the nature of the development of the organism are dependent mainly on the interplay of genetic factors and environmental influences. Certain deviations, smaller or greater, may occur, which usually result from genetic predispositions; additional environmental factors, such as nutrition, infections, energy output, and so forth, participate in forming the resulting status of the organism. This concerns the beginning and further development of obesity during growth, and also the reaction of the organism to its prevention and treatment. Early development since the beginning of life is the period when deviations start to appear, and when it is desirable to interfere and compensate for the effect of undesirable negative influences. Under normal conditions, physiological factors are recommended for the rectification and introduction of desirable growth and development from all points of view. The assessment of genetic predisposition makes intervention more efficient and timely. During more recent periods, a great deal of attention was focused on the effect of genetics on the development of obesity early in childhood (Bouchard et al. 1988, 1993, 1997a,b,c, Bouchard and Tremblay 1997, Farooqi and Rahilly 2000, 2008, Farooqi et al. 2000, 2003, 2007). This was partly due to observations that the impact of comparable environmental factors could give different results in different individuals. Because of various genetic conditions, more and/or less significant interventions are required. In the context of health development and overall fitness under the conditions of present life, attention has also been focused on body composition, functional capacity, and physical fitness, as related to the health status of the organism. Therefore, excess fat deposition along with accompanying functional, biochemical, hormonal, and health complications are of interest in many recent complex studies including genetic factors. With regard to the rate and magnitude of the increase in obesity prevalence in so many populations during a relatively short time, a significant change in the gene pool cannot be considered as the most decisive and essential

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cause. However, genetic factors obviously play an important role in the sensitivity of the organism to environmental influences. What appears as an urgent problem is also an increasing prevalence of overweight and obesity during very early stages of growth and development. It is important to emphasize that during these early periods rectification and interventions can be achieved easier than later on in life; hence an early diagnosis including genetic predispositions is highly desirable. The results of various interventions may be significantly related to genetic predispositions of a particular child, and could be more or less efficient, and also lasting or not. Early diagnosis and exact evaluation of the status of the child is an essential starting point for efficient intervention (O’Brien et al. 2004), and especially in children where heredity may be decisive. The extent of the effect of monitored EI and output and their balance, which belong to the most important environmental cause of different degrees of both low and excessive fat deposition, are thus associated with genetic factors. All this also depends on the developmental period, especially during its early stages. To date, most studies have been conducted in adult populations. Children were followed up more rarely, especially during early and preschool age.

8.3.1

GENETIC ENDOWMENT: TWIN AND FAMILY CLUSTERING

Studies of genes in members of the same families and populations offer information on genes and mutations associated or linked not only to obesity but also to fat distribution and other relevant phenotypes (York and Bouchard 2000). Accumulation of an increased number of obese subjects in a family makes heredity a very probable cause. The effect of heredity was mainly demonstrated by the similarity in fatness levels among parents (especially the mother), children, and siblings. Studies in twins proved the prevalence of obesity in families and concluded that genetics contributes to obesity development (Bouchard 1997a,b,c). Twins are also similar with respect to somatotypes (Song et al. 1994). Stunkard (1986) followed monozygotic and dizygotic twins and defined the correlation coefficient of the heredity of body weight between 0.78 and 0.81. The highest degree of heredity of BMI is in twins (0.6–0.9), which is comparable to the heredity of body height. This relationship is smaller at birth or at an early age. Genetic analysis of weight and overweight was conducted in 4-year-old twin pairs and showed a significant genetic contribution to weight development. Unlike the results later on in life, weight and overweight in 4-year-olds also suggest a significant effect of shared family environment (Koeppen-Schomerus et al. 2001). Similar twin studies were conducted in other populations; Taiwan (Wu et al. 2003), Iran (Mirmiran et al. 2002), United States (Faith et al. 2002), and elsewhere. A significant effect of parental obesity was found in children from Italy and Thailand (Maffeis et al. 1994, 1998, Mo-suwan and Gaeter 1996, Chen et al. 1997), Australia (Burke et al. 2001), Tehran (Mirmiran et al. 2002), Brazil (Engstrom and Anjos 1996), etc. This was often accompanied by similarity not only in the level of PA (Joosen et al. 2006) but also in dietary intake. The relationships were more evident when the parent’s obesity was of higher degree. It was also shown that children from both normal-weight and obese parents initially had the same weights, but the latter had marginally higher weights later on. In Hispanic children, a quantitative

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trait locus on chromosome 18q for PA and dietary intake was proved; MC4R is a strong positional candidate gene for both (Cai et al. 2006). Muscle strength and muscle characteristics are associated in monozygous and dizygous twins (Karlson et al. 1979). A more pronounced trend for increased fatness can be assumed later on in life (Eck et al. 1992). In Scandinavia, a 40-year longitudinal study proved the highest risk of obesity for offspring of obese parents and grandparents along with greater morbidity and mortality in individuals who were also obese during puberty (Mossberg 1989). Combined genetic and environmental determinants of pediatric obesity were “unique” rather than “common” in nature (Faith et al. 1998). Both genotype and environmental factors exerted a greater influence on the BMI of black adolescents, in which the variance of BMI was greater, than white adolescents (Allison et al. 1994). The increment of weight under conditions of overfeeding is more similar in adult twins (Bouchard and Tremblay, 1997). Pearson’s correlations revealed a stronger association among monozygotic than dizygotic twins for BMI and percentage of fat in adults. Greater similarity in weight decrements under a weight reduction regimen (diet, exercise, behavior intervention) was shown in adult female monozygotic twins. This was demonstrated, when compared to controls, by high correlation coefficients, which varied interindividually (Hainer et al. 2000). During growth no comparable study during both overfeeding and reduction treatment has been reported yet. Adopted children resemble their biological parents much more than their foster parents even when they do not share the same environment (Stunkard 1986). A study in international adoptees showed differences in the prevalence of overweight between various groups of adoptees, and differences between adopted and nonadopted subjects, which are probably due to the variability in genetic individual susceptibility to develop overweight and excess fatness (Johansson-Kark et al. 2002). Further studies in families showed heredity of BMI, skinfold thickness, and waist circumference characterized by correlation coefficient r = 0.46–0.60. The correlation coefficient for fat distribution (waist circumference related to BMI) was not dependent on total subcutaneous fat thickness and achieved values of 0.29–9.48 (Katzmarczyk et al. 2000). The Quebec Longitudinal Study revealed familial aggregation of BMI and subcutaneous fat assessments, which also concerned the distribution of fat, an important marker of health risk. Simple univariate familial correlation analysis of the change scores and bivariate analysis of the longitudinal measures were appropriate for the evaluation of factors leading to both change and stability of certain characteristics across this period (Rice et al. 1995, 1996, 1997). Mother and child correlations in anthropometric parameters, including fat patterning, were found (Parˇ ízková 1996; see Chapter 3). Children followed from 6 to 12 years showed a strong relationship of BMI with that of both their parents (Guillaume et al. 1993). The familial link extended beyond one generation because the obesity problems of grandparents (Davies et al. 2008) were related to the BMI of parents and also to obesity in children. The correlation between birth weight and current BMI of the children was revealed in the youngest age group of girls, and birth weight correlated with BMI of the mother. In these children, EI was high and energy output was low because of reduced PA. This study indicates that excess fatness and obesity can

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be traced through three generations in familial clustering, and is evident already at birth. Statistical analyses suggest that during the growth period familial factors have a more significant effect on obesity in children than other environmental factors (Guillaume et al. 1995, Frisancho 2000, Fuentes et al. 2002). However, this could also concern family lifestyle. Leocard et al. (1992) showed that parental overweight and birth overweight of their children are closely related to the degree of obesity at the age of 5 years. The response in total and abdominal visceral fat to 20 weeks of exercise was investigated in families participating in the Heritage Family Study. There was little evidence of a multifactorial heritability for either total or visceral fat. The response to exercise in the family appears to be primarily due to putative major genes (Rice et al. 1996, 1997). Heredity concerning lifestyle, especially diet and PA, has also been considered. For example, melanocortin 4 receptor gene (MC4R) is a strong positional candidate gene for the regulation of food intake and energy expenditure, as revealed in a group of Hispanic children (Cai et al. 2006, 2008). Increased deposition of fat is also caused by genetically conditioned behaviors in adults (Bouchard 1997a). Not only diet and its energy content but also food habits (both preferences and aversions) can be similar in family members (Birch and Davidson 2001). The volume and character of PA during defined periods of time were shown to be more similar in mono- than in dizygotic twins (Ledovskaya 1972). The structure of performing a certain motor task, for example, gait, run, gesticulation, etc., or performing athletic disciplines demonstrated by visual methods was most similar in monozygotic twins (Sklad 1972). The same applies to other motor faculties (Missitzi et al. 2007). Similar, more recent studies on the structure of simple motor tasks and the volume of PA have not been available in twins up to now, especially in growing subjects. Familial indicators such as PA of parents may also be a predictor of the activity levels of prepubertal children (Brock et al. 1999). Respiratory quotient (RQ) and EE correlated significantly in mothers and children as well as in mothers and girls in terms of moderate PA. With regard to fathers, only the time spent in low PA correlated with that of children. Children with a high level of PA and EE had parents who were mostly active and with high EE; a similar trend was found for RQ. The relationship of child inactivity and parent inactivity was stronger than that for vigorous PA (Fogelholm et al. 1999). Earlier AR as a marker for more probable development of obesity in later life was observed in children of obese parents (Klesges et al. 1995). To date, however, there has been no study concerning AR in both parents and their children, and its association with eventual later obesity. Modifiable variables, especially nutrition and PA, accounted for more of the variance in child BMI than nonmodifiable variables, namely obesity in parents (Klesges et al. 1990, 1995, Goran et al. 1995, 1999). This might indicate a lesser role of parental obesity at an earlier age and the possibility of using exercise to rectify the situation even under negative genetic conditions. Other observations showed that parental obesity was associated with a lower level of PA in children, which was quantified directly in the natural environment (Klesges et al. 1990).

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RMR was significantly lowest in obese girls with both parents obese, as compared to girls with parents who were not obese, after adjustment for age, degree of pubertal development, and body composition. However, neither TEE nor EE as an indicator of PA (TEE-BMR) differed between the groups (Wurmser et al. 1998). Measurements of EE in parents and children with different degrees of fatness did not support the hypothesis that obesity in children of obese parents is caused by major defects in their EE (TEE measured during 2 weeks using DLW). After all adjustments, parental obesity did not show any effect on the EE of children (Goran et al. 1995). A review of the literature on the role of genetic factors in daily PA, participation in sports and exercise, and RMR indicates variability from low to moderately high, which was calculated from twin and family data. Offspring or co-twins of active relatives are more likely to be active too. A linkage between RMR and uncoupling protein 2 (UCP1) markers was reported (Beunen and Thomis 1999). Parental obesity may identify children at risk as related to excess fatness and unhealthy behaviors—inactivity, increased fat intake, smoking, and alcohol drinking (Frelut 2001, Bandini et al. 2002). Early childhood and middle childhood are special periods for the development of food preferences and/or aversions, patterns of food intake, and eating style (Birch et al. 2001a,b) as well as PA patterns and interests (Parˇ ízková and Hills 2001, 2005). A permissive environment in present industrialized societies, starting with family, may be part of the genetic influence that transfers obesity to the next generation. Children from overweight/obese families had higher preferences for fatty foods in a taste test, less of a preference for vegetables, and more of an “overeating type” of eating style. There was also a stronger preference for sedentary activities and more involvement in sedentary pastimes. However, there were no differences in the speed of eating or in the reported frequency of intake of high-fat foods (Wardle et al. 2001a,b). The longitudinal Framingham Children’s Study showed that paternal eating style characterized by dietary restraint, disinhibition, and perceived hunger evaluated by the Three-Factor Eating Questionnaire (Stunkard and Messick 1985), along with anthropometric characteristics of parents and children, indicated that parents who displayed high levels of disinhibited eating, especially when coupled with high dietary restraint, may foster the development of excess fat in their children. Parents modeling unhealthy eating behaviors or more indirect behaviors, perhaps unconsciously, can suppress the child’s innate regulation of dietary intake (Hood et al. 2000). As defined in terms of a parent’s activity and dietary patterns, children from obesogenic families can be considered at a greater risk for obesity development. Best correlates for the risk of overweight with regard to BMI in girls aged 5 years were mother’s change of BMI, father’s EI and his enjoyment of activity, and the girl’s percentage of energy from fat (Davidson and Birch 2001). Insulin resistance in children seems to be a function of excess weight rather than of other factors such as birth weight, or early change of weight, underlining that childhood obesity enhances the health risk (Wilkin et al. 2002). Because heredity can influence many characteristics of the offspring significantly, it is desirable to always intervene in the whole family in order to minimize the health risk, and as early as possible.

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There was also a difference between BMI resemblances with regard to full or half-siblings; the almost twice as strong BMI correlation between maternal halfbrothers compared to paternal half-brothers illustrates the importance of factors of nonadditive genetic origin. The significant BMI association between unrelated individuals from the same family emphasizes that assorted mating, perhaps linked with regional clustering, should be considered when the heritability of BMI is estimated (Magnusson and Rassmussen 2002). Spousal resemblance with regard to obesity has also been analyzed (Katzmarczyk et al. 2002).

8.3.2

GENES AND EXCESS FATNESS

Studies concerning childhood obesity suggest the heritability of fat mass, and disorders of energy balance and lipid metabolism that arise from genetic defects. Twin studies as well as multigenerational family studies helped in identifying gene disorders resulting in an early onset of obesity. Genetic factors influence not only the regulation of body weight and fatness, but also individual responses to environmental factors such as diet and PA. The identification and characterization of monogenic syndromes helped in understanding the nature of the inherited component and in dispelling comments on individual defects in behavior with no biological basis. These discoveries have biological and clinical implications (Farooqi and O’Rahilly 2000, Farooqi 2005). Genuinely genetic obesities include Mendelian hereditary syndromes; to date, about 20 genetic syndromes have been identified. Obesity is only one of the manifestations. The heredity of these syndromes is either autosomal or X-linked. These syndromes also include mutations of genes, which have no abnormalities in their clinical characteristics and cannot be included among the known syndromes. Purely genetically conditioned obesities manifest without any effect of the environment, and are the result of chromosomal abnormalities or mutations of genes. They are often accompanied by mental retardation, dysmorphisms, and inborn developmental abnormalities of various organs: Prader–Willi, Bardet–Biedl, Alstro˝m, Fragile X, Cohen, Momo, Borjesson–Forssman–Lehmann, Mehmo, Albright hereditary osteodystrophy syndromes, and others. They represent a special category of clinical problems and have a very low prevalence—that is, fractions of percent of the population—as compared to simple obesity (Hainerová 2007, Lisá 2007). Obesity can be the result of both monogenic and polygenic origins. There exist some rare cases of obesity that are caused by mutations of only one gene—called monogenic. They represent only a small part of the obesity cases, but their identification contributes significantly to the discovery of new pathophysiological processes in the regulation of energy balance, namely at the level of the CNS. They are characterized by very early manifestations of the serious degree of obesity. More often obesity is conditioned by several gene variants—the polygenic form of obesity. It was shown that some individuals who are carriers of some gene variants are more sensitive and thus at a greater risk toward obesity development. This applies especially when interacting with an obesigenic environment. “Thrifty genes” (Neel 1999, James et al. 2002) help in economizing better energy from ingested food. The thrifty genotype hypothesis proposed that early-life

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metabolic adaptations promote survival, with the developing organism responding to cues of environmental quality by selecting an appropriate trajectory of growth. A thrifty genotype—also considered as an adaptive maternal effect—is adaptive in a longer period, preparing the organism for a probable adult environment, which finally could be inappropriate and lead to adverse effects on health. This exists even under conditions of scarcity, and these genes have been suggested as another factor, especially in populations where economic conditions changed rapidly during more recent periods. Among others, exposure to the “toxic” Western environment in postnatal life perpetuates the undesirable effects of these genes in combination with inadequate diet and reduced PA. In addition to obesity, MS is also explained by the effect of thrifty genes (Wells 2003, 2007). A “thrifty phenotype” was also considered as an adaptive maternal effect (Wells 2007). A number of other studies identified certain populations that are genetically predisposed to obesity, for example, Pima Indians, Hispanics, and African Americans in the United States, or citizens of the Pacific Islands. This phenomenon concerns, for example, immigrants from less developed to technologically more developed countries. Another hypothesis of the origins of obesity is that an increased rate of assorted mating may have contributed to its recent increase in some populations, especially to the rates of morbid obesity. This hypothesis is not so well documented, and it is necessary to have further proof (Hebebrandt et al. 2000). More recently, the impact of constituents influencing the organism very early in life could also result in delayed effects including modified reactions to the environment, namely diet. The identification of genes associated with obesity, following both mono- and polygenic forms, is due to studies in laboratory models using experimental animals (e.g., mice). Animal models are obtained by spontaneously originated mutations or genetic intervention in their genotype—that is, transgenic animals. On the other hand, there exist mice models where expression of the gene is strengthened. On the basis of these models and the information gained therefrom, the first monogenic forms of obesity in human subjects were described, which may resemble each other in their clinical manifestation. For example, MC4R mice models show similar clinical features as humans (obesity, hyperphagia, hyperinsulinemia, hyperleptinemia, etc.; for more details see below). These models are useful for the assessment of the role of mutations of newly discovered genes and for the possibilities of intervention in various additional factors. The role of melanocortin 3 receptor gene (MC3R) was followed in obese children, which could contribute as a predisposing factor to childhood obesity and influence the human phenotype. MC3R may also have a role in human weight regulation (Lee et al. 2007). Genetic analysis is oriented to the research of candidate genes and genetic screening. A candidate gene takes part in the particular health problem or is situated in an area that is associated with the concerned phenotypic characteristic. In the case of obesity the gene takes part in energy balance (EI and output), in the metabolism of nutrients, and/or in autocrine or paracrine signalization. This includes food behavior, PA, hormonal levels, BMI, body composition, and further anthropometric characteristics. The research of candidate genes is realized using association or linking studies. The aim is to find the relationship between the variants of candidate

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genes with a certain phenotype manifestation. The results were often contradictory, which obviously follows from the genetic variability of populations and the different environments; this has a significant effect on the expression of genes (Hainerová 2007). In recent years several single gene disorders resulting in an early onset of obesity have been characterized (Farooqi and O’Rahilly 2000). The discovery of these genetic defects has biological and clinical implications that are greater than the rarity of health problems that might be expected. Especially in children, noninvasive methods of measurement are recommended for use in genetic studies. This includes, for example, sampling of mucal mucosa, hair, and cerumen in infants, which causes no anxiety. Whole genotype screening can help in defining new areas with a biological function that was not yet elucidated. With the help of screening, areas that have a relationship with the phenotype studied can be defined on the basis of association or linking studies. These problems have to be studied in large groups of families, which enables the definition of heredity. The method of whole genotype screening has been successful in the research of obesity because new genes were discovered (e.g., GDA2, etc.), which regulate food intake at the hypothalamic level. Further chromosome areas related to the phenotype of obesity were followed and analyzed recently. The Human Gene Map published in Obesity Research (also available on the internet). Bouchard (1999) founded a database of chromosomal loci, genes, and mutations related to the phenotype of obesity. Actualization was made in 2005, and in the last year more than 600 genes, markers, and chromosomal areas connected with obesity have been mentioned. In recent years, significant advances in the genetic underpinnings of obesity have appeared, and the role of individual and/or combined gene mutations has been followed up. This has facilitated the early diagnosis of obesity, which enables effective early intervention. Genetic influences on body weight at the beginning of life might be independent of those that influence BMI during adulthood.

8.3.3

POLYMORPHISMS AND MUTATIONS OF GENES: THEIR ROLE IN OBESITY DEVELOPMENT

Food intake control may be affected by polymorphisms in the genes encoding taste receptors and a number of peripheral signaling peptides such as insulin, leptin, ghrelin, and cholecystokinin, and corresponding receptors. Polymorphic central regulators of EI include hypothalamic neuropeptides Y, agouti-related protein, melanocortin pathway factors, CART (cocaine- and amphetamine-regulated transcript), some other neuropeptides, and receptors for these molecules. Potentially important polymorphisms in the genes encoding EE modulators (alpha- and beta-adrenoreceptors, uncoupling proteins, and regulators of adipocyte growth and differentiation) are also considered (Loktionov 2003). People can become severely obese as a result of genetic disruption of a single element of a homeostatic system regulating energy balance (Bouchard 1997c, Liu et al. 2003, Farooqi et al. 2003, Yeo et al. 2003, Chen et al. 2004). It concerns mainly the

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disruption of the adequate control of ingestive behavior (O’Rahilly et al. 2003). An increasing number of studies and information on gene–diet interactions in obesity development is convincing. Regulation of the energy balance at the level of the CNS is regulated by a complex interplay of peripheral signals and signals of the CNS. The hypothalamus is the center of satiety and hunger, which is influenced by hormones from the periphery (see Chapter 5). Genes also play an important role in this respect. The leptin– melanocortin pathway regulates energy balance; the importance of the orexigenic and anorexigenic axis was demonstrated in both experimental models and obese subjects who were carriers of gene mutations, the products of which apply in energy regulation, that is, genes such as MC3R, MC4R, LEPR, POMC, etc. (see below). The most frequent cause of obesity due to the mutation of one gene is the mutation of MC4R (Farooqi et al. 2000, 2003, Dubern et al. 2001, Zakel et al. 2005), which can be identified in 6% of the heavy cases of obesity at an early age. A pathogenic MC4R mutation was found among subjects with severe early-onset obesity, but not among morbidly obese adults (Valli-Jaakola et al. 2004). It was also shown that 81.3% of childhood obesity-associated heterozygous MC4R leads to intracellular retention of the receptor, which has implications for the pharmacological intervention and treatment of childhood obesity-associated MC4R mutations (Lubrano-Berthelier et al. 2003). Another study stressed the importance of characterizing the properties of MC4R variants and mutations associated with early-onset severe obesity (Tao and Segaloff 2003), and also in Chinese children and adolescents (Wang et al. 2006). A mutation in the MC4R gene is inherited in a codominant manner; its mutations that lead to complete loss of function are associated with a more severe phenotype. The association between the signaling properties of these mutant receptors and energy input underlines the key role of this receptor in the control of eating behavior and the development of obesity (Farooqi 2005). A study in French children showed that MC4R mutations may not be a negligible cause of serious obesity, with variable expression and penetrance. However, in some populations MC4R mutations are infrequent in the obese, for example, in the Mediterranean child population (Miraglia-Giudice et al. 2002b) and in others (Mo et al. 2001). A study in 300 Czech children revealed a 2.4% prevalence of MC4R mutations. One homozygous carrier (Gly181Asp) was characterized by serious obesity during the first months of life. Heterozygous carriers did not differ from obese noncarriers of MC4R mutation (Hainerová et al. 2007). MC3R may contribute as a predisposing factor to childhood obesity, influencing human phenotype; it also has a role in human weight regulation (Lee et al. 2007). The role of MC3R was studied with regard to the differences in phenotype between two related heterozygotes, obese siblings, and the observation of obesity in other family members without mutation. It was suggested that obesity results from a varying combination of environmental, behavioral, and multiple genetic factors other than MC3R, even in the same family. The contribution of propiomelanocortin (POMC) gene variants seems to increase the sensibility to develop serious obesity at an early age, but may be limited for childhood obesity as shown by the lack of differences in BMI-SD scores. New mutations of the POMC gene were reported; certain polymorphisms may represent one of the

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genetic variations that explain the linkage between obesity and POMC (Miraglia del Giudice et al. 2001). Trp64-Arg mutations of the beta3-adrenergic receptor gene may also predict the result of dietary intervention in obese children. It was not shown, however, as a major factor influencing body weight in a study of Chinese children (Xinli et al. 2001). The effect of uncoupling protein 3 (UCP-3) genetic variants was also followed, but the mutations of the coding sequence of UCP-3 were deemed unlikely to be a usual monogenic cause of obesity (Halsall et al. 2001). A certain polymorphism of UCP-2 appears to be associated with the onset of childhood obesity. The UCP-2/UCP-3 genetic locus seems to play a role in body weight development during growth (Yanovski et al. 2000). A study in Mexican-Americans suggested that variations in UCP-2 and UCP-3 genes are unlikely to have a significant effect on the expression of obesity-related phenotypes in this population (Commuzzio et al. 2003). An association study pertaining to alleles of two polymorphisms of glucose transporter 4 gene in youth with extreme obesity and/or reduced weight was also conducted (Friedel et al. 2002). A linkage in an autosomal genome scan for loci influencing a longitudinal burden of BMI from childhood to young adulthood was followed in white siblings that might harbor genetic predisposition affecting the propensity to develop obesity (Bogalusa Heart Study; Chen et al. 2004). A significant linkage on chromosome 6q22,31–q23.2 for childhood obesity-associated traits in a genome-wide scan in French families was revealed (Meyre et al. 2004). Leptin is an important regulator of the mass of adipose tissue and body weight. Some polymorphic genes involved in the regulation of leptin, that is, the leptin gene (LEP A19G), the leptin-receptor gene (LEPR Q223R, K109R, and K656N), and the peroxisome-gamma gene (PPARG P12A and C161T), were examined as a possible cause of obesity. Some heterogenic variants for leptin reduce leptin levels and thus increase fat mass. Several single genes that disrupt molecules in the leptin– melanocortin pathway (causing severe obesity in humans) were identified (Farooqi and O’Rahilly 2008), which should help in understanding the physiological role of leptin and melanocortins in the regulation of body weight and neuroendocrine function. Mutations in the leptin-receptor gene (LEPR) were studied as related to serious, early-onset obesity in children. The prevalence was 3%; circulating levels of leptin were not disproportionately increased, which indicates that serum leptin cannot be used as a marker of the deficiency of leptin receptor. Congenital leptin-receptor deficiency should be considered in the differential diagnosis in any child with hyperphagia and severe obesity in the absence of developmental delay or dysmorphisms (Farooqi et al. 2007). The role of peroxisome proliferator-activated receptor gamma (PPARG) in energy balance and food intake was shown to be varied and complex, influencing fat deposition and growth velocity early in life, with potential impact on the control of EI and appetite regulation. This could provide a target for treatment and antiobesity agents (Cecil et al. 2006). Neuromedin U (NmU) gene is an anorexic neuropeptide expressed in the hypothalamus. Amino acid variants in NmU are associated with overweight and obesity,

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suggesting that NmU is involved in energy regulation in humans (Hainerova et al. 2006). A potential role of the K121Q polymorphism or derived nucleotide pyrophosphatase/phosphodiesterase-1 (ENPP1) haplotypes on increased susceptibility to the development of early obesity, and impairment of glucose and insulin metabolism in children were revealed (Bottcher et al. 2006). Several variants of the ENPP1 gene have an essential role in the development of obesity, insulin resistance, and T2D. The underlying molecular mechanism can be common to both these conditions (Meyre et al. 2005, Bottchard et al. 2006). Tumor necrosis factor alpha (TNF-alpha) gene G-308A polymorphism and polymorphism Gly972Arg variant insulin receptor substrate-1 (IRS-1) gene, and G-308A TNF-alpha gene did not seem to be associated with the degree of obesity and insulin resistance in children (Pyrzak et al. 2006a,b). The insulin gene VNTR influences the secretion of insulin, and thus body weight was identified (LeStunff 2000). The presence of more gene variants can aggravate phenotypic manifestation (cumulative interaction gene–gene): for example, interaction of UCP-1 and beta 3-AR (Trp64Arg) gene, and obesity increases during life (Clement 1996). The influence on the expression of the gene is demonstrated in variants of the promontory part of the UCP-3 gene, which influences body weight according to the level of PA (Octabe 2000). Among others, the components of eating behavior as characterized by the Eating Inventory (restricted of eating, disinhibition, hunger; Stunkard and Messick 1985) were shown to be dependent on genetic factors, for example, polymorphisms of more genes—PPAR-gamma, receptor of glucocorticoids (GRL), neuromedin beta, GAD2, etc. The ability to preserve weight decrements after reduction treatment is influenced genetically (PPAR-gamma, UCPy, serotonin receptor, beta 3-AR). The description of mutations of other genes such as SMI, CART, and SORBS 1 did not completely reveal the exact mechanisms of obesity development until now, despite an increasing number of references (Farooqi et al. 2003, Clement and Ferre 2003, Valli-Jaakola et al. 2004). Associations between polymorphism in the 11-beta hydroxysteroid dehydrogenase type 1 gene and body composition were studied in overweight and normal-weight children (Gelertner-Yaniv et al. 2003). Changes in adiposity were found to be related to glucocorticoid receptor polymorphism in a long-term study of young females (Tremblay et al. 2003). At least seven genes on chromosomes result in obesity, influencing fat mass and its distribution, energy output, hormone levels, etc. (Perusse 2005). The inability to oxidize fats can result in obesity, which is influenced, for example, by UCP-2, UCP-3, PPAR-gamma, MC4R, etc. Genes for adrenergic receptor beta 3 (beta 3-AR) and UCPy increase body weight by influencing energy metabolism. Gene–gene interaction and the synergistic effect between PPAR gamma 2 and ADR beta 3 increase the obesity risk in children and adolescents, as shown by Ochoa et al. (2004). Ghrelin can induce obesity through central and peripheral mechanisms; administration of ghrelin results in increased food intake and decreased fat utilization in laboratory animals. Polymorphism within the ghrelin gene was associated with different weight extremes, including obesity in German children and adolescents (Hinney et al. 2002).

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MAIN ASPECTS OF THE ROLE OF GENETICS

Great attention has been focused on genetics with regard to increasing obesity, as similar environments often caused different results in individual subjects. It is possible at present to name a number of genes that were traced in subjects with a more serious degree of obesity. However, a full explanation of obesity has not been possible regarding genes and their mutations and variants, in spite of the essential importance of inborn factors. The determination of the differentiation between environmental and genetic factors is extremely difficult, even in one family. Up to now most studies have been conducted in adult subjects, and also in adolescents, but very rarely at an early stage of growth and development. As mentioned above, most cases of obesity are caused by the interaction of gene variants with the environment. The sensitivity to factors other than obesity itself is hereditary. The amount and frequency of gene variants (polygenic) interacting with, for example, increased EI, reduced PA, and stress influence mostly the individual disposition to become obese. As is apparent, the expression of a gene is modified by environmental conditions. However, the results of many studies still do not agree, and interactions between the environment and genes are further followed up when defining obesity of polygenic origin. Analyses are still not conclusive because the relative risk associating a specific gene allele to obesity remains low. Therefore, regular genotyping obesity seems premature at present, even when genetic factors have to be considered. However, genetic testing may help in discriminating between subtypes of obesity and in defining adequate treatment. Focusing attention on the family situation is essential, which concerns especially the history of a particular subject, a young child, at the beginning of the treatment, as intervention has to be undertaken with regard to both activity and diet regimens (Pinelli et al. 1999). Parents rarely recognize the importance of PA in obesity development and the accompanying risks (Eteleson et al. 2003), and therefore they have to be instructed. The treatment and prevention of childhood obesity have to be developed in cooperation with, and with the participation of, the whole family, because in children at an early age environmental factors (diet and exercise) mostly depend on the family situation. In addition, possible caretakers, teachers in kindergartens and schools, pediatricians, and public and governmental institutions should develop their activities in cooperation with the families.

8.4

MATERNAL AND FAMILIAL FACTORS IN THE DEVELOPMENT OF CHILDHOOD OBESITY

Experimental models were used for the elucidation of developmental programming with regard to the consequences of varied nutrition. The hypothesis on “fetal origins of adult diseases” (Barker 1986, 1990, 1992, 1994) has established a relationship between adverse intrauterine environment and an offspring’s diseases in adult life. This phenomenon of “fetal programming” concerns the process where stimuli in utero establish a permanent response in the fetus, leading to enhanced susceptibility to later pathological stimuli. Both reduced and abundant nutrition during pregnancy can result in undesirable consequences later on in life. Some studies indicated

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that maternal overnutrition is negative for the offspring and can result in a phenotype that is characteristic for MS including obesity (Armitage et al. 2005). With regard to environmental influences, their combination and interplay, and timing have the most significant impact, which may be of different character due to various hereditary predispositions. The combination of maternal prepregnancy obesity and lack of breast-feeding was shown to be possibly associated with a greater risk of childhood overweight, and special attention had to be given to children of obese mothers who did not breast-feed their babies (Li et al. 2005). An association was found between childhood and adult obesity in women followed longitudinally, but the results of this study did not confirm the concept of a critical period in childhood concerning changes in total fat cell number (Noppa et al. 1980). The Avon Longitudinal Study of Parents and Children (ALSPAC) revealed that mother–offspring and father–offspring associations for BMI suggest that intergenerational acceleration mechanisms do not make an important contribution to offspring BMI at the age of 7.5 years (Davey et al. 2007). Additional factors after birth may contribute to obesity development in children of obese parents. However, the mother’s obesity during early pregnancy more than doubled the risk of obesity in children 2–4 years old, which applied especially to low-income mothers (Whitaker 2004). Prevention measures were therefore considered especially for children of obese mothers (Durand et al. 2007). Another study indicated a relationship between parental obesity and short sleeping hours as a possible risk factor for obesity in preschool children (Sekine et al. 2002). However, it is necessary to consider that the parent’s obesity may include a number of changed characteristics in family lifestyle—“heredity of kitchenbook,” hypokinesia, etc. Quite the opposite situation was shown to have an important effect. The Dutch famine at the end of World War II enabled one to study the long-term consequences of a markedly reduced food intake during pregnancy. Undernutrition during gestation was shown to be associated with increased disease susceptibility and reduced lifespan. This famine was a unique counterpart for animal models that study the effect of restricted maternal food intake during different periods of pregnancy. Increased coronary heart disease, an atherogenic lipid profile, disturbed blood coagulation, increased obesity, and increased stress responsiveness were seen among those exposed to famine early during pregnancy. Glucose intolerance was found after famine during any period of pregnancy (Roseboom et al. 2000, 2001, 2006). Also, blood pressure was negatively influenced (Painter et al. 2006). The effects of famine depend on timing during pregnancy and emphasize the importance of the effects during this particular critical period, which may not even be so excessive. In India, increasing obesity and other accompanying comorbidities starting with diabetes are considered a consequence of malnutrition of the mother during her pregnancy (Yajnic 2000, 2004). Obviously, well-balanced harmonious nutrition is the optimal guarantee for successful development of the offspring. Critical periods for obesity development include gestation and early infancy, the period of AR (occurring between 5 and 7 years), and then adolescence (Dietz 1994). More recently, except for genetic factors, further influences resulting from the mother’s initial health and nutritional status, and from multifactorial effects during pregnancy and then during early periods of growth of the offspring began to be

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analyzed and considered. A review of risk factors for overweight and obesity in preschool children showed strong evidence for a direct association between childhood overweight and maternal prepregnancy body size, maternal smoking during pregnancy, and children’s TV media use, strong evidence for an inverse relationship between breast-feeding and overweight, and moderate evidence for children’s PA (Hawkins and Law 2006). Maternal weight gain is associated with infant birth weight (Shapiro et al. 2000). The association between birth weight (as a result of fetal situation and effect of mother’s status) and later development was mentioned in Chapter 3. The best predictors of early childhood obesity were a higher fat ratio of the mother before pregnancy, a higher birth weight and fat ratio of the child at birth, and a higher fat ratio at the age of 1. In addition, maternal age, prolonged breast-feeding, and the late introduction of solid foods seem to be related to early obesity development (Bal et al. 1994). A higher fat ratio at the age of 1 year and during pregnancy and delivery complications contributed most to the prediction of obesity in puberty. These observations correspond to the theory of Rolland-Cachera et al. (1984), which indicates that the early rebound of BMI predisposes a child toward later obesity. Similar conclusions on “critical periods” (including preschool age) for the development of obesity were reported simultaneously by Dietz (1994). EI and EE in infants born to lean and overweight mothers can vary too (Roberts et al. 1988). Evidence for an association between poor nutrition in early life and subsequent obesity is still considered inconclusive. A study concerning the association between stunting, wasting, and underweight at 2 and 4 years of age, and body composition in adolescent males followed since birth showed that undernutrition was not a risk factor for overweight and obesity in a Brazilian population (Gigante et al. 2007). In this study it was shown that fetal and infant growth primarily determined the development of height at the age of 18 years. Weight-related indices, including the fat/lean mass ratio, were more affected by later growth in this population, in which no clear critical periods of growth during which absolute masses of lean and fat tissue are programmed could be identified. It is difficult, however, to compare the results and conclusions of individual studies with varying population samples, ages, methods, length of observations, etc. Among 36-month-old white children, parent eating behavior was associated with their own BMI, but not with BMI or their children’s adiposity. Only a weak relationship between parental BMI and child adiposity was found. Despite sharing genes and environment within families, children may not yet express differences in susceptibility to obesity at this early age (Whitaker et al. 2000). “Appetite regulatory peptides” and their potential role in the early programming of the appetite regulatory system were studied in model experiments in sheep and rodents (McMillen et al. 2005). Analysis of data from the Observational Twin Study suggested that the intrauterine environmental influences on birth weight have an enduring impact on adult height but not on relative adult weight, which did not confirm fetal influences on adiposity (Allison et al. 1995). Birth size along with subsequent growth and weight gain have a cumulative effect on the later incidence of overweight and obesity up to adolescence (Monteiro et al. 2003) and adult age (Eriksson et al. 2001b).

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The Barry Caerphilly Growth Study revealed that an increase in weight velocity from 1 year and 9 months to 5 years of age was the most important predictor of BMI, waist circumference, and sagittal abdominal diameter in young adulthood. Birth weight did not predict adiposity on the basis of weight gain in childhood in another study by McCarthy et al. (2007). Results of the New Delhi Birth Cohort proved that birth weight and BMI gain during infancy and early childhood predict adult LBM more strongly than adult adiposity. A greater BMI gain in late childhood and adolescence predicted increased adult adiposity (Sachdev et al. 2005). T2D and cardiovascular diseases are also associated with birth size and subsequent weight gain at the beginning of postnatal life (Ong 2006). The mother’s gestational diabetes and higher birth weight can predict obesity during later periods of growth of children (Gillman et al. 2003). Maternal obesity, gestational diabetes mellitus, and birth weight were found to be associated with MS in childhood (Boney et al. 2005). Obesity and pregestational diabetes are independently associated with an increased risk of LGA delivery, which is in some cases considered as a risk for easier development of later obesity. Abnormal maternal body habitus exhibits the strongest influence on the prevalence of LGA (Ehrenberg et al. 2004), which emphasizes the need for early prevention in mothers and during pregnancy. Maternal nutrition and fetal growth were studied in Indian villages. It was shown that poor food intake resulted in reduced birth weight due to poor muscle and small abdominal viscera. Such a body composition reflects the “thrifty phenotype” of Indian babies, who are programmed from their intrauterine life to deposit fat. Exaggeration of this trend is associated with obesity and insulin-resistance syndrome later on in life (Yajnik 2000). Increased food intake along with genetic predisposition or previous multigenerational malnutrition obviously increased maternal insulin resistance in later pregnancy and promoted increased fetal deposition of fat tissue even in the absence of marked hyperglycemia (Yajnik 2004). Low birth weight is also linked to early stunting and predisposes to abdominal obesity and MS, which enhances the risk for diabetes, hypertension, coronary heart disease, and probably some cancers in later life (James 2002). The mentioned observations may explain the increasing prevalence of obesity in countries that have too rapidly changed their economic, social, and cultural conditions recently. Conclusions on the effect of breast-feeding and its duration are still controversial, but longitudinal data in an Australian population showed that infants breast-fed for more than 12 months were leaner at 1 year, but not at 8 years. Breast-feeding for a shorter period of time, or just for 4 months, was associated with a greater risk of overweight and an adverse maternal lifestyle (Burke et al. 2005). The results of another study on the duration of breast-feeding highlighted the importance of prolonged breast-feeding for the prevention of overweight during childhood and adolescence in U.S. individuals (Gillman et al. 2001) and in German children (Weyermann et al. 2006). Other studies, however, did not confirm the positive role of breast-feeding duration on obesity prevention (Araujo et al. 2006, Michels et al. 2007). Studies were not always comparable with regard to their arrangement and possible intervention of further additional factors (which were not reported); however, breast-feeding has always been emphasized as a factor for reducing obesity risk (Armstrong et al. 2002).

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Breast-fed infants grew more slowly during infancy than bottle-fed infants in a study of UK infants. Offspring of primiparous mothers were small at birth, but caught up and were heavier and taller from the twelfth month onward; offspring of maternal smokers were also small at birth, and showed complete catch-up over the first 12 months (Ong et al. 2002). In a study of children of the Commonwealth of the Northern Mariana Islands, after adjusting for age, gender, birth weight, and years of mother’s education, children who were breast-fed had a markedly lower BMI than children who were not breast-fed (Novotny et al. 2007). The same applied to the results of the longitudinal study of children, Centers for Disease Control and Prevention Pediatric Nutrition Surveillance System (Grummer-Strawn et al. 2004). Other studies, similar to the previously mentioned ones, analyzed the effect of more factors simultaneously. The Toyama Study revealed the influence of factors on the development of obesity in 3-year-old children, namely, parental overweight and overweight at birth as host factors, physical inactivity and snacking irregularity as behavioral factors, and the mother’s job as an environmental factor (Takahashi et al. 1999). Eight factors in early life were shown to be associated with an increased risk of obesity at the age of 7 years in the Avon Longitudinal Study of parents and children in the United Kingdom, namely, very early BMI or AR, more than 8 h spent watching TV per week at 3 years, catch-up growth, standard deviation score for weight at age 8 and 18 months, weight gain in the first year, birth weight, and short sleep duration at age 3 years (Reilly et al. 2005). Especially with regard to the effect of breast-feeding, most studies analyzed simultaneously the effect of more factors, or the effect of their partial combinations and interrelationships; hence the conclusions were hardly comparable, especially when the studies were conducted in different population and ethnic groups, at different final ages, etc. The National Longitudinal Survey of Youth: Child–Mother suggested that prenatal characteristics, particularly race, ethnicity, maternal smoking during pregnancy, and maternal prepregnancy obesity, have an influence on the child’s weight status through an early trend toward overweight, which is perpetuated with increasing age of the child (Salsberry et al. 2005).

8.5 EARLY FACTORS IN OBESITY DEVELOPMENT The Bogalusa Heart Study showed that childhood levels (2–17 years) of both BMI and triceps skinfold were associated with adult levels of BMI and adiposity. Overweight (BMI for age ≥ 95th percentile) 2–5-year-olds were >4 times as likely to become overfat adults (Freedman et al. 2005a,b, 2007). Weight gain at the beginning of life contributed to the development of increased weight in adulthood. As found in a cohort study of European-American formula-fed infants, weight gain during the first week of life may be the critical determinant for the development of obesity several decades later (Stetter et al. 2005). Early rapid weight increase predicted overweight at the age of 12 years along with parental influences (Vogels et al. 2006); the latter may have a significant relationship to weight gain. Increases in overall and central adiposity in 3–8-year-old children are important predictors of increased blood pressure (Eisenmann et al. 2005), which was also proved for increased BMI especially in boys (Field et al. 2005).

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The National Institute of Child Health and Human Development Study of Early Child Care and Youth Development longitudinal study showed that children who were overweight (>85th percentile), that is, ≥1 time overweight at ages 24, 36, or 54 months during the preschool period, were >5 times as likely to be overweight at age 12 years than those who were below the 85th percentile for BMI at all three periods of preschool ages. This study confirmed that children with higher BMIs than the 85th percentile are more likely to continue to gain weight and reach overweight in adolescence (Nader et al. 2006). Children who caught up between birth and 2 years were fatter and had more central fat distribution in 5 years than other children (Ong et al. 2000). Rapid infancy weight gain and increasing rates of childhood obesity increase the risk for the development of insulin resistance (Dunger et al. 2007). The Early Childhood Longitudinal Study—Kindergarten revealed a significant negative association of body weight with physical exercise and number of siblings. Household insecurity score was not a significant predictor. Children’s body weights were significantly lower in households with higher parental education and incomes, and significantly higher in households where more time was spent in TV viewing and there was no parental care (Bhargava et al. 2008). The above-mentioned effect of smoking during pregnancy, or the effect of the risk of giving birth to high-birth-weight children on early determinants of overweight at 4.5 years, was seen in the Quebec Longitudinal Study of Child Development (QLSCD). It was recommended that, in this case, particular attention should be paid to rapid weight gain in the first months of life to prevent later increased adiposity (Dubois and Girard 2006). This was also seen in Japanese children (Mizutani et al. 2007). As mentioned earlier, children who are overweight at an early age remain like that later on too. Approximately half of the children who were overweight at the age of 6 years were still overweight after puberty (Johansson et al. 2006b). Children of overweight (high-risk) and/or lean (low-risk) mothers did not vary in BMI at the age of 2 years. By year 4, weight, BMI, and LBM were greater in the high-risk group, and by year 6, weight was even greater in the high-risk group. Also, for the first time, fat mass was greater in the high-risk group than in the low-risk one. Accelerated weight gain was predicted by high-risk group status, greater weight at year 2, and lower family status (Berkowitz et al. 2005). Concentrations of metabolites, hormones, and neurotransmitters during critical periods of early periods of growth and development have an important role in the programming of possible health problems and diseases later on in life. The long-term consequences of early feeding on later obesity risk were reviewed by Koletzko (1999, 2006). As mentioned above, breast-feeding reduces the odds ratio for obesity at school age by about 20%, which can be at least partly explained by the lower rates of infant weight gain due to different substrate intakes: the protein intake per kg body weight is about 55–80% higher in formula-fed than in breast-fed infants. It is hypothesized that high early protein intakes in excess of metabolic requirements may enhance weight gain in infancy and later obesity risk (Rolland-Cachera 1995, Agostoni et al. 2006). The European Childhood Obesity Project is testing this hypothesis in a randomized double-blind intervention trial in more than 1000 infants in five European countries; the results may give an instruction for obesity prevention. It was also considered that a higher animal protein, especially with dairy protein intake at 12 months,

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may be associated with an unfavorable body composition at 7 years. The age of 5–6 months may represent another critical period of protein intake for later obesity (Gunther et al. 2007). A prospective cohort study (ALSPAC) revealed an association of obesity in childhood and postnatal catch-up growth, which was predicted by factors relating intrauterine restraint of fetal growth. Children who showed catch-up growth between 0 and 2 years were fatter, and had more central fat distribution at 5 years than other children (Ong et al. 2000). Other factors were also considered with regard to overweight in 4–7-year-old Latino-American children, for example, family restaurant choices. Children who were most likely to be overweight (BMI ≥ 85th percentile) came from families who ate most often at fast-food chains. Both child and parent BMIs were lowest in families selecting Mexican restaurants. Eating at fast-food and other Anglo-oriented restaurants may contribute to a higher prevalence of obesity linked to acculturation among Mexican-Americans (Duerksen et al. 2007). Overweight prevalence was not different in children from kindergarten differing in length of care and food availability in Stuttgart, Germany (Rapp et al. 2005). However, the range of differences was obviously not large enough in this comparative study. Parents usually have a poor perception of the overweight of their offspring, as shown in a study of 3–5-year-old UK children (Carnell et al. 2005). This could be an obstacle to efficient prevention of obesity at present and later on. The Weight of Opinion Study concerning the emotional intensity of the mother’s perceptions about the child’s eating and weight status at the age of 2–5 years suggests that interventions, including communications, need to go beyond information and engage with a parent’s emotions (Pagnini et al. 2007a) so as to be effective with regard to obesity prevention. Fat intake can have different effects on the adiposity of children of lean and/or obese parents (Nguyen et al. 1996). Education and professional development opportunities would support early childhood staff of preschools and long day-care centers in promoting healthy eating, active play, and working with parents (Pagnini et al. 2007b). The education of parents always plays a role, due to the income and SES of the family. Boys with low household income were more likely to be overweight or obese compared with those with high household income as seen in the Australia National Nutrition Survey, 1995 (Wang et al. 2002), similar to adults in other countries. Dietary counseling during childhood can influence dietary intakes, serum lipids, and lipoproteins (STRIP Study; Niinikoski et al. 2007). Soda consumption was greater in obese children and subjects who gained weight compared to normal-weight subjects across a 2-year period (Blum et al. 2005). A link between soda consumption and overweight was found in 2-year-old MexicanAmerican children in California (Warner et al. 2006). Sugar-sweetened beverage consumption at 5 and 7 years was not associated with overweight and fatness in UK children aged 9 years old. The positive association between consumption of lowenergy beverages and fatness at 9 years, which was explained by overweight status at 5 and 7 years, suggests that heavier children may consume low-energy beverages in an effort to control weight, which was not successful (Johnson et al. 2007). It seems that soda consumption is associated with obesity, especially in some ethnic or SES population groups of children. However, beverage consumption was shown

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to decrease with time in adolescents followed up in the Bogalusa Heart Study (Rajeshwari et al. 2005). The ED of food did not seem to be causative factors of increasing overweight and obesity in some studies (Kral et al. 2007a,b). In these studies other factors of lifestyle and environment that could interfere and/or compensate simultaneously were not usually followed up. Soda consumption, which is higher in, for example, MexicanAmerican children 2–5 years old (Warner et al. 2006), can result in obesity and should be reduced. The same applies to TV viewing coupled with sweetened beverage consumption, which is linked to increased overweight (Ariza et al. 2004). Dietary ED was found to increase in children from 3 to 6 years with a high and low risk for obesity (based on maternal prepregnancy weight), and weight indices were not correlated with ED (Kral et al. 2007a,b). As the spontaneous level of PA also increases during this period of growth (Parˇ ízková 1995b,c), it may compensate for the ED of their food. When considering the influence of ED, the impact of further factors should also be analyzed. Reduced PA in children, resulting in reduced EE and positive energy balance, has been emphasized as a reason for increased adiposity during growth (Maffeis et al. 1998, Tremblay and Wilms 2003, Reilly 2005, 2006), and was also revealed in further studies (Butte et al. 2007). Longitudinal studies in Czech children followed from preschool age to the first class of primary school revealed the reduction of spontaneous PA in the latter case, not only during weekdays but also during weekends (Parˇ ízková and Hainer 1990). This was confirmed in another similar study in Czech children later (Sigmund et al. 2008). Perhaps this developmental change could have been one of the reasons why children were decided to start school at this particular age, that is, 6–7 years. TV viewing has been considered as a marker of sedentarism, and the time thus spent was associated with fatness in many studies on children and youth in many parts of the world (Dennison et al. 2002, Saelens et al. 2002, Burdette et al. 2003, Levin et al. 2004, Jago et al. 2005, Utter et al. 2006, Gable et al. 2007). This was also seen in Pima Indians, who are genetically predisposed to obesity (Fitzgerald et al. 1997). TV viewing in early childhood can predict adult BMI (Viner and Cole 2005). The association between maternal obesity and depression symptoms with TV viewing time in low-income preschool children was also shown (Burdette et al. 2003). TV viewing is also associated with the consumption of advertised foods (Francis and Birch 2006), which are mostly inadequate from the health point of view. TV and video viewing may be associated with fast food intake in preschool children (Taveras et al. 2006). TV viewing and its evaluation were systematically reviewed in children, and it was found that most of the studies used self-reported surveys and only very rarely results of direct observation. It was recommended that evaluation of the effect of TV viewing be used only if psychometric data and other objective parameters to support the validity and reliability of the conclusions were available (Bryant et al. 2007). Moreover, most studies on TV viewing did not report the other activities of children that were followed up, for example, exercise, diet, etc. There is always the possibility that children with increased TV viewing can also participate more in exercise during the remaining time or eat healthier food.

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A link between short sleep duration and obesity was found, and more sleep was recommended to prevent obesity (Taheri 2006). As shown by a 32-year prospective birth cohort study, sleep restriction in childhood increases the long-term risk for obesity (Landhuis et al. 2008). Early AR was found in children with congenital hypothyroidism, which was associated with a greater risk of adult obesity (Wong et al. 2004).

8.6 EVALUATION OF OBESITY Even in children, being overweight and having a high BMI does not always mean excess fatness, that is, obesity, as shown by densitometry and skinfold thickness measurements (Parˇ ízková 1961b, 1977). Some authors, such as Ditschuneit (1992), define “juvenile obesity” as a twofold increase in body fat mass above normal controls and “overweight” as a 20% increase above the percentiles for body weight and height. Usually, BMI correlates significantly with fatness; however, a considerable proportion of fatter children may maintain normal weight and BMI (“hidden obesity”) and, on the other hand, a considerable proportion of children who are not too overweight may be relatively lean (Parˇ ízková 1961a, 1977). Therefore, the most reliable criterion for obesity is the assessment of the most essential item—the amount of body fat (Krebs et al. 2007). Numerous methods have been used since for the evaluation of the degree of adiposity and body composition in obese subjects (Haroun et al. 2005). Tsukuda et al. (1994) screened Japanese children 3–6 years old using bioelectrical impedance (BIA). The results of the BIA were compared with BMI and percentage of fat ratio in relation to standard weight, and significant correlations were found. Regression equations were also derived. However, it seems that a comparison of data assessed with more exact methods would be necessary to validate the results concerning amount of body fat in preschool children. For rapid and safe screening of excess adiposity in preschool children, BIA might be recommended, even when some authors, such as Widhalm et al. (2007), or Bláha and Parˇ ízková (2007), did not find satisfactory associations between the results of adiposity evaluation using BIA and BMI. The early diagnosis of excess depot fat, and its correction, is of essential importance: a 40-year weight history and adult morbidity and mortality in a cohort of 504 Swedish overweight children, aged 2 months to 1 year, through adulthood showed that overweight children remained overweight as adults (Di Pietro et al. 1994). Subjects who died during the 40-year follow-up and those reporting cardiovascular disease were significantly heavier at puberty and in adulthood than healthier subjects. Patients with an early onset of obesity displayed a greater frequency and higher levels of emotional distress and psychiatric symptomatology than patients with a late onset of obesity (Mills and Andrianopoulos 1993).

8.6.1

ANTHROPOMETRIC METHODS FOR THE EVALUATION OF ADIPOSITY

For a long time, anthropometric measurements remained the most frequently used procedure for the evaluation of the degree of obesity. Since then, the technology has advanced considerably (Wang et al. 1995), and many new methods are now available, at least for some richer institutions.

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With anthropometry, the protocols are very similar to those used for studies of normal children and youth (de Onis 2004). For quite a long time, these criteria were not accepted and depended on the local situation in a particular country. Most commonly, BMI and its comparison with international and/or national standards are used. The 85th percentile has been accepted as a criterion for overweight, and the 97th percentile as a criterion for advanced obesity. However, this can differ among populations and the cut-off points might not be the same as mentioned before (Cole et al. 1990, 2005, 2007, Vignerová and Blaha 2007). The absolute BMI values, of course, vary markedly in different growth periods as well as in boys and girls. Up to now there has been no general consensus on the BMI percentile as a criterion for obesity in young preschool children. Even when some doubts exist on the possibility of estimating fat mass from BMI values (Widhalm 1999, Bláha et al. 2000), it has been widely used for the evaluation of obesity in children. The BMI in subjects aged 18 and 21 years was found to be correlated with the BMI in subjects aged 7 years; BMI in early childhood was associated with both age of AR and BMI at that age. Predicting BMI in young adults from childhood data using two approaches to modeling AR was suggested, which may be a more practical way of predicting later BMI (Williams et al. 1999). Regarding the effect of risk factors for obesity, it was considered whether a shift of the entire BMI distribution in some populations occurred or whether only upper percentiles shifted in groups. In the Czech population, it was shown that the latter occurred during the last decades (Vignerová et al. 2008). Studies in German children at obligatory school entry showed that maternal overweight and high infant weight gain shifted the entire BMI distribution with emphasis on upper quintiles to higher BMI values. In contrast, parental education, formula feeding, excessive TV watching, low meal frequency, and mother’s smoking during pregnancy resulted in a shift to upper quintiles only (Toschke et al. 2005, 2008a,b). Shifts among the upper BMI percentiles distribution might be due to the interference of additional factors or to genetic predispositions indicating susceptible subpopulations. The best measure of adiposity change in growing children was considered: even though BMI z-score is at present optimal for the evaluation of adiposity on a single occasion, it is not always optimal for the evaluation of the change of adiposity, as the within-child variability over time depends on the child’s degree of adiposity. The evaluations on BMI, BMI%, BMI z-score, or BMI centiles were compared in a group of Italian children 29–68 months old, by assessing BMI three times over a 9-month period. It was shown that BMI itself or BMI% was a better alternative (Cole et al. 2005). Many countries also have standards for other anthropometric characteristics such as circumferential and breadth measures, skinfold thicknesses, and percentage of fat indices (waist/hip and waist/height ratios centrality index as mentioned before; see Chapter 4). Again, similar percentiles for BMI are used for the evaluation of individual anthropometric values that exceed the usual range of these characteristics, qualifying those subjects as obese. Anthropometric measurements are relatively simple, and their validity and reproducibility are good when taken properly, that is, after adequate instruction and practice. They can also be used in very young subjects and under field conditions, and across larger population samples. These indices can

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supplement the evaluation of obesity type. Waist circumference has been used more during recent periods with regard to central obesity. It was shown that central fatness increases relatively more than general fatness in British children during the period from 1987 to 1997 (McCarthy et al. 2003, 2005). Waist circumference predicts the occurrence of sleep-disordered breathing in obese children (e.g., Carotenuto et al. 2006). An index relating waist circumference to body height (WC/HT) was suggested, and was also used for children (McCarthy and Ashwell 2006). This index was shown to be more closely related to childhood morbidity than BMI, and was suggested for use as an alternative measure to BMI in children as well as in adults.

8.6.2

ASSESSMENTS OF BODY COMPOSITION AND FATNESS

Skinfold thickness measurements were widely used, especially in younger subjects and in those for whom more complicated assessments were not suitable due to possible non-cooperation and/or ethical reasons. In Czech children measurements were conducted in representative samples of preschool children (Parˇ ízková et al. 1984a, Parˇ ízková 1993a, 1995b,c). Studies were conducted in other populations as well, for example, in Chinese children, along with the estimation of total body composition (Zhonghua et al. 2000). BIA is based on the principle of a frequency-dependent impedance to the spread of an applied alternating electrical current that develops in biological tissues. At frequencies between 500 and 800 kHz, the current passes through both intra- and extracellular fluids. Due to the high conductivity of fluids, the fat-free tissues have a far greater conductivity than fat. Two electrodes are fastened, mostly to the hand and foot, and electrical conductivity is measured (L/resistance) as an excitation current is introduced to the subjects. Various prediction equations are used for total body water, depot fat, and fat-free body mass. The results correlate satisfactorily with the results of other methods (Fidanza 1991, Heysfield 1991). Bipedal bioimpedance has been recently used widely for children too. However, some researchers found underestimated values of the fat ratio in children (Eisenkohl et al. 2001, Bláha and Parˇ ízková 2007). The method of BIA is easy, does not require a great deal of active cooperation, and thus is very suitable for children (Goran et al. 1993). However, there are doubts on whether any of the regression equations can give acceptable results on body composition in growing children. Deurenberg et al. (1989, 2003) used bioelectric impedance simultaneously with densitometry in pubertal children. Goran et al. (1993) compared body composition (estimated from total body water and with bioelectric resistance, which was crossvalidated by two independent laboratories in 4–6-year-old children. On the basis of these measurements, it was concluded that bioelectric impedance may only be an adequate method to assess body composition in epidemiological studies when population-specific prediction formulas are used. This procedure also showed that an increased protein intake accelerated the catch-up growth in malnourished children and restored the reference body composition in children recovering from malnutrition (Kabir et al. 1994).

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Some authors still claim that BMI or body density gives more exact results for the evaluation of body composition (Lukaski et al. 1986, Deurenberg et al. 1989). The same applies for the evaluation of body composition using regression equations with skinfold thickness measurements, which gives results with a precision similar to the best-fitting equations involving bioimpedance (BIA). Children with normal and/or increased body weights were followed up using this method in numerous studies (Tsukuda et al. 1994). However, the clinical applicability of BIA is still controversial. Further technical improvements will certainly contribute to a wider utilization of this method in young children. Another method highly suitable for children is the total body conductivity method (TOBEC). Special apparatuses were developed and used for the youngest infants (Fiorotto and Klish 1991). This technique, like BIA, is based on the differences in the electrical properties of fat and fat-free tissues. The measurement chamber of the TOBEC apparatus consists of a large cylindrical cell. An oscillating electrical current is injected into the cell, inducing an electromagnetic field in the space enclosed by the coil. A meter attached to the system measures the change in coil impedance as the subject passes through the instrument core. The change in impedance is related to the dielectric and conductive properties of the body and, like BIA, equations for water, fat, and fat-free body mass were developed (Fidanza 1991). As in the case of BIA, the between-day reproducibility of TOBEC measurements in healthy subjects is excellent (2–3% for estimates of FFM; Heymsfield 1991); correlations with total body water (dilutometry), protein, and fat-free body mass are also excellent (Fidanza 1991). Body composition can be assessed by measuring total body water, that is, dilutometry. A comparatively safe and valid approach is deuterium oxide dilution (D2O) or tritium dilution. The latter is a ␤-emitter and the former is a stable isotope. Because deuterium is a stable isotope, it has been used extensively. Orally ingested D2O is readily absorbed in the gastrointestinal tract and is in equilibrium with body water within a few hours. The equilibrium concentration can be determined in blood, urine, or saliva. About 2% of D2O exchanges with H+ in the body, but this slight correction is easily made. Apparently, D2O is not selectively excreted by the kidneys and is nontoxic in trace amounts. A variety of analytical techniques have been used to measure D2O concentration, including infrared absorption, the falling drop method, freezing point elevation, mass spectrometry, and gas chromatography. Another approach involves exposing the sample to gamma ray irradiation with subsequent measurements of neutron emission. In addition, D2O doses as low as 10–20 g can be used. This method was most widely used for body composition measurements in young children (Davies and Christoffel 1994, Davies et al. 1994, 1995a). Computed tomography (CT) represents a major advance in body composition evaluations. The novelty is, in particular, in the use of CT in depicting internal and visceral fat, and subcutaneous fat, along with other tissues. The relatively high radiation exposure of CT does not allow measurements in very small children, especially in longitudinal studies of growth (Fidanza 1991). Soft tissues and bone minerals in the skeleton attenuate emitted photons to different degrees, a property that underlies the dual photon absorptiometry (DPA) method. DEXA as a newer method is faster, requiring 10–15 min for a whole-body analysis.

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The relatively low radiation exposure allows studies to be repeated. The results of DEXA correlated significantly with total carcass chemical analysis in pigs with a weight range of 5–16 kg. However, significant differences in the partitioning between bone mineral content, nonbone lean tissue, and body fat compartments were revealed. The influence of these differences in the body composition analyses by DEXA was examined in a group of boys aged 4–12 years (Ellis et al. 1994). Sex-linked differences in body composition were generally evident after puberty, as shown by DEXA assessments in subjects 4–26 years old (Nuutinen and Knip 1992). Nuclear magnetic resonance (NMR) shows promise in studies of human tissue metabolism. This process of NMR imaging is also referred to as magnetic resonance imaging (MRI). The method is based on the principle that nuclei containing an odd number of protons, an odd number of neutrons, or both have an angular momentum arising from their inherent spin. The utilization of this method for studies of growth and nutrition problems is still limited, but is extremely promising. MRI evaluation of adipose tissue and muscle tissue mass has already been used, for example, in children with growth hormone deficiency, Turner’s syndrome, and intrauterine growth retardation treated by growth hormones (Leger et al. 1994). Adipose tissue was measured in infants using MRI, along with total body water and TEE (stable isotopes). This validation showed a precision of 2%, the same as in adult women. Simultaneous caliper measurements correlated significantly with MRI measurements, enabling the prediction of body fat from skinfolds of infants, with a precision of 5–7%. Whole-body three-dimensional photonic scanning was introduced as a new technique for obesity research and clinical practice (Wells et al. 2007b), but children of early age have not yet been followed. Densitometry, that is, hydrostatic weighing with simultaneous measurements of air in the lungs and respiratory passages, is simple in principle and reliable, and it has been used for the calibration of nearly all the new methods. However, for smaller children, it is usually not feasible because it demands a great degree of cooperation, no fear for water, and skill. Our youngest subjects were 6–7 years old (Parˇ ízková 1959, 1961a,b), and it took a very long time to teach them the procedure in order to obtain reliable data (Parˇ ízková 1977). 40K whole-body counting is generally used to estimate total body potassium. There are different types of whole-body counters, for example, the 3π whole-body counter containing several plastic scintillators with varying total volume of the chamber with efficient iron shielding. This method can be combined with neutron activation analysis. Intracellular potassium concentration is relatively constant and distributed entirely within the fat-free LBM (Fidanza 1991). There is very little potassium outside the cells. Therefore, potassium can serve as an indicator of LBM. 40K spectrometry was used simultaneously with bioelectric impedance and skinfold thickness measurements in subjects 3.9–19 years of age (Ellis and Shypailo 1993). Obesity in childhood also enhances the development of bones with regard to bone mass and bone dimensions (Leonard et al. 2004), which lasts until later age. For example, the bi-iliocristal dimension is significantly larger in obese adolescent boys compared to normal-weight boys of the same age after correction for the fat layer (Parˇ ízková 1977). This was not found in girls. In adolescents the foot structure was

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negatively influenced by excess weight, which manifested especially in older prepubescent subjects (Morrison et al. 2007).

8.7 RESULTS OF STUDIES IN YOUNG OBESE SUBJECTS The prevalence of obesity varies in time and in different age categories. The last result of NHANES (Kuczmarski et al. 1994) showed a permanent increase in the average value of BMI in the adult US population, which means that the goals claimed within the framework of the program “Health for All in the Year 2000” will not be fulfilled. Instead of reducing the values of BMI, the very opposite occurred because of changes in the lifestyle of all age categories. This includes nutrition, PA, stress management, and many other variables that are associated with body weight and fatness. In addition, the prevalence of individuals who meet the BMI criteria for obesity has increased significantly by 8%. This problem develops from early childhood, and is reflected not only in an increased fatness but also in a decreased level of physical fitness. This has been best documented by studies in the United States by Rippe et al. (1991). Most alarming was the finding that by the age of 12, 40% of children have at least one major risk factor for heart disease, including obesity. In conjunction with this, it was again pointed out that cardiologists have been telling us for a long time about the genesis of atherosclerosis in childhood (Kannel and Dawber 1972). The Bogalusa Heart Study showed that lipids measured in the umbilical cord blood were related to atherosclerotic plaques in the aorta in some of these children who died by accident in their teens (Newman et al. 1996), indicating the influence of negative early factors. A similar situation occurred in the United Kingdom and in many other countries, including the developing industrial nations that include well-off social strata. There are fewer data on the changes in body weight of Central and Eastern Europe populations; however, in the 1990s childhood obesity prevalence increased there too. There has been increasing evidence that in all countries with a certain level of industrial development and economic level, the prevalence of childhood obesity with accompanying comorbidities is increasing. During the growth period, the prevalence of overweight and obese children also varies. In our studies of preschool and school children, the prevalence of obesity differed—in preschool age it was rather low (2–3%) and later it increased up to 10–15% during the prepubertal and pubertal period (which applied to the seventh and eighth decade of the last century; Parˇ ízková et al. 1984). It was difficult to compare the prevalence of obesity before BMI was introduced and generally accepted because most countries had different growth grids and different criteria, and there has been little agreement as to when obesity starts. However, some ex post evaluations can be made using height and weight values. As mentioned before, the BMI percentiles in Czech children are higher than those in French children (Prokopec and Bellisle 1993); regarding secular trends, the BMIs of Czech children increased from 1895 (Matiegka 1929) up until recently (Bláha 1991, Hainiš 1993). Recent studies in Germany showed an increased prevalence of obesity at preschool age. In the Czech Republic in the early 1990s and in 2001, an increase in more severely obese

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children above the 97th percentile of local BMI standards was found (Vignerová and Bláha 2007). Related studies in Czech children comparing the age of AR in the 1950s and at the beginning of this millennium showed a significant shift of AR to lower age. In 1951, AR at the 50th percentile occurred at the age of 6.2 years in boys and at 6.4 years in girls, and in 2001 at 4.9 years in boys and at 5.2 years in girls. AR occurred in 2001 by 1.3 years earlier in boys, and by 1.2 years earlier in girls (Vignerova et al. 2003, Parˇ ízková 2008), which means a greater predisposition to obesity during later development. This was accompanied by an increasing prevalence of obesity in Czech children during the last decades, especially after the social and political changes in the early 1990s (Parˇ ízková 2008).

8.7.1

MORPHOLOGICAL CHARACTERISTICS AND BODY COMPOSITION IN CZECH PRESCHOOLERS

As a criterion for child obesity, +2 SD above the average weight for a given age in the particular country is mostly used. Actually, the 90th percentile of BMI is suggested as a borderline for child overweight, and the 97th percentile for obesity (Vignerová 2007). Regarding the percentage of total body fat, there is no general agreement on standard values during the growth period as there are still relatively few data on this variable measured directly by reliable and advanced methods. The critical value for the definition of obesity varies according to factors such as growth period, sex, etc. In the Czech Republic, we use the average values of the percentage of fat assessed by densitometry (Parˇ ízková 1961a,b, 1977) as a standard for comparison. A measure of +2 SD and/or the 85th percentiles of depot fat ratio and/or skinfolds were considered as criteria for the onset of obesity in relation to the percentage of body fat; the critical value varies significantly according to age (Parˇ ízková 1977, Parˇ ízková and Hills 2001, 2005). However, different authors used slightly different fatness criteria up to the present time. Obese children differ from normal-weight children in relation to not only larger skinfolds but also the different distribution of subcutaneous fat characterized by indices: there is a significant sex-linked difference in the amount of total fat and in its typical gynoid (“pear”) distribution (i.e., relatively more fat on the hips, buttocks, thighs, etc.). This sex-linked difference in the amount and distribution of fat is absent in the obese even during puberty, when both obese girls and boys have a subcutaneous fat distribution similar to older women (Parˇ ízková 1961a, 1977). Exceptionally, this type of fat distribution can be found in young children. Other morphological variables are also different in the obese: children and youth usually have greater LBM and sometimes (especially in individuals who start becoming obese quite early in life) greater robusticity of the body frame, as shown by higher values of breadth measurements (Parˇ ízková 1977). Needless to say, circumferential measurements are larger, and waist/hip, as well as waist/thigh and waist/ height, ratios may be different in the obese during growth. In obese prepubertal boys there is also a significantly greater bi-iliocristal breadth compared to normal lean boys of the same age. The difference was marked even when the bi-iliocristal breadth

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was corrected for the thickness of subcutaneous fat in this region. In girls, this difference due to obesity was not apparent (Parˇ ízková 1977). Measurements of the heart volume showed significantly greater absolute and relative values in boys 12–15 years of age. However, after 3 years, no further increase in heart volume was found in spite of continuing growth and increase in height, weight, LBM, etc. (Parˇ ízková 1977). As mentioned previously, the prevalence of more marked obesity in preschool age was lower than its occurrence later in younger school age and/or in adolescence. Heavier children were also taller and bigger and seemed to be generally more advanced in their development, but not typically obese in the same way as older children or adults. Table 8.1 gives data on three groups of preschool children from survey B (6.4 years of age): underweight, average, and overweight to obese. The differences in BMI are

TABLE 8.1 Anthropometric Variables in Preschool Children with Different Body Weights Overweight

Weight (kg) Boys Girls Height (cm) Boys Girls BMI (kg/m2) Boys Girls Circumferences Abdomen (cm) Boys Girls Arm (cm) Boys Girls Thigh (cm) Boys Girls Chest (cm) Boys Girls

x–

Average Weight

SD

x–

28.8 28.5

3.9 3.9

119.5 118.3

Underweight

SD

x–

SD

22.5 21.9

2.2 2.2

18.5 17.7

1.9 1.7

6.0 9.9

118.5 117.9

5.3 5.0

117.8 118.1

6.2 7.1

20.3 20.3

1.1 1.0

16.1 15.7

0.9 1.0

13.3 12.7

0.8 0.9

63.0 63.6

6.1 6.6

55.4 54.8

3.2 3.5

52.2 51.0

4.4 5.6

21.5 21.8

2.3 2.1

18.4 18.4

1.3 1.3

16.6 16.6

1.1 1.3

41.3 43.0

4.9 4.3

35.7 37.3

2.6 2.7

35.6 33.6

2.4 2.9

65.4 65.3

4.6 4.8

59.4 58.0

2.4 2.4

56.0 54.8

2.3 3.0

Source: Adapted from Parˇízková, J. and Hainer, V., chapter in Current Therapy in Sports Medicine-2, Torg, J.S., Welsh, R.P., and Shephard, R.J., Eds, Dekker, Toronto, 1990, 22.

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apparently similar to the differences in body weight. All circumferential measurements were greatest in the obese and smallest in the underweight. Other morphological variables were not measured in these groups of children. More anthropometric variables were also measured in older obese children, before and after reduction treatment. These results have been reported previously. To our knowledge, there are no results of reduction treatment in preschoolers, but there are some recent studies concerning older children.

8.7.2

FOOD INTAKE IN OBESE PRESCHOOLERS

Food intake was followed either directly by the research team or by using diaries completed by kindergarten teachers and parents. There was a very limited opportunity to assess the food intake in obese preschool children as the prevalence was so low. In our surveys G, H, and J, no relationship between actual dietary intake, on the one hand, and body weight, BMI, and percentage of fat, on the other hand, was found. In older children, it was possible to use diaries completed by children who were instructed and supervised. However, the results of the assessments of actual dietary intake did not show any significant differences compared to children with normal body weights; intake was generally slightly higher than energy output. The intake of proteins and fats (especially those of animal origin) was somewhat higher than Czech RDAs and much higher than EC or US RDAs. The intake of calcium, fiber, and vitamin C was often lower than the RDAs. Marked intra- and interindividual variability was found. However, such a type of dietary intake was also found in children who were not obese. So it seems that the actual intake of food is not the main cause of a higher fat ratio in young children. However, the effects of an obesogenic food environment have been increasing during recent decades (Carter and Swinburn 2004, Cash et al. 2004). With regard to food intake, studies of dietary intake conducted mostly in older children and adolescents did not prove higher intake, but a shift to energy-dense foodstuffs (with high sugar, salt, and saturated fat contents) and sweetened beverage consumption as mentioned before. More detailed studies of food intake in preschool children with regard to body composition are rare (Parˇ ízková 1995, Parˇ ízková et al. 1984a). In markedly obese prepubertal girls in Tunisia, an increased food intake was found along with a lower energy output (Parˇ ízková et al. 1995). These girls were obviously in the dynamic phase of obesity, and their food intake was very high (16.2 MJ/day). In chronically obese children and adolescents however, food intake might be even lower than in children of normal weight (Parˇ ízková 1977).

8.7.3

PA AND ENERGY EXPENDITURE IN THE OBESE

Classical observations of Jean Mayer (1968) showed that the level of spontaneous PA was lower in obese children, and during the same games obese children were much less active than children of normal weight. This was documented by shooting a motion picture of the children. However, upon completing a questionnaire this reduced activity appeared equivalent to taking part in the same activity for the same

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period as normal children. This means that PA could be wrongly reported by the usual questionnaires, and that more exact methods giving information on the intensity and character of PA have to be used. Such methods, for example, accelerometers (see Chapter 6), have been used, as only a certain threshold level of PA can be effective. Huttunen et al. (1986) used questionnaires for assessing the history of the PA of obese and normal children from 5.7 to 16.1 years, which were completed by the children and their parents. There were no significant differences in daily activities between obese and nonobese children, but the sports grades at school were lower and participation in the training teams of sports clubs was less frequent among obese subjects than among normal-weight subjects. The “fattening of America,” which also concerns children, has been explained by a number of authors, for example, Kuczmarski et al. (1994), as due to the lack of PA. Discretional activities are mostly devoted to TV programs, video games, and films, and very little time is spent on different PAs and exercise. Even usual everyday activities have become more and more limited because of public transportation, the use of cars, etc. (Sandler et al. 1994). REE in obese subjects 3–18 years old was assessed by indirect calorimetry, and new predictive equations were derived (Derumeaux-Burel et al. 2004). Measured and predicted data may not always correspond, but the inclusion of lean FFM for the prediction of REE improves the precision of results (Schmelzle et al. 2004). These equations may enable the estimation of TEE per day, using the procedure of WHO (see Chapter 6). Estimation of TEE makes it possible to compare EI and EE, and eventually rectify the energy balance in a proper and more exact way. BMR can be influenced by body composition, and the comparison of BMR adjusted for lean FFM and fat mass (FM) does not vary in obese and nonobese children. Increased adiposity in the obese can be explained especially by decreased TEE due to reduced PA and sedentarism. A disbalance between EE and EI is most often considered as the most frequent cause of obesity during growth, for example, in Hispanic children in the United States (Butte et al. 2007b). Blair (1992), who studied the development of risk factors and/or their reduction in adults, showed that even very ordinary activities such as taking a walk, climbing stairs, low-level recreational activities, and housework and yardwork can make an important contribution to physical fitness and health in sedentary and unfit adult subjects, including a reduction of excess fat and of cardiovascular risk. Cardiorespiratory fitness is lower in obese subjects with reduced PA. Aerobic power, that is, max O2 per kg body weight, is generally lower in the obese (Parˇ ízková 1977), as was also found, for example, in Indian boys (Chatterjee et al. 2005). PA was measured by accelerometers in obese rural boys, and a negative association with depot fat was proved (Treuth et al. 2005), that is, lower PA was accompanied by higher adiposity. This also applies to young children, whose spontaneous activity is at a much higher level than later on in life (Parˇ ízková 1977, 2008, Parˇ ízková and Hills 2001, 2005). The risk for obesity markedly increased starting with early infancy, then within the period of AR, and later during prepuberty and puberty, and is related to the reduction of PA (Goran et al. 1999). Parents’ perception of the elevated adiposity of

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their children is usually at a low level, and underestimation of their children’s status, including lifestyle, is frequent. Advising parents on the use of BMI and also more exact measurements of adiposity can help as a strategy for obesity prevention in children (Miller et al. 2007). PA as a part of daily EE is, at an early age, significantly dependent on family lifestyle; there is a relationship between family environment and TV viewing (Van Zupthen et al. 2007). In families with children 0–4 years old, behavior patterns related to overweight at a later age were frequently observed. Not only inadequate diet and food patterns, but also a lack of PA and exercise was observed (BoereBoonekamp et al. 2008). Perspectives for PALs in preschoolers are parental perspectives: more than 30–90 min of daily PA are recommended, which should be ingrained during preschool years (Irwin et al. 2005). This also applies to day-care centers where obese children display sedentary characteristics; an improvement in dietary habits and an increase in PALs are recommended (Vasquez et al. 2006). When obesity develops, PA is reduced earlier in life than in normal-weight children (Gillis et al. 2006). As mentioned before, a longitudinal study of the same children revealed a reduction in spontaneous weekly PA after entering the 1st class of primary school, even during weekends (Parˇ ízková and Hainer 1989, Sigmund et al. 2008). The Toyama cohort study showed that temporal changes of BMI from the age of 3–6 years were significantly associated with both environmental and behavioral factors at 6 years of age, that is, rapid eating, short sleep duration, early bedtime, long periods of TV viewing, avoidance of PA, and frequent bowel movement (Sugimori et al. 2004). In obese children aged 4–17 years, the amount of TV viewing is associated not only with the severity of obesity but also with blood pressure. TV viewing is a target for addressing not only obesity but also hypertension (Pardee et al. 2007). BMI correlated positively with blood pressure in children and adolescents in Beijing (Wang et al. 2004). In Iranian children, obesity was associated with cardiovascular risk factors (Hamidi et al. 2006). The 2005 National Nutrition Survey: a cross-sectional study in Colombian children also revealed that TV viewing was positively associated with overweight. The majority of children in Colombia live in densely populated cities, and appear to engage in excessive TV viewing. Findings on the above-mentioned associations are of public health relevance for the prevention of obesity in children (Gomez et al. 2007). The risk factors for child obesity in China are similar to those found in European countries and elsewhere (Jiang et al. 2005, 2006). Fat intake, low-intensity activities, and active transport to/from school along with paternal overweight and obesity seem to be a risk for obesity in China as reported by Li et al. (2007), and may be a suitable entry point for overweight prevention among Chinese children. In preschool children, prevention is recommended as based on the observation in Urumqui, where preschool obesity is higher than elsewhere. Causes of this are defined as multifactorial, including low PA (Maimaiti et al. 2008). As is apparent from the given results, PA is an essential item for healthy development and obesity prevention—justified by well-known experiences from previous times. The most important problem involves recent environmental changes— “nowhere to play.” A relationship was found between the location of outdoor play areas and deprivation in Glasgow, indicating problematic access to appropriate

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facilities, which is a key determinant of participation in PA (Ellaway et al. 2006). Increased adiposity and increased body weight function as a barrier for PA in obese children, who are especially vulnerable in this respect. The reduction of such barriers may serve as PA intervention, improving the status of children (Zabinski et al. 2003). Local neighborhood environment is considered to be related to childhood overweight and obesity (Timperio et al. 2007). Analysis of the data from the German Socio-Economic Panel Study indicated that obese children attain a lower level of skill (verbal skill, activities of daily living, motor and social skills; Cawley and Spiess 2008). “KinderSportstudie (KISS),” a study design of a randomized control trial of a PA program for schoolchildren, gave promising preliminary results with regard to fitness and health (Zahner et al. 2006). For preschoolers, the formative research and development of strategies for a PA component of a social marketing campaign was developed to prevent obesity at an early age. Barriers were also identified by parents, which included time, safety, weather, lack of knowledge, and self-efficacy. “Food Friends Get Movin’ with Mighty Moves” (TV) as part of a larger social marketing campaign to reduce the risk of overweight and obesity, especially for low-income preschoolers, was suggested and prepared (Bellows et al. 2008).

8.7.4

FUNCTIONAL CAPACITY

8.7.4.1 Cardiorespiratory Fitness Generally, it is assumed that obese individuals are clumsy and have a low level of physical fitness. Here again it is necessary to specify and differentiate which items of physical fitness and functional capacity are most influenced by excess fat deposition. Finally, there are not many comparable measurements of physical performance in the obese of any age. This applies mainly to children of younger age. A very negative situation is found in cardiorespiratory fitness evaluated with the help of measurements of maximal oxygen uptake during an increasing workload on a bicycle ergometer, on a treadmill, or during the step test. The oxygen uptake may be normal or even quite high, but related to body weight and/or LBM, it is reduced. This corresponds to the general experience that obese subjects are at a disadvantage, especially in dynamic, weight-bearing exercise. This also concerns endurance; runners for short and long distances are never heavy. Physical fitness was mostly tested in obese schoolchildren and adolescents; for example, aerobic power, evaluated with the help of measurements of maximal oxygen uptake, was significantly lower in relation to total and lean body weight. PWC170 was also lower in obese children. Max O2 was achieved after a shorter run and lower speed on a treadmill as compared to normal-weight children. In addition, performance in various sports and disciplines, especially running and jumping, was also worse (Parˇ ízková 1963, 1977). Vital capacity and forced expiration, especially in relative values (per kilogram of total and lean body weight), were also reduced. In general however, muscle strength was at an adequate level (Parˇ ízková 1977). Absolute values of max O2 were greater in the obese, but relative values (related to TBW or LBM) were lower or the same in both Czech and US children (Goran et al. 2000). At preschool age maximal workload has not been implemented for obvious reasons, because

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only children 6–7 years old were able, and not in all cases, to undergo such a test. Also, REE was measured only in older children, similar to most fitness testing. Huttunen et al. (1986) found a lower level of physical fitness in both obese and normal-weight children 5.7–16.1 years old, as evaluated by pedaling time in an exercise test. VO2 max/kg LBM was also lower in obese children. In 5–6-year-old children, Gutin et al. (1990) showed a positive correlation between diastolic blood pressure and fatness and a negative correlation between diastolic blood pressure and fitness level, as evaluated by the submaximal treadmill test. The fitness level was inversely related to body fatness for boys and girls, and thus these small children showed risk factors similar to those in adults. However, we found no significant relationships between the results of the step test, body weight, BMI, and fatness in a smaller group of 4–6-year-old children (Parˇ ízková et al. 1986b). 8.7.4.2 Motor Development The same group of asthenic, normal, and overweight preschool children (see Table 8.1) was tested in the 20-m dash, broad jump, and ball throw. More marked, significant differences were found for the broad jump and ball throw (Figure 8.1a through d). Leaner children had significantly better results, that is, they jumped farther compared to overweight children. There was no difference in the 20-m dash. Differences in dynamic performance usually appear later on in school age. Endurance was not tested in this survey. 8.7.4.2.1 Skill Regarding throwing a ball and walking on a horizontal beam, the effect of body weight did not play a role in preschool age; however, in the forward roll there were considerable differences, particularly in girls. Evidently, the influence of different body weights is only manifested in some specific exercises. In selected instances, that is, broad jump and forward roll (which require the transfer and manipulation of one’s own body weight in space), the negative effect of being overweight is already clear at preschool age. In many other exercises such as walking at a given rhythm, catching a ball, “opening and closing the hands,” and laterality, the results were again practically the same as those in normal children (Parˇ ízková et al. 1986b). More recent measurements confirmed these trends of physical fitness in obese preschoolers. 8.7.4.2.2 Muscle Strength When considering some positive points of obesity, muscle strength, which depends mainly on body mass, is not influenced by excess fat (Parˇ ízková and Hills 2005). The reverse is true—obese subjects usually have increased LBM, including muscles. Thus, muscle strength in absolute terms (N) is usually greater in obese subjects than in lean or normal ones. However, in relation to body weight, muscle strength may be the same or even lower. By contrast, performance in static exercise is not hampered by excess weight and fat. This is well known in athletics—most representatives of static sports disciplines, such as weightlifters and wrestlers of higher weight categories, generally have high fat ratios, but are also very muscular (Parˇ ízková 1986). An example is seen in Japanese sumo wrestlers, whose preparation (training and special diet) starts during their growth period.

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With regard to skill, certain activities that demand the coordination of smaller muscle groups of one extremity may be performed without a problem in well-adapted subjects. This applies especially to working skills: many workers performing their special task (mostly of static character) can perform very well. The same applies to static activities in children. When coordination of the whole body is involved in a more dynamic action, the level of performance is usually low, with the exception of special cases of adapted athletes mentioned above. Within the normal population, a good level of overall skill in the obese is rare. The development of selected skills and/or strength depends significantly on the beginning of the adaptation process during ontogeny. Subjects who adopted certain skills at a younger age may still preserve or more easily learn them later. As is apparent from Figure 8.1a–d, being overweight did not interfere with the throwing abilities of preschool children: in this activity, muscle strength and coordination of the upper extremities play a decisive role.

8.7.5

BIOCHEMICAL CHARACTERISTICS

The serum levels of cholesterol were usually higher in obese children, mainly in boys. In contrast, the increase in cholesterol was lower in obese adolescent girls (Parˇ ízková 1977). The same applied to the blood level of triacylglycerols. The value of nonesterified free fatty acids (FFAs) at rest in the serum of obese boys was 1.18 mEq/L. There were no differences in the resting values of glucose and esterified fatty acids (EFAs) among groups of prepubertal obese and nonobese boys and girls (Parˇ ízková 1977). Under conditions of stress, for example, workload on a treadmill (maximal workload testing aerobic power), there was an increase in glycemia during the workload, which continued after 10-min recovery. The level of esterified fatty acid remained the same, decreasing slightly after 10-min rest. The FFA level decreased significantly after maximal workload, remaining the same after 10-min rest. There was a significantly negative relationship between the increase in pulse rate during maximal workload and the change in FFA level: the higher the increase in pulse rate during the load (i.e., the lower the level of physical fitness), the greater the decrease in FFA. This result seems to indicate that a higher fitness level runs parallel to a greater ability to mobilize FFA (which prevents their decline in the blood) as a source of energy (Parˇ ízková 1977). In healthy preschool children not followed up in pediatric institutions and the like, there was limited opportunity to assess the above blood lipid indicators in the obese, as they are very rare at this age period. (However, as mentioned above it was possible to take blood samples in cooperation with a clinical department.) There was a significant positive correlation between percentage of body fat and blood level of TGs (r = 0.494, 0.02 >p > 0.01) and between percentage of body fat and level of blood cholesterol (r = 0.448, 0.02 > p > 0.01) in 52 preschool children with different BMIs and depot fat ratios (Parˇ ízková et al. 1986a,b). It can be assumed that under conditions of a highly increased deposition of body fat, the blood lipid indicators would also be higher than those in preschool children of normal weight. The Bogalusa Heart Study showed, in 5–17-year-old subjects, a close direct independent

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s

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FIGURE 8.1 Comparison of physical performance—20-m dash (a), broad jump (b), throwing a ball with the right hand (c), and throwing a ball with the left hand (d) in 6.4-year-old boys and girls subdivided according to their weights (survey B).

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relationship between serum very-low-density lipoprotein (VLDL) levels related to obesity (Kikuchi et al. 1992).

8.7.6

HORMONAL VARIABLES

Molnar and Porszasz (1990) recorded the influence of fasting hyperinsulinemia on physical fitness in obese children. The hyperinsulinemic obese children had a lower level of physical capacity (in absolute values, and when corrected for body weight and LBM) than the nonhyperinsulinemic obese children. The exercise period was not significantly different in the two obese subgroups. While fasting plasma insulin levels showed a significantly negative correlation with exercise duration and relative physical working capacity in obese children, the anthropometric parameters did not. Gonzales et al. (1989) followed the values and the circadian rhythms of insulin and cortisol in obese children and their relationships to anthropometric variables, including body fat. Higher plasma insulin levels were confirmed in obese children. No correlation between insulin and cortisol values, on the one hand, and body fat, on the other hand, was observed. There were some changes in the circadian rhythms of both cortisol and insulin, but they did not have any relationship to the duration of obesity. These studies mostly included schoolchildren. Studies of biochemical and hormonal indicators in very young children with simple obesity are rare. In studies mainly focused on nutrition problems, blood lipids were examined in larger samples of young children (Gregory et al. 1995).

8.8 HEALTH COMPLICATIONS OF OBESITY IN CHILDREN Obesity at an early age has been demonstrated not only as a health problem in itself, but also as a situation that multiplies other health problems. There is evidence on childhood growth and chronic diseases from countries undergoing nutrition transition since early life (Stein et al. 2005), which appears markedly in China. Studies include changes in childhood obesity prevalence along with comorbidities (Li et al. 2005, Ma et al. 2006). Fatty liver prevalence was revealed during growth (Schwimmer et al. 2006). During more recent periods, MS was assessed in many obese children and adolescents (i.e., obesity, dyslipidemia, hypertension, and glucose intolerance) and occasionally in preschoolers. MS in childhood was associated with increased birth weight, maternal obesity, and gestational diabetes mellitus. Children of obese mothers were at increased risk of developing MS. Children born as LGA at birth and exposed to an intrauterine environment of either diabetes or maternal obesity were at increased risk of developing MS (Boney et al. 2005). MS appeared along with childhood obesity in developing countries too (Kelishadi 2007). The above demonstrates the multigenerational problem of perpetuating cycle obesity, which should be prevented by adequate measures from the very beginning, that is, at least at the beginning of pregnancy. Maternal waist circumference was a significant predictor of the child’s MS when adjusted for the mother’s concentrations of TGs, cholesterol, and glucose, and age. This was consistent with known familial associations of obesity and type 2 diabetes (T2D; Hirschler et al. 2007). Obesity

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increased MS risk factors in school-aged children in Mexico city (Perichard-Perera et al. 2007). Association of obesity and MS was also found in Chinese children and adolescents; lifestyle intervention combined with metformin had significantly positive results (Fu et al. 2006). A study in subjects aged 5–18 years proved that fatness was a significant predictor of cardiovascular diseases—elevated blood pressure and serum lipoproteins (Williams et al. 1992). However, Aberdeen children of the 1950s’ prospective study did not show any relationship between BMI at a mean age of 4.9 years and risk of coronary heart disease and stroke in middle age. There was no linear association between childhood BMI and stroke risk, but those who were obese in childhood (top 2.5% of body BMI distribution) compared to all the others had an increased risk of stroke (Lawlor and Leon 2005). Adverse health effects of childhood obesity were also seen in Hong Kong (Chan 2008). Data from the longitudinal Cardiovascular Risk in Young Finns Study indicate that obesity characteristics assessed during growth (3–18 years) are significantly associated with increased carotid artery intima–media thickness (IMT) and decreased elasticity in adulthood—an important cardiovascular risk (Raitakari et al. 2005). Obese children can have arteries with walls as thick as those of individuals 40–50 years old. The Early Bird Study shows the correlation between insulin resistance and weight at 5 years of age, but not with birth weight. Variability in PA among young children was attributable to children but not to the environment. Fatness was not correlated with insulin resistance in this study. Because of the dissociation between fatness and insulin resistance, an up-to-date explanation concerning only the role of overnutrition and lack of PA does not seem to be sufficient (Wilkin et al. 2004). A significant positive correlation was found between glomerular filtration rate and BMI in schoolchildren, and a positive correlation was found between BMI standard deviation and inflammatory mediators and glomerular filtration rate. Inflammatory mediators increased significantly in obese children, and glomerular filtration rate increased as BMI increased (Cindik et al. 2005). Even in childhood, inflammatory parameters increased in obese subjects; PA and physical fitness counteracts this association (Halle et al. 2004). The STRIP study in an atherosclerosis prevention trial starting in early childhood revealed that individualized dietary and lifestyle counseling given twice a year since infancy decreases the prevalence of overweight even without any primary energy restriction (Hakanen et al. 2006). Childhood diabetes was significantly promoted by increased adiposity during growth, which is its most obvious risk factor in a global perspective for T2D, as shown by numerous authors (e.g., Silink 2002). An association between insulin and obstructive sleep apnea (OSA) with habitual snoring was prevalent in obese children, and insulin was independently associated with the condition (Li et al. 2006). Short sleeping hours and childhood overweight and obesity were inversely associated as shown in the “Quebec en forme” Project (Chaput et al. 2006). Association of overweight with high incidence rates of respiratory morbidity, snoring, and delayed gross motor skills was reported in the first 2 years of life (Shibli et al. 2008). Children’s overweight status in kindergarten and their academic achievements later on were explored, demonstrating that overweight had significantly lower math

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and reading test scores compared with nonoverweight children in kindergarten, and later at the end of grade 1. However, these differences became insignificant when adjusted to socioeconomic and behavioral indicators, indicating that overweight is a marker but not a causative factor. Ethnicity and mother’s education were stronger predictors of test score gains or levels of overweight status. Overweight is more easily observable compared to socioeconomic characteristics, and its significant (unadjusted) association with worse academic performance can contribute to the stigma of overweight as early as the first year of elementary school (Datar et al. 2004).

8.9

MANAGEMENT OF OBESITY: PREVENTION AND TREATMENT AT AN EARLY AGE

Because of the global epidemic of obesity during growth, greater attention is being paid to the management of increased adiposity in the growing organism, which has not yet achieved full maturity. Management is more difficult in children than in adults—children have to continue growing in body size, maturing, and differentiating tissues and organs, and at the same time reduce their adipose tissue. This implies that the procedures used in adults are most often not suitable for children, and a monitored diet with not much of a reduction in energy content but with increased EE due to PA is mostly acceptable. This kind of treatment was introduced in a central pediatric clinic in Prague in the 1950s (Parˇ ízková 1977, 1995c) and also in other cities. Due to increasing prevalence, obesity interventions during growth and development were reviewed (Parˇ ízková and Hills 2001, 2005, Flodmark et al. 2004, 2006, Doak et al. 2000, 2006, Uauy et al. 2006) and treatment centers were established. Positive short- and long-term effects for the treatment of child obesity were achieved using combined dietary–behavioral–PA intervention during 3 months (Table 8.2; Nemet et al. 2005). A 2-year family-based behavior treatment for obese children in China had successful results after 2 years of implementation (Jiang et al. 2005). The importance of PA in the prevention of obesity was reviewed, showing that attractive and nonrestrictive PA has encouraging results (Steinbeck 2001). Expert committee recommendations for the prevention, assessment, and treatment of child overweight and obesity were also prepared (Barlow; Expert Committee 2007). However, a specialized system of obesity management, including PA for preschool children, has not yet been satisfactorily developed, and greater effort in this respect should be made. A large number of publications and monographs concern the treatment of obesity in adult age, when it is mostly accompanied by comorbidities. As mentioned above, today this also concerns children and adolescents in many parts of the world. Obesity during development was indicated as an urgent health problem for present and future periods of life (Parˇ ízková and Hills 2001, 2005, Burniat et al. 2002, Wabitsch et al. 2005). The best management of obesity is not to let it develop at all, from the beginning of life. As discussed in previous chapters, because the risks for obesity development appear very early in life, attention has to be paid to the fetal period and the first weeks and month of life, and of course during later preschool years. Best prevention is assured when health, nutrition, and fitness status of the mother are taken

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care of, and optimal dietary and PA regimens are adhered to during pregnancy. The growth of the child at the beginning of life when optimal monitored nutrition is given, neither reduced nor abundant, should correspond to standard values. Adhering to an optimal PA regimen should of course continue in later life (Parˇ ízková and Hills 2001, 2005). However, when starting as early as possible— due to positive development of skills and cardiorespiratory fitness—optimal development is more easily achieved and obesity is prevented. Fetal and early childhood adequate interventions should reduce the risk of later diseases, including obesity, accompanied by risk for comorbidities at present and also later in life. A synthesis of evidence with “best practice” recommendations for the reduction of obesity and related chronic disease risk in children was prepared (Flynn et al. 2006, Klesges et al. 2008). Full economic costs of diet, PA, and comorbidities were evaluated, for example, in China (Popkin et al. 2006). The FitKid Project was also implemented for obesity prevention in children (mean age 8.7 years) with positive results (Yin et al. 2005). Limited information is available concerning the management of obesity during preschool age, when more marked obesity was less frequent until recently. Pilot community-based family intervention tackling toddler obesity was introduced, based on the experience with schoolchildren, which gave promising results (Wolman et al. 2008, Boere Boonekamp et al. 2008). Further prevention and treatment projects concerned mainly family interventions, but evidence on the results of overweight management during early life is still rare.

8.9.1

PROCEDURES USED TO REDUCE BODY WEIGHT DURING GROWTH

Even under conditions of a desirable lifestyle, when a sudden imbalance occurs, excess fat is stored in a child, for example, during convalescence after an illness or after an accident. Under these conditions, PA decreases significantly, although food intake may not be reduced. After some time, it becomes necessary to reduce this excess fat in order to prevent the development of permanent obesity. Special outpatient clinics, separate from the endocrinological out- and inpatient departments in pediatric clinics, used to exist in the Czech Republic. These clinics took care of obese children of all ages. Starting in the early 1950s, initial experiences with reduction therapy, based only on limited food intake, did not give good results. Using a diet of about 1000–1200 kcal, that is, 4182–5000 kJ, children slowed down and even ceased to grow in height, that is, it was comparable to the onset of stunting due to malnutrition in spite of a well-balanced, low-energy diet. Very-low-calorie diets (VLCD) in childhood are not recommended, and increased PA and exercise are preferred (Canadian Task Force of the Periodic Health Association 1994, Parˇ ízková 1977). Because of this experience, a comprehensive reduction therapy was developed in the late 1950s, which gave much better results. The following list illustrates some of the steps involved: • Diet was monitored. • An intense, structured but adequate regimen of PA and exercise was implemented.

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• Behavioral and psychological intervention, adapted for children, was also included in the reducing regimen. The main principle of this procedure was that the energy balance was corrected using an increased energy output (and not only a reduced EI). The dietary intake was monitored, but children were not left hungry. Energy-dense foodstuffs (fat, especially saturated ones, simple sugars, etc.) were markedly reduced, or even eliminated, as well as sweetened beverages. This therapy was most effective when children could spend 7 weeks during their holidays in special summer camps for reduction therapy. Their monitored dietary intake was, on average, 1700 kcal, that is, 7109 kJ/day. All regulations for a reducing diet with modifications for growing children were observed. The intake of highquality protein was at the level of RDAs for this age group or was slightly higher so as to make normal growth and development possible. The intake of fats and sugar was limited. Complex carbohydrates were the most important source of energy, with lots of fruits and vegetables. The diet was palatable, but not excessively attractive. The intake of beverages was limited to tap or mineral water; the intake of sweet fruit and juices was reduced to a certain amount per day. In these camps, mostly children of younger school and prepubertal age participated. Thus, the individual food intake varied according to age, sex, and degree of initial fat ratio (Parˇ ízková 1977). A very attractive program of sports activities and exercises, including dance, suitable for children and youth, was prepared and supervised by specialized physical education teachers. All suitable sports disciplines were included in the daily program, which varied so as to ensure the interest and spontaneous involvement of children. Excursions to interesting places and walks were also part of the program. When children felt too tired, dancing parties, discotheques, and balls were organized. These events were never missed by any of the children. The greatest stress was placed on PA regimen and exercise as the most natural and physiological means during growth and development. Increased PA is always considered a significant positive factor in obesity prevention (Council on Sports Medicine and Fitness: Council on School Health 2006). However, in this respect parents have an essential role, especially when considering family model and education since the very beginning of life, which applies also to obesity treatment. Obesity prevention programs for early ages suggested child-age-appropriate parental influences (Pugliese and Tinsley 2007). For preschool children such summer recreation and reduction camps have not yet been arranged (from the available references), so the emphasis is on the family and its lifestyle. The mentioned principles, however, are applicable under these conditions. Further, day-care centers and outpatient departments can play an important role in efforts to reduce weight and excess fatness in this age period. Very obese children were also treated with special spa therapy for several weeks. In the spa, morbidly obese children could exercise at the beginning of treatment in the swimming pool; this enabled them to develop some skills and endurance under conditions in which weight-bearing exercise was facilitated by Archimedes’ principle. Later on, when some reduction of weight was achieved, children could exercise

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while lying or sitting on floor mats and then on a bicycle ergometer. Finally, when they were closer to normal weight and acquired some skills, they could participate in general exercise programs for the obese, which were similar to physical education programs for normal children. Other components of the reduction therapy, that is, monitored diet and behavioral intervention, were practically the same as those in the above-mentioned summer camps for obese children organized by one of the university children’s hospitals. Behavioral intervention consisted of lessons in healthy nutrition, PA, and suitable exercises, and the psychological treatment of difficult situations that obese children may often be faced with in school classes or in peer groups (ridiculization, aggression, etc.). The greatest advantage of these summer camps was that there were only obese children; hence inhibitions during exercise were absent because all the children were somewhat clumsy, especially in the beginning. During that period, most children learned a lot, lost on average 10–15% of their initial body weight (which was mostly fat), and improved their physical performance level significantly (Parˇ ízková and Hills 2001, 2005). Unfortunately, the situation deteriorated in many of the children when they returned to their normal home lives. An increase in body weight that did not correspond to their growth in height occurred. However, after repeated stays at these camps, most of the children improved permanently and almost preserved normal body weight (Parˇ ízková 1977, 1993a,b). The mentioned changes were individual, depending on genetic predispositions (e.g., obesity of parents and siblings), the situation at home and school, duration of obesity, and so on. As followed from the life histories of obese children, the reaction to reduction treatment was related to the onset of a high fat ratio and/or obesity— children with higher birth weights and/or above-average body weights during preschool age had more difficulties losing weight and most of them regained weight (Parˇ ízková 1977, Parˇ ízková and Hills 2001, 2005). The treatment of children in the outpatient program of the central pediatric clinics in Prague used the same principles for weight reduction, that is, monitored diet, PA regimen and exercise, and behavioral intervention. The results were not as good or as permanent, even when improvement was observed. Everything depended on the family and the ability to adhere to the prescribed regimen within the family. The results of Koivisto et al. (1994) demonstrated that parental influences on children’s eating habits may have implications on special food preferences, which are not always adequate and may later lead to a higher fat ratio. The situation was also more difficult when there were some normal-weight siblings who ate at the same table. In this case, better results were observed in older children and adolescents, who were able to adopt the reduction regimen as their own program for which they were personally responsible. With smaller children this was generally impossible. As follows from the actual trends, it is necessary to consider ways of influencing even slightly overweight young children: the sooner the intervention, the better the results. Recently, similar reduction procedures with monitored diet and exercise programs have been used more often in schoolchildren and adolescents.

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249

MORPHOLOGICAL, FUNCTIONAL, AND BIOCHEMICAL CHANGES AFTER REDUCTION TREATMENT

Reactions to reduction treatment in preschool children have been less studied as compared to those in subsequent growth periods. Most studies concerned subjects during prepuberty and puberty, when obesity starts to become urgent from the point of view of health. This is now changing because timely interventions are becoming more successful and easier (Parˇ ízková 1977, Parˇ ízková and Hills 2001, 2005). Along with the decrease in body weight and BMI, body composition also changed after reduction therapy. Even when exercise and PA were included in the reduction program, a small proportion of weight decrease in obese schoolchildren was in LBM. This was found when using densitometry or when changes in body composition were assessed by regression equations with skinfold thickness values (derived for Czech children including the obese; Parˇ ízková 1961b, 1977). This decrease in LBM was obvious only when weight reduction was substantial, that is, in very obese subjects. As mentioned above, very obese children and adolescents are characterized by a greater LBM; hence, a small decrease may be tolerated. This applies especially when no functional deterioration was obvious, and the growth in height continued. Most of the anthropometric variables diminish too. This applies mainly to circumferential measures or to breadth values, which may be influenced by a layer of fat. Hence, it was difficult to evaluate changes in the skeleton. In very young children of preschool age, this therapy has been rarely applied in the Czech Republic. In overweight children, there has been an effort to reduce the weight increment, along with a further increase in height, so that the child “grows up” to his/her appropriate BMI. This trend is often applied in older children with elevated body weights. It would be difficult, however, to stimulate an adequate BMI when a child is grossly obese. Nuutinen and Knip (1992) studied the ability to predict weight reduction in obese 6–15-year-old children. After 1 year of treatment, those who successfully lost weight had a lower body weight, less LBM, and lower fasting concentrations of circulating insulin than unsuccessful children. A decrease in the mother’s BMI and in documented EI over the first year, as well as EI at 1 year were significant predictors of success therapy after 2 years. The combination of these three predictors resulted in the correct classification of about 75% of cases as either successful or unsuccessful weight losers. Preservation of the results of reduction treatment may be difficult, as shown by other studies (Sothern et al. 1994). Jirapinyo et al. (1992) followed 10 obese children 8–13 years old who participated in a 4-week program of weight reduction. A regimen of 800 kcal/day and mild exercise were the main features of this program. Mildly and moderately obese children lost more than 5% of their body fat and less than 1% of their LBM. Morbidly obese children lost more than 5% of their body fat and LBM. It was speculated that for the treatment of morbid obesity, a different sort of treatment must be considered, for example, spa treatment with exercise in a pool as mentioned above. Patients from the above-mentioned outpatient programs and summer camps were tested using a number of methods. First of all, aerobic power was checked before and

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after the reduction of excess fat in the summer camp. Along with somatic changes, the aerobic power, characterized by VO2 max (oxygen uptake during a maximal workload), increased significantly in a group of prepubertal boys from 38.8 to 40.7 mL/kg/min. Children were also able to run longer on the treadmill and finish the test after achieving a higher speed, that is, the whole performance was at a higher level along with a higher level of aerobic power. However, after only 7 weeks of reduction treatment in the summer camp, the VO2 max in mL/min/kg LBM remained the same (Parˇ ízková 1977, Parˇ ízková and Hills 2001, 2008). Oxygen uptake and pulse rate during a submaximal workload decreased significantly after weight and excess fat reduction. The same workload was thus executed more efficiently and economically. Vital capacity and performance in a number of disciplines (running for various distances, jumping, throwing, etc.) also improved significantly. After this summer camp, some children who were not able to run continuously for 50 or 60 m were able to cover it in a time comparable to that of the general child population (Parˇ ízková 1977). The results of skill tests also improved significantly, which was due to not only weight reduction but also simultaneous adaptation to a number of exercises that were unusual and not feasible for these children before (Parˇ ízková 1977). Along with weight increases, which happened in some children after their return home to their usual way of life, some functional tests also deteriorated. Many obese children underwent the above-mentioned treatment in summer camps repeatedly, and their functional capacity finally improved in spite of temporary fluctuation in their body composition and BMI (Parˇ ízková 1987). However, in 3–6-year-old children, there was no opportunity to follow changes in functional capacity after weight reduction. Huttunen et al. (1986) found a significantly positive impact of weight reduction on the level of physical fitness and aerobic power. In a group of 6–15-year-old children, 25 lost weight and their VO2 increased significantly from 44.2 to 47.1 mL/min/kg of LBM. Androgens also changed after reduction therapy (diet, exercise, behavioral intervention during 1 year) in 4–14-year-old children; dehydroepiandrosteronsulfate (DHEAS) correlated with BMI (Reinehr et al. 2005). More hormonal changes were seen after weight reduction treatment in adolescent obese youth (Šonka et al. 1993, Parˇ ízková and Hills 2005). More detailed information on young children is not available. In prepubertal children, no marked changes were found in the rest values of glycemia and essential fatty acid after weight reduction. However, the blood FFA level decreased to half its pretreatment value, that is, 0.613 mEq/L. Moreover, the reaction to a maximal workload was different, that is, the FFA level remained the same during the load and increased significantly after 10-min rest, in spite of the fact that its value was much lower after reduction treatment. Changes in the FFA level seem to indicate that the ability to mobilize and utilize FFA as a source of energy during the workload has markedly improved, because during the work the level of FFA did not decrease as before treatment. By contrast, after the work the level increased significantly. These results are consistent with the reduction of body fat that was utilized during exercise as fuel for muscle work and was, therefore, the most important part of the treatment (Parˇ ízková 1977).

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Serum lipids mostly decreased significantly after weight reduction—total cholesterol, TGs, LDL-cholesterol, and others. This was found in more follow-ups of children and youth (Nemet et al. 2008). Preschool children were not followed up after weight reduction.

8.10

GENERAL CONSIDERATIONS: ROLE OF OBESITY INTERVENTIONS FOR OPTIMAL DEVELOPMENT AT AN EARLY AGE

Past and present studies have shown that using an adjusted energy balance (with an energy output increased by exercise and by monitoring the EI by an adequate diet) is still the best way of ensuring desirable morphological, functional, metabolic, and biochemical situations of obese children during growth (Parˇ ízková 1977, Parˇ ízková and Hills 2001, 2005). The number of studies has recently increased, but they concern mostly schoolchildren and adolescents. This is because more serious degrees of obesity occur during these growth periods. However, evidence on delayed consequences of increased birth weight, or weight at the age of 1 year, and earlier AR with regard to the development of obesity later on in life show that attention to overweight and obese children should be paid much earlier. The same applies to preventive measures (Davies and Christoffel 1994, Parˇ ízková 1977, Parˇ ízková et al. 1984, Ray et al. 1994). During puberty many serious problems may appear due to obesity, including psychological ones; reduction treatment is much more difficult and often without lasting effects. Weight reduction is then achieved with a simultaneous decrease of LBM. This may not be of great functional harm in very robust and grossly obese subjects, although it is not desirable during this stage of development. Dietary treatment of obesity in childhood is incomparably more difficult, because any deficiency or too much of a reduced intake may cause a slow-down of growth in height and LBM. Compared to 30–50 years ago, the habitual PA of children and youth has decreased considerably. This is basically due to the drastic reduction in walking (to school, for some errands, etc.), the reduced availability of suitable play areas (parks, playgrounds, gymnastic halls, etc.), lack of free outdoor games with peers, and so on. Wallace (1994) researched this phenomenon in UK children, presenting it well in a TV program entitled “Our kids are not all right.” The lack of opportunity for the usual levels of PA in children is less natural than that in older subjects, having serious consequences in many respects, including a higher fat ratio, obesity, and a low level of cardiorespiratory fitness. Therefore, it is essential to provide ample opportunities for a high level of spontaneous PA from early childhood. The child can learn to move and exercise a lot, but he/she can also learn the opposite—that is, moving as little as possible (Koch 1977, 1978). Distractions such as sensationalistic TV programs interfere with the abovementioned pedagogic trends. In fact, children spend too much time in front of the TV, a situation that is true in the United States (Gortmaker et al. 1990) as well as in other countries. While watching TV children can actually reduce their metabolic rates when compared to the same conditions without TV (Klesges et al. 1993). Education has an essential role in early childhood obesity prevention and involves

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the whole family (Chen et al. 2008). Intervention with regard to nutrition and PA can have a significant effect in preschool age (Eliakim et al. 2007). Adequate possibilities, such as suitable locations for outdoor play areas, should be guaranteed (Ellaway et al. 2006). Other programs were also introduced (James et al. 2007) for improving the health outcomes (Kim et al. 2005). The best guarantee of high spontaneous activity is early imprinting of proper motor habits, partiality for and enjoyment of motion, and cultivation of a need for exercise. This may be ensured not only by teaching but also by supporting the development of a higher level of fitness that reduces the strain of exercise and renders it enjoyable (Council on Sports Medicine and Fitness 2006). All this is essential for the enhancement of natural interest and participation in exercise activities throughout life, which is provided by early intervention. PAs were quite natural not very long ago. However, today’s large cities and urban agglomerations are not constructed for healthy living and for the recommended level of PA. At the same time, adequate PA has been more and more emphasized as an indispensable preventive measure against obesity with all the accompanying comorbidities. There remains a question as to which measure would be more economical— providing adequate conditions for a healthy lifestyle, or spending more for medical care, earlier loss and/or reduction of economic productivity, and expected shortening of the lifespan.

9

Influence of Environmental Factors

9.1 INTRODUCTION The environment includes all sorts of influences of varying character, such as geographical, climatic, social, economic, cultural, familial, nutritional, lifestyle, and PA factors; human development can be significantly altered due to their interrelationships. Sensitivity to such factors may be modified by genetic predispositions, and eventually by early factors, which are responsible for the extent of the consequences. This applies especially to the period of growth, when the organism is more sensitive than later on in life. There have appeared, in the past, modifications due to developing and changing environments; their criteria and importance, set some decades before, may not be fully valid at the present time. The association of economic and social situations (SES) and dietary intake is evident in both industrially developed and developing countries. Analysis of the influence of the environment and its differentiation from hereditary factors is often quite difficult: for example, the economic situation of the family depends, at least partly, on selected genetic predispositions, educational level of the parents, number of children in the family, etc. Moreover, this varies in different parts of the world and in different countries, depending on local conditions as mentioned above. WHO criteria do not seem to be objective for all young children even in the same country, that is, in the United Kingdom (Wright et al. 2008). Hence, criteria for growth, BMI cut-off points for obesity, standard values for the fitness test, etc., have not been homogeneous and can vary significantly. Some consensus on growth criteria has been achieved only recently, and even this might not be quite definitive (Cole et al. 2000, 2007). As mentioned before, the values of BMI criteria of overweight and obesity in Asian or African subjects are lower than those in Western individuals. Overweight criteria may be very similar or identical, but for obesity they can be different (Wang and Wang 2002). Further, morphological, functional, body composition, and metabolic parameters can have different criteria and recommended standard values when they are compared in subjects of various ethnic and geographical environments. Changing environments in the same country influenced child growth and development significantly and also the prevalence of obesity, for example, after the reunification of Germany (Apfelbacher et al. 2008). SES influenced childhood obesity in Germany differently when comparing local and immigrant populations adapted previously to other conditions; the latter displayed more obesity (Kuepper-Nybelen et al. 2005). SES also influenced motor development in German children, that is, it was at a lower level in children with lower social level (Scheffler et al. 2004). 253

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Differences according to SES depend on a certain range, which has generally been difficult to define and has not been specified and homogenized in various countries until the present time. Westernization of dietary habits and nutritional behavior was observed in immigrants. For example, newborns from Chinese families living in France in the first generation were never breast-fed; after 12 months many adhered to their traditional diet and ate few dairy products and fresh fruit. New food has been introduced recently, and children were seen to consume a large number of soft drinks (RovilléeSausse 2005). Influences on diet and PA across three generations of Turkish, Greek, Indian, and Chinese population groups in Australia were observed, which also tackled the prevalence of obesity. Undernutrition at an early age, common in developing countries, has a decisive impact not only on somatic growth but also on physical fitness, especially when it is of intense degree (see Chapter 7). This was followed in greater detail, for example, in a growing Senegalese population; more severely malnourished children performed worse than well-nourished children from the Czech Republic. The differences were partly explained by changes in body size; after removing the effect of age and body size, differences between nutritional groups in some motor performance tests disappeared, but persisted in certain motor coordination items (Bénéfice 1990, 1995, Bénéfice and Malina 1996, Bénéfice et al. 1999, Bénéfice and Ndiaye 2005), etc. However, all comparisons showed that especially obesity has been increasing in most parts of the world, regardless of the criteria used (Jackson-Leach and Lobstein 2006). An obesogenic environment (including, for example, an energy-dense diet and reduced activity, also depending on TV and videogame viewing) is one of the main environmental factors responsible for increasing adiposity (see Chapters 5 and 8), because of reduced PA; this phenomenon applies to most countries in spite of their different geographical character (Chatrath et al. 2002, Parsons et al. 2005, Al-Hazzaa 2007, Al-Hazzaa and Al-Rasheedi 2007, Mondini et al. 2007, Kuriyan et al. 2007). Declines in cardiovascular endurance fitness performance across all the studied Asian nations over the past 10–15 years were revealed (Macfarlane and Tomkinson 2007), which was comparable to Western countries (Tomkinson et al. 2003; see Chapter 7). Selected child populations in, for example, Saudi Arabia displayed a growth pattern that is more similar to a US reference population than to a national population (Al-Rowaily et al. 2007), indicating the greater importance of social economic conditions and environment than ethnic and regional differences. The role of the environment was reported by parents with regard to intra- and interpersonal barriers related to healthy eating and PA among preschoolers: accessibility to healthy foods, media influence, weather, lack of safety, and inaccessible resources (Dwyer et al. 2003, 2008). The “food marketing Maelstro˝m” is one of the most inadequate environmental stimuli for children, and should be viewed as a societal issue and addressed as such. The restriction of unsuitable commercials and advertisements for children is common in industrial democracies other than the United States, and corrective actions are suggested for the government (Linn 2004). Up to now, a few studies have focused on the influence of the above-mentioned factors on the level of functional capacity and motor development in young children,

Influence of Environmental Factors

255

as related to somatic development. The similarities and differences between 4- and 5-year-old children from Flanders and United States were tested and evaluated using the movement assessment battery for children (Van Waelwelde et al. 2008). US norms were shown to be appropriate for 4-year-old Flemish children in spite of environmental differences, but some adjustments for special cases of 5-year-old children were needed. One of the most dangerous environmental factors is the radiation level. Kozlova (1998; personal communication) followed children from 6 to 17 years in an area of increased radiation (Korosten, Zhitomir district in the Ukraine) before and after the Chernobyl disaster. Her findings confirmed previous observations that small doses of radiation stimulate an increase in the heights and weights of children. Such a trend does not continue for more than 2–3 years, and thereafter a slow-down in the development of the child appears. This was confirmed by longitudinal observations of the same Ukrainian children for 3 years, that is, from 1990 to 1993. Long-term observations of children exposed to small doses of radiation revealed a higher level of vegetative lability, general weakness, apathy, and sleepiness, frequent headaches and colds, and a decreased efficiency and economy of the work of the heart muscle. Measurements of physical working capacity on the level of the heart rate 170 per minute (PWC170) showed a lowered level of functional capacity of children (Kozlova 1998; personal communication). In a large number of children, some deviations in the function of the cardiovascular system were observed, in addition to the enlargement of the lymph nodes and the thyroid gland. The latter becomes more serious with advancing ages of the children. An increased prevalence of thyroid cancer was followed from 1991 by experts of the WHO in the framework of the IPHECA project. Observations of children after the Chernobyl disaster have continued since 1990. Small doses of radiation seem to have a significant impact on children, which varies according to other interfering factors, including the level of PA. Special observations of preschool children have started in various countries recently. The problem of radiation was analyzed in further documents in greater detail (concerning environmental criteria in environmental epidemiology studies— International Program of Chemical Safety IPCS, WHO, Geneva 1986, and CEC 1986). In industrially developed areas, the influence of the environment is mainly related to one’s exposure to noxious factors (IPCS and CEC 1986). Usually the influence of various environmental factors is mixed, with the differentiation of one particular factor being difficult according to their mutual relationships and dependence. A few studies regarding the effect of the environment have focused attention on a greater number of aspects of growth and development simultaneously—not only basic anthropometric parameters and body composition but also motor development and performance, food intake, body posture, etc. An example of a growth study in preschool children with satisfactory nutrition was conducted (see Chapters 3 through 9) and evaluated from the point of view of environment in a satisfactorily developed country (i.e., the Czech Republic, where SES has been rather homogeneous).

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Nutrition, Physical Activity, and Health in Early Life

9.2 INFLUENCE OF LIVING CONDITIONS IN THE CAPITAL AND IN OTHER PARTS OF THE CZECH REPUBLIC 9.2.1

SOMATIC DEVELOPMENT AND BODY POSTURE

In survey B of a representative sample of preschool children 6.4 years old (i.e., measured in spring just before entering primary school), we compared the development of morphological variables, body posture, and motor and sensomotor development in subgroups of children from Prague, the capital, on the one hand, and from other parts of the Czech Republic, on the other hand. The BMIs did not differ (Table 9.1), but the average values of height, weight, and circumferential measures were, in almost all cases, significantly higher in children

TABLE 9.1 Heights, Weights, and BMIs in Preschool Boys and Girls from Prague and All Other Parts of the Czech Republic (Survey B) Prague Measurement Height (cm) Boys Girls Weight (kg) Boys Girls BMI (kg/m2) Boys Girls Circumferences Chest (cm) Boys Girls Abdomen (cm) Boys Girls Arm (cm) Boys Girls Thigh (cm) Boys Girls

x–

All Other Regions SD

x–

SD

120.3 118.4

5.6* 8.4

118.5 117.7

5.3 5.2

22.7 22.5

3.3* 3.4

22.1 21.6

3.2 3.3

15.7 16.1

1.2 1.4

15.7 15.6

1.2 1.3

60.1 59.2

3.3* 4.0

59.2 57.9

3.3 3.7

56.0 55.5

5.7* 5.3

55.2 54.8

4.3 5.0

18.3 18.7

1.5 1.9*

18.2 18.3

1.7 1.8

35.1 37.2

3.5 3.8*

35.5 37.2

3.5 3.6

Source: Adapted from Parˇízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a. Note: *p < 0.05.

Influence of Environmental Factors

257

from the capital. In both subgroups of children, there were obvious sex-linked differences, although slight, in the anthropometric variables, which in this large group were significant. However, all values of body size, BMI, etc., were within the standard reference values of the Czech Republic. Simultaneous assessments by questionnaires also showed a higher economic level in Prague children, in which the per capita income in the family was higher than in other parts of the country; however, these differences did not mean a significantly lower level of SES out of the capital. With regard to larger body size in Prague, the impact of increased stimulation of higher nervous activity in children, which accelerates their overall development, was also considered. A comparison of the results found in children from Prague and children from other regions in the Czech Republic (i.e., Bohemia and Moravia) reveals a clear trend of poorer body posture in the former. The depth of cervical and lumbar lordosis was significantly greater and the average data, that is, the position of the neck, abdomen, and spinal column, indicate a significantly higher ratio of grades 2 and 3 in Prague children (Parˇ ízková et al. 1984). When we evaluated body posture in the individual districts of the Czech Republic, which vary with environmental factors, the comparison showed that, apart from Prague, a relatively poorer posture was recorded in boys and girls from the central Bohemian region. In other parts of the republic, the highest average values of cervical and lumbar lordosis were rarely found in the remaining regions, for example, mainly in the south Moravian and north Bohemian regions. Regarding the depth of cervical and lumbar lordosis, high average values were recorded in the north Moravian region, where the children also had a more accelerated somatic development. As in Prague, a higher per capita income in the north Bohemian region was recorded. On the whole, the differences among regions were not very marked, although a trend for poorer body posture in children from Prague, or in more industrialized districts such as central and north Bohemia, was obvious. A comparison of our results with those assembled two decades ago revealed that the average value of cervical and lumbar lordosis increased. This may be explained by an accelerated growth rate, along with an increase in bodily dimensions of children of equal age in comparison to then and now. We must also speculate on the possibility of a certain deterioration in body posture, which results from greater weakness of the skeletal muscles. This is more marked in the capital, where the opportunity for spontaneous PA, games, physical education, and exercise may be more limited (at present, however, it seems that even when space is available for games and exercise in smaller communities, it is not utilized). Flabbiness of muscles is manifested most markedly on the abdominal wall, where the highest ratio of grades 2 and 3 in the capital was recorded.

9.2.2

MOTOR AND SENSOMOTOR DEVELOPMENT

Motor performance was tested using the same protocols as mentioned above (see Appendix 3). The performance level in children from Prague and the remaining parts of the Czech Republic was compared in a similar fashion as anthropometric variables and body posture. Performance levels in running, jumping, and throwing a ball with both hands are given in Figure 9.1a–d. Performance was better in boys, and

258

Nutrition, Physical Activity, and Health in Early Life (a)

* 6.4

s

6

5.6

5.2

Prague

All reg. exc. Prague

cm

(b) 109 108 107 106 105 104 103 102 101

Prague

All reg. exc. Prague

(c)

*

1100

cm

1000 900 800 700 600 500

Prague

All reg. exc. Prague

Prague

All reg. exc. Prague

(d) 1100

cm

1000 900 800 700 600 500 Boys

Girls

FIGURE 9.1 Comparison of physical performance: 20-m dash (a), broad jump (b), throwing a ball with the right hand (c), and throwing a ball with the left hand (d) in 6.4-year-old boys and girls living either in the capital of Prague (1.2 million inhabitants) or in the rest of the Czech Republic (survey B). *Stat. significance of differences p < 0.05.

Influence of Environmental Factors

259

tests characterizing skill showed statistically better results in girls. Only in one (the last) variety of catching a ball (i.e., throwing it vertically above the child, who catches it from the air; Appendix 3) were boys slightly better. All these differences, although small, were statistically significant (Parˇ ízková et al. 1984). Comparing the motor performance in children from Prague with that in children from other regions of Bohemia and Moravia reveals poorer results in Prague boys and girls in the 20-m dash, that is, a longer time in seconds (Figure 9.1a). Performance in the broad jump was also somewhat worse in Prague children (although not significantly), despite the fact that Prague children were taller and thus had longer lower extremities (Figure 9.1b). Performance in throwing a ball was also significantly worse in Prague (Figure 9.1c and d). In tests of walking on a beam and standing on one leg, there was a certain trend toward better performance in boys and girls from Prague, but the differences were not significant. With respect to the forward roll, the performance of Prague boys was significantly poorer. However, in girls these differences were smaller and not as significant. The other results did not differ significantly (Parˇ ízková et al. 1984). The evaluation of individual regions showed that the best results in running, jumping, and throwing were recorded in the south Moravian region. A relatively good performance was also recorded in the east Bohemian region. The majority of children examined in these regions were from smaller cities and villages. On the other hand, the poorest performance in these disciplines was recorded not only in Prague but also (regarding running) in, for example, the central Bohemian region, which is characterized inter alia by a higher level of pollution. The other tests gave varied results. In Prague and in other parts of the Czech Republic, differences in the level of sensomotor development are contradictory: Prague children have a trend toward better results than children from other parts of the country. In four instances, Prague boys performed significantly better in the tests of “opening and closing the hands.” In all six cases Prague girls performed better. Prague girls were significantly better in spatial orientation, and boys did not differ. Prague children were also significantly better in the laterality test. In the comparison of sensomotor tests in individual regions, the results were always the best in Prague. Relatively good results were observed in the north Bohemian region, which is highly industrialized and therefore has a family per capita income that is higher than anywhere else. Better results were observed in the last subtest of “opening and closing the hands,” which is the most difficult one. In this case, the performance of north Bohemian boys and girls is better than that of Prague children. The results of children from other regions were worse, and there are no further differences among these regions. Similar conclusions can be drawn from the results of tests of spatial orientation and laterality: the best results were found in children from Prague and the north Bohemian region. The differences between other regions were not marked. In addition, children from the representative sample of survey B were divided into five categories of cities and localities according to the population number so as to show the influence of the size of communities in greater detail. A total of 11.4% lived in communities with less than 1000 inhabitants, 32.0% in those with less than 5000

260

Nutrition, Physical Activity, and Health in Early Life

inhabitants, 34.8% in those with less than 20,000 inhabitants, 11.4% in those with 20,000–100,000 inhabitants, and finally 14.2% in cities with more than 200,000 inhabitants. Sociological factors varied according to the size of the community: the lowest per capita income was found in communities with less than 1000 inhabitants. The larger the town, the higher the income, and obviously the higher the standard of living of the family. It may be assumed that this also includes a better dietary intake and a higher EI. However, these differences may also be due to the fact that in small communities the families were larger, that is, with more children, compared to families from towns. In small communities, there were also fewer broken and divorced families than in larger towns. Body height was most closely related to the size of the particular locality (Figure 9.2). Body weight and BMI did not show as clear a relationship as circumferential measures. The thigh circumference was, on the contrary, smaller in boys from larger towns. This seems to be associated with the greater linear constitution of boys in larger towns. In smaller communities there was a trend toward better body posture and lower values of the depth of cervical and lumbar lordosis. These differences were most marked when children from smaller communities were compared with children from larger towns and from Prague. There was a trend toward better motor performance in children from smaller communities than in children from larger towns (20-m dash, throwing a ball). Skill and sensomotor tests were accomplished successfully by a somewhat greater percentage of children from large towns; however, these differences were not marked and significant (Parˇ ízková et al. 1984). Another study of 200 preschool children from Prague and from a smaller community in an area under the mountains showed worse results in the development of gross motorics in children from the capital (Kárniková 1983).

Boys Girls

cm

119

117

115 >1000

>5000

>20,000 >100,000 Number of inhabitants

<200,000

FIGURE 9.2 Comparison of height in boys and girls 6.4 years old from localities with different numbers of inhabitants (survey B).

261

Influence of Environmental Factors

9.2.3

INFLUENCE OF LIFESTYLE ON FOOD INTAKE, BLOOD LIPIDS, AND PERFORMANCE

Another more detailed survey (I) was made separately in groups of preschool children from a small town in central Bohemia (16,000 inhabitants; Nymburk) and in Prague (survey J; n = 37). Because no significant sex-linked differences were found in any of the variables studied, boys and girls were evaluated together, both in Prague and in Nymburk. Blood sampling did not permit investigations in larger groups. Figure 9.3a shows the comparison of anthropometric variables in both groups. As in other surveys, children from Prague were slightly but significantly taller and heavier than children from Nymburk, along with a greater deposition of fat. Food intake also differed according to locality: the intake of energy, proteins, fats (total, animal, plant), carbohydrates (Figure 9.3b–e), minerals, and vitamins (Table 9.2a) was higher in Prague children. (a) 25

* Capital Small town

* 20

* 15

BMI (kg/m2)

Weight (kg)

Depot fat (%)

(b)

*

10,000

KJ

9000 8000 7000 6000 Capital

Small town

FIGURE 9.3 Comparison of somatic development (a), intake of energy (b), protein (c), fat (d), carbohydrate (e), and blood lipid level (f), that is, total, HDL cholesterol, and TGs, in a group of preschool children living either in Prague or in a small town (survey I). *Means statistical significance of differences, p < 0.01.

262

Nutrition, Physical Activity, and Health in Early Life (c)

* 70 Plant (g) Animal (g)

60 g

50 40 30 20

Capital

Small town

(d)

*

100 90

Plant (g) Animal (g)

g

80 70 60 50

Capital

Small town

(e) 300

*

g

250

200

150

Capital

Small town

(f) 5

Capital Small town

mmol/L

4 3

*

2 1 0 TC

FIGURE 9.3

(Continued)

HDL

TG

263

Influence of Environmental Factors

TABLE 9.2a Intake of Minerals and Vitamins per Day in Preschool Children from Different Localities in the Czech Republic C

Minerals Ca (mg) Fe (mg) Vitamins A (μg) B1 (mg) B2 (mg) PP (mg) C (mg)

x–

S SD

x–

SD

750 9.6

208* 1.8*

527 7.3

215 1.6

1091 0.9 1.2 12.0 68

378* 0.1* 0.2* 2.1* 50**

734 0.7 0.8 9.4 22

240 0.1 0.2 1.7 9

Source: Modified from Parˇízková, J., unpublished data, 1986–96. Note:

*p < 0.01; **p < 0.05; C, capital; S, small town.

Physical performance in the broad jump and ball throw was significantly better in Nymburk children (Table 9.2b), which might be the result of better opportunities for games and spontaneous PA in a smaller community compared to a larger urban agglomeration. On the other hand, Prague children of this particular group participated more often in some sort of organized physical education (which was in contrast to the results of representative sample B). In this case the results of the 20-m dash were also the same, showing that dynamic performance was not influenced by lifestyle at this age (Table 9.2b). In conjunction with this, the level of serum lipids was compared. The level of total cholesterol and TGs was the same, but the level of HDL was significantly higher in

TABLE 9.2b Motor Performance in Preschool Children from Different Localities in the Czech Republic C

20-m dash (s) Broad jump (cm) Ball throw (cm)

x– 5.1 84 489

S SD

x–

SD

0.6 8 173

5.1 97 632

0.5 17 236

Source: Adapted from Parˇízková, J., unpublished data, 1986–96. Note: C, capital; S, small town.

264

Nutrition, Physical Activity, and Health in Early Life

Prague children (Figure 9.3f), with the level of ApoB being significantly lower. Obviously, factors other than lifestyle also influenced a more favorable blood lipid spectrum of Prague children. The results of this particular survey seem to indicate that more exercise in a smaller city can improve skill, but not dynamic performance, for example, running. Therefore, serum lipid levels are not more favorable.

9.2.4

BODY SIZE AND FUNCTION: IS BIGGER ALSO BETTER?

The accelerated somatic development of Prague children is consistent with findings in other countries where children from large urban agglomerations attain mostly larger body size at a given age than children from small towns and rural areas. The same applies to children from the north Bohemian and north Moravian regions, which have more industries and hence a higher level of per capita family income. (It is important to mention that even the lowest values of factors such as body height, BMI, etc., were still within the values of national standards and centiles for height, weight, and BMI. Lower values did not imply retarded development.) Larger body sizes, however, did not ensure better development of other variables, as indicated by the evaluation of body posture or performance in selected disciplines. There was a much higher percentage of children with poorer body posture from Prague than from other regions. The more marked cervical and lumbar lordosis could be associated with larger body sizes, while a greater incidence of factors such as flabbiness of the abdominal wall or unequal height of the shoulders is associated with other causes, among them reduced muscular tone and general weakness of the skeletal muscles. As shown by the questionnaires, participation in organized physical education (especially for children together with their mothers and/or fathers; see Chapter 10), as well as the opportunity for spontaneous PA in Prague, was—in this group of preschool children (survey B)—lower than that of children in other regions of the Czech Republic. Prague children obviously had more favorable prerequisites regarding the development of skill and coordinating abilities as shown by the better results in some sensomotor tests. However, without proper stimulation and ample opportunity for exercise, the potential for the development of a higher level of motor abilities was not realized, as seems to be the case in children from other regions of the Czech Republic. On the other hand, accelerated somatic development cannot be considered an impediment to physical efficiency because children from the north Moravian region, where somatic development was also accelerated, also had a higher level of performance. Larger body size alone, however, does not predispose children to a higher level of motor performance. A higher level of economics ensured a better quality of dietary intake in Prague children. The opportunity to exercise improved skill in a smaller town, but did not yet improve dynamic performance in running, that is, cardiorespiratory fitness. Therefore, in spite of higher values of anthropometric variables and increased EI, along with a different composition of diet, the blood lipid spectrum was more favorable in Prague children, that is, the HDL level was higher.

Influence of Environmental Factors

265

9.3 ECONOMIC LEVEL AND BIRTH RANK In our studies, the economic situation was related to the size of the community and to the characteristics of the particular region of the Czech Republic. The influence of extreme differences in the economic level of the family could not be demonstrated, but smaller differences during shorter exposures, were obvious (Parˇ ízková et al. 1984). Children of survey B from families with the highest average per capita income were the tallest and the heaviest, and also had the highest values of some other anthropometric variables. Children from families with the lowest per capita income were the smallest. However, all these values were within the range of standard values of the Czech Republic and/or of international standards. Again, BMI did not vary markedly. The somewhat smaller body sizes of children from families with a lower economic standard do not imply poorer physical performance. On the contrary, comparisons showed that taller and heavier boys from families with the highest economic standard ran worse than boys from families with the lowest income. A similar trend was also found in girls, although the differences were not statistically significant. There were no significant differences among groups in throwing the ball. Bigger children from better-off families were not predisposed to a higher level of physical fitness and performance in gross motorics tests compared to children with smaller body sizes (Parˇ ízková 1978c, 1980, Parˇ ízková and Heller, 1991). This applies, however, only within certain limits, in a country without malnutrition and larger differences in body size; moreover, at that time obesity among children was lower. In relation to the influence of birth rank, firstborn children were usually taller and heavier than children born later. Therefore, our representative sample of children 6.4 years of age (survey B) was also examined with this in mind. Somatic, motor, and sensomotor developments in groups of children born as first, second, and up to the fourth to the 15th in the family were compared. It was confirmed that children born first were taller and heavier. BMIs did not differ markedly according to birth rank (Parˇ ízková et al. 1984). When the level of physical performance was compared, boys from the most extremely differing subgroups (i.e., born as the first and/or the fourth to the 15th) were roughly equal. Smaller girls born later in the family were significantly better regarding performance than bigger, firstborn girls. Firstborn children (also often the only children in a young family) attended kindergarten more frequently and participated more in organized physical education (special physical education classes of children with mothers and/or fathers, etc.). In these children, there was a trend toward better results in the “open and close the hands” test along with better results in testing orientation and laterality (Parˇ ízková et al. 1984). However, even under all these conditions, these firstborn children, who seemed to be better predisposed to larger body size and a higher level of sensomotor development, did not achieve a higher level of physical performance.

266

Nutrition, Physical Activity, and Health in Early Life

9.4 ENVIRONMENT, RISK PREGNANCY, FAMILY CONDITIONS, AND HEALTH In another similar sample of preschool children aged 4–6 years (survey D; n = 9587) the influence of a number of factors was tested, including the degree of air and water pollution (as related to the conditions of life in different districts of the Czech Republic), risk pregnancy, birth weight, and health problems at the beginning of life, resulting in the need for regular medical checkups during the first year. Further aspects were also examined, for example, the beginning of independent walking of the child, family conditions, and the level of education and qualifications of the parents. Table 9.3 shows a relatively high prevalence of risk pregnancies and a prevalence of children who were not really sick but had to be checked regularly by a medical doctor up to the end of the first year. About 5% of the children wore glasses at preschool age. The results on number of siblings, duration of attendance at the daycare center, and participation in physical education are given in Table 9.3. The children were evaluated in groups according to the above-mentioned variables and divided into two subgroups according to age, that is, up to 5 years and older.

TABLE 9.3 Prevalence of Risk Pregnancies, Medical Checkups of Children until the First Year of Life, Start of Independent Walking until the End of the First Year, Wearing of Glasses (Percent of Children), Number of Siblings, Years at the Day-Care Centers and Number of Hours Spent There Per Day, and Years of Physical Education (Absolute Values, Years, Hours; Survey D) Age (Years) 4–5 Risk pregnancy (%) Medical checkup (%) Start of walking (%) Glasses (%) Number of siblings Years in kindergarten Hours per day Years of physical education

x– SE x– SE x– SE x– SE

Boys 22.8 26.0 62.1 5.1 0.97 0.01 1.91 0.01 7.66 0.03 1.04 0.04

5–6 Girls 28.3 26.0 64.3 4.2 0.99 0.01 1.89 0.01 7.56 0.03 1.02 0.03

Source: Parˇízková, J., unpublished data, 1986–96.

Boys 23.0 21.9 64.6 4.8 1.07 0.01 2.55 0.01 7.44 0.02 1.08 0.03

6–7 Girls 23.9 22.6 65.9 5.7 1.07 0.01 2.52 0.02 7.47 0.02 1.31 0.08

Boys 23.9 22.3 61.1 6.9 1.12 0.03 3.04 0.04 7.54 0.05 1.32 0.08

Girls 23.5 22.7 66.1 7.2 1.09 0.03 3.00 0.04 7.47 0.05 1.48 0.06

267

Influence of Environmental Factors

TABLE 9.4 Motor Development in the Subsample of Preschool Children (Survey D) Age (Years) 4–5

N 20-m dash (s) 500-m run (s) Broad jump (cm) Ball throw—right (cm) Ball throw—left (cm)

x– SD x– SD x– SD x– SD x– SD

5–6

6–7

Boys

Girls

Boys

Girls

Boys

Girls

138 6.6 1.8 219.2 41.1 87.8 17.6 618.5 232.2 444.3 187.2

158 6.9 1.7 231.3 44.7 84.0 18.3 467.3 148.3 372.6 122.6

301 6.3 1.7 201.0 47.3 100.4 20.2 800.7 308.6 560.6 216.9

267 6.2 1.6 208.1 45.7 95.5 19.8 600.6 229.5 462.2 162.7

67 5.7 1.4 183.3 40.4 110.6 17.0 938.9 304.9 638.2 239.3

74 5.8 1.4 188.7 32.3 106.2 17.4 639.4 146.7 523.8 193.6

Source: Modified from Parˇízková, J., unpublished data, 1986–96. Note: n = 1005.

A subsample of 1005 children was examined by teachers and physical education instructors in greater detail with respect to both somatic and motor characteristics (see Tables 4.6a,b, and 9.4). Analysis of variance and hierarchical loglinear analysis showed that, except for birth weight, the influence of the factors mentioned above was not manifested significantly in the variables assessed at 4–6 years of age.

TABLE 9.5 Birth Weight (g) of Children Examined at the Age of 4–6 Years (Categories 1–5) Boys Category 1 2 3 4 5

Girls

x–

SD

n

x–

SD

n

2220 2925 3440 3895 4519

305 166 141 145 253

33 126 186 136 24

2111 2835 3288 3741 5234

311 153 153 139 189

23 111 220 120 25

Source: Adapted from Parˇízková, J., Nutrition in Pregnancy and Growth, S. Karger, Basel, p. 109, 1996.

268

Nutrition, Physical Activity, and Health in Early Life (a)

5

125 4

cm

115

3 2

105 1

95 I Boys II

I Girls II

kg

(b)

5

25 23 21 19 17 15

4 3 2 1 I Boys II

I Girls II

(c)

5

64

4

cm

60

3

56

2

52 48

1 I Boys II

I Girls II

FIGURE 9.4 Comparison of height (a), weight (b), chest circumference (c), waist circumference (d), hip circumference (e), and throwing a ball with the left hand (f) in younger (I < 5 years) and older (II > 5 years) boys and girls born with different birth weights (five categories; see Table 6.4; survey D).

However, in survey A occasionally significantly positive correlations were found between the period of breast-feeding, the length measurements of the lower extremities, and the circumference of the abdomen and arm. The onset of independent walking correlated significantly with circumferential measures on the trunk (Parˇ ízková et al. 1984).

269

Influence of Environmental Factors (d)

5

60 4

56 cm

3 2

52 1

48 I Boys II

I Girls II

cm

(e)

5

68 64 60 56 52 48

4 3 2 1 I Boys II

I Girls II

(f)

5

700 4

cm

600 3

500 2

400 300

1 l boys ll 1

FIGURE 9.4

2

l girls ll 3

4

5

(Continued)

9.5 EFFECT OF BIRTH WEIGHT In the Czech Republic, very low birth weight can occur in pathological situations; such children were not included in our samples. All children were full term, and their birth weight depended mostly on nutritional status, present food intake, and PA of the mother. Children of survey D were divided into five subgroups according to their

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birth weights (Table 9.5). The average values of weight, height (Figure 9.4a and b), z-scores for height and weight, and circumferential measurements (chest, waist, and hips; Figure 9.4c through e) varied significantly according to birth weight, that is, children born heavier showed proportionately larger body sizes at the age of 4–6 years. Analysis of this variance showed that BMI did not differ significantly according to the birth weight category, but only according to age (Parˇ ízková 1996). In survey A similar results were found, that is, birth weight correlated significantly positively with circumferential measurements of the head, chest, abdomen, forearm, thigh, and length of the iliospinale-tibiale of children 3–6 years of age (Parˇ ízková et al. 1984). In spite of more marked morphological differences following different birth weights, the level of gross motor development was much less influenced at the age of 4–6 years. Analysis of variance showed significant differences according to birth weight only in the left hand ball throw, which was longer in children with higher birth weights (Figure 9.4f). Similar differences in the right hand ball throw were not significant. It was assumed that throw performance with the right hand could be influenced by previous training. Performances in the 20-m dash, broad jump, and 500-m run-and-walk were not related to birth weight and actual body weight and BMI (Parˇ ízková 1996). Most children were not yet differentiated with regard to handedness at this age. The results of the balance test (standing on one leg for 10 s) were better in girls born and remaining heavier. Occasionally, a trend appeared toward better results in other skill, sensomotor, laterality, and orientation tests in children with greater birth weights (Parˇ ízkovà 1996). There is the question of whether these differences will accentuate later on or not. This will surely depend on the following environmental (and other) factors and influences.

9.6 EFFECT OF FAMILY SITUATION In survey D, the influence of family situation was analyzed in the whole sample (boys n = 4822; girls n = 4765), where the level of somatic development was evaluated. Children were subdivided into four subgroups: 1. 2. 3. 4.

Complete family without any problems (boys 89.9%; girls 90.6%) Broken family (divorced or separated parents; boys 6.8%; girls 6.4%) Family with a stepfather (boys 3.1%; girls 2.7%) Family with a stepmother (boys 0.2%; girls 0.2%)

The parents of the children were young and had been married for a short period of time; hence the ratio of divorced or separated parents (which is now >50% in the capital and about 35% in the rest of the country) was low. First, BMI, the level of height and weight development (expressed as deviation from the 50th percentile), and the proportionality of somatic development were evaluated in the individual subgroups. When all the children were evaluated together, a significant influence of family situation was apparent in the growth of height and weight: children from complete families (subgroup 1), that is, those with the best family situation, were mostly

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advanced in growth. BMI and proportionality were not significantly influenced. When evaluating boys separately, only body weight was significantly higher in subgroup 1. In girls, only height was significantly higher in subgroup 1. Children of subgroup 4 (with a stepmother) were always ranked as last, then came children from families with a stepfather, followed by children from broken families. However, the differences among subgroups 2 and 4 were not significant. As mentioned above, the distribution of children in individual subgroups was unequal, because in younger couples married for a shorter period of time divorce was less frequent. All these children were within standard values and norms for the Czech Republic; nevertheless, these slight differences were significant. With regard to the level of physical performance, which could only be followed in a subsample of 1005 children, the influence of family situation, on the whole, was not significant. A trend for better results in children from complete families (subgroup 1) appeared. Results in some disciplines (throwing a ball) tended to be better in children with stepfathers, although these differences were not significant.

9.7 EFFECT OF EDUCATION OF PARENTS Children of survey D (for the number of children, see above) were also subdivided according to the educational level of their parents: 1. 2. 3. 4.

Basic level Skilled manual worker High school with higher school certificate University education

Regarding the educational level of fathers, the percentage of children in individual subgroups was as follows: 1. 2. 3. 4.

Boys 5.9%, girls 5.6% Boys 55.5%, girls 53.85% Boys 23.9%, girls 24.92% Boys 14.7%, girls 15.54%

Regarding the educational level of mothers, the percentage of children in individual subgroups was as follows: 1. 2. 3. 4.

Boys 11.9%, girls 11.9% Boys 37.4%, girls 36.5% Boys 40.7%, girls 41.3% Boys 9.9%, girls 10.3%

Children varied significantly according to the level of education of fathers in BMI, height, and weight: growth in height and weight was accelerated in subgroup 4 (fathers with the highest level of education), and the BMI in this subgroup was the

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lowest. When evaluating boys and girls separately, the differences were the same (the differences for boys were significant for BMI and height only). The influence of the educational level of the mother was similar—boys and girls were slightly, but significantly, taller and heavier and had a lower BMI. Growth was accelerated especially in children with a father from subgroup 4 and a mother from subgroup 3. These results indicate that children of parents with this level of education (which, however, has not been related to economic level in the Czech Republic) are more advanced in height and weight development and are more slender. All variables, however, were again within national standards and centiles. Regarding physical performance, the results in the 20-m dash were significantly better in children whose fathers had a higher level of education (subgroup 4). There was also a trend for better results in the 500-m run and broad jump in children of the same subgroup. The level of education of mothers did not show any significant influence on the level of physical performance in the subsample of 1005 children of survey D.

9.8 HEALTH STATUS OF CHILDREN The following analysis in survey D concerns the influence of health status and morbidity of children in survey D. Subgroup 1 included children who were sick rarely or not at all (boys 6.4%, girls 7.4%); subgroup 2 included children who were occasionally sick (boys 85.5%, girls 86.6%, which has been most frequent in the normal child population); subgroup 3 included children who were sick quite often (boys 5%, girls 4%); and, finally, subgroup 4 included children with some chronic health problems who needed permanent medical checkups (boys 2.7%, girls 2.0%), but could attend day-care centers with other children. When evaluating all the children together, no significant differences in growth and BMI were evident. When evaluating boys alone, BMI was lowest in subgroup 4 compared to subgroups 1, 2, and 3; only subgroup 2 differed significantly from the others. In girls, no differences were observed. With regard to the level of physical performance, a trend toward better results in subgroups 1 and 2 was not significant, perhaps because the number of children in subgroups 3 and 4 at individual age levels was too small. It is necessary to emphasize, however, that in this survey (D), as in other surveys, no children with really serious health handicaps were included.

9.9 GENERAL CONSIDERATIONS In early childhood, the influence of various stimuli in the environment, which were within common range and intensity, was usually not manifested markedly because of short exposure times. This is of course different when more marked differences in environmental condition influence the development of the population of children, which was referred with regard to, for example, SES. It was not possible to follow this up in the Czech Republic due to lack of more marked SES differences. There were some smaller morphological and motor differences between children living in the capital and in the rest of the Czech Republic (especially in smaller rural communities) and/or between children from parents with the highest and/or lowest

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level of education, children from complete or divorced families, and children from families of various economic levels. Also, the birth rank of children in the family and the years spent in kindergartens had a small but significant effect with regard to certain parameters (survey B). Even when all the results were within the range of standard values, differences were in some cases significant, demonstrating the effect of environment, which is generally normal. The influence of birth weight in a country with rather homogeneous SES conditions (which depends, under physiological conditions, on the mother’s size and nutritional status as a delayed effect; see Chapter 3) was more evident by preserving bigger body size along with better results in a few motor and sensomotor tests than the influence of family lifestyle in different districts of the Czech Republic, characterized by conditions such as air and water pollution. The same applies to risk pregnancy, family situation (broken and/or divorced families), common morbidity, start of independent walking, and the necessity for regular medical checkups. The situation in Czech countries was therefore not socially differentiated enough— especially with regard to SES—to show more marked environmental influences. A comparison of preschool children in this country and Senegal, or in other countries such as Turkey, demonstrated significant differences in selected aspects (Chapter 7). This was associated with economic, social, nutritional, and cultural differences, in addition to possible various ethnic characteristics of a particular population. In connection with these differences, especially dietary intake—total amount of energy and composition of diet—was essential, which resulted in various growth and developmental levels of the functional and motor faculties. When the whole group of survey D was analyzed globally, children born with higher birth weights remained bigger, started to walk earlier, had a lower rate of morbidity, showed better results in a few motor and sensomotor tests, and wore glasses less often. Enrolment in regular physical education was less frequent in children who were born and remained smaller in body size. All this testifies to the significant early effect of environmental factors on the organism during the fetal period itself. Other factors concerning environment, including the conditions of life in different parts and districts of the Czech Republic and/or of the family, did not show any significant influence at this age. Even so it may be speculated that after a long period of exposure to more polluted air and water (e.g., in the north Bohemian districts), some somatic and functional variables may change later on in older children. However, at preschool age, this was not yet apparent, and has also not been found in older children. This may be because individual factors of the environment were not marked and significant enough to change the measured parameters, and also because other factors that could have influenced the measured parameters significantly were not evaluated. It was also found that the prevalence of inborn defects did not differ in various regions of the Czech Republic differentiated by the degree of air and water pollution, which has not been, however, critical or dangerous, but different in various parts of the country. This mostly concerns inborn defects that develop during later periods of pregnancy (i.e., defects of the brain, which could also be manifested in motor development). Specialists from the Institute of Experimental Medicine of the Czechoslovakian Academy of Sciences (who studied these problems in greater detail)

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explained this by a possible perishing of the imperfect embryo during certain early periods of pregnancy, especially during the initial period. This is not always registered or even correctly recognized, which may apply to the more heavily polluted region of northern Bohemia. Babies, in spite of being born out of risk pregnancies but at full term, were obviously less affected by the environment, and thus no marked deterioration of the somatic and motor development was observed in these children at 4–6 years of age in any region of the Czech Republic. Also, children who should have been followed up until the end of the first year because of some health problems did not show any changes in somatic or motor development at the age of 4–6 years. At present, the situation of the Czech Republic with regard to pollution has improved significantly. However, selected results show that even at an early age, the consequences of certain differences in the conditions of life can manifest themselves significantly before achieving school age. This is important from the point of view of the education of children, possible rectification of some defective conditions with regard to possible improvements, and/or elimination of negative factors.

10

Influence of Motor Stimulation, Physical Education, and Spontaneous Physical Activity

Exercise of man ought to begin in the spring of life, i.e., during childhood. All teaching ought to be divided according to the degrees of age, so as not to have something to learn what is not acceptable for understanding. — J.A. Comenius (1592–1670)

10.1 INTRODUCTION In the complex of all factors that influence the growth and development of children from birth until adulthood, the level of motor stimulation and physical activity (PA) is one of the most important. A small child can learn to be active, skillful, and efficient or can learn to become the opposite—unwilling to move, thus remaining clumsy and easily tired. In this respect, early stimulation plays an essential role. For those with favorable genetic endowment for skill and other motor predispositions, an optimal level of PA is easier and more acceptable, but through proper education all children can achieve a desirable level for health. Geneticists usually recognize three main genetic dispositions—for music, mathematics, and “acrobatics”—that is, an optimal neuromuscular coordination suitable for exercise. A child learns best through imitation. Therefore, the role of the mother and father and of the whole family is important: children learn to imitate before they know how to act. The example set by those around them can be either encouraging or discouraging. The development of children in all age categories shows large interindividual variability, as demonstrated by the above-mentioned morphological and functional measurements. The level of motor ability is an important indicator for the overall development of the child, as defined and described by a number of authors (e.g., Koch 1977, 1978, Wolanski and Parˇízková 1976, Cooper 1991).

10.2

MOTOR DEVELOPMENT OF INFANTS

There are two kinds of movement for children: (i) spontaneous movements, which are made by the child without any external stimulation, and (ii) directed, learned 275

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movements, adapted to the physiological and functional abilities of the child during individual periods of life. The starting point for directed movements is spontaneous movements. During the first period, a trend has been established to give the child enough room to move, keeping him/her in a free sleeping environment and permitting just enough spontaneous movement. Crying is also quite a vigorous physical exercise for an infant. As mentioned before, conditioned reflexes, including motor reactions, can already be elaborated in infants. At the age of 3–5 months, a reflex for a conditioned turning of the head to a sound stimulus was elaborated (Papousek 1961, Papousek and Papousek 1975, 1979). Therefore, the character of stimuli and their eventual regular repetitions during this early period may be important. The infant period until the end of the first year is characterized by a marked and fast development, that is, an increase in weight and other bodily dimensions. The nervous system develops remarkably, and signs of cerebral cortex activity and of individual senses—sight, hearing, and touch—appear. All that a child learns at this time is a starting point for further learning and progress (Koch 1977, 1978). Some facilitation of motor development in normal healthy children may be introduced. Special activities and games, that is, a system of motor stimulation of the infant, were elaborated to promote motor development of the child, for example, by Koch (1977, 1978). In conjunction with this, it is necessary to point out once more that the influence of motor stimulation and activity in early childhood goes beyond motorics. There are many inborn reflexes, such as searching, grasping, sucking, swallowing, and crawling. In infant “gymnastics,” position reflexes can be used. When an infant is raised, held under the armpits, and bent forward, the head always takes a position facing forward, and the extremities are also raised. This is already apparent during the first month of life. Orientation reflexes also exist, helping the infant to become familiar with his/her surroundings. Education during the first month of life aims to facilitate infant contact with the environment. The infant can be taught that certain signals have a certain meaning. Fixation of sight on a certain object can be taught at the age of 1 month. The human voice is the best sound stimulus and should also express some meaningful signal. Slight signs of contact with the environment at the second and third months are already apparent. When the child lies on his/her back, the upper and lower extremities are bent, fists are closed, and the head is turned to one side (during the earliest period of life, the activity of flexors prevails). Motions are more fluid and softer. During the second to third month, the infant is able to raise his/her head and turn it to both sides when lying on his/her tummy; he/she can also lean with both hands on the ground, and neck lordosis starts to develop. The infant plays with his/her hands and observes the surroundings. Visual contact and movement of the neck can be established with the help of a colorful toy. The infant is left free to move spontaneously during more prolonged periods as well as while bathing in a bathtub. The infant starts to reach for objects, and motions become more intentional. The kicking of the legs is more energetic.

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During the second to third month, the infant learns to fix his/her sight on one object and tries to follow it during its movement in all directions. The movement of the eyes is followed by the movement of the head. In the second month, the infant starts to seek the source of a certain sound with his/her eyes and eventually finds it. The infant calms down and displays satisfaction on hearing his/her mother’s voice. Activities then appear that can be considered the onset of playing (i.e., a selfsatisfying and self-developing activity of the child). Progress in emotional development is manifested by smiling and growling, which enables the development of social contacts. The infant also begins to adapt to the biorhythms of day and night. Greatest progress in motor development is achieved during the second quarter of the first year of life (fourth through sixth month), and this holds the leading position in the overall development of the child. Developmental progress of the infant’s personality depends on motorics. Therefore, parents who stimulate and develop certain activities in their children observe more progress than others who do not devote as much attention (Koch 1977, 1978). In the fourth month, the infant masters movements of the head, and is able to bend it back and look up. He/she can hold the head upright and turn it to all sides, raise it when lying on the back, draw the chin to the chest, and look at his/her feet. There is marked progress in the development of the hands and feet. The development of grasping and manipulation is essential for the development of playing and thinking. At the age of 3 months the grasp weakens, but at the age of 4 months it becomes strong again: when the infant is offered a finger, he/she can hold it and draw himself/ herself to a sitting position. In the beginning, the arms of the infant are erect, that is, inactive, but later, at the age of 5 months, he/she can bend the arms and draw his/her head so as to sit up actively. At the age of 6 months, the child is able to draw himself/ herself to a sitting position as well as to a standing position. Grasping is so strong that the child can stay in a hanging position or in a standing position on a ladder (Koch 1977, 1978). When lying on the tummy, a 3-month-old infant can only lean on its hands. Later, he/she can reach for a toy and carry the weight of the head and chest, turning from the back to the tummy and, later, the other way around. Then, some children start to crawl spontaneously. Movements of the feet are mastered last: gross (fourth through fifth month) and finer movements of the legs (sixth month) develop during the second trimester of life. The development of the senses is also remarkable during that period; the infant starts to recognize and differentiate faces, objects, voices, etc. The first signs of play then appear. The child also discovers his/her own body and its individual parts, playing with both hands and feet and manipulating objects. There is a saying that “the intelligence of an infant can be recognized by how he/she takes things in the hands” (Koch 1977, 1978). The manipulation of objects by the hand is very important for the development of thinking as the child starts to understand certain relationships between his/her own actions. The emotional status of the child is also more apparent, and some habits can already be introduced. In the third trimester (seventh through ninth month) of the first year, the child becomes more independent and begins to understand certain sounds and words. Motor development is characterized by the development of abilities concerning not

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only the individual parts of the body but also the whole body. The main motor abilities that develop are crawling, sitting, standing, and the beginning of walking. It is essential that the child learn how to crawl before sitting. Children who learn to sit too early often do not crawl at all, and because of too much sitting, their body posture deteriorates. A child who crawls a lot usually starts to stand up earlier. During the fifth month, standing is very uncertain, until the ninth month when the child is able to grasp something from the ground by squatting from the upright position. The development of fine motorics is related to the development of play, learning, experiences, and thinking (Koch 1977, 1978). Before the fifth month, the child grasps objects with one hand. When offered another object, he/she lets the first one fall down. During the sixth month, the child can hold an object with both hands and can switch it from one hand to the other. During the seventh month, the child can turn the object around and can hold something in both hands. These manipulations render it possible to acquire various experiences with subjects. Gradually, the movements become more and more precise. The ability to grasp and also to let some object go at the right moment (which is more difficult) are both very important. Manipulation play is one of the most important self-developmental activities in the third and fourth trimester of life. From nonspecific manipulation, the child develops specific manipulation, that is, when the character of objects is already understood and used specifically. Using an object intentionally can be considered a manifestation of thinking, which shows an understanding of the relationship between things and surrounding phenomena. In addition, children already react to some words, but the development of active speaking is still limited. The characteristic of motor development during the second half of the first year involves an increasing amount of purposeful movements and actions. Therefore, motor stimulation and play should also be purposeful, which includes achieving some goal, solving some tasks, and overcoming some obstacles. The movements of the hand are more precise, and all actions become more and more meaningful for the development of the whole personality of the child (Koch 1977, 1978). During this period the child also needs more space, more time, and more contact with people and objects. Let us not forget that the original purpose of a toy is as a substitute, and that the child is longing to get hold of things that are used by adults. It is recommended that we allow children to play with such things (of course only with those that are not harmful, fragile, breakable, etc.). The aim of motor education during this particular period is to further develop abilities acquired during the previous period. It could be explained as starting the engine of an old-fashioned old car, an action that can later occur spontaneously. For this reason, direct motor stimulation is more limited, and the child is stimulated according to his/her own spontaneous activity. This means allowing the child to play according to his/her personal liking, with a certain range of purposeful activities. The infant starts to “think with his/her hands” (Koch 1977, 1978). The child plays in many different ways: handling objects, opening drawers, shuffling objects, emptying or filling boxes, displacing objects from one space to the other, placing a stick in the hole of a box, etc.

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At the end of the first year of life (10th to 12th month) the child has become independent, can already move around a little, can handle some objects, and can have some sort of contact with his/her environment. During the 12th month the child can usually take his/her first independent steps, without being held or leaning on something. Children who are motorically stimulated usually start walking during the 10th to 11th month (Koch 1977, 1978). The age when individual children start walking independently varies by several months. A possible association between independent walking and the development of other characteristics has not yet been reported. In fine motorics, the child is able to intentionally grasp a selected object, adapt the fingers according to its size, and grasp tiny things with the thumb and index finger. Another change occurs in the ability to release a grasped object at a specific moment or to place it in a certain place. It is now possible to witness the development of the intellectual abilities of the child, in addition to some experiences that are used in everyday activities. The development of gross motorics is aimed at overcoming a small obstacle, getting up from the sitting to the standing position or sitting down, and walking without assistance. It is not recommended that one speed up motor development by using baby walkers. As shown by Crouchman (1986), frequent users of walkers showed a significant delay in the onset of prone locomotion compared with a low-user and nonuser group of babywalkers. After the ninth month, a baby starts using one object to acquire others; for example, he/she draws a toy with the help of a tablecloth. The use of tools is an expression of thinking; it proves that the child understands the relationship between two objects and deliberately uses one to achieve a result with the other. At 9 months, the baby is also capable of solving simple problems of bypassing, for example, going around a barrier to reach a toy. Motor stimulation should be adapted to the character of individual children, their speed of development, their reactions, and so forth. As mentioned above, the goal is not only to favor motor development but also to develop the child all-round—somatically, intellectually, emotionally, and socially. Joyous goal-oriented play is one possible nonverbal stimulating contact that one can have with the child (food, emotions, and environmental factors), which helps in developing an optimal human being before intellectual and rational education take place. Experiences from other cultural settings, where children live under more natural or even more primitive conditions, showed that children at the beginning of life are motorically more advanced. Later, this acceleration is lost, because more advanced stimulation and motor education which is usual in our cultural setting is lacking (in more natural primitive conditions). Koch (1977, 1978), a recognized psychologist who suggested a special system of motor stimulation, followed three groups of stimulated and nonstimulated infants during the first year of life. This project was inspired by the following two chance discoveries. To give infants more space for PA in the nursery, they were placed in higherthan-normal playpens: 6 feet by 4 feet, 2 feet above the floor, with sides 18 inches high, made of crossed bars. Among other things, by the eighth month the infants could crawl and by the ninth month they could stand up using the wall of the pen.

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They next began climbing the wall of their pens; hence there was a danger of them falling out. Therefore, at the age of 8 months they were placed on a clean floor and given a small ladder. Even infants who were not yet able to walk easily climbed up the vertical ladder (supervised by an adult). This showed that climbing a ladder was easier than walking without help. In order to rear infants naturally and make use of their inborn scope for development, a wall with rungs was made accessible to the infants, who first learned to crawl on the floor and then climb the ladder. In the end, they walked on the floor without support. Obviously, “normality” of motor development, as perceived in our cultural setting, does not completely correspond to the natural predispositions and abilities of infants. If the infant’s feet are left bare, he/she often learns to grasp objects with them (e.g., he/she plays with an inflated ball hanging above with both hands and feet, then with one hand, one foot, and so forth). If the infant has his/her feet wrapped all the time, he/she never touches or feels with his/her feet (Koch 1977, 1978). These observations led to the following conclusions: (i) not only the development of movements, but also development in general, was strongly influenced by motor stimuli that the infant received at an early age, and (ii) a change in the method of stimulation could alter the infant’s development. In spite of some ethical reservations, physiological evidence supported the practice of adequate motor stimulation during the first year. In addition, experience from history and from some countries of the Third World gave rise to the transport hypothesis. Here, the mother carries her baby during all her daily activities; the child in turn cannot stay entirely inactive, but has to adapt to the mother’s movements (bending, etc.) by holding his/her head up, moving his/her trunk and limbs, and holding on with his/her hands and feet. The baby is therefore stimulated and activated by these energetic movements for long periods of time (Koch 1977, 1978). Similar experiences concerning the possible influence of certain customs and delayed consequences were mentioned in conjunction with nutritional practices and weaning in Sioux and Yurok Indians (see Chapter 3), which included limitations of spontaneous movements during the beginning of life (Erikson 1950). Infants in our cultural setting are equipped with the same mechanisms. These include so-called postural reflexes (the baby holds his/her head in the extension of the trunk when you lean him/her forward or to the side) and the grasping reflex (the baby holds our hands so firmly that he/she can be lifted up). When the infant is carried around, this is also a very intensive and natural exercise for him/her. Although an ancient practice, it is becoming popular again.

10.3

EXPERIMENTAL OBSERVATIONS ON THE IMPACT OF MOTOR STIMULATION IN INFANTS

The aim of any stimulation, including motor stimulation, is not to speed up development but rather to render it harmonious and all-round. The child must not be burdened with too many demands, but stimulated by an adequate amount of appropriate factors. However, lack of stimulation and neglect also have unfavorable results. It is known that the consequences of malnutrition can at least partly be compensated for by proper stimulation of the child, including some motor activities.

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Koch (1977, 1978) followed three groups of infants: the first group (I) consisted of infants who lived at the Institute for the Care of Mother and Child from birth up to the age of 6–7 months. One specialist devoted himself to each infant everyday for a period of wakefulness (about 2 h), played with him/her to stimulate the movements as described above, and recorded the development from the fourth week to the end of the sixth month. The second group (II) consisted of infants who lived at home with their parents and, during their first year, visited the above-mentioned institute regularly once or twice a week, in all about 20 times. Parents were taught to stimulate their babies’ movements: at the same time the infants were examined. The parents then worked with their children at home, as described above. After the first year the parents were not instructed anymore, but the development of the children was followed up through their third year. The third control group (III) consisted of infants who attended one of Prague’s children’s centers for regular routine pediatric checkups. They lived under normal family conditions without special stimulation. Every child was examined once, in the third, sixth, ninth, or 12th month of the first year of life. The parents were of all social groups (the population in the Czech Republic was at that time more homogeneous than in other European countries). They were not informed about the purpose and aims of our study and regarded it as part of the medical checkups. In all groups, there were both boys and girls. For the presentation of homogeneous data, only boys were selected, but the results of the motor stimulation of girls had the same trend. Group I consisted of 10 boys and Group II consisted of 20 boys. In Group III there were 10 boys aged 3 months, 13 aged 6 months, 11 aged 9 months, and 15 aged 12 months. The development of head movements, upper limbs, lower limbs, complex locomotion, play, and speech in all children was recorded. Two hundred developmental traits were statistically processed, about 15 each month. The statistical significance of the differences was evaluated as follows. No infant was able to transfer a toy from one hand to the other in his/her third month. In the ninth month, all children were able to do this. The number of children capable of this task was determined during all measurements and statistically evaluated. The results of Koch’s study (1977, 1978; published in two editions also in the United States) showed that the two groups stimulated (Groups I and II) showed a similar progress of development, while the nonstimulated group (Group III) lagged behind. The more complex the testing activities, the more significant the statistical differences between stimulated and nonstimulated infants. The differences increased with age and with the complexity of the activity. The infants were mainly stimulated with respect to motor activities, but the difference also appeared in the development of play and speech. On the other hand, the differences between Groups I and II, that is, between infants stimulated at the institute and at home, decreased with age. The results of children stimulated at the institute were, in the beginning, better, which was explained by the fact that they were stimulated by experts. Later on, when the parents gained enough experience and practice, this difference disappeared. The differences in the development of children who were systematically stimulated at home (II) and those who were not stimulated and lived under usual traditional

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conditions (III) were remarkable and gradually increased. This document emphasizes that intensive early motor stimulation is soundly based and contributes to better infant development. The differences concerned not only the development of movements but also overall development, the reason being obvious. At first, pure and isolated locomotor stimulation is not possible. When the baby is stimulated to move, the parents or whomever is in close social contact talk to the baby and give him/her toys. This is a complex stimulation, where locomotor stimulation is stressed because it also influences the development of speech and thinking. Thus, the influence of motor stimulation goes beyond motorics only, as in later periods of childhood. Next, parents who succeed in a complex child-rearing method tend to develop their baby in all aspects and deliberately favor the other functions also (Koch 1977, 1978). Motor stimulation and play, however, make up a complex program on how to treat a child: quite often parents do not really know what to do with their children or how to play with them so as to educate them simultaneously. It remains an open question as to whether the higher quality development of a baby, which has been systematically stimulated during the first year of life, is permanent or temporary. The material collected later does seem to indicate that this development is permanent, especially when the children are systematically stimulated further. A special experience was also gained by swimming with the children at the beginning of life, a program that was developed by L. Diehm and M. Hoch (Faculties of Physical Education in Cologne, Germany and Prague, the Czech Republic), which showed a very favorable influence on the development of children. These efforts continued later on too. Since it was shown that during the first year of life psychological development can be given impetus and direction, this possibility should be studied and developed further. Evidence from other areas of theoretical research, as well as from teaching experiences, shows that early stimulation of any nature (which is positive and adequate according to the developmental stage and individual characteristics of the organism) gives desirable results and is advantageous for the child and can even persist after the growth period.

10.4 TODDLERS In the second year, the main goal of parents should be to support the natural tendency of toddlers to move spontaneously, to teach them the changes in attitudes and positions, to protect them from accidents, and to aid in the final development of walking. In the third year, the moving abilities of the upper extremities develop intensively, and locomotion is much more rapid. The main task of parents then is to give ample opportunity for the child’s spontaneous PA, to develop his/her ability to run, jump, crawl, and play different games, and to teach cultural behavior. The exercise of one parent with the child is a more precise program, as it is already possible to profit from certain motor abilities and previous experiences. Last but not least, all activities should have an element of play but must also be interesting and fun. Under these conditions, the child will persevere with the exercise

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and thus benefit from it. More recently, this period of growth has been recognized as essential from the point of view of not only influencing present and later development, but also suggesting special systems of physical education in the family and in special organizations for physical education and exercise for the child and his/her mother, father, or any other caretaker (Berdychová 1975). This system has been introduced in some day-care centers. Aide-moi à faire seul, Ne-fais pas à ma place, Mais soi présent,

Help me to do by myself, Don’t do it in my place, But remain with me. —Maria Montessori

10.5

MOTOR DEVELOPMENT AND EDUCATION OF CHILDREN AGED 3–6 YEARS

In the fourth year of life the child is beginning to overcome clumsiness, his/her motions become more exact, and his/her ability for intentional activities further increases. Children like rhythmic activities, are more independent, are not afraid to jump from a height of 30–40 cm, and are able to achieve a certain level of performance. The main goal of motor education is to develop skill, adequate body posture, and a well-balanced gait. It is recommended to start children on some sports activities (of course very carefully chosen for young children), for example, skiing and swimming. Up to 6 years of age, these abilities improve further. This period is defined as the golden age of motorics (Wolanski and Parˇízkóvá 1976), when the level of spontaneous motor activity is higher than later on. It is therefore very important to make use of these tendencies for PA and interest in suitable motion games. When proper motor habits and skills are introduced in time and when a certain level of cardiorespiratory efficiency, speed, endurance, and muscle strength is achieved, a good basis for later performance and interest in exercise is created. Preschool children have at their disposal good prerequisites for aerobic endurance training and also natural movements involved in spontaneous playing rather than striving to reach maximal performance. As mentioned in Chapter 6, a young child can achieve a heart rate >200 per minute during activity (Kucˇera et al. 1975). The preschool child loves to play; hence it is desirable to profit from this by playing games that focus on the continuing development of adequate gait, fast runs, courageous jumps, skillful crawling, throwing, and so forth. Stimulation of motor and fitness development has to be adequate with regard to age and individuality of the particular child, which requires proper physiological and psychological knowledge. Until recently, information has been relatively more limited with regard to normal healthy preschool children, because more attention was paid to children with developmental or health defects. The Committee on Sports Medicine and Fitness of the American Academy of Pediatrics analyzed fitness, PA, and sports participation in preschool children in 1992. Estimation of motor skill tests using the pass-or-fail approach resulted in a selection of special items (e.g., skipping, bouncing a ball, and turning on one leg) for the evaluation of the level of motor development. Similar suggestions were prepared

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for Japanese children from 3 to 5 years of age, from observations of children’s behavior in daily life (Goshi et al. 2000). Relationships between children’s and parents’ stereotyping of PAs were analyzed, showing significantly higher scores (Physical Activity Stereotyping Index) for kindergarten and second-grade children (Pellett and Ignico 1993). The influence of parents, overall family lifestyle, and the example set by both parents are essential (Beets and Foley 2008). The overall PA of children in preschool children is higher than later, as shown repeatedly by longitudinal measurements (Parˇízková and Hainer 1990, Sigmund et al. 2008), and therefore it is desirable to profit from this natural characteristic from the point of view of later development. Factors that facilitate proper PA development are gender (higher PA in boys), education level of parents, history of preterm birth, nature of child-care center, father’s BMI, etc. (Finn et al. 2002). Child care during daytime can be very important (Bower et al. 2008). Children with low motor performance also display a lower level of physical fitness, and 5 years of longitudinal follow-up showed worse results in tests for cardiovascular endurance, the 50-m run, and balance but not for body composition, overhand throw, and standing broad jump (Hands 2008). PA and resulting fitness have been studied most often in mixed age groups, starting with preschool children up to school children and adolescents, often also along with other parameters characterizing nutrition, etc. The level of physical fitness can be assessed using a new standardized treadmill walking test requiring low motor skills in children 4–10 years of age (Waffler-Kammermann et al. 2008). The nature of activity is important, for example, aerobic training improves cardiovascular fitness and increases agility and self-esteem following the exercise program (Alpert et al. 1990). Aerobic fitness reduces the adiposity in white and black children, which was not the case in this study for EE (Johnson et al. 2000), even when a direct association between these variables was found in other studies. A higher level of PA can improve cardiorespiratory endurance or reduce fatness from preschool years, but significant effects may not be immediately apparent (Grund et al. 2000, Al-Nakeeb et al. 2007, Weymans and Reybrouck 1989): PA cannot achieve such an intensity as possible in later age, and for a time duration that is indispensable for the manifestation of significant changes in the parameters usually followed up. Studies of the effect of PA level and participation in exercise programs should be developed, which are currently used, for example, in Germany: the module “Motorik” in the German Health Interview and Examination Survey for Children and Adolescents (KIGGS) also included preschoolers in the whole population (Opper et al. 2007, Lampert et al. 2007). In addition, young children who increase their aerobic fitness or decrease their BMI do not increase their blood pressure, as is usual during this period of growth (Shea et al. 1994). The lack of opportunity for playing is a great handicap—neighborhood disorder and unsafe conditions interfere with PA level (Molnar et al. 2004). Neglect of motor development, possibly resulting in clumsiness and a low level of fitness, is no means for the successful development of other faculties of the child. Hence, the selection of games depends on the purpose. Nearly all exercise can be turned into play when we give the exercise an attractive name that interests the child, and

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when we set the rules of the game and how it will be played: this gives the game some guidelines, however simple. For some games it is necessary to have more children, occasionally at least three. When the child has no siblings, parents should participate; this is sometimes difficult because of time constraints. Children should also have the company of other children, which teaches them to adapt to peers. At preschool age, the need for the company of children increases and mutual relationships are established among children on the basis of games. Observations on how the child plays can help define his/her personality and his/her later relationship with other activities (Berdychová 1975– 1985, 1978, 1993). In many countries, organized physical education for preschool children has come to pass more or less recently, either in day-care centers or in special physical education classes for preschool children along with one of the parents (mother, father, grandmother, or caretaker) organized by various sports organizations in individual countries. However, this has existed since a long time in countries such as Spain, France, Germany, the United States, Italy, Bulgaria, Slovenia, Cuba, and, more recently, Canada, New Zealand, Australia, and many others. This kind of physical education mainly exists in individual sports organizations or in selected day-care centers and institutions, and requires a qualified pedagogic and physiological approach. In former Czechoslovakia, this type of physical education was introduced in 1964 and developed on a mass scale in all parts of the country. The initiator was Professor Jana Berdychová (the system is described in her monographs and has been translated into many languages; Berdychová 1975, 1985, 1978, 1993), who received the main credit for the creation and establishment of this system of physical education at an early age of the child. During the more than 50 years of its existence, special physical education classes for preschool children with their mothers or fathers have become an integral part of the general physical education system of the Czech Republic; the participants also appear in national gymnastic displays, organized at regular intervals. Under the present conditions, this type of physical education represents the initial, first article of the system of physical education of the national (as well as international) association “Sokol” (the Czech word for falcon; founded in 1862) and of the association “Sport for All,” attached to the Olympic Committee of the Czech Republic. Fortunately, along with all the changes occurring in the Czech Republic, the tradition of physical education for preschool children with one of the parents or a caretaker has been developing further on a massive scale. The results of this system of physical education were presented and analyzed, for example, in an International Seminar “Child-motion-family,” sponsored by the Council of Europe in December 1994 in Prague. Other scientific meetings were organized during later years, all of which testified to the positive role of PA and special exercise systems on child development. However, as mentioned above, the results often appear only as delayed effects, after a longer duration of this stimulus—improved cardiorespiratory fitness, strength, bone development, a more favorable level of serum lipids, reduced blood pressure, reduced adiposity, etc. (Stewart et al. 1995, Hussey et al. 2007, Specker and Vukovich 2007, Daly 2007, Scheffler et al. 2007).

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The undesirable effect of inactivity is manifested already in preschool age, in which TV viewing, considered as a marker of sedentarism at all ages, plays a negative role. The term “couch potato” is applicable to children 5 years of age, and motor symptoms can appear as a result (Kammerer 2006). The Framingham Children’s Study and others showed that TV viewing can increase body fatness during preschool years (Moore et al. 1995, Grund et al. 2001, Proctor et al. 2003, Hancox et al. 2004), especially in children with low SES (Dennison et al. 2002). The behavior of parents is important, and behavioral patterns related to overweight at a later age were frequently observed (Boere-Boonekamp et al. 2008). Five spearheads for parents were recommended: breast-feeding, more outdoor play and physical exercise, a regular wholesome breakfast, less consumption of sweetened drinks, and less TV viewing and computer use. Implementation of intervention in young age groups with the help of family can prevent unhealthy lifestyles leading to obesity and reduced physical fitness. Another study revealed that BMI at 3–6 years of age is predicted by TV viewing and PA and not by food intake (Jago et al. 2005). Studies in Polish children showed that in parallel to genetic and maternal factors cultural factors related to traditional customs and social practices also determine the motor traits of children (Wolanski et al. 1992). In addition to social, nutritional, and environmental influences, ethnic differences with respect to local customs and culture had a role in children from Senegal (Bénéfice et al. 1996, 1999), Nigeria (Toriola and Igbokwe 1986), and elsewhere, as mentioned above. Children with health problems also benefit from exercise and increased PA—for example, by reducing excess fat in obese preschoolers (Epstein et al. 2008) and improving the situation of children with diabetes (Kirk et al. 2005, Giannini et al. 2006, Rachmiel et al. 2007). Screening from kindergarten to grade eight identified medical areas of concern, which included children with a high risk of diabetes type 2, BMI, and also fitness characteristics such as aerobic capacity, upper body strength, etc. (Smith et al. 2002); this may be positively influenced by increased PA and exercise. Preschool children with moderate fine motor delays improved not only their fine motor skills but also self-care, mobility, and social function during a special course of the school year for preschoolers (Case-Smith 1996). Mentally retarded children are not the topic of this book, but they are worth mentioning. In many industrially developed countries, the number of handicapped children has increased because of improved perinatal care, which enabled their survival. The physical education of such individuals can help; we know from the Special Olympics that these individuals are often capable of admirable feats that many healthy people cannot achieve. Running exercises were used as a means of improving play or school activity for preschoolers with mental retardation, which was demonstrated especially for those who simultaneously improved their performance in running (Yamanaka et al. 1994). Favorable effects, that is, improved functional ability and physical fitness of a short-term daily treadmill exercise, were shown in children with intellectual disability (Lotan et al. 2004). The positive effect of specialized PA and exercise systems was also revealed in children with cerebral palsy, myopathy, and respiratory allergy, during postoperative rehabilitation of congenital heart disease, etc. Observations concerned mostly older children and adolescents.

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The early introduction of some exercises can help these children improve a lot, and the influence of exercises again goes beyond just motorics. Special systems of physical education for the handicapped were suggested and applied (Kvapilík and Cˇerná 1992) also in the Czech Republic. We recall the example of a 3-year-old girl with Down’s syndrome who participated in the above-mentioned regular physical education classes with her mother without any problems; her overall situation improved markedly.

10.6

WHAT TO AVOID IN THE MOTOR STIMULATION OF YOUNG CHILDREN

It should again be pointed out that all physical education in this period of early development of healthy normal children should be adjusted to the special traits of this stage of child development, keeping in mind the health and the physiological, psychological, and social traits of small children (Rowland 1990). In essence, all activities should be natural and spontaneous, and thus liked by the child. Without spontaneity and the individual involvement of the child, the results of all pedagogical efforts, including motor education, are always less successful. Even the reverse situation can result: that is, refusal and negativity of the child and deterioration of his/ her potential because of inadequate handling of his/her motor abilities. Overburdening, that is, demanding too much, or the reverse—demanding too little—are undesirable. This can apply to any other educational effort. Safe conditions for all exercise activities must be guaranteed (Gould and DeJong 1994). In motor activities, respecting the spontaneous involvement of the child implies a certain self-regulation, thus avoiding physically overloading the child. When the enthusiasm of the child for some very attractive activity is excessive, it is necessary to regulate and influence it. In such a case, the child is unable to self-regulate himself/herself. This mainly involves dynamic games and activities, especially with older peers. The play activities of children have different character, and three kinds with consecutive age peaks were defined: rhythmic stereotypes peaking in infancy, exercise play peaking during preschool years, and rough-and-tumble play peaking in middle childhood. The latter two are of greater prevalence in males. Rhythmic stereotypes in infancy are hypothesized to improve the control of specific motor patterns. Exercise play is hypothesized to function primarily for strength and endurance training (Pellegrini and Smith 1998). Generally, static exercises are not recommended for a child. Overloading of individual joints with static exercises is forbidden. All one-sided activities are also unsuitable, that is, specialization in one type of game or even in the preparation of some sports activities. Unfortunately, certain disciplines, in which it is mostly the youngsters who win gold medals (gymnastics, figure skating, tennis, etc.), urge some parents to commence specialized training even before the child starts going to primary school. This is nothing new—in ancient times and in the Middle Ages circus acrobats trained their children excessively “from the cradle” itself. It is better to avoid this despite the fact that there will always be some youngsters who can develop a high level of performance without any harmful consequences. For the overall child population however, this is not acceptable.

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Two extremes seem to exist. The majority of parents neglect developing the motor abilities of their child properly, and thus they also miss the opportunity of using motor education for the promotion of other faculties of their child. On the other hand, a small minority tend to burden their child so as to cultivate a sports star as early as possible, thus exploiting him/her. This is very similar to child labor, and satisfies more the parents’ ambitions (often unsatisfied) than the desires of the child. Exercise has to be safe to prevent injury, and strategies for 0–3-year-old children were developed (Agran et al. 2003) along with the implementation of safety measures during their activities (Kahl et al. 2007). For the proper education of the child, including motor education, it is necessary that parents are well aware of all the existing possibilities in preparing their child for his/her future optimally. It is true that sometimes everything goes very well for the child without any great effort from the parents. The reverse is also true: great care does not always give the best results. When it is too late, however, much less can be done. When parents adequately intervene in all respects, including motor stimulation and education along with other factors such as nutrition, better results can be expected. Some examples of complex results can be given from the studies in normal healthy preschool children mentioned before (Chapters 4–7). Not only height, weight, and BMI, but also other parameters—body composition, motor and functional— were followed up in representative samples of the population. The following studies focused attention on the effect of regular exercise.

10.7

INFLUENCE OF EXERCISE IN PRESCHOOLERS

10.7.1 SOMATIC DEVELOPMENT AND BODY POSTURE The mean values of height, weight, BMI, and chest circumference in preschool children 6.4 years old (survey B) exercising during different periods of time (0, 1, 2, and 3 years) are presented in Table 10.1. Children who participated for the longest period of time in a regular physical education program were the tallest and the heaviest and had the highest values of chest circumference, which might be partly due to the selection of the studied subjects. The BMIs tended to be the lowest in boys who exercised regularly during the longest period of time, but these differences were slight. In girls there did not seem to be any differentiation of BMI according to the duration of participation in the physical education program. Other measurements showed significantly higher values of thigh and chest circumference in boys who exercised during the longest period. In girls, these differences were not significant. Regarding the posture of the neck, abdomen, and spine, the results were more favorable for children who took part in regular exercise during the longest period of time. Grade 1 was most frequent in these children, and grades 2 and 3 were much less frequent. The worst situation was found in children who were completely inactive. The influence of regular physical education (mostly physical education classes of the child with one of the parents or grandparents) was analyzed in survey C (Table 10.2) comprising children aged 4–5, 5–6, and 6–7 years. For this analysis, children were subdivided according to both participation in organized physical

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TABLE 10.1 Anthropometric Variables and Motor Performance in Preschool Boys and Girls Differentiated According to Systematic Participation in Physical Education (2–3 Years) (Survey B; Age 6.4 Years) 0 Physical Education (Years) Height (cm) Weight (kg) BMI (kg/m2) Chest (cm) 20-m dash (s) Broad jump (cm) Throwing a ball—right (cm) Throwing a ball—left (cm)

Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls

x– 118.6 117.6 22.2 21.6 15.8 15.6 59.2 57.9 5.4 5.7 108.0 100.7 1060 676 672 519

2–3 SD

x–

SD

5.3 5.2 3.2 3.3 0.9 1.1 3.3 3.7 1.1 1.2 20.9 20.4 391 220 240 163

120.8 119.0 23.6 22.1 15.7 16.6 61.0 58.2 5.5 5.7 119.9 110.6 1081 717 752 551

5.1 5.5 2.3* 3.6 1.0 1.1 3.4 4.1 1.2 1.2 22.3* 18.4 419 240 302 168

Source: Adapted from Parˇízková, J. et al., Growth, Fitness and Nutrition in Preschool Children, Charles University, Prague, 1984a. Note: *p < 0.02.

education and age. The same trends were found in somatic development: children enrolled in regular physical education were, as a rule, the tallest and the heaviest, with higher values of circumferential measures (chest and thigh) (Parˇízková 1978c, 1980). Because of the smaller number of children in the individual subgroups and their younger age, the differences were less apparent than those in 6.4-year-old children (survey B) (Parˇízková et al. 1984). In survey D (boys n = 4822; girls n = 4765), children were subdivided into subgroups according to their enrolment in regular physical education: 1. 2. 3. 4.

Regular exercise once or twice a week Occasional exercise No exercise at all Limited exercise for health reasons.

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TABLE 10.2 Physical Performance of Preschool Boys and Girls Regularly Enrolled (PE) and Not Enrolled (i.e., Control, C) in Physical Education (Survey C) Ball Throw (cm) 20-m Dash (s) Age 4–5 years Boys Girls 5–6 years Boys Girls 6–7 years Boys Girls

Broad Jump (cm)

Right

Left

PE

C

PE

C

PE

C

PE

C

SD

6.2 1.3 6.4 1.3

6.7* 1.6 7.7** 1.8

88.1 44.0 81.4 24.4

91.0 87.1 80.7 59.2

655 281 472 163

538** 238 429* 149

486 189 377 138

429* 170 340* 127

x– SD x– SD

5.6 1.2 6.0 1.4

6.0 1.5 6.3* 1.7

113.6 107.8 102.1 65.9

100.6 38.9 95.3 51.7

880 363 613 189

815 344 582 191

564 224 476 165

556 209 452 150

x– SD x– SD

5.5 1.4 5.6 1.3

5.5 1.4 5.7 2.7

118.0 61.1 114.6 88.8

120.4 80.4 105.7 45.6

1095 397 740 228

1054 394 697* 218

695 255 563 196

705 266 550 252

x– SD x–

Sources: Adapted from Parˇízková, J., Principles, Practices and Application, R.J. Shephard and H. Lavallée, Eds, Charles C. Thomas, Springfield, IL, p. 238, 1978b; Parˇízková, J., Proc. Int. Symp. Université de Quebec, Oct. 1980; Parˇízková, J., Wld. Rev. Nutr. Diet., 51, 1, 1987. Note: *p < 0.05; **p < 0.01.

The percentage of children in these groups was as follows: 1. 2. 3. 4.

Boys 11.5%, girls 19.4% Boys 7.4%, girls 8.1% Boys 80.9%, girls 72.2% Boys 0.2%, girls 0.3%

The distribution of children in individual subgroups was unequal. In spite of the opportunity to exercise (especially in classes with parents), participation was low, especially in boys. The majority of children did not take part in any regular exercise. The last group included very few children. The development of height and weight, BMI, and proportionality of growth was examined in this survey. Children of subgroup 1 had significantly lowest values of BMI. Regarding height and weight development, no consistent differences among the subgroups mentioned above were apparent in this last survey because the groups of exercising children of different ages were small.

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1 year

291

0 year

1100 900

Broad jump (mm) Throw—right hand (cm) Throw—left hand (cm)

700 500

Boys Girls

Boys Girls

Boys Girls

FIGURE 10.1 Physical performance in 6.4-year-old boys and girls enrolled during various periods in regular physical education (survey B).

10.7.2 PHYSICAL PERFORMANCE, SKILL, AND SENSOMOTOR DEVELOPMENT The influence of physical exercise varied in relation to the results of different disciplines (survey B). There were no significant differences in the 20-m dash (see Table 10.1 and Figure 10.1). The broad jump results, however, were significantly better in children who participated during the longest period in physical education. In throwing a ball with the right and left hand, the performance was best in exercising children. Children not engaged in regular physical education had the worst physical performance (Parˇízková et al. 1984). In tests of skill, children participating regularly for the longest period in physical education were more successful than children who did not participate. The results of tests in the forward roll, walking on a horizontal beam, and catching a ball were also the best in children who exercised for the longest period of time. The same applied to the results of testing sensomotor development, that is, “open and close the hands” test. In this case, significant differences were evident in the most difficult items of this test (Parˇízková et al. 1984). Obviously, regular structured exercise can have a significant effect during preschool age. In survey C, similar results were obtained. Generally, there was always a trend toward better results in children who enrolled regularly in physical education. However, the interindividual variability was again large, and only in some disciplines were there significantly better results in exercising children (e.g., the 20-m dash and throwing a ball; see Table 10.2) (Parˇízková 1980). In survey D the results of physical performance were also analyzed in a subsample of 1005 children subdivided according to criteria 1 through 4. Again, there was a trend toward better results in all disciplines in the regularly exercising children. The influence of regular physical education was significant in the results of the 20-m dash, the broad jump, and the ball throw with the right hand but not with the left one.

10.7.3 VARIABILITY OF THE IMPACT OF EXERCISE IN EARLY LIFE In contrast to other evaluations, larger bodily dimensions in children who exercised were also associated with an obvious trend toward a higher level of motor performance, which was significant in several items.

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However, another question appears: the group of children who exercised regularly could have been primarily more advanced in their somatic and motor development and, thus, more interested in physical exercise because it was easier for them. Therefore, they may have adhered to it regularly and for a longer time, and the results of comparison were automatically better for them. This problem is apparent in all age categories, including adolescents and adults. It is not possible to pick some children for exercise and to refuse others in order to have homogeneous comparable groups for experimental analyses. In everyday life, this is not acceptable with normal healthy children, especially when pedagogues are interested in getting everyone to take part in regular exercise. However, the differences in the body sizes of exercised and nonexercised children were of similar character as when groups classified according to other criteria, such as urban versus rural children, economic status of the family, birth rank, and so forth, were compared. In contrast with these cases, however, the motor development of exercised children was significantly better. Therefore, we may assume that even when genetic factors played an important role, the more favorable development of gross motorics in bigger, active children was, in this case, mainly the result of a positive adaptation to exercise. This especially applies to jumping, throwing, and skill tests, as the development of speed does not seem to be influenced by regular exercise at this age yet. This may also be due to the fact that the physical education classes for preschoolers were more focused on the development of skills rather than on the development of speed, which does not seem appropriate at this age. With regard to body composition, functional capacity, etc., the effect of PA and exercise was not always marked and significant, and only some trends of improvement were apparent. The intensity, duration, frequency, and character of PA could not be implemented in the same manner as in older children, but positive trends could be considered as an optimal starting point and predisposition for later desirable development. Positive interventions were shown to have marked results when implemented by the family or day-care centers. This may be considered as a suitable beginning for developing and also preserving a higher level of PA and interest in exercise in later periods of life, which is at present much more emphasized as a preventive measure against obesity and accompanying health problems.

10.8

SPONTANEOUS PA, SOMATIC AND FUNCTIONAL DEVELOPMENT, FOOD INTAKE, AND BLOOD LIPIDS

As indicated by serum lipid levels in preschool children in the capital and in smaller communities, the theoretical opportunity for greater motor activity alone does not always manifest itself in an improved level of morphological, functional, and biochemical variables. Any sort of adequately increased PA under safe conditions is a desirable factor favoring the development of the child. At preschool age, it is difficult to find children who exercise systematically and long enough to manifest some positive effect. As mentioned above, it was only possible to show the significant influence of exercise on

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certain aspects of somatic and motor development at the age of 6.4 years (survey B) and only occasionally before this age (surveys C and D). However, it is of interest to examine the influence of PA even earlier. One of the characteristic features of an individual from the very beginning of life is the level of his/her spontaneous PA, which is higher than that in school age (Parˇízková and Hainer 1990, Sigmund et al. 2008) and varies interindividually. This is even manifested in the framework of the same family, and can be manifested early after birth. As mentioned previously, genetic factors are factors that can significantly influence motor characteristics. A great similarity in the motor pattern of running was described by Sklad (1972) in monozygotic twins, where the total volume of PA during certain periods of time (number of paces per day) varied less than that in dizygotic twins (Ledovskaya 1972). The number of paces per day was shown to be a permanent characteristic of the individual (Gapon 1972). However, other epigenetic factors have to be considered too. In early childhood, the influence of different levels of PA is much less apparent because of the child’s very short life history. Thus, it is insufficient to draw on the duration of the influence of this particular factor. Some children, however, can spontaneously exercise quite vigorously and at a high level, as shown by telemetric measurements of the heart rates, which could be 210–220 beats per minute (Kucˇera et al. 1975, Kucˇera 1994). Generally, it is considered unacceptable to induce overintensive, regular physical exercise at the age of 4 years. But, it can be assumed that a high level of spontaneous PA at an early age might run parallel to other metabolic characteristics of the individual. Because it was not possible to find 4–5-year-old children who would exercise long and intensively enough on an organized basis, the level of spontaneous PA was followed up in a kindergarten in Prague, and children were subdivided accordingly. We tried to characterize children by observing them during a period of free play (2 h in the morning, just after arrival; in total during 1 week). Ten aspects of PA levels were followed and registered. We found that children varied quite a lot, and that the results of such a trial assessed during individual days very rarely correlated and then only weakly (p < 0.30). It was obvious that such a short period is not representative enough for the evaluation of the level of spontaneous PA of the preschool child. In additional methodical experiments, we used pedometers, sport-testers, and heart beat totalizers, which were made for older individuals and not yet adjusted for preschoolers; these apparatuses did not give reliable results. We had no opportunity of using DLW. Therefore, we developed a special questionnaire for kindergarten teachers and parents, which evaluated the level of spontaneous PA during the whole year. Individual items concerned the initiative in active play, social contacts in playing and the ability to draw other children into play, reactivity to both positive and negative orders (i.e., either to move or to stop—the latter was a specific problem for some children!), the approximate time spent in action or at rest, the preference for active dynamic games or quiet activities with limited movement, etc. A general evaluation by the teacher was also considered, based on observations during the whole year. Evaluation of this questionnaire rendered the categorization of preschool children possible (Parˇízková et al. 1986a).

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TABLE 10.3 Anthropometric Variables of Active and Inactive Children (4.9 ± 0.5 Years of Age, Survey J) Active

Height (cm) Weight (kg) BMI (kg/m2) Fat (%) LBM (kg)

x– 109.6 18.8 15.7 14.1 15.9

Inactive SD

x–

SD

4.4 1.7 1.1 2.4 1.7

109.9 19.8 16.4 17.5 16.2

6.3 3.3 0.9 4.4 2.0

Source: Adapted from Parˇízková, J., et al., Hum. Biol., 58, 261, 1986.

This study was undertaken with two kindergarten groups of children from 3 to 5 years of age (n = 22; mean age 4.7 years) in Prague. Eight of the most active and nine of the most inactive children were selected on the basis of the above-mentioned procedure. The rest of the children without any marked trend for either great activity or inactivity were not included in the final evaluations. Somatic development, step test, dietary intake, blood lipids, and creatine kinase (CK) activity were assessed. Sex-linked differences were not apparent in this group (survey J). Heights, weights, BMIs, fat (%), LBM (kg) (Table 10.3), circumferential measurements (Figure 10.2a), breadth measures, skinfold thicknesses (Harpenden caliper; Figure 10.2b), and somatotypes (Figure 10.2c) were assessed. As shown by (a) 60 50

cm

40 30 20 10 Head

Chest

Arm

Thigh

Calf

FIGURE 10.2 Comparison of anthropometric characteristics: circumferential measures (a), skinfolds by the Harpenden caliper (b), somatotype (c), intake of energy—MJ (d), protein, fat, and carbohydrate—g/day (e), blood lipid level, that is, total, HDL, LDL cholesterol, TG (f), and indices of cardiorespiratory efficiency ST1, CE1, CE2 (g) in 3–5-year-old children characterized by a very high and/or a low level of spontaneous PA (survey J).

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10 9

mm

8 7 6 5 4 Triceps

Subscapular

Suprailiac

Calf

Biceps

(c) 6 5 4 3 2 1 Endomorphic comp. (d) 7.6 7.4

MJ

7.2 7.0 6.8 6.6 6.4

FIGURE 10.2

(Continued).

Mesomorphic comp.

Ectomorphic comp.

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Nutrition, Physical Activity, and Health in Early Life (e) 250

200

g

150 100 50 0 Protein

[mmol/L]

(f )

Fats

5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0

Carbohydrates

*

TCh

HDL

LDL

TG

(g) 90 80 70 Index

60 50 40 30 20 10 0 ST1

CE1 Active

FIGURE 10.2

(Continued).

Inactive

CE2

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the results, there was a trend toward lower values of weight, fat, BMI, LBM, and circumferential measurements (with the exception of the thigh) in active children. Breadth measures varied only slightly. Skinfold thicknesses measured by a Harpenden caliper tended to be lower in active children, similar to the percentage of fat calculated according to Brook’s formula (1975), but the differences were not significant. Ten skinfolds measured by a modified Best caliper were also larger in inactive children. Regarding somatotype (Heath and Carter 1967), active children had a lower endomorphic component, the same mesomorphic component, and a higher ectomorphic component (Figure 10.2c). These differences were not significant. The LBM/10 cm height index was only slightly higher in active children. The energy and fat intakes were somewhat higher than local RDAs. When comparing the food intake with RDAs of the EC and the United States, the energy and protein intakes of the children were higher than the EC (Nutrition and Energy Intake in EC 1993) and the US RDAs (10th ed. 1989, LSRO 1981) and to the estimated values of energy requirements according to the procedure suggested by WHO393 (see Table 5.3). Active children tended to have a higher food intake than inactive children (Figure 10.2d through f), but the differences were not significant. The intake of minerals and vitamins did not differ from the RDAs for this age group. The results of the step test showed that the workload increased the heart rate by about 40% compared to the initial values. The steady state was established during the second to third minute, and the heart rate returned to resting values during the second to fourth minute of recovery. Boys tended to have slightly, but not significantly, better results, which also applied to the STI and the cardiac efficiency indexes CEI1 and CEI2. Therefore, the results were evaluated together for boys and girls. Active children tended to have better results in the step test, especially regarding the above-mentioned indices, but the differences were not significant. Sex-linked differences were not apparent; therefore, the average values of serum lipids for both boys and girls together are given. Only the HDL level was significantly higher in active children. The level of LDL tended to be higher in inactive children (Figure 10.2g). The average values of TC in Czech subjects 2–17 years of age were 4.46 ± 0.92 mmol/L. Mean HDL cholesterol was 1.23 ± mmol/L and LDL cholesterol was 2.70 ± 0.92 mmol/L. The lowest values were always found in the youngest children (Šamánek and Urbanová 1997). Serum lipids decreased from the late 1960s to the early 1990s by an average of 7 mg/L, as shown by the Third National Health and Nutrition Examination survey (Hickman et al. 1998). The average values of CK activity in the blood were about half the values assessed in adults and were slightly and insignificantly higher in active children. Only a few differences between highly active and inactive children reached the level of statistical significance. However, they had a consistent trend, which was similar to that found in the comparisons of older children and/or adolescents: highly active children with significantly higher HDL tended to have lower body weights, were less fat and more ectomorphic, had spontaneously higher energy intakes, and showed a slightly higher level of cardiorespiratory fitness (higher values of STI, and CEI1 and CEI2 indices) and a higher level of fine motor skills, along with a trend toward higher CK activity in the blood. In older age categories, where the influence

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TABLE 10.4 Short- and Long-Term Beneficial Effects of a Combined DietaryBehavioral PA Intervention in Obese Children Changes After 3 Months

Changes After 1 Year

Obese

Control

Obese

Control

N = 24

N = 22

N = 20

N = 20

Body weight (kg)

−2.8 ± 2.3

1.2 ± 2.2

0.6 ± 6.0

5.3 ± 2.7

BMI

−1.7 ± 1.1

−0.2 ± 1.0

−1.7 ± 2.3

0.6 ± 0.9

Fat %

−3.3 ± 2.6

1.4 ± 4.7

TC (mg/dL)

−24.6 ± 15.1

0.8 ± 18.7

LDL

−23.3 ± 15.2

−3.7 ± 17.3

215 ± 107

50 ± 116

Fitness

Source: Based on data of Nemet, D., Barkan, S., Eptein, Y., et al., Pediatrics, 115, e443, 2005.

of exercise persisted for longer periods of life, these differences were larger and statistically significant, depending on a certain threshold of the intensity, character, and duration of increased muscle work and activity (Parˇízková and Heller 1991), indispensable for the manifestation of significant changes. Similar results were also found previously in older youth (Parˇ ízková 1977), and confirmed in a group of children characterized by a larger age span, in which PA intervention changed selected parameters of somatic and biochemical status positively (Table 10.4; Nemet et al. 2005). Children with the highest PA tended to have better results in tests for fine motor control, which was manifested mainly in drawing tests and creativity (Mateˇ jícˇek and Strnadová 1974, Mateˇ jícˇek and Vágnerová 1976, Parˇízková et al. 1986a).

10.9

OTHER SURVEYS ON THE EFFECT OF PA AND EXERCISE AT AN EARLY AGE

The influence of exercise on children of preschool age varied in the individual surveys, which was mainly apparent regarding positive results of functional parameters at the age of 6.4 years and only occasionally (and not as markedly) in younger age groups. The influence of exercise was also differentiated in relation to various motor tasks and tests. There was mostly a trend toward better results in children participating in regular physical education classes for children and their parents. Most often, better results were found in the broad jump (which characterizes both skill and explosive strength of the lower extremities). Thus, a test of jumping seems to be a good approach for the evaluation of motor abilities. Studies in other preschool children confirmed the positive results of early intervention in increasing PA and exercise (Iurko et al. 1993, Kuchma et al. 2006, Krombholz 2006). Muscular strength and muscular endurance can be improved during childhood years: introduction of a higher repetition moderate resistance training program can be used, starting at 5 years of age (Feigenbaum et al. 1999).

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Although the above-mentioned investigated sample varying in the level of spontaneous PA was small (which was due to striving for a comprehensive methodological approach including blood sampling, which is very difficult to obtain in healthy preschoolers), anthropometric variables, body composition, cardiorespiratory fitness, dietary intake, psychological development, and overall lifestyle of the children and their families did not differ significantly from the results in our previous surveys of larger groups of preschool children of the same age. Functional parameters, that is, the reaction to the step test, corresponded generally to the results reported before (Parˇ ízková 1977, Parˇ ízková et al. 1984). The same applies to dietary intake, which did not differ from the usually increased values for Czech children, including higher fat intake. Therefore, we can speculate that the complex results gained in this survey might apply more generally. Similar results were later found in another study of U.S. children of the same age (DuRant et al. 1993a). Higher levels of cardiovascular fitness and lower levels of fatness were associated with more favorable serum lipid and lipoprotein levels as in our survey. Physical fitness appeared to have an indirect association with serum lipid and lipoprotein values through its relationship with a higher level of PA (Greaves 1990, Greaves and Thompson 1993), fitness, and a lower deposition of fat. Fitness, activity, and participation in sports activities in preschool children were also analyzed by the American Academy of Pediatrics (1992) with regard to the present situation, which seems to be unnatural and harmful from the point of view of the actual and future consequences of morphological, functional, metabolical, and biochemical characteristics (Greaves 1990). The significantly higher level of HDL in active children (Figure 10.2f, Tables 10.3 and 10.4) is important with regard to the decreased risk of cardiovascular disease morbidity at a later age: it was shown that children who had favorable levels of blood lipids at an early age generally preserved them later on (Bogalusa study; Newman et al. 1986, Vobecky and Vobecky 1982, Vobecky et al. 1988, 1993). As mentioned in Chapter 6, a significant correlation of total cholesterol and TG level with total body adiposity was found in preschool children (Parˇ ízková et al. 1986a,b). The mentioned data seem to indicate that a genotype characterized by a high level of spontaneous PA, and thus representing a particular “motor individuality,” has a more favorable spectrum of serum lipids, namely a higher level of HDL. Such a predisposition may limit the risk of cardiovascular diseases in later life. Usually this is associated with similar traits in one or both parents. However, it may also be presumed that the introduction of an active way of life might result in similar favorable changes of serum lipid levels in children. Increased activity, both spontaneous and induced, can obviously give positive results, and health promotion strategies are therefore recommended starting with infants, toddlers, and preschoolers (Gunner et al. 2005, Trost et al. 2008). The feasibility and efficacy of a PA curriculum for preschool children were also proved, and integrating movement experiences into an existing early childhood curriculum was recommended as a potentially efficient strategy for promoting enhanced PA and exercise starting with preschool age (Trost et al. 2008). Further studies showed positive results of school-based nutritional-PA intervention in preschoolers, that is, favorable changes in BMI percentiles, fat percent evaluated by skinfolds, and fitness level

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(i.e., endurance time; Eliakim et al. 2007). Similar results were obtained by other previous studies (Parˇízková 1977, 2008).

10.10 GENERAL CONSIDERATIONS Because of increasing obesity in children, proper PA regimens and organized exercise have been considered as a suitable means for improving the energy balance (Chapter 8). The role of exercise in this respect has been reviewed more recently with regard to early age by more authors. The need for a structured and systematic approach was considered (Saunders 2007, Connelly et al. 2007). Even when the effect of exercise in preschool age is not always marked and significant, it is manifested, for example, by improved skills (Reilly et al. 2006), which may contribute to greater interest in participating in PA programs during subsequent years of life. For this reason, increased PA and reduction of sedentarism are recommended for the prevention of obesity from early childhood (Reilly 2008). As mentioned above, the effects concerning BMI and adiposity may manifest only later, when the intensity, duration, frequency, and overall character of exercise can achieve a higher level; an early start facilitates that significantly, and is a good predisposition for optimal development later in life. Therefore, it is important to start with the introduction of higher PA and support for adequate exercise as early as possible. A desirable family model, especially that of the mother, but including both parents and also siblings and other peers, should be a good start even when positive results are not obvious immediately at preschool age. This concerns especially children who were already obese (Sabin et al. 2007). Policies preventing childhood obesity in the EU were elaborated, for example, by IOTF (Lobstein and Baur 2005). The essential role of parents is always emphasized in all interventions when introducing such programs for preschool children (Bluford et al. 2007, Summerbell 2007, Wollman et al. 2008). All the mentioned propositions are not original and new, but, under the present conditions of life, changing environment and lifestyle actualized plans and suggestions are required so as to achieve significant positive effects. Further research of all growth parameters and the effects of both PA and diet in their mutual relationship in preschool children in different parts of the world are therefore essential. A suitable way of life for the whole family with an adequate diet and a desirable level of PA and exercise can contribute to the reduction of health risks in any child. The same applies to the regimen of diet and exercise in kindergartens, day-care centers, and other institutions for preschool children. Such efforts should be supported and developed by governmental institutions, sports organizations, and clubs. This will surely guarantee better fitness and health achievements than when starting only later on in school age and/or in adolescence.

11

Criteria for the Evaluation of Morphological and Functional Development in Preschool Children: Recommendations

11.1 BODY SIZE AND BODY COMPOSITION Developing a global definition for acceptable ranges of body size is a difficult task. The usual approach includes establishing reference values of basic anthropometric characteristics—height, weight, selected circumferential measures and derived indices, BMI, and others. On the basis of the measurement of a certain population, average values were evaluated as norms or, more recently, as percentiles. The 50th percentile is generally accepted as a standard for the population in question. However, the most common or average value in a population does not always translate to the optimal value. Body size not only reflects the level of development and its adequacy, but also serves as a basis for RDAs, especially regarding energy and proteins. There has always been a dilemma concerning reference standards for the growth of children from industrialized countries—should they be accepted as universally relevant or should local standards be used (WHO 1985). Children in many developing countries are already smaller at birth than those in industrialized countries, and grow at a slower rate during infancy and early childhood. Evidence suggests that in young children these differences are primarily due to environmental factors (including inadequate nutrition) and genetic and ethnic factors are of less importance. Thus, young children of different ethnic groups should be considered as having the same or similar growth potentials, which, however, changed during many generations before our time. As shown by numerous comparative studies, even a healthy privileged population can show a wide variation in the size of its children. Up to now, very limited information concerning the possible relationship of body size to health, well-being, or physiological function was available. However, in some communities where children’s growth is severely limited by environmental factors, there is evidence of an association between functional impairment and deficit in linear growth. In such cases, it is necessary to differentiate between the degrees of growth deficit so as to define health risk. 301

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In studies comparing marginally malnourished and well-nourished children, at both preschool age and prepubertal age, it was shown that larger body size was not a self-evident predisposition for a higher level of functional capacity, physical fitness, and health—not mentioning other faculties. This applied to the level of cardiorespiratory fitness (Ferro-Luzzi et al. 1977, Parˇ ízková 1977) and to factors such as skill, or psychological and intellectual abilities. Obviously, when the degree of growth deficit did not violate certain limits and did not affect the development of vital organs and tissues, there was no obvious functional deterioration. The above-mentioned studies point to the necessity for the examination of a greater number of characteristics concerning growth and body composition, mainly those that are markers of the functional capacity of the organism and of “positive health”—at present for preschool age, but also for future life. The process of selection and validation of such markers, focused on functional and motor abilities, was one of the main aims of our surveys. Expert consultants of the joint FAO/WHO/UNU (1985) felt that the growth potential of children should be fully expressed, and that all estimates for requirements such as energy and protein should allow this. For this reason, not only this expert committee but also several others recommend that the reference growth standards be published for international use by the WHO (1985, 1990, 1991, 1997, 1997a). In epidemiological studies of children who are undernourished, it is conventional to accept −2 SD from the median (or the 3rd to 10th percentile of BMI) as the cut-off point between “normal” and “malnourished,” corresponding approximately to the third percentile, or to 80% of the median for weight and 90% for height. Similarly, +2 SD weight for height may be taken as the cut-off point for obesity. During the last decades, BMI percentiles were agreed on, and were used preferably. Growth monitoring was recommended for the evaluation of the overall development of children (Hall et al. 2008). Growth grids for BMI were developed as mentioned above (Rolland-Cachera et al. 1988, Hammer et al. 1991). Standard definitions for child overweight and obesity, specifying the measurement, the reference population, age, and sex-specific cut-off points worldwide, were established using the international surveys of six nations (UK, Brazil, Hong Kong, The Netherlands, USA, and Singapore; Cole et al. 2000). BMI cut-off points to define the thinness in children and adolescents were also determined (Cole et al. 2007). However, the use of some of these grids and definitions can exaggerate the prevalence of obesity in some child populations compared to local definitions. The limitations of international definitions, due to averaging data from different countries and the choice of reference age, need to be known (Chinn and Rona 2002). In the United States, BMI grids were elaborated by the NCHS in collaboration with the National Center for Chronic Disease Prevention and Health Promotion (2000). The use of this particular reference population is recommended on the basis of several criteria. Cole et al. (2005) considered the measures of adiposity change of growing children, that is, BMI, BMI%, BMI z-score, or BMI centile, and established, on the basis of an international survey, a standard definition for child overweight and obesity as well as for thinness (Cole et al. 2000, 2005).

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The values of BMI for the 50th percentile vary with age; generally, BMI increases with age. The IOTF consented to BMI growth grids for both genders, which have been recommended for use. However, they might not be valid for all countries, especially those with different economic and social levels. The cut-off values of BMI for different child populations also vary, for example, the 85th percentile for overweight and the 90th percentile for obesity for the US population (National Center for Health Statistics and National Center for Chronic Disease and Health Promotion, 2000) and the 90th and 97th percentiles for the Czech population (Bláha 1991, Vignerová and Bláha 2007). According to these criteria, conclusions on the relative prevalence of obesity may vary, even when the number of local subjects with the same increased BMI in compared populations is the same. Therefore, the optimal, desirable values of BMI for different national age categories need validation, using additional functional and health variables. A Consultation Document to Guide Development of a WHO Global Strategy for Diet, Physical Activity and Health (2004) was also prepared to enable the evaluation of child development. The average values of height and weight have been changing during the last decades, that is, they have increased; for example, in the United States (Gortmaker et al. 1990, Kuczmarski et al. 1994) the higher values of body weight are mainly due to an increasing adiposity of the U.S. population. The age when AR occurs and the nature of BMI changes during the period of preschool growth (usually between 5 and 6 years) are very important markers for predicting the future development of obesity. However, the age when AR occurs can be different in different countries (e.g., in China). In spite of some doubts on a “lasting solution” to the international definitions of overweight and obesity, BMI has been widely used, at least for the initial approximation for the evaluation of child development and nutritional status. Chest circumference was most often measured along with height and weight. In addition to body composition measurements, it is recommended that one measure waist and hip circumferences and calculate the waist/hip ratio. These indices may differentiate between different types of obesity: diffuse gynoid, pear-shaped, and/or android, apple-shaped obesity. The latter usually occurs later on in life with a number of pathological changes, such as glucose intolerance, prediabetes and/or even non-insulin dependent diabetes mellitus (NIDDM), dislipoproteinemia, hypertension, ischemic heart disease, etc. (Parˇízková 1993a). However, it was recently also found in childhood and adolescence. Thus, it may help to define and select, as with indices of fat distribution, individuals at risk for such diseases on the basis of very simple anthropometric measurements. Bouchard and Johnston (1988) already consider fat distribution in childhood as a marker of later health risk. More recently the waist/height ratio has also been used for children, which resulted in a more detailed evaluation of the developing physique (see Chapter 4). Circumferential measures of the head and neck already differentiate boys and girls at a very early age. These measures display, in preschool children, the lowest variability from all the other circumferential measures, and may be very similar in individuals with other much more differentiated somatic characteristics. Circumferences of the extremities may also give relevant information on body composition: this applies mainly to arm circumference, which is an important indicator

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of both muscle and fat development. When the circumference, as well as skinfold, is measured, the net circumference of the muscle mass of the upper arm can be calculated according to the formula (Imbembo and Walser 1984) AMC (mm) = midarm circumference (mm) - (0.314 ¥ triceps skinfold in mm) Upper-arm fat area (UFA) was also suggested for the evaluation of adiposity (RollandCachera 1995): UFA = arm circumference ¥ triceps skinfold/2 Thus, it is possible to evaluate musculature status and nutritional status according to the degree of fat deposition. The first parameter was used for measurements in children of Third World countries, and the second parameter was used for European children, for example, in France (Rolland-Cachera et al. 1990). The circumference of the thigh is important in the evaluation of obesity development: the fat layer deposited in the trochanteric region (RTG) correlated best with the total amount of fat. Such measurements are rare, and are not allowed today if only for research purposes. The waist/thigh ratio is also calculated and used for the evaluation of the type of fat distribution on the body surface. Length measures were used for the evaluation of body proportionality assessments; for example, the index relating sitting/total height makes it possible to evaluate the relationship between the length of the trunk and of the lower extremities and how this changes during growth. Other measures on the extremities were used for the evaluation of the body physique of dancers or athletes specializing in different disciplines. There also appear to be changes during growth and development, characteristic of individual growth periods (Parˇ ízková et al. 1984). Breadth measurements of the trunk can help evaluate body proportionality; this applies especially to the biacromial, bi-iliocristal, and bitrochanteric measures. As shown by our results, at preschool age the proportionality evaluated with the help of indices relating these measures to total height and/or mutually does not change markedly. This occurs later on; indices characterizing relative breadths correlate significantly with body composition (Parˇ ízková 1977). Breadth measures on the extremities characterize the robusticity of the skeleton, that is, bone mass, which changes remarkably during growth. There are also sex-linked differences that are already apparent during preschool age, and that help characterize the individual in actual and future development. In the context of malnutrition and/or obesity, it is important to measure body composition and some indicators of LBM and fat in the body. Assessment of the layer of subcutaneous fat measured as skinfold thickness can give an appropriate answer to body composition, as it is also possible to use certain standard values for individual skinfolds for comparison (Parˇ ízková 1961a, 1977, 1993b) and/or for the calculated percentage of depot fat (Parˇ ízková 1961b, 1977). This is important in light of the great variability in body composition, which can differ even when height, weight, and BMI are the same or very similar. Moreover, a thin child with a low BMI may have quite a lot of fat or vice versa—a child with a high BMI and a high percentile of BMI can be lean and can have very little fat. When possible, BIA can be used, but there are still objections that especially at a young age the results of adiposity assessments might not be as exact as later on in life.

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Fat distribution (pattern) calculated as the ratio of individual skinfold thicknesses (subscapular/triceps, or sum of skinfolds on the trunk/sum of skinfolds on the extremities) is actually considered an early marker, already important during the growth period for later development, of diabetes or cardiovascular diseases (Bouchard and Johnston 1988). In adults and adolescents, significant correlations were found for indices of fat distribution and blood lipid levels (Parˇ ízková et al. 1995). Many other methods exist for the evaluation of body composition, as mentioned in Chapter 4. Under the present conditions, anthropometry and BIA are used most frequently, and eventually also DEXA.

11.2

FUNCTIONAL MEASUREMENTS: CARDIORESPIRATORY FITNESS

Anthropometric measurements are easier than functional evaluation, which has been used less often in very young children. The selection of functional and motor tests, the results of which were presented, is certainly not the only approach. Other batteries of motor tests were introduced (see Chapter 6), which were used and validated in older age categories, some of them also for young children. It is necessary to stress that their selection was not accidental, but a result of long testing and trials. The main consideration in their selection for the evaluation of Czech preschoolers was having tests that would be natural for the children, but at the same time reliable and valid, under conditions of preserving measurements that should be standardized. All experimental workers have to be therefore trained and tested. As mentioned in Chapter 6, physical fitness and the functional capacity of the growing organism have many facets that may be developed in a synchronic or an asynchronic way. Therefore, the use of a battery of validated tests, usable under available conditions, is desirable. On the other hand, significant mutual correlations were found; therefore, it was possible to make a selection of some to characterize the level of functional capacity. With standards and norms, there is a problem similar to that with morphological development. Obviously, values established in one country cannot always serve as norms in another country or in a different part of the world. Therefore, the data given in this book can serve as a guideline or as reference values that should be validated in other countries. However, because the tests were chosen to remind of “sports” activities, they may also be more attractive for young children. Moreover, were gained in a population with satisfactory economic level. Whether average values or 50th percentiles are the best criteria is generally controversial. Let us not forget that the average values of BMI or of total cholesterol levels increased in some countries, especially developed ones: such values can hardly be considered reference values. The same applies to functional variables; for example, aerobic power deteriorated (by ca. 0.5% per year during the past decades) both in industrially developed countries and in some developing countries of the world (Tomkinson et al. 2003) that adopted the lifestyle, including diet and PA, of industrially developed countries (Shephard 1991). As in “positive health,” an optimal, not average, variable of functional capacity should be used as the criterion and as

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the goal. Then, the assessed values should be evaluated considering both the average for a given population and the optimal, desirable reference value. Therefore, percentiles as for BMI would be the preferable choice. In cardiorespiratory fitness, the step test (using a step) proved to be a suitable test for young children because it is a natural activity (at least in industrially developed countries). Even when certain procedures were developed using a modified veloergometer (e.g., stimulating the child by showing him/her a picture that appears only when the child maintains a special frequency of pedaling, during the necessary period of time), such a test is still less natural because not all children know cycling; those who do are at an advantage. Running on a treadmill is also a natural activity, but it may be frightening for 3–4-year-old children; 5–6-year-old children were tested using Balke’s walking test. A 6-min walking test on a treadmill was induced, and was shown to be satisfactory for 5–6-year-old children. However, both these procedures are much more expensive and difficult to arrange under field conditions. Climbing a step can be fixed more easily. Standard values that are optimal for cardiorespiratory fitness (and also skill, strength, etc.) are preferred to average values. The most important criteria for a favorable result in the step test are the following: • An increase in heart rate by about 50% as compared to the rest value • Establishment of a steady state during load • Return of the heart rate to the resting value at the end of the recovery period (third to fourth minute of recovery) The values of CEIs can serve as reference values for individual age categories, as presented in Figure 6.1a and b and in Tables 6.4 and 6.5. Calculation of CEI1 and CEI2 (Cˇermák et al. 1973), which relates performed workload (climbing, weight in kg to the height of the step in cm, related to one heart beat), evaluates performance in a more homogeneous way, which makes the comparison of individual children possible.

11.3

MOTOR DEVELOPMENT

As mentioned in Chapter 6, motor tests were selected to characterize speed (20-m dash) and the explosive strength of muscles of the upper and lower extremities (throwing a ball, broad jump) along with skill, endurance (500-m run-and-walk), and hand grip strength. Details of the procedures and results have been described in detail in previous chapters. The values are given in Tables 6.4, 6.6 and in Figures 6.3, 6.4. It is recommended that we use tests that include activities that the children are familiar with on a daily basis. The majority of preschool children, at least the older ones, are able to fulfill skill tests such as walking on a beam, standing on one leg, performing a forward roll, walking at a given rhythm, and catching a ball in different ways (Appendix 3). Additional tests, such as the sit-and-reach, the shuttle run, and many others, were also used in other studies (Cratty et al. 1973, Oja and Jürimae 1998). Reference values for preschool children are still rare and should be elaborated further to eventually become more culturally specific. The reference values for muscle strength

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(which requires special equipment) are presented in Figure 6.5; however, when using different methods, standard values must be obtained specifically for them. Assessment of these natural skills gives information on development as related to average somatic development, and their satisfactory level means a predisposition for greater interest in PA and exercise in future years. Clumsiness dissuades children from participating in games and exercise with peers, who may perhaps ridicule them; however, when assessed in time, it could be rectified, at least partly, and enables the child to improve and develop desirable PA during subsequent growth periods and later on in life. As mentioned before, children “copy” the activities of older age categories, including sport, and accept such tests with greater interest and involvement.

11.4 SENSOMOTOR DEVELOPMENT Fine motorics is an important predisposition for many other abilities and skills in school and elsewhere. The testing of sensomotor development shows the level of development of the child and calls attention to the state of the child, who may need some assistance. The “open and close the hands” test can differentiate individuals at a higher level because only some preschool children are able to fulfill all items of this test before the beginning of school. This test was widely used for children in the United States, the Czech Republic, and other countries and gives valid information on the level of development of the child. The development of fine skills continues during early school age. The test of spatial orientation is the easiest for children; testing of laterality gives less satisfactory results, which is partly caused by the fact that this is not yet definitively differentiated before entering primary school.

11.5 DIETARY INTAKE AND BIOCHEMICAL CHARACTERISTICS Assessments of dietary intake have a long tradition, as described in numerous textbooks (see Chapter 5). These procedures gave valuable information; however, in our studies personal interviewing by specially trained personnel and parents was conducted, and preferred whenever possible. Such procedures were also used by Gregory et al. (1995) in a national diet and nutrition survey in the United Kingdom. As mentioned in Chapters 5 and 8, RDAs for children undergo some minor modifications; they are at present slightly reduced and also related to EE. The changes have not been basic and decisive; there is great stress on individualization, within a certain optimal range of dietary intake, taking into account especially the resulting status of the child, which should be as best as possible from the point of view of health and overall development. Due to that, there is no absolutely unified receipt for all children. This process has not been definitely agreed on, and further modifications can be expected. Most important, however, is the mentioned individualization, that is, to recommend what is really needed not only for growth but also for PA, which can vary markedly. The same applies to assessments of biochemical parameters such as serum lipids (Gregory et al. 1995). In this respect, there are incomparably better experiences as compared to the evaluation of cardiorespiratory, motor, and sensomotor development in normal healthy young children.

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Summary of Experimental Results

PA and motion, closely interrelated with dietary intake, are not only a basic manifestation of life, but also a means of significant modification of a number of variables characterizing the organism. This includes morphological, functional, nutritional, biochemical, motor, and sensomotor variables; the opportunity to intervene using both diet and exercise in optimal mutual relationships seems most effective when introduced early in life. The influence of varying degrees and kinds of PA can be both positive and negative; the resulting changes also depend on the initial state of the organism in question—age, that is, stage of growth and development, genetic predisposition, and epigenetic factors. In addition, the range and degree of motor stimulation, and its character, intensity, and frequency, which should be adequate according to the age and individuality of the child but should achieve a certain and significant threshold, should be considered and implemented.

12.1 STUDIES IN EXPERIMENTAL MODELS WITH LABORATORY ANIMALS The results of experimental model studies using laboratory animals showed a significant influence of the change in PA regimens of pregnant rats and of the dietary changes at the beginning of life of the offspring (lactation period). As shown by a series of experiments, changes in PA were closely related to changes in dietary intake and vice versa. Rats weaned in large nests (more than 12 pups), that is, those that had a lower intake of mother’s milk, were not only smaller and less fat, but also developed a higher level of spontaneous PA in rotation activity cages, in contrast to rats weaned in small nests (less than six pups). The sizes of vital organs (heart, adrenals) and muscles were the same, and depot fat was reduced. Along with this, there were differences in the parameters of lipid metabolism, that is, animals from small nests had higher concentrations of total lipids and fatty acids in the small intestine of females and a higher synthesis of lipids in the small intestine of both males and females. Cholesterol synthesis in the liver and in the carcass was the same in all groups, but cholesterogenesis in the liver was higher in males from large nests. Cholesterogenesis in the carcass was also higher in animals of both sexes from large nests. Apparently, temporary manipulation of dietary intake early in life influenced body size and fatness, level of spontaneous PA, and lipid metabolism long after this intervention was made, when the diet was the same in all compared groups. A higher level of PA showed that the functional status of animals was good in spite of early marginal 309

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malnutrition, which resulted in reduced body size and adiposity (Parˇ ízková and Petrásek 1979, Parˇ ízková 1989, 1990). Similar consequences were observed when eight pups were weaned in one nest; their mothers were fed a reduced protein diet (10%) and a low energy diet during the whole period of lactation, and then the same diet with 5% of protein was used for the animals after weaning (28th day) until the 49th day of life. The offspring spontaneously consumed less of this diet, that is, their intake of both protein and energy was reduced (REP). Thereafter, REP animals had the same laboratory diet as control animals fed ad libitum all their life. Reduced growth, lower depot fat, the same size of vital organs, and better energy economy as characterized by a lower food intake/1 g of weight increment during the growth period along with a significantly higher level of spontaneous PA in rotation cages characterized animals with a reduced protein and energy intake at the beginning of life (REPA). This was proved by a series of experiments; some delayed changes in lipid metabolism were also found (a higher concentration of lipids and lower liposynthesis in the liver in REPA animals; Parˇ ízková et al. 1979). The introduction of a high-fat diet early on in life (18–30th day of life), which was followed with a special regimen of self-selected diets (pure starch, fat, casein), significantly changed the free choice of mentioned dietary components, that is, temporarily increased the spontaneous intake of fat and later that of protein compared to animals without a high-fat diet early on in life. In addition, the reduction of body size and depot fat found in animals living during the whole experimental period on the selfselected diet of pure foodstuffs was prevented by a high-fat diet at the beginning of life. Therefore, the introduction of a special diet early in life had a number of significant consequences that only became apparent later in life (Parˇ ízková 1961c). Increased PA, that is, exercise of the mother rat during pregnancy (mild aerobic exercise, daily run on a treadmill, 15 m/min for 1 h), had a significant impact on lipid metabolism variables in the offspring later in their adult life, which was not seen in the offspring of control, inactive rat mothers. The cholesterol concentration in the liver was increased in both female and male offspring of exercised mothers. Significant changes of liposynthesis studied in vivo after injection of Na-acetate-1-14C were also observed. In vitro study showed a lower total lipid and fatty acid concentration in the liver and a higher level of serum-free fatty acids in adult male offspring of exercised mothers. A higher concentration of cholesterol, a higher synthesis of fatty acids, and a lower cholesterogenesis in the small intestine in adult male offspring of exercised mothers compared to the offspring of control mothers were also found. The daily workload during pregnancy resulted in significant delayed changes of lipid metabolism in the liver and small intestine of adult offspring (Parˇ ízková 1989, Parˇ ízková and Petrásek 1978). Exercise during pregnancy also had a significant delayed impact on offspring’s cardiac microstructure: young adult offspring of exercised mothers had a significantly higher density of muscle fibers and capillaries, a higher capillary to fiber ratio, and a significantly shorter diffusion distance in the heart compared to offspring of control, inactive mothers. This influence, which may be physiologically interpreted as positive, was further amplified by exercise of the offspring during their own postnatal ontogenesis. However, according to the differences between control offspring of exercised mothers and exercised offspring of control mothers, the influence of

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exercise during pregnancy seemed to be more important in adult age (Parˇ ízková 1975, 1978a,c, 1979). Changes in diet and PA early in life are closely interrelated. This is evident from the elevation of the level of spontaneous PA in rats with early marginal protein energy malnutrition (REP) and in rats from large nests that had less milk from their mothers. Such animals are characterized by the above-mentioned slight reduction in body size, reduced fatness, and better energy economy when increasing weight (i.e., less energy needed for 1 g of weight gain), simultaneously with an elevated spontaneous PA (i.e., higher energy output) in rotation cages during the whole lifespan (REPA). Along with that, the cardiac muscle of these animals had, in adult age, a higher resistance against noxious factors, for example, isoprenaline, which induces experimental cardiac necrosis. After the administration of the same dose of isoprenaline, smaller, leaner, and more active animals developed a lower degree of cardiac damage and died spontaneously less often than normally ad libitum fed animals, which were heavier and fatter, with a lower spontaneous PA level in rotation cages (Parˇ ízková et al. 1982). Apparently, marginally reduced energy and protein content in a more modest diet (compared to ad libitum intake) early in life, as well as workload during pregnancy, can have, in an experimental model, positive delayed consequences manifested in the adult offspring as changes in body size, fatness, level of spontaneous PA, modifications of lipid metabolism, positive changes in the microstructure of the cardiac muscle, and a greater resistance to noxious factors inducing cardiac necrosis.

12.2 OBSERVATIONS ON THE INFLUENCE OF MATERNAL NUTRITION ON THE NEWBORN The follow-up of Italian women (Alberti-Fidanza et al. 1995a,b, 1998) during pregnancy regarding their anthropometric variables, fat pattern, dietary intake, and blood lipids revealed a significant relationship between maternal variables and those in the newborn offspring. Mother to son correlations were found to be most frequent (birth weight, skinfolds, fat distribution). The mother’s weight gain correlated negatively with BMI and skinfolds in sons, and positively with birth weight, BMI, and subscapular skinfolds in daughters. Fat distribution, characterized by indices (relating skinfold thicknesses on the trunk and on the extremities, which are considered markers of cardiovascular risk), correlated most closely in mothers and newborn sons (Alberti-Fidanza et al. 1995a,b, 1998); even closer correlations were found in mothers and sons aged 2–5 years old (Parˇ ízková 1995a,b,c). With maternal diet and cord blood lipids, most relationships were found for total energy intake and energy provided by carbohydrates, and for total cholesterol and HDL-cholesterol in sons only; these relationships were significantly negative. The energy provided by proteins and fats in the maternal diet correlated positively with the total cholesterol of the offspring; when considering genders separately, it was significant only in newborn sons. HDL-cholesterol of the offspring correlated positively with the percentage of energy provided in the maternal diet by fats and negatively with that provided by carbohydrates. Maternal TGs correlated positively with cord blood HDL-cholesterol in the joint group of all offspring, but when evaluating

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sexes separately the correlation was significant in girls only. Maternal total cholesterol correlated positively with TGs and with the HDL-cholesterol/total cholesterol ratio only in girls. In newborns, significant correlations between total cholesterol and fat distribution were found. All correlations were low, but were mostly highly significant and occurred systematically. The accumulation of weaker but significantly negative factors (e.g., composition of the diet) affecting mothers during pregnancy may have undesirable influences on the newborn (Alberti-Fidanza et al. 1995b, 1998). These results indicate the importance of the composition of the mother’s diet regarding blood lipids of the newborn, especially those of sons. Significant relationships between the fat distribution of the mother and the son point out the possibility of a link between maternal nutritional status and markers of cardiovascular risk to the offspring, namely sons. As indicated by other authors (Newman et al. 1986, Vobecky et al. 1993), the serum lipid level at birth correlates with the level assessed later and with atherosclerotic plaques during the prepubertal period. These results seem to indicate that the composition of the maternal diet during pregnancy deserves more attention than it has had up to now.

12.3

MORPHOLOGICAL AND FUNCTIONAL SURVEYS IN PRESCHOOL CHILDREN

Measurements in nine cross-sectional studies, including those of the representative samples of thousands of children in the Czech Republic, and in three longitudinal follow-ups made in the 1970s and 1980s gave more detailed and complex information on somatic, functional, motor, and sensomotor development and on dietary intake and serum lipids of children 3–6 years old. In total, 142 indicators were assessed. (It is also worth mentioning that measurements in healthy normal preschoolers, who do not need any medical assistance, are incomparably more difficult than in schoolchildren and adolescents.) The results were dependent on the time and years of measurement, but with regard to the changes that occurred since, that is, increasing BMI and adiposity, decreasing PA and fitness, more frequent inadequate composition of the dietary and beverage intake, etc., given that data could be more appropriate as standard values than those assessed at present. The impact of environmental factors, including diet and exercise, at preschool age was also investigated. The selection of procedures and methods was from previous studies with a larger battery of tests (Parˇ ízková 1977, 1978b,c, 1980, Parˇ ízková et al. 1984). Cross-sectional morphological and functional measurements in four age subgroups from 3–4 to 6–7 years (survey A) in a group of 238 children, and five longitudinal measurements during the same age period (survey E) in 58 children were carried out using total and sitting height; weight; BMI; length of the upper extremity; acromion-radiale; radiale-stylion; length of the lower extremity; bispinale-tibiale; tibiale-sphyrion; breadth measurements on the trunk and extremities (i.e., biacromiale, chest breadth, and depth); bi-iliocristal, hand, wrist, femoral condyles, and ankle breadths; and circumferential measurements on the head, neck, chest, abdomen— waist, arm, forearm, thigh, and calf. In addition to these factors, indices characterizing body build and proportionality were also evaluated. All variables increased with advancing age, some of them more (weight, length measures) and some very little

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(head, neck circumferences). Head circumferences were always greater in boys; length and breadth measures on the trunk and extremities and other circumferences tended to be greater in boys, but this was mainly significant in the oldest age group (5–6- and 6–7-year-old children). Interindividual variability was always large. Skinfolds on the cheek and chin, on two sides of the chest, and over the triceps, biceps, subscapular, abdomen, suprailiac, thigh, and calf were measured as a characteristic of body composition using a modified Best caliper (with adjusted constant pressure; Parˇ ízková 1961b, 1977). Skinfolds over the triceps, subscapular, suprailiac, calf, and biceps were also measured using a Harpenden caliper (Parˇ ízková 1980, 1993b, 1995a,b,c) on both sides of the body. Subcutaneous fat was greater in girls and was the only variable that did not change (in girls) or decrease (boys) in children 3–6 years old. Indices of fat distribution relating to the subscapular and triceps and/or skinfolds measured on the trunk and on the extremities were evaluated along with somatotypes (endomorphy, ectomorphy, mesomorphy). These variables were stable at preschool age (Parˇ ízková 1977, Parˇ ízková et al. 1984, 1985). There was a trend toward higher endomorphy in girls and higher ecto- and mesomorphy in boys, although the differences were not significant. Body posture, that is, the position of the neck, back, and abdomen from the side view, the depth of the neck and lumbar lordosis, and the position of the shoulders, scapulae, and spine in the upright and bent forward position from the back view, was also studied. Body posture deteriorated from 3 to 6 years as indicated by both crosssectional and longitudinal studies (Parˇ ízková et al. 1984), obviously due to muscle flabbiness resulting from inadequate PA. For cardiorespiratory fitness, the step test was employed (as the only test feasible, including 3-year-old girls and boys) in the above-mentioned groups, both cross-sectionally and repeatedly in the same children in longitudinal studies. Children climbed a step 25 cm high (oldest children 30 cm) 30 times/min, assisted (but not helped) by a technical assistant; the heart rate was measured during 3 min of rest, during 5 min of climbing the step, and during 5 min of recovery. The average heart rate during all periods of testing decreased with age; a steady state was established during the workload and the heart rate returned to rest values before the end of the recovery period, indicating that this test was not excessively strenuous for preschool children. The CEI values (CEI1, CEI2), calculated from the values of performed work as related to one heart beat assessed during various phases of the step test, revealed an improvement in the economy of work of the cardiorespiratory system with advancing age. The heart rate was slightly higher in girls. However, in our groups these differences did not reach a level of statistical significance (Parˇ ízková 1977, 1994, Parˇ ízková et al. 1977, 1984). The development of gross motorics was tested in an evaluation of performance in the 20-m dash, broad jump, and ball throw with both the right and left hands, selected as natural activities for young children. Hand grip strength of the right and left hands was measured using a dynamometer (tensometric principle) specially adapted for young children’s palms. The performance improved significantly with age. Regarding sex-linked differences in the tests of gross motorics, boys performed significantly better in tests demanding maximal effort (Parˇ ízková 1977, 1978c, 1980, Parˇ ízková et al. 1984).

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Skill and balance were evaluated using the following tests: walking on a horizontal beam, standing on one leg for 10 s, forward roll, walking at a given pace, and catching a ball (five modifications). In skill tests, girls tended to be better, manifested in particular in standing on one leg and in the forward roll. Performances in the other tests did not differ. The results of these tests improved significantly with advancing age (Parˇ ízková et al. 1984, Parˇ ízková and Douglas 1995). The cooperation of children was well assured in all the mentioned tests, as they were used as a component of games during a particular time in the kindergartens. In several smaller subgroups of children in Prague and Nymburk, dietary intake was assessed repeatedly (entering 7-day records with the help of kindergarten teachers and parents). An elevated intake of energy, protein, and fat was assessed in comparison to local RDAs. The intake of food was even more excessive when compared with RDAs for the United States (1989) or for the EC (1993) (which are lower especially for protein). Higher values of BMI were assessed in Czech children in the preschool period; we might speculate that increased obesity and cardiovascular risk, resulting in a higher morbidity and mortality from cardiovascular disease in the adult Czech population, could be inter alia also due to early overeating. Marked obesity was not yet apparent in our groups of preschool children; however, it could appear later on due to this predisposition at an early age, as reduced energy expenditure resulting from reduced PA, and mostly inadequate composition of the diet at school age, might enhance the development of increased adiposity. Assessments in smaller subsamples of preschool children revealed normal levels of total, HDL- and LDL-cholesterol, and TGs, which did not correlate with the actual food intake (Parˇ ízková 1994, 1995a,b,c, 1996, Parˇ ízková et al. 1986b). Follow-ups of height, weight, BMI, circumferential measurements, performance in the 20-m dash, broad jump, and ball throw, along with skill and sensomotor tests were repeated in three other cross-sectional surveys (B, boys n = 2839, girls n = 2759; C, boys n = 1848, girls n = 1864; D, in total 9590, subsample 1005) and in another longitudinal survey (F, boys n = 367, girls n = 397). Longitudinal observations confirmed the conclusions of the above-mentioned cross-sectional surveys (Parˇ ízková 1994, 1995a,b,c, 1996, Parˇ ízková et al. 1984, 1986b). Economic and family situation, education of parents, birth weight of children, beginning of independent walking (i.e., whether before or after 1 year of age), morbidity of children, and characteristics of the environment in different districts of the Czech Republic were evaluated, as in the above-mentioned surveys A and E. Additional information on children’s lifestyle was also assessed by questionnaires, and all children were evaluated globally as well as in subgroups differentiated according to these characteristics in surveys B, C, and D. Reference values of the above-mentioned variables were established for individual age groups (based on national BMI percentiles, using cross-sectional data, which were also validated by longitudinal measurements). These data were used repeatedly in the Czech Republic for evaluation of the level of morphological, functional, motor, and sensomotor development in further follow-ups of preschool children. Adequacy of the development and its deviations from the above-mentioned points of view were thus made possible, also to be compared and evaluated. In special cases, retarded development could be defined and a talent for special motor activities could be

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selected. Particular attention was then paid to such children, and pedagogic intervention in groups of individuals was rendered possible. Regarding reference values, the results of the last measurements (survey D) were used (Parˇ ízková 1993a,b). On the basis of comparisons of repeated measurements over time in the Czech Republic, as well as on the basis of international comparisons, it was recommended that reference values for morphological, functional, gross, and fine motor variables should be prepared, when possible, in the individual countries, especially those that vary more in geographic, climatic, cultural, social, and economic conditions. In all instances, the presented methods and results may serve as guidelines for further research and pedagogic intervention in preschool children, which of course should be supplemented with other innovative ideas, and national and local experiences.

12.4

SURVEYS OF CHILDREN WITH VARIOUS ENVIRONMENTAL CONDITIONS AND DIFFERENT LEVELS OF NUTRITION

A comparison of the results assessed in different parts of the Czech Republic, for example, when comparing body size and motor performance in the capital and in small villages, showed significant differences. Significantly greater bodily dimensions, usual, for example, in Prague, were not always a predisposition for better physical performance in individuals of the same age, as shown by comparisons of children from Prague and rural areas, from families with higher and lower incomes, with children born first and last in families, etc. Children most advanced in somatic development, that is, with largest body sizes, were not the best in physical performance, in spite of a simultaneously higher level of sensomotor development (Parˇ ízková 1994, Parˇ ízková et al. 1984). A comparison of the results of our measurements with some data on morphological, functional (step test), and motor development in other countries, for example, different parts of Italy, Turkey, Estonia, and Senegal, showed some differences among preschool children; for example, in Italy (Ferro-Luzzi et al. 1977) it was shown that the most important differences were due mainly to social, nutritional, and environmental conditions. Children in areas with similar lifestyles did not differ markedly in morphological and functional parameters. However, when comparing smaller and leaner children from poor areas of southern Italy with preschool children from richer northern Italy, it was revealed that their body sizes were smaller due to a significantly lower food intake, but the results of the step test, indicating better cardiorespiratory efficiency, were more favorable. This may be considered as more desirable from the point of view of health. There were only very slight differences between Estonian and Czech children (Oja and Jürimae 1998). Turkish children were slightly smaller and less efficient in some functional and motor tests (Türnagöl et al. 1995). The most important differences were found between Senegalese children (Bénéfice 1990, 1995) on the one hand, and all other children on the other. Their body sizes were markedly smaller, and their motor performances were also poorer. However, when the results of performance tests were adjusted to body size, the differences diminished. In some tests (e.g., the broad jump) the results were even better in

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Senegalese than in Czech children. The results of the step test differed slightly from the results of Czech children: the heart rates during rest, workload, and recovery were the same for the joint group of all Senegalese children as for Czech girls of the same age. Thus, it was confirmed that in dynamic, weight-bearing PAs, smaller children with poorer nutrition may not be at such a disadvantage as compared to their bigger, more abundantly fed peers. This only applies, however, to a certain range of the reduction of both food intake and body size, that is, to cases of marginal (not severe) malnutrition. This is still within the adaptation limits of the growing organism and obviously, under such conditions, does not reduce the size and function of vital organs or diminish LBM to a greater extent. However, in this case, performance, which depends more on muscle mass such as muscle strength, is worse in children with reduced food intakes and smaller body sizes (Bénéfice 1990, 1995, Malina and Bushang 1985, Malina et al. 1991, 1995). As follows from the literature, severely malnourished children are functionally and motorically handicapped in all respects (Waterlow 1992). Functional measurements in severely malnourished children were made mainly under conditions of rest and not during workloads. Unfortunately, many severely malnourished children have quite intense workloads; hence more knowledge is needed on this issue. Another extreme, that is, obesity, can serve as an example of the undesirable consequences of a food intake that does not correspond to the actual energy requirements. At preschool age, excessive food intake does not seem to result in the development of apparent obesity, which usually occurs later in childhood or during adolescence (Parˇ ízková 1977, 1993a); we found that only 2–3% of children were overweight according to our surveys at that time. These children were not only heavier, but also taller and had higher BMI, skinfolds, circumferences, and estimated LBM; their physical performances (especially in jumping, shown to be one of the most relevant motor tests, which is related to body weight) were at a lower level compared to their peers with normal or lower BMIs. Performance in the 20-m run did not yet deteriorate. The morphological development in overweight children seemed to be generally accelerated. This does not concern, however, functional development, which revealed some handicaps compared to children with normal weight. In our study, weight and fat in preschool children were not significantly related to actual dietary intake, which showed great variability. The low prevalence of marked obesity at preschool age did not allow more opportunities to follow up on further deviations in functional and other variables. However, a significantly positive correlation between the percentage of depot fat (calculated from skinfolds) and the level of total cholesterol, as well as that of TGs (Parˇ ízková 1989, 1990, 1994), revealed that excess fat at preschool age is already a serious health risk in relation to the later development of atherosclerosis and other diseases of the cardiovascular system. The same was found in older children; after a reduction in fat and weight with diet and exercise, a decrease in total cholesterol was also found, especially in prepubertal boys. As shown by some longitudinal observations, when the dietary intake and general lifestyle are not modified in a desirable way, children later develop real obesity; this is usually manifested at school age. Regarding the influence of environmental factors, except for the size of the community where the children lived, no marked changes due to environment (air and

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water pollution in different areas of the Czech Republic) were found. Children from Prague or other larger communities were bigger, but their physical performances were generally lower in spite of a higher level of sensomotor development (Parˇ ízková 1977, 1978a, 1980, Parˇ ízková et al. 1984). No differences in somatic and motor development according to risk pregnancy and health status (i.e., indication for regular medical checkups until the end of the first year of life) at the age of 4–6 years were found (Parˇ ízková 1996). Regarding age at the onset of independent walking, some relationships to anthropometric variables were found (Parˇ ízková et al. 1984). Analysis of the influence of birth weight revealed that children born heavier started to walk earlier and had higher values of height, weight, and circumferential measures (average values, z-scores) at the age of 4–6 years. They were sick less often and wore glasses less often. The BMI values did not differ. With motor development, there were significant differences only in ball throw with the left hand in both sexes (which was longer in children born heavier) and in some skill tests (better results in the test of standing on one leg in girls; Parˇ ízková 1996). The influence of family situation (i.e., complete or incomplete families) was also significant: children from complete families were more advanced in somatic development, that is, had the highest values of height and weight, but the BMIs and the level of motor development did not differ. Regarding the education of parents, children whose fathers had the highest level of education (university level) were the tallest and the heaviest and more slender; performance in the 20-m dash was also significantly better. The education of mothers did not influence the motor performance of children. When analyzing the influence of both parents, most favorable results in somatic and motor development were found in children whose fathers had a university education and whose mothers had a high school education (Parˇ ízková 1996). Common morbidity from normal childhood diseases did not have any significant influence on the child’s morphological, functional, and motor development; however, it is necessary to stress that children with more serious health problems were not followed up in our surveys.

12.5

OBESITY IN YOUNG CHILDREN

Obesity, which is today a global problem of epidemic proportions, has recently affected preschool children too. Increasing attention has been focused on the reasons for obesity, both genetic and environmental. Genetic studies have not yet revealed decisive causes; however, family reasons (obesity of parents and their lifestyle), epigenetic factors, early nutrition, and PA were shown to have a significant impact on the start of obesity and subsequent development in preschoolers. In our study, it was possible to differentiate children with highest and lowest body weights and BMIs. At the time of our study, marked obesity was not yet seen in preschoolers as at later age in Czech schoolchildren and adolescents. However, heaviest children with highest BMI and highest circumferential measures achieved worse results in broad jump, but not in other disciplines such as, for example, running. Worsening of dynamic activities could be expected only later. Most studies, also in Czech children, proved deteriorated aerobic power and worse results in dynamic sports disciplines (Parˇ ízková 1977, Parˇ ízková and Hills 2001, 2005).

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Best rectification of overweight and obesity during the growth period could be achieved using a monitored diet (not too reduced in energy, but avoiding high-density foodstuffs and beverages) along with an increased energy output due to exercise. More recent literature observations of young children confirmed the role of a monitored diet and exercise in the prevention of obesity in preschoolers.

12.6 INFLUENCE OF EXERCISE The impact of regular exercise, mainly in the framework of the system of physical education for the child and the mother (or father, grandmother, etc.; Berdychová 1970–1985, 1977, 1993), was found to be significant in more of our follow-ups. Children who enrolled regularly in physical education had, as a rule, significantly higher values of height, weight, and other morphological characteristics. In contrast to the biggest children, for example, from the capital or from families with highest per capita income or born first, exercised children also had best results in motor performance. This applied especially to broad jump (surveys A, B, C, and D), but also to the 20-m dash and ball throw with the right hand. As mentioned above, larger body size alone does not guarantee better physical performance, which can only be induced with regular longer-lasting exercise (Parˇ ízková 1977, 1980, 1994, Parˇ ízková et al. 1984). The results of skill tests were also best in exercising children. Better results of physical performance were apparent in older preschool children after a longer exposure to exercise. When we wanted to examine the possible differences between physically active and inactive children at a younger age, that is, 4–5 years, we had to compare those who were spontaneously very active or generally inactive. This differentiation was made possible by a longitudinal follow-up of a smaller subgroup of 4.6-year-old children (J) during the whole year by teachers and parents, with the help of special questionnaires prepared by us for this purpose. Children who were spontaneously most active during the whole year of observation tended to be taller, heavier, and leaner (more mesomorphic), with a slightly higher dietary intake and better results in the step test. These differences, however, were not significant. Only the serum level of HDL-cholesterol was significantly higher in very active children compared to inactive ones (Parˇ ízková et al. 1986a). The results seem to indicate that a genotype characterized by high spontaneous PA (or a subject with induced high activity) has significantly higher HDL along with a trend for larger body size, less depot fat, higher food intake, and higher cardiorespiratory and motor fitness, which already manifests itself at preschool age. It may be assumed that the introduction of adequate exercise in less active preschool children may result in similar favorable characteristics as those in older age. Thus, exercise and motor stimulation proved to be beneficial for young children as for older ones. Therefore, a system of motor stimulation for infants (Koch 1977, 1978) and special physical education for preschool children and parents has been developed and introduced on a massive scale in the Czech Republic for more than 50 years (Berdychová 1970–1985, 1993). Similar systems have already been used in many other countries, but they are still less frequent. Selected activities and exercises were described for systematic physical education in young children. It was revealed that such a system during infancy already had a positive influence on child

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development, manifested not only in motor but also in social and psychological development. As described above, the influence of exercise on preschool children was found to be beneficial, provided it was individually adjusted and included exercises suitable only for this early period of growth. During more recent periods, there is an increasing amount of research data reconfirming this positive effect of increased PA and exercise. The early introduction of an adequate regimen concerning both activity and diet since the beginning of life is a desirable start for its continuation until adult and advanced age. It is at present recommended to be more physically active, as the role of exercise can protect against overweight and obesity with accompanying comorbidities during the complete lifespan.

13

Perspectives: Physical Activity, Early Prevention of Diseases, and Development of Positive Health

It is not a soul, it is not a body, that we are training up, but a man, and we ought not divide him. —Montaigne (1888)

Life and motion cannot be separated—motor activity and exercise can be used as a part of general education, which goes beyond motorics. The close relationship between diet and PA links both these factors, and adequate manipulation of both at an early age in a mutual relationship (which implies energy balance and turnover) has a decisive influence on the individual, not only now but also later on because of delayed consequences. The fetal period was proved to be an important stage from more than one point of view: the relationship between maternal diet and cord blood lipids shows the importance of the composition of the diet of the future mother during her pregnancy. The same applies to the relationship of fat patterns in the mother and newborn son, indicating the genetic conditioning of this marker and a possible health risk at the very beginning of life. Similar relationships were revealed with regard to the PA of the pregnant mother and the outcome of her offspring. All potentials of the human organism should develop in mutual harmony from the earliest periods of life. When we also include the criterion of “positive health,” requiring mainly a high level of cardiorespiratory fitness and resistance to noxious environmental factors as well as long life expectancy in full activity, we must develop more objective evaluation criteria. The endeavor to “achieve maximal growth potential,” which up to now was mostly identified with the achievement of greater body size, should be further specified. As has been repeated many times, children all over the world have the right to reach the highest level of potential, including body size, provided enough food is available. Under conditions of the real world, it does not seem wise to consider body size as a priority, but rather the level of positive health, physical as well as overall fitness, and thus also economic productivity and longevity. Therefore, additional reference values of functional, motor, metabolic, and health variables are needed for the characterization of the growing organism at an early 321

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Nutrition, Physical Activity, and Health in Early Life

age. This may give a more exact evaluation of the level of development and in time may also give information on whether the child is developing in an adequate way. The disclosure of more discreet deviations from desirable development, which might later become a more serious health risk, has become an essential issue in the appraisal of child development. Measuring body size is the first, most important approximation, but it is necessary to know more, if at all possible. With regard to recent undesirable trends of increasing body size, adiposity, and simultaneously deteriorating physical fitness, present data do not seem to be the best criteria; thus, previous standards could be more acceptable than the present ones. The available characteristics of functional and motor development in early life that were used in our studies is only a very modest addition, which should be developed further. With the help of the above-mentioned measurements, we were able to reveal relationships between slightly increased and differently distributed depot fat and serum lipids in young children (and the possible consequences). We also demonstrated the influence of the composition of the diet during pregnancy on serum lipids in newborns, especially sons. We tried to analyze the inconsistencies between body size and certain functional parameters relating mainly to cardiorespiratory fitness (which concerns both overfed and underfed growing individuals) or the inconsistencies between the level of somatic, sensomotor, and gross motor development under conditions of insufficient motor stimulation. Attention should also be paid to problems of deteriorating body posture before the child enters primary school and to other issues that are relevant in relation to future health development. Body posture is a characteristic not only from the aesthetic point of view, but also regarding the proper function of all organs in the thorax—adequate functioning of the lungs and the heart, then the muscles around the vertebral column, and others as well. It was presumed that this deterioration takes place only after entering school, but the results of our measurements indicate that the present way of life deteriorates posture even earlier. This is, inter alia, evidence for muscle weakness due to reduced PA and stimulation, and is supported by present changes in lifestyle—sedentarism from an early age due to TV viewing, playing videogames, and the like. Unsatisfactory availability of areas for games and exercise, and decreasing security especially in greater urban agglomerations also contribute to the above-mentioned negative consequences during growth, starting with overweight and obesity. Reservations regarding the actual RDAs, which are now considered too high (especially those for the Czech Republic at the time) for generally hypokinetic young children, do not imply the promotion of a very low food intake and/or the promotion of an inadequately intense workload. Under the conditions of industrially developed countries, the dietary intake of children has reached levels that do not correspond to the real needs of the young child. The increasing prevalences of obesity, dyslipoproteinemias, MS, diabetes 2, disorders of carbohydrate metabolism, and psychological and orthopedic problems have manifested already in preschoolers, and have become another negative manifestation of the consequences of today’s lifestyle. All this stimulates an earlier onset, and precipitates the development, of atherosclerosis and cardiac diseases, which remain the main killer in developed countries, especially in genetically predisposed individuals. The present lifestyle—inadequate diet not adjusted to the real needs of the organism, especially under conditions of

Perspectives

323

hypokinesia—can precondition even normal healthy children to pathological problems later on in life and to a shorter lifespan. The composition of usual dietary intake is another problem, and seems to contribute more to the inadequacy of present nutrition during childhood. To recommend more modest nutrition contradicts family customs in most industrially developed countries. However, the example set by long-living populations (such as in Abkhasia in the 1960s–1970s), as well as the results of experimental models, seems to indicate that such an adjustment would be useful. “Has malnutrition only bad consequences? What is the definition of health?” were the questions posed by Fanconi (1969), who showed a number of advantages of adequately but moderately lower food intakes. The population explosion and the occasional lack of resources result not only from the number of inhabitants in the actual world but also from their size: all of these together require more and more resources. The definition of some “optimal minimum” or “minimal optimum” of diet seems to be justified, because not enough food is available under the present conditions in all parts of the world. Even under adverse circumstances, adequate manipulation of a reduced dietary intake can ultimately result in at least acceptable development of the growing child. As indicated by the assessments in children from developing countries, under conditions of “marginal malnutrition” (i.e., only slightly smaller body size and reduced fat deposition, with preserved size and function of the vital organs and essential muscle groups), a better level of cardiovascular fitness can be achieved. Moreover, there seems to be evidence that such a physical status used to be natural not very long ago, when motion and greater physical workloads were a much more integral part of life. Consider the following scenario (which represents the situation today): the chassis increases in size, but the engine remains the same, or even decreases, due to understimulation; that is, BMI and fatness increase, but vital organs probably do not increase in the same manner and at the same pace as other organs and tissues in the body. There is no information about this at all, even when the acceleration of growth of external body size has been followed up. This should be another task for further research. In spite of the fact that it is impossible to directly apply the conclusions from animal studies to humans, there seems to be corresponding evidence from a number of experimental models. The importance of the level of PA during pregnancy or of certain dietary modifications, including a more modest intake of protein and energy at the beginning of life, was shown to have positive results on the later development of spontaneous PA, on changes in body composition or certain characteristics of lipid metabolism, and on cardiac microstructure, resistance to noxious substances inducing the development of cardiac necrosis, etc. The experience with high RDAs for proteins and fats (which were mostly exceeded) in the Czech Republic not only results in higher BMI in early childhood, but also might have contributed to enhanced morbidity and mortality from atherosclerosis and other cardiovascular diseases during the decades following World War II, especially in Eastern Europe. Recent trends toward improving these conditions run parallel to certain adjustments and corrections in the diet, and further follow-ups have already shown some improvements in health parameters in this part of Europe. This will improve even more in the future— provided diet and PA, among others, also improve.

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Nutrition, Physical Activity, and Health in Early Life

For physiological reasons, during growth it is more justifiable to adjust energy balance and turnover by increasing energy output—mainly by increased PA and exercise—rather than to reduce the food intake corresponding to reduced energy output, as this is associated with risks of imbalance and deficiencies of some essential dietary ingredients. The definition of a reduced but fully adequate diet for young growing children under conditions of prevailing hypokinesia would be very difficult in daily life. The influence of inadequately increased and imbalanced food intake is not always manifested immediately in preschool age, but seems to be a predisposition for later obesity, dyslipoproteinemias, MS, etc., thus increasing the health risk in later life. Therefore, even if modifications of the actual diet are required, the main adjustment concerns the general lifestyle with much more activity and exercise since the early period of development. The growth of children in long-lived populations, for example, in the Caucasian area during the last century, was slower; sexual maturation occurred later and the growth period was longer than elsewhere. People were characterized by a more marked development of LBM, especially of muscles, and a low fat ratio. They also had a very active lifestyle starting from childhood until advanced age. There certainly existed other factors that influenced the lifespan of these people; however, these people may serve as a model for our present lifestyle. Promotion of a higher level of PA and exercise in early life seems to be justified or even self-evident. Unfortunately, in industrially developed countries, most parents stop being interested in further motor development when their child is able to walk unassisted. This is exactly the moment, however, when motor abilities can be developed to a higher level, which is also a predisposition for a higher level of fitness and functional capacity later on in life. Well-developed motor abilities are a predisposition for more intense interest and involvement in physical exercise, which becomes more enjoyable because it is less strenuous. This also encourages children to remain active throughout life, which is presently being recommended not only for children but also for adults. The role of family is essential, and it is therefore worth mentioning a comment of G.B. Shaw: there are two professions that are essential for mankind, and do not require any professional training—parenthood and politics. The results of this situation, often regrettable, witness (correspond agree with) that. Natural gifts for successful parenting and education are not given to everyone, and more education, instruction, and advice for parents is recommended. It is a great mistake to leave the development of motor abilities to chance. Many parents think that with further growth the child will automatically learn new skills, and that all the necessary motor abilities will develop without any assistance. This does not apply to other faculties that need education, and it is also not true for motor development—at least not in every child and under the present life conditions. Along with motor skills and other improvements in functional capacity, the child acquires other faculties—courage, readiness, independence, a proper attitude to unknown situations, and so forth. Of course, it is necessary to supervise children and not leave them unattended in unsafe situations. All the above-mentioned qualities are advantageous not only for children but also for their parents.

Perspectives

325

Slight retardation in motor development does not translate to a great handicap. It is a warning, however, for parents to make an effort to improve the situation and not neglect it. Motor stimulation at an early age can support and improve the development of children in relation to functional, motor, and work performance, which may apply even under conditions of reduced dietary intake; motor stimulation may also have, under special conditions, an anabolic influence on the growing child (provided it is adequate according to the developmental stage). This may be a supporting factor in the development and rehabilitation of populations with limited resources. Better rehabilitation of undernutrition using increased PA was also achieved. The anabolic effect of PA applies, however, to normally nourished children too. Some of the main issues on the program of international congresses on nutrition during the last decades focused on two problems: consequences of the lack of food (eventually leading to child labor), especially in children of Third World countries, and consequences of excess eating along with hypokinesia. The latter belong to the most important pathogenetic factors of diseases that are the main killers in industrially developed countries and which increase elsewhere too. The importance of early intervention regarding diet and PA regimens in young children is now recognized. Many of these changes can be made by returning to old customs of a more modest diet and ample opportunity for play and exercise in early life. Education, in any respect, has to be individualized and adjusted to the particular character of the child: as J.A. Comenius (1646–1650) reminds us “some need a bridle, the others spurs . . . .” The same applies to motor education; an individual approach is needed, created around a child’s particular predisposition and liking. The cultivation of motor abilities, skill, and cardiorespiratory fitness since early childhood facilitates and promotes optimal PA throughout life. Even under adverse conditions of any kind, the achievement of an optimal performance level helps in attaining higher economic production, immunoresistance, higher resistance to noxious factors, and longer life expectancy. Because of significant environmental changes that have been continuing during more recent decades, we need to not only reconsider the wisdom and experiences of yesteryears, but also bring in innovative ideas and actual approaches and methods for improving the optimal development of children. Early intervention in PA, dietary regimen, and functional development starting in the family can improve our perspectives, under conditions of both abundance and scarcity. The hope of universal reform of the world depends entirely on the fi rst stage of education. Our nature—in body, mind, morals, pursuits, conversation, and gesture—is conditioned by our earliest education and training of adolescence that follows it. If this is right and aims at high standards of truth and goodness, those who had the advantage of it must exceed the others … —J.A. Comenius (1640), Pampaedia

Appendix 1: Body Posture

Name: Date of examination:

Date of birth: View from profile 1

2

3

Neck (axis)

Vertical

Slightly bent forward

Markedly bent forward

Outline of back (S-shaped curvature)

Slight

Increased

Very marked

Scapulae

Adjacent, not protruding

Slightly protruding

Protruding

Abdomen (xiphoid process)

Does not proceed

Proceeds, can be drawn in

Bulged, relaxed, flaccid, abnormally large

Depth of cervical lordosis (cm): Depth of lumbar lordosis (cm): View from back 1

2

3

Shoulders

Equal height

One shoulder slightly higher (+1–2 cm)

Considerably higher (>+2 cm)

Scapulae (inner margins)

Parallel

Diverging and protruding slightly

Asymmetrical and protruding considerably

Deviates slightly

Deviates considerably

Course of spine Back straight

Identical to string of plummet

From string of plummet

From string of plummet

Deep forward bend (outline of back)

Symmetrical

Slightly asymmetrical

Very asymmetrical

327

Appendix 2: Step Test Name: Date of examination:

Date of birth: Weight:

Rest (X)

Work load (A)

Recovery (B)

123

12345

12345

X (S/3)

A (S)

B (S)

HR/min.

Heart rate: Minutes:

HR = mean heart per minute at rest HRwr = sum of heart beats during work (A) and recovery (B) HRP = HRWR – 10 × HR X CEI1 = Kpm/HRWR

Kpm = weight of the child × 150 × height of the step (25 cm) (150 = 30 mounts during 5 min of workload)

CEI2 = Kpm/HRp HRR = B – 5 × HR X Index = 30,000/S 2nd + 3rd + 5th minute of B (Brouha)

329

Appendix 3: Motor Performance Name: Date of examination:

Date of birth:

Dash 20 m from high start ................ s

Standing broad jump ................ cm

Throwing Right hand ................ cm Right hand ................ cm

Left hand ................ cm Left hand ................ cm

(1) (2)

Crossing horizontal beam

Yes

No

Standing on one leg (10 s)

Yes

No

Forward roll Perfect turning on shoulders straight Correct but small deviation of direction Incorrect turning on back of head Impaired direction, incorrect procedure Not properly “followed,” deviation, incorrect

5 4 3 2 1 Yes

No

1. The child throws a ball on the ground and after the ball strikes the ground, the child

Catches

Does not catch the ball

2. The adult throws the ball two steps in front of the child; after it strikes the ground, the child

Catches

Does not catch the ball

3. The same, but catching with one hand (the palm upwards)

Catches

Does not catch the ball

4. The adult throws the ball above the child who is supposed to catch it in the air

Catches

Does not catch the ball

Walking at a given speed, rhythm Catching ball:

Note: The evaluation of tests with two grades (Yes = 1, No = 2) gives the average numbers which for values exceeding 1 define also the percentage of subjects not fulfilling the test (2).

331

Appendix 4: Sensomotor Tests Opening and closing the hands 1. Both hands are opened and closed simultaneously 2. One hand opens continuously, the other remains closed 3. Same with other hand 4. One hand opens and closes, the other hand opens and closes 5. Alternate opening and closing hands: one hand opens, the other closes etc. 6. Consecutive opening and closing of hands: one opens, the other one closes

1 Yes Yes Yes Yes Yes Yes

2 No No No No No No

Yes Yes

No No

Yes Yes

No No

Yes Yes

No No

Spatial orientation 1. Point hand downwards 2. Point hand upwards Laterality 1. Show your left hand and right hand 2. Show with your left hand your right knee Special comments 1. Child wears spectacles 2. Other abnormalities

333

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Index A Acromion-radiale, 93 Activity energy expenditure (AEE), 127, 137 Actualization, 216 Acylation reactions, 117 Adenosine triphosphate (ATP), 117 Adequate intake (AI) of linoleic acid, 108 Adiposity rebound (AR), 57, 59, 108, 141, 212, 237, 251 evaluation of, 228–230 AEE. See Activity energy expenditure AI. See Adequate intake Allix, E., 2 Étude sur la Physiologie de la Première Enfance, 2 ALSPAC. See The Avon Longitudinal Study of Parents and Children AMC. See Arm muscle circumference American Academy of Pediatrics, 283 American Dietetic Association, 97 Amino acid metabolism, 117 Anemia, 113 Anthropometric variables, 44–51, 62 in boys, 49 cross-sectional surveys of, 61–74 during various trimesters of pregnancy, 44–45 relationships with fat distribution of mothers and preschool children, 51 Applied activity, 14–16 Archimedes’ principle, 247 Arm muscle circumference (AMC), 176 Assorted mating, 214 ATP. See Adenosine triphosphate Australia National Nutrition Survey, 226 Avon Longitudinal Study of Parents and Children (ALSPAC), 221, 226

B Back pain, 89 Barry Caerphilly Growth Study, 223 Basal metabolic rate (BMR), 102–105, 136, 197, 237 in children, 102, 127

energy output, 104 estimation of, 103 B-complex, 116–117 Best caliper, 60 modified, 84 Beta-hydroxybutyric acid, 20 BIA. See Bioelectrical impedance Bi-iliocristal breadth, 65 Bioelectrical impedance (BIA), 228, 230–231 measurements, 176 Biotin, 117 Bipedal bioimpedance, 230 Birth rank, 265 Birth weight (BiW), 4, 38–39, 47, 267–270 BiW. See Birth weight Blood cholesterol dietary determinant of, 109 Blood lipid, 38, 167, 292–298 cord, 47, 50 level, 167 maternal, 46 newborns, 44 BMI. See Body mass index BMR. See Basal metabolic rate Body composition, 81–85, 230–233, 301–305 bi-iliocristal breadth, 234 computed tomography (CT), 231 in Czech preschoolers, 234–236 densitometry, 232 dilutometry, 231 dual photon absorptiometry (DPA), 231 and fatness, 230–233 40K whole-body counting, 232 magnetic resonance imaging (MRI), 232 morphological characteristics, 234–236 nuclear magnetic resonance (NMR), 232 whole-body three-dimensional photonic scanning, 232 Body density measurements, 82 Body height relationship with pulse rate, 3 Body mass index (BMI), 36–37, 40, 42, 53, 56, 63, 98, 100, 102, 106, 109, 119, 130, 140, 150, 154, 178, 201–202, 206, 213–214, 222–225, 229, 233, 249–250, 264–265, 270, 288, 294, 302 adult, 58 aerobic fitness, 284

391

392 Body mass index (BMI) (Continued) African urban children, 208 by ANOVA analysis, 45 average value of, 167 centile, 302 centile crossing, 58 charts, 56–57 child’s, 39, 58, 244 childhood obesity, 61 Chinese children, 207 cut-off points, 302 Czech adult, 59 Czech children, 59, 126 development, 101 distribution, 244 Dutch children, 205 of French children, 204 French standards, 63 grids, 302 lower values of, 63 maternal, 39–40, 42 obesity of parents and children, 211 paternal, 42 percentiles, 302 pregnant women, 44 prepregnant, 39, 58 prevalence of overweight and obesity, 204 recent average values of, 5 reference curves, height-specific, 56 schoolchildren, 244 standards, 56, 99 UK children, 126 values above critical percentiles, 61 variations (Mean ± SD) in Czech children aged 3–7 years, 57 z-scores, 100, 302 Body size, 301–305 Body weight (BoW), development, 28, 99 food intake, 11 for children, 100 physical activity, 11 prepregnant, 49 after Quetelet, 4 rotation wheels in groups, 11 Russian children, 5 Body posture, 89–93 Boehringer tests, 166 Bogalusa Heart Study, 224, 227 Bone growth, 111 Bone mineral density effect of calcium, 111 Bone-stimulating effect, 111 Breast-feeding, 34, 39–41, 83, 98, 221, 223 breast-fed infants, 40 duration, 40 formula-fed infants, 40 growth acceleration hypothesis, 40

Index infants, 224 protective effect of, 40 reduction of obesity, 42 serum leptin level, 42 British Nutrition Foundation Annual Conference, 9 Brouha’s step test index (STI), 145–148 Bruce walking treadmill protocol, 151

C CA (control diet), 14 Calciferol, 115 Calcium balance, 110 Candidate gene, 215 Carbohydrates, 110 Cardiac damage impact of isoprenaline, 25–26 spontaneous activity, 26 Cardiac efficiency indices (CEIs), 143, 145, 148, 154, 168–169, 183–185, 297, 313 changes, 148 Cardiac necrosis, experimental impact of interactions between early diet and PA, 26–30 influence of PA, 24–26 Cardiac resistance isoprenaline, 27–30 Cardiorespiratory efficiency, 5, 148 testing, 161 Cardiorespiratory fitness, 141–149, 176, 183–186, 239–240 efficiency of, 141 functional measurements, 305–306 methods of testing, 142–143 recovery period, 145 Cardiovascular functions, 149 responses, 149 system, 5 Cardiovascular Risk in Young Finns Study, 244 CARS. See Children’s Activity Rating Scale CART (cocaine- and amphetamine-regulated transcript), 216 Catching a ball, 152 CDC. See Center for Disease Control and Prevention CEIs. See Cardiac efficiency indices Center for Disease Control and Prevention (CDC), 205–206, 224 Centile crossing, 58 Centrality index, 60 Cervical and lumbar lordosis, 91 Chernobyl disaster, 255 CHRF. See Coronary heart risk factors Childhood diabetes, 244

393

Index Child labor problems of, 198–199 Children breast-fed and formula-fed, 42 creeping, 35 growth and development, 6 height and weight in European, 100 influence of environmental factors, 6–7 air pollution and noise, 6 conditioned reflexes, 6 inadequate diet during fetal and postnatal ontogeny, 6 medicines, 6 motor stimulation, 6 orientation reflex, 6 malnourished, 10. See also optimal health and fitness preschool growth and somatic development, 58 realimented, 10 resting energy expenditures (REEs) of, 102 sniffing, 34 Yurok, 35 Children’s Activity Rating Scale (CARS), 123 Cholesterogenesis, 18 Cholesterol, 46 in boys, 49 concentration, 18–19 in small intestine, 19 synthesis, 19 CK. See Creatine kinase Cobalamin, 117 Comenius, J.A., 2 teacher of nations, 2 three principles, 2 UNESCO anniversary, 2 Commission on Global Governance, 173 Common Wealth of the Northern Mariana Islands, 224 Control offspring of inactive, control mothers without exercise (CC), 22–24 Coronary heart disease, 126 Coronary heart risk factors (CHRF), 169 Correlation coefficients, 156, 162 14C-palmitate, 20 Creatine kinase (CK) activity, 138, 168, 294 in blood, 297 Cyanocobalamin, 117 Czech children, 58–59, 70, 154 Czech preschoolers, 82–85 dietary intake and energy output cross-sectional and longitudinal surveys, 119–125 Czech Republic birth weight effect, 269–270 blood lipids, 261–264 body size and function, 264

cross-sectional and longitudinal measurements, 61 economic level and birth rank, 265 education of parents, effect, 271–272 environment, 266–269 family conditions, 266–269 family situation effect, 270–271 food intake, 261–264 health, 266–269 health status of children, 272 influence of living conditions, 256–264 motor and sensomotor development, 257–260 Olympic Committee, 285 performance, 261–264 physical performance, 258 prevalence, 266 risk pregnancy, 266–269 somatic development and body posture, 256–257 somatic development in preschool children, 73–74

D Day-care centers, 61–63, 266, 282–283 in Prague, 120 Dehydroepiandrosteronsulfate (DHEAS), 250 DEXA. See Dual-energy X-ray absorptiometry DHA. See Docosahexaenoic acid DHEAS. See Dehydroepiandrosteronsulfate Diabetes in pregnancy, 12 Dietary intake, 44–51, 97 biochemical characteristics, 307 biochemical evaluation, 118 in Czech preschoolers, 119–125 evaluation methods, 118–119 of individual children, 120 maternal intake, 49 of minerals and vitamins in preschool children, 182 of preschool children in Ankara and Turkey, 181 of protein, fat, and carbohydrate, 125 Dietary reference intakes (DRIs), 97, 99 Diet-induced thermogenesis (DIT), 136 DIT. See Diet-induced thermogenesis Dizygotic twins, 128, 212 DLW. See Doubly labeled water Docosahexaenoic acid (DHA), 108 Doubly labeled water (DLW), 102, 104, 126–128, 137 method, 125, 140 DPA. See dual photon absorptiometry DRIs. See Dietary reference intakes

394 Dual-energy X-ray absorptiometry (DEXA), 36 Dual photon absorptiometry (DPA), 231 Dutch children, 58

E EANS. See European Academy of Nutritional Sciences EAR. See Estimated average requirement Early childhood obesity early factors in development, 224–228 evaluation of, 228–233 anthropometric methods for adiposity, 228–230 body composition and fatness, 230–233 genetic and hereditary factors, 209–220 genes and excess fatness, 214–216 genetic endowment, twin and family clustering, 210–214 polymorphisms and mutations of genes, 216–219 role of genetics, 220 health complications, 243–245 interventions for optimal development, 251–252 maternal and familial factors in the development, 220–224 prevention and treatment, 245–251 morphological, functional, and biochemical changes, 249–251 procedures, 246–248 results, 233–243 biochemical characteristics, 241–243 food intake in obese preschoolers, 236 functional capacity, 239–241 hormonal variables, 243 morphological characteristics and body composition in Czech preschoolers, 234–236 PA and EE in obese, 236–239 Early Childhood Longitudinal Study— Kindergarten, 225 Early child life biochemical variables, 169–171 blood pressure, 169–171 cardiorespiratory fitness, 141–149 cross-sectional and longitudinal surveys, 144–148 methods of testing, 142–143 other child populations, 149 evaluation of PA and physical fitness, 139–141 fatness in other populations, 169–171 functional development and physical activity, 135 metabolic and biochemical characteristics, 166–169

Index cardiorespiratory efficiency, 167–169 dietary intake, 167–169 methods and subjects, 166–167 somatic development, 167–169 motor and sensomotor development, 149–166 methods of testing, 150–152 motor and sensomotor testing, 152–164 other surveys of preschool children, 164–166 obesity early factors in development, 224–228 evaluation of, 228–233 genetic and hereditary factors, 209–220 health complications, 243–245 interventions for optimal development, 251–252 maternal and familial factors in the development, 220–224 prevention and treatment, 245–251 results, 233–243 PA, EE, and physical fitness, 136–139 Early dietary manipulations consequences of, 17 Early diet, delayed effects, 9–17 growth, body composition, and physical activity, 9–11 impact of, 27 influence of temporary diet with lower energy and protein, 13 to isoprenaline, 27–30 sensitivity of cardiac muscle, 27 Early life energy requirements, 98–106 nutritional status and dietary intake, 97 Early postnatal nutrition, 41–43 EC. See Exercised offspring of control mothers without exercise Ectomorphic components, 89 Ectomorphy, 86–87 ED. See Energy density EE. See Energy expenditure EFAs. See Esterified fatty acids EI. See Energy intake Eicosapentaenoic acid (EPA), 108 EMG activity, 135 Endemic goiter, 114 Endomorphic component, 89, 181 Endomorphy, 86 Energy and Protein Requirements, 1 Energy density (ED), 106 Energy-dense diet, 207, 247 Energy expenditure (EE), 137, 194, 212, 227, 236–239, 307 for children, 105 modulators, 216 Energy intake (EI), 41, 46, 49, 99, 104–105, 183, 218, 220, 249 absolute and relative, 98

395

Index character and intensity of PA, impact, 102 cholesterol and TGs related to, 46, 47 differences in adiposity, 40 from food, 98 of infants, 98 measurements, 138 mother’s, 49 of nutrients, 49 proteins account, 107–108 reduced, 247 satisfactory, 52 variability of, 121 Energy output Czech preschoolers, 119 other preschool child populations, 125–129 EPA. See Eicosapentaenoic acid Epididymal fat pads, 10 Esterified fatty acids (EFAs), 241 Estimated average requirement (EAR) of energy for children, 105–106 European Academy of Nutritional Sciences (EANS), 123 European Childhood Obesity Project, 225 Examination Survey for Children and Adolescents (KIGGS), 284 Exercised offspring of control mothers (CE), 22–24 Exercised offspring of control mothers without exercise (EC), 22–24, 104, 111, 115, 120, 297 Exercised offspring of exercised mothers (EE), 22–24 Experimental cardiac necrosis influence of PA, 24–26

Fetal period lipid metabolism, 12–13 Fetal programming, 220 FFAs. See Free fatty acids FFM. See Fat-free mass Finnish children, 81 FitKid Project, 246 Flavin adenine dinucleotide (FAD), 116 Flavin mononucleotide (FMN), 116 FM. See Fat mass FMN. See Flavin mononucleotide Folate and folacin, 117 Food and Agricultural Organization (FAO), 1, 97 Food and Agricultural Organization and United Nations University, 98 Food intake, 292–298 interindividual variability, 124 preschool child populations, 125–129 Framingham Children’s Study, 213, 286 Free fatty acids (FFAs), 12, 20, 27, 241 concentration, 12 in fetal plasma, 20 fluctuations, 19 level, 250 maternal–fetal, 20 in maternal plasma, 20 non-essential, 20 nonesterified, 241 placental clearance of, 12, 20 serum level, 18 umbilical blood flow, 20 unidirectional transfer, 20

G F FAD. See Flavin adenine dinucleotide Family clustering, 210–214 FAO. See Food and Agricultural Organization Fast food consumption, 130 Fat, 108–109 distribution, 305 malabsorption, 114 TGs, 108 Fat-free body mass, 102 Fat-free mass (FFM), 36, 231, 237 Fat mass (FM), 237 Fat pattern, 81–85 Fat-soluble vitamins, 108, 114–116 Fattening of America, 237 Federation of European Nutritional Sciences (FENS), 123 FENS. See Federation of European Nutritional Sciences Fetal adipose tissue, 20 Fetal growth, 12 lipid transfer, 12

Gastrointestinal system, 3 changes in nutrition and function, 3 Genes and excess fatness, 214–216 polymorphisms and mutations of, 216–219 Genetic defects, 214 Genetic endowment, 210–214 Pearson’s correlations, 211 Genetic predisposition, 38 Genotype screening, 216 German Health Interview, 284 German kindergarten children, 119 German Socio-Economic Panel Study, 239 Glucose transporter 4 gene, 218 Goiter, 114 Grasping reflex, 280

H Half-mile-run performance, 164 Hand grip strength, 151, 161 HANES. See Health examination surveys Harpenden caliper, 60, 83, 84, 294

396 HDL. See High-density lipoprotein Health examination surveys (HANES), 54, 197 Heart weight/body weight, 28 Height divided by cube root of weight (HWR), 88 table, 88 Heritability, 37 Heritage Family Study, 212 Hidden obesity, 228 High-density lipoprotein (HDL), 47 cholesterol, 49, 261, 312, 314 cord blood, 49 in newborn boys, 49 levels, 169, 297 values, 168 Himalayan mountains, 177–178 Homeostatic system regulating energy balance, 216 Human Gene Map, 216 HWR. See Height divided by cube root of weight Hyperplasia and hypertrophia, 12 Hypochromia, 113 Hypothalamus, 10, 217

I IBP. See International biological programme IGF-1. See Insulin-like growth factor-1 IKEM. See Institute of clinical and experimental medicine Iliospinale-tibiale, 93 ILO. See International Labor Office Immune system, 114 IMT. See Intima–media thickness Inadequate energy balance, 139 Individual organs’ weight newborn and adult, 3 Infants grasping, 277 gymnastics, 276 motor development of, 275–280 motor stimulation, experimental observations, 280–282 personality, 277 to avoid motor stimulation, 287–288 Toddlers, 282–283 Institute of clinical and experimental medicine (IKEM), 166 Insulin-like growth factor-1 (IGF-1), 40, 42 deficiency, 43 early postnatal diet, 43 level, 43 Insulin receptor substrate-1 (IRS-1) gene, 219 International biological programme (IBP), 63 International Labor Office (ILO), 198

Index International Obesity Task Force (IOTF), 56, 303 based prevalence of overweight and obesity, 204 International Program of Chemical Safety (IPCS), 255 International Union of Nutritional Sciences (IUNS), 123 Intima–media thickness (IMT), 244 Iodine, 114 deficiency disorders, 114 thyroid hormones, 114 IOTF. See International Obesity Task Force Iowa Bone Development Study, 141 IPCS. See International Program of Chemical Safety Iron, 112–113 absorption, 112 availability, 113 breast feed, 113 deficiency anemia, 113, 178 impaired status, 113 IRS-1. See Insulin receptor substrate-1 Isoprenaline, 25 cardiac damage, 25–26 cardiac resistance, 27–30 cardiotoxicity of, 27 Isotonic trunk muscle strength, 157 IUNS. See International Union of Nutritional Sciences

J Japanese sumo wrestlers, 240

K Keshan disease, 114 KinderSportstudie (KISS), 239 KISS. See KinderSportstudie

L Laboratory animals experimental models, 309–311 Lachema tests, 166 Lactation in different societies, 33–35 period, 13–17 Large-for-gestational age (LGA), 36 L-ascorbic acid, 116 Laterality, 164 LBM. See Lean body mass LCPUFAs. See Long-chain polyunsaturated fatty acids LDL-C. See Low-density lipoproteinscholesterol

Index LDL/HDL ratio, 169 Lean body mass (LBM), 138, 169, 190–191, 197, 223, 225, 234, 239–240, 243, 249, 294 absolute amount, 167 in cardiorespiratory efficiency, 169 development of, 169 fat-free, 189, 232 robusticity, 167 LEPR. See Leptin-receptor gene Leptin, 218 Leptin-receptor gene (LEPR), 218 deficiency, 218 LGA. See Large-for-gestational age LGA delivery, 223 Life tables, 177 Limited activity (LA), 25 Linoleic acid, 108 Lipid metabolism, 18–20 changes in, 13–17 during fetal period, 12–13 influence of, 12 in offspring lactation period, 13–17 in pathogenesis, 19 in skeletal muscles, 27 in small intestine, 14 Lipogenesis and lipolysis, 12 Lipogenetic substrate, 12 Lipolytic activity, 12 Lipoprotein lipase activity, 20 Liposynthesis, 18 Na-acetate-1-14C, 18 unchanged, 18 Locomotor stimulation, 282 Long-chain polyunsaturated fatty acids (LCPUFAs), 12 beneficial effect, 12 substantial effects, 12 Low-density lipoproteins-cholesterol (LDL-C), 166, 169, 251, 297, 314 levels, 168–169

M Magnesium, 112 Malnutrition, 174 of appetite centers, 10 consequences of, 10 degree, 176 protein-energy, 195 somatic development and physical fitness, 193 Maternal–fetal gradient, 12 Maternal nutrition, 223 MC3R. See Melanocortin 3 receptor gene MC4R. See Melanocortin 4 receptor gene

397 Mean rest values, 144 Mediterranean diet, 131 Megaloblastic bone marrow, 117 Melanocortin 4 receptor gene (MC4R), 212, 215, 217, 219 childhood obesity-associated heterozygous, 217 mutations, 217 Melanocortin 3 receptor gene (MC3R), 215, 217, 219 Mendelian hereditary syndromes, 214 Mesomorphic components, 89 Mesomorphy, 87, 181 Metabolic rates (MR) of organs and tissues in man, 101 Metabolic syndrome (MS), 36, 58, 206 Mg–ATP complex, 112 Microcytosis, 113 Minerals and trace elements, 110–114 calcium, 111 phosphorous, 111 Monozygotic twins, 37, 128 Mother’s nutritional status anthropometric, dietary, and serum lipid variables, 44–51 anthropometric variables and indices of fat distribution of, 51 and birth weight, 38–39 daily energy and nutrient intake, 50 dietary intake of, 46 food intake analysis, 45 high-calcium food consumption, 111 postnatal nutrition, 81 prenatal nutrition, 81 subcutaneous fat distribution, 48 Motor activity degree of, 26 level, 26 Motorics golden age of, 283 gross and fine, 149 Motorik, 284 Motor and sensomotor development, 149–166, 257–260 results, 152–164 Motor development, 186, 306–307 directed, learned movements, 275 for infants, 275 muscle strength, 240–241 normality, 280 skill, 240 spontaneous movements, 275 Motor performance, 263 Bruininks–Osseretski test, 164 half-mile-run performance, 164 in preschool children, 156 Motor stimulation, 279

398 Motor tests qualitative and quantitative, 149 MR. See Metabolic rates MS. See Metabolic syndrome Muscle metabolism, 103 Muscle strength, 189–193 first Senegalese survey, 189–190 functional and/or motor development surveys, 192–193 second Senegalese survey, 191 Tunisian survey, 190 Turkish survey, 189 Zapotec survey, 191 Myocardial damage, 26 Myocardial necrosis, 25

Index Nicotinamide adenine dinucleotide phosphate (NADP), 116 Nicotinic acid and nicotinamide, 116 NIDDM. See Non-insulin dependent diabetes mellitus Nitrogen accretion, 106 NmU. See Neuromedin U NNR. See Nordic Nutrition Recommendations Non-insulin dependent diabetes mellitus (NIDDM), 303 Non-smoking mothers, 58 Nordic Nutrition Recommendations (NNR), 119 Nutrient and Energy Intakes for the European Community, 5 Nutritional individuality, 98

N NAD. See Nicotinamide adenine dinucleotide NADP. See Nicotinamide adenine dinucleotide phosphate National Center for Chronic Disease Prevention and Health Promotion, 54, 302–303 National Center for Health Statistics (NCHS), 54, 182, 303 National food balance sheets, 177 National Health and Nutrition Examination Survey (Second) (NHANES II), 132, 233 National Institute of Child Health and Human Development Study of Early Child Care and Youth Development, 225 National Institute of Public Health, Prague, 120 National Longitudinal Survey of Youth: Child– Mother, 224 National Medical Association Consensus Report, 111 National Nutrition Survey, 238 National Research Council (NRC), 112, 115 Natural and experimental models, 9 NCHS. See National Center for Health Statistics Neophobia, 130 Nestle Pediatric Nutrition Workshop, 97 Neuromedin U (NmU), 218 Newborns anthropometric, dietary, and serum lipid variables, 44–51 influence of maternal nutrition on, 311–312 subcutaneous fat distribution, 48 New Delhi Birth Cohort, 223 NHANES II. See National Health and Nutrition Examination Survey (Second) Niacin, 116 Nicotinamide adenine dinucleotide (NAD), 116

O Observational Twin Study, 222 Obesity in preschool children. See also Early childhood obesity Belgian province of Limburg, 204 biochemical characteristics, 241–243 childhood, 61, 81, 201 Czech Republic children, 206 Danish children, 205 Dutch children, 205 early diagnosis of, 216 energy expenditure, 236–239 functional capacity, 239–240 German children, 204–205 health complications of, 243 Hispanics and African-Americans, 203 Hispanics and Americans, 238 hormonal variables, 243 Iranian children, 238 Italian children, 205 Maghrebian immigrants, 208 Malay preschool children, 208 motor development, 240–241 nonhyperinsulinemic, 243 PA intervention in, 298 parental, 213 physical activity, 236–239 prevalence of, 56–57 different countries, 203 prevention and treatment, 245–251 prevention of, 58 reduction of, 42 Spain and Portugal children, 205 UK children, 204 Obstructive sleep apnea (OSA), 244 Offspring cardiac microstructure of, 22 cardiac muscle of, 22 functional parameters, 44

Index impact of maternal status on, 38–44 effect of breast-feeding, 39–41 effect of early postnatal nutrition on later development, 41–43 influence of mother’s nutritional status and birth weight, 38–39 influence of physical activity and exercise of mothers, 43–44 influence of genetic factors, 37–38 Ontogeny, pre- and postnatal exercise during, 22–24 Oprotrak Motion Analysis System, 149 Optimal health and fitness, 1–7 aims, 7 growth acceleration, 4 historical aspects, 2 pedagogy and education, 2 influence of environmental factors, 6–7 air pollution and noise, 6 conditioned reflexes, 6 inadequate diet during fetal and postnatal ontogeny, 6 medicines, 6 motor stimulation, 6 orientation reflex, 6 positive health, 1 potential for health, 1 physical activity (PA), 1 secular trend acceleration of growth, 4–6 Organism-related stressors, 36 OSA. See Obstructive sleep apnea

P PACER test, 164 Pantothenic acid, 117 Parent eating behavior, 222 Parental eating attitudes, 36 Peak bone mass, 110 Pedagogy and education, 2 Peroxisome proliferator-activated receptor gamma (PPARG), 218 PGA. See Pteroylglutamic acid Phosphorus, 111–112 Physical activity (PA), 1, 17, 97–98, 105, 107, 129, 137, 191, 212, 220, 236–239, 275, 284, 309 in boys, 123 character, 102 combined dietary behavioral, 298 development, 284 duration and frequency of, 138 during early childhood, 135 during pregnancy later development of offspring, 17–18 evaluation, 139–141

399 exercise of mothers, 43–44 genetic factors, 128 high level of spontaneous, 10 influenced by early diet and cardiac resistance to isoprenaline, 27–30 intensity, 25 intensity and character, 102 modest level, 106 optimal level, 275 pedometer-determined, 140 regimen levels, 135 in rotation activity cages, 13, 26–27 spontaneous, 26–27, 104, 292–298 threshold of intensity of, 137 U.S. Hispanic children, 137 Physical activity levels (PALs), 13, 106, 127, 137 habitual, 140 Physical activity ratio (PAR), 136 Physical fitness, 136, 173 evaluation, 139–141 Physiology of children, 2–4 PL. See Pyridoxal Placental delivery, 12 Placental transfer, 13, 20 PM. See Pyridoxamine Polyunsaturated fatty acid (PUFAs), 47, 108, 116 POMC. See Propiomelanocortin Population-specific prediction formulas, 230 Positive health, 1 Postural reflexes, 280 PPARG. See Peroxisome proliferator-activated receptor gamma Prague children blood lipids, 256–261 breadth measurements of extremities, 67 breadth measurements of trunk, 66 breadth measures, 64 children, 62, 256–261 circumferential measurements of head and trunk, 68 circumferential measurements of the extremities, 69 dietary intake, 125, 256–261 height, weight, sitting height, and body mass index (BMI), 64 indices of body build and proportionality, 70 length measures on the extremities, 65 longitudinal measurements, 62–64 Ministry of Education, 62 performance, 261 robusticity of the skeleton, 65 sex-linked differences, 64 Preadolescent children, 140 Pregnancy aerobic exercise during, 22

400 Pregnancy (Continued) anthropometric variables during various trimesters of, 44–45 average weights, 44 blood lipids, 46 breast-feeding period, 35 different trimesters of, 47–50 influence of factors during, 20–21 lactation in different societies, 33 later development of offspring, 17 maternal calcium intake, 111 metabolic reactions, 17–20 variability of practices during, 33–35 Pregnant mothers nutrition children in early life, 33 position in industrially developed countries, 35 Preschool children 500-m run-and-walk test, anthropometric variables, 75, 165, 289 active and inactive children, 294 physical education (2–3 years), 289 with different body weights, 235 anthropometric variables and indices of fat distribution, 51, 59 Asian children in Sheffield, 125 aversions in, 129–131 ball throw test, 153, 163 biochemical variables, 169 blood lipid level, 167 blood pressure, 169 body posture in, 89–93 longitudinal observations, 92–93 Bogalusa heart study, 71–72, 241 Brazilian, 178 breadth measurements of the trunk and the extremities, 78 broad jump test, 153, 163 Brouha’s step test index (STI), 145–148 California schoolchildren, 159 cardiac efficiency indices, 143, 145 cardiorespiratory fitness, 141–149 centile crossing, 58 chest circumference, 80 circumferential measurements, 79 comparison of RDAs of vitamins, Czech children, 150 birth weight effect, 269–270 blood lipids, 261–264 body size and function, 264 cross-sectional and longitudinal measurements, 61 economic level and birth rank, 265 education of parents, effect, 271–272 environment, 266–269 family conditions, 266–269

Index family situation effect, 270–271 food intake, 261–264 health, 266–269 health status of children, 272 influence of living conditions, 256–264 intake of minerals and vitamins, 263 motor and sensomotor development, 257–260 muscle strength in, 151 performance, 261–264 risk pregnancy, 266–269 somatic development and body posture, 256–257 somatic development in preschool children, 73–74 dietary intake and energy output in Czech, 119 dietary intake in Ankara, Turkey, 181 dietary intake of minerals and vitamins, 182 early prevention of diseases, 321–325 eating patterns, 130 endurance time, 151 fat in U.S., 124 fatness, 169 Fels longitudinal study, 58 Finnish children, 149 food habits, 129–131 food intake and energy output in others, 125–129 food intake in obese, 236 food intake of protein, fat, and carbohydrate, 125 food preferences, 129–131 neophobia, 130, preference of beverages, 130 forward roll test, 152 functional capacity, 239–241 functional development criteria for the evaluation, 301–307 functional surveys, 312–315 GENESIS study, 57 growth and somatic development of, 53 hand grip strength, 156 health status, 272 heart rate, 185 height, weight, body mass index (BMI), and sitting height, 76 individual surveys of, 62 influence education, 275 environmental factors, 253 motor stimulation, 275 spontaneous physical activity, 275 influence of exercise, 288–292, 318–319 physical performance, skill, and sensomotor development, 291

401

Index somatic development and body posture, 288–291 variability, 291–292 intake of minerals and vitamins, 122, 182, 263 iron-deficient, 178 Latino children in the United States, 126 length measures on extremities, 77 longitudinal studies of, 74–80 Mexican children, 178 Moroccan children, 178 morphological development criteria for the evaluation, 301–307 morphological survey, 312–315 motor development, 164, 240–241 in subsample, 267 motor development and education, 283–287 motor performance, 154, 187, 263, 289 physical education (2–3 years), 289 motor performance and abilities in Senegal, 188–189 motor performance and skill test, result, 161 motor performance variables of, 165 muscle strength and skill test, 151 neophobia, 130 Nigerian children, 150 Nymburk children, 263 obesity early factors in development, 224–228 evaluation of, 228–233 genetic and hereditary factors, 209–220 health complications, 243–245 interventions for optimal development, 251–252 maternal and familial factors in the development, 220–224 prevention and treatment, 245–251 results, 233–243 PACER test, 164 performance tests, 162 physical activities, 321–325 physical performance of, 290–292 portion size and energy density, 130 positive health development, 321–325 RDAs of minerals for, 112 relationship between heights and weights of parents and anthropometric variables of, 93 results of the step test from Ankara, Turkey, 184 rhythm, response, and coordination, 152 Scottish children, 137 Senegalese children, 150 sensomotor development, 159–160, 291 skill development in, 158, 291

skill tests, 157 skinfold thicknesses, 83–85 measured by the harpenden caliper, 85 measured longitudinally five times by the Harpenden caliper, 87 somatic development in the Czech republic, 73 somatic development, longitudinally 75, 80 somatotype method in, 88 somatotypes measured longitudinally five times in, 88–89 step test and motor performance in, 156 sum of skinfolds, 85–86 measured by different calipers, 86 standing broad jump tests, 151 standing on one leg test, 152 SWEDES study, 58 testing of spatial orientation and laterality, resust, 160 to avoid motor stimulation, 287–288 TV program, 251 TV viewing, 227–238, 286 U.S. children, 126 UK children, 126 waist/height ratio index of, 71 walking on a beam test, 151 Zapotec children, 192, 197 Prevention of Adult Cardiovascular Diseases in Early Childhood, 1 Propiomelanocortin (POMC) gene, 217–218 Protein energy malnutrition, 182 Protein intake of small children (safe level), 107 Protein requirements, 106–108 P/S ratio (polyunsaturated/saturated fatty acid), 47 Pteroylglutamic acid (PGA), 117 PUFAs. See Polyunsaturated fatty acid Puritanism, oral, 35 Pyridoxal (PL), 116 Pyridoxamine (PM), 116 Pyridoxine (pyridoxol PN), 116

Q QLSCD. See Quebec Longitudinal Study of Child Development Quack stick, 176 Quebec Longitudinal Study, 211 Quebec Longitudinal Study of Child Development (QLSCD), 211, 225

R Radiation level, 255 RDAs. See Recommended dietary allowances

402 Receptor of glucocorticoids (GRL), 219 Recommended dietary allowances (RDAs), 5, 97–98, 100, 106–108, 110–112, 114, 116–117, 120–121, 131, 247, 297, 301, 307, 314 for children, 116–117 Czech preschool children, 122, 168 of EC, 108, 123 for EI in children, 120 for energy, 128 for preschool children, 131–133 total energy expenditure (TEE), 127 United States, 122, 236, 297 REEs. See resting energy expenditures Reference intakes for all healthy preschool children, 109 Regional Lipid Reference Center, 166 REP (reduced energy and protein), 13, 27–28, 310–311 REPA (PA in rotation cages), 13, 27–29, 310–311 REPI (relatively inactive), 29 Resting energy expenditures (REEs), 102, 127, 240 Resting energy metabolism in children, 103 Resting metabolic rate (RMR), 102, 129, 136, 213 Riboflavin, 116 Right ventricle/body weight, 28 RMR. See Resting metabolic rate

S Satisfactory growth, 99 School of infancy, 2 Sedentarism, 141, 227 Selenium, 114 Sensomotor development, 149–166, 307 test, 160–161 Serum cholesterol, 169 Serum lipid variables, 44–51 SES. See Social and economic status Sex-linked differences, 144, 152, 154, 158, 161, 166–167, 183, 234 SGA. See Small-for-gestational age Skeletal robusticity, 72 Skinfold thicknesses in boys and girls, 55, 180 Small-for-gestational age (SGA), 36 Smoking mothers, 58 Social and economic status (SES), 53, 56, 137, 180, 203, 205, 253, 255, 257 influenced childhood obesity, 253 Socio-demographic determinants, 201 Somatic development, 179–183, 292–298 body posture, 256, 288–291

Index functional development, 292–298 Italian survey, 179–180 Senegalese survey, 181–183 Turkish survey, 180–181 Zapotec survey, 183 Somatic development and physical fitness cardiorespiratory fitness, 183–186 Italian survey, 183–184 Senegalese survey, 185 Turkish survey, 184–185 evaluation of, 54–61 growth and development, 173–174 influence of severe malnutrition, 193–198 influence of varying nutrition and dietary intake, 175–179 motor development, 186–193 Senegalese survey, 188 Turkish survey, 186–188 muscle strength, 189–193 first Senegalese survey, 189–190 functional and/or motor development surveys, 192–193 second Senegalese survey, 191 Tunisian survey, 190 Turkish survey, 189 Zapotec survey, 191 problems of child labor, 198–199 varying in environment and dietary intake, 179–193 Italian survey, 179–180 Senegalese survey, 181–183 somatic development, 179–183 Turkish survey, 180–181 Zapotec survey, 183 Somatotypes, 85–89 Step test, 62 in preschool children from Ankara, Turkey, 184 Step test index (STI), 145–146, 148 STI. See Step test index Striking parallelism, 165 Stunting, 174 Subcutaneous fat distribution, 60 Sweetened-beverage consumption, 110 Systolic blood pressure, 169

T TABP. See Type A behavior patterns TCH. See Total body cholesterol TCH/HDL ratios, 169 TEE. See Total energy expenditure TEF. See Thermic effect of food Temporary exercise delayed consequences, 26 Test of infant motor performance (TIMP), 149 TGs. See Triglycerides

403

Index Thermic effect of food (TEF), 136 Thiamin, 116 Third National Health and Nutrition Examination survey, 297 Three-Factor Eating Questionnaire, 58, 213 Thrifty phenotype, 215 Thyroxine, 114 TIMP. See Test of infant motor performance TOBEC. See Total body conductivity method a-Tocopherols, 115–116 Total body cholesterol (TCH), 169 Total body conductivity method (TOBEC), 231 measurements, 231 Total body water, 231 Total cholesterol, HDLs, 166 Total energy expenditure (TEE), 127, 136–137, 193, 213, 232, 237 free-living, 129 Toyama Study, 224 Triglycerides (TGs), 12, 46–47, 49, 58, 108, 132, 166, 169, 243, 251, 261 in adipose tissue, 108 during pregnancy, 20 levels, 169 in lipoproteins, 12 Triiodothyronine, 114 Trochanteric region (RTG), 304 Trp64-Arg mutations, 218 Trunk-to-limb fat ratio, 36 Trunk-to-limb skinfold thickness ratio, 36 t-test, 46 Tumor necrosis factor alpha (TNF-alpha) gene, 219 Twin clustering, 210–214 Type A behavior patterns (TABP), 169

U UCP1. See Uncoupling protein 2 UCP-3. See Uncoupling protein 3 Uncoupling protein 2 (UCP1) markers, 213, 219 Uncoupling protein 3 (UCP-3) genetic variants, 218–219 United Nations University, 1 U.S. child’s diet, 132

Vigorimeter, 165 Vitamins, 114–117 fat-soluble, 114–116 for preschool children, 115 water-soluble, 116–117 Vitamin A, 114 deficiency, 114 Vitamin B1 (Thiamin), 116 carbohydrate metabolism, 116 Vitamin B2 (Riboflavin), 116 flavin coenzymes, 116 Vitamin B6, 116–117 Vitamin B12 (cobalamin), 117 Vitamin C (L-ascorbic acid), 116 Vitamin D (calciferol), 115 deficiency in children, 115 skeletal formation and mineral homeostasis, 115 Vitamin E (tocopherols), 115–116 deficiency, 116 Vitamin K green leafy vegetables, 116 VLCD. See Very-low-calorie diets VLDL. See Very-low-density lipoprotein

W Waist circumference/arm circumference, (WC/AC), 72 Waist circumference to body height (WC/HT), 230 Waist/height ratio index of, 71 Waist–hip ratio, 36 Walking at a given rate, 152 Walk–jog movements, 164 Wasting, 175 Water-soluble vitamins, 116–117 Weaning, 34 Weight of Opinion Study, 226 WHO. See World Health Organization WHO/FAO/UNU Expert Committee, 103 World Health Organization (WHO), 1, 6, 56, 97, 99, 109–110, 120, 123, 132, 166, 253 2006 growth charts, 202

Y V Veloergometer, 142 Very-low-calorie diets (VLCD), 246 Very-low-density lipoprotein (VLDL), 243 Vierordt, K., 2–3 Physiology of Childhood, 2 relationship of body height and pulse rate, 3 writings of, 4

Young children accelerometry-measured activity, 140 adult adiposity, 201 cardiorespiratory fitness, 141–149 energy expenditure (EE), 136–139 exercise-promoting measures, 141 obesity, 201–202, 317–318 BMI value, 201–202 Chinese adolescents, 202

404 Young children (Continued) Dutch Caucasians, 202 early factors in development, 224–228 evaluation of, 228–233 functional capacity and metabolic and biochemical variables, 201 genetic and hereditary factors, 209–220 health complications, 243–245 interventions for optimal development, 251–252 maternal and familial factors in the development, 220–224 physical activity (PA), 202 prevalence with time in different countries, 203–209 prevention and treatment, 245–251 results, 233–243

Index obesity development and its influence on functional capacity, 201 pedometer-determined steps, 141 physical activity, 136–139 physical fitness, 136–139 racial/ethnic disparities, 201 to avoid motor stimulation, 287–288 U.S./Indian Alascan children, 201 Yurok child training, 34

Z Zero concentration gradient, 20 Zinc, 113–114 deficiency, 113 from animal products, 113 marginal deficiency, 113