From an Inactive and Obese to a Fit Child: How Long Is the Way? Czech Experiences^,

Abstract

To achieve a higher level of overall fitness and to prevent obesity with accompanying comorbidities requires life-long effort starting early in life during the prenatal period. A sufficiently intense, regular, and ongoing physical activity regime and adequate exercise are indispensable, along with monitored diet. Once acquired, a desirable level of body composition and functional capacity can be lost relatively quickly due to regime interruption. Adhering to the optimal regime of diet and activity that not long ago used to be the norm is especially difficult under present life conditions, and new and innovative procedures have to be defined and introduced.

Introduction

For an adequate evaluation of the level of child growth and development today, not only morphological criteria but functional variables related to environmental conditions are also required; this might be more important than body size, provided more marked deviation is absent (1). Research in child growth and development in the Czech Republic started at the end of the 19th century, when height and weight along with some other variables (e.g. lung function) were assessed in school children by J. Matiegka (2). They enable, inter alia, the ex post evaluation of BMI and its secular changes. Children at that time were smaller and obviously also leaner than at present.

Previous studies concerning somatic and physical fitness development, e.g. the International Biological Program (IBP) (3,4), were also conducted on an international level during the 1960s (5). In another study, up to 100,000 growing participants were measured in 10-y intervals starting with the 1950s in the Czech Republic. Tens of anthropometric variables along with environmental characteristics (nutrition, physical activity, etc.) have been repeatedly assessed until the beginning of this millennium (6–8). Not only were secular changes in the development of Czech children found, i.e. usual acceleration of growth, but also a significant shift in the age of the adiposity rebound (AR) to earlier periods of growth in Czech children. Due to that, children with earlier onset of AR than average can become more easily and more frequently overweight and/or obese during later life (6–9).

From the 1950s until the present, detailed studies of specially characterized groups of children and adolescents were also executed. Along with the changes in body composition and physical fitness, the problem of obesity has acquired great attention due to numerous comorbidities that may appear already during growth, e.g. type diabetes 2, hypertension, dyslipidemia, and, more recently, metabolic syndrome, along with orthopedic and psychological problems (1, 8–10, 12, 13).

Methods and criteria

Somatic development, including body composition, i.e. the absolute and relative amounts of lean, fat free body mass and depot fat, was examined since the end of the 1950s using hydrodensitometry. Underwater weighing with simultaneous measurement of the air in the lungs and respiratory passages in children from 7 to 18 y was conducted, along with the measurements of 10 skinfold thickness with a caliper. Regression equations enabling the evaluation of fat ratio from skinfolds were derived (1, 12), which made it possible to evaluate body composition from skinfolds in large population samples of Czech children under field conditions. In later studies, bioimpedance analysis (6) was also implemented in children and adolescents. Physical fitness variables included aerobic power (oxygen uptake during standard and maximal work loads on the treadmill and/or on a bicycle ergometer), muscle strength measurements, motor tests, etc. (3, 4). Criteria and standards for morphological and functional development for Czech children from preschool age to adolescence were elaborated (1, 3, 10, 12). In the framework of IBP, 74 somatic, morphological, motor, and functional variables were assessed in 3762 Czech participants of both gender differentiated according to the level of adaptation to various work loads (3, 4). The adolescent population included 1903 boys and girls from 12 to 18 y of age. Similar follow-up measurements including body composition and functional variables during more recent times and in larger population samples have not been conducted again.

In cross-sectional and longitudinal studies, the intake of food from the point of view of energy and individual macro- and microcomponents was also assessed. Clinical variables included the assessment of blood pressure, lipid, and hormonal levels in the blood and hematological variables, which were mostly used in obese participants, especially during reduction treatment (1, 12).

The effect of physical activity, exercise, nutrition, and their interrelationship

The aforementioned factors have changed over time due to the contemporary lifestyle. There is an imbalance between energy intake and expenditure, and changes in their mutual relationships resulting in negative effects on energy balance and turnover, both of which are considered as the most important factors with regard to undesirable consequences of somatic development, body composition, and functional capacity. Such changes have been critical, especially during earlier growth periods, with marked delayed consequences in overall fitness level and health status as well as in their prognosis for later life (10).

Previous studies concerning these problems included mostly a limited number of factors and variables (prevailingly morphological) and very rarely more of them together, or longitudinally during more years of growth. Results on dietary intake, nutritional status, physical fitness level, metabolic, biochemical, and hormonal variables were thus given mostly separately, which did not make it possible to evaluate the effect of their mutual relationships.

The level of physical activity that was common several decades ago and resulted in a higher level of physical fitness has significantly decreased. Along with that, the level of physical fitness and aerobic power has also declined by ∼0.5%/y (14), along with the increase in overweight and obesity prevalence. Pedagogues, teachers, pediatricians, and others complain that children are often not able to perform the most simple motor tests, such as forward bent touching the ground, or catching a ball, which may be considered markers of physical fitness.

A significant effect of the level and character of exercise and training on body composition and fitness level has been revealed, indicating great sensitivity of these variables with regard to the changes in lifestyle. This effect was followed-up during 5 y of measuring both total and subcutaneous fat in growing gymnasts. Reduction of body fat was apparent even while energy intake increased due to more intense training, and vice versa (1, 11).

The same effects of the development of body composition were measured in groups of regularly training boys who were followed longitudinally from ages 11 to 18 y. Comparison of body composition and aerobic power (max O₂ measured during a maximal work load on a treadmill) confirmed the significant positive effect of regular training of various types on both of these morphological and functional characteristics. However, the condition of this effect on body composition and aerobic power was always dependent on sufficient intensity, regularity, and systematic adherence to the training regime during more prolonged periods of time regulated by pedagogic oversight and control. Interruption of training was also significantly reflected by changes of both body composition and fitness level (1, 11). In groups of other young athletes, similar changes in body composition and aerobic power were found; simultaneously, an increased food intake was always observed, e.g. in adolescent hockey players (11). The same results were observed in IBP studies showing very small differences of BMI, but a significant reduction in body fat and an increase in aerobic power (VO₂ during maximal work load on a bicycle ergometer; IBP) in participants taking part in regular exercise and sport training (3, 4).

Decreased adiposity and increases in lean body mass due to intensive exercise (e.g. in male gymnasts, skiers) compared with inactive controls were always apparent despite high food intake (1).

An optimal balance between energy intake and expenditure was best achieved when both were on a high level. The natural characteristics of a young growing organism compared with an adult are the relatively high food intake along with high levels of spontaneous physical activity. A higher level of spontaneous physical activity and exercise during growth periods than during adulthood may be also the result of relatively lower increase of oxygen uptake and energy expenditure in terms of basal metabolic rate (lower values of the multiples of basal metabolic rate, MET) during the same work load (4). This means that a younger organism can pass from inactivity or low activity to a greater work load more easily than an older organism.

Additional findings in an experimental model, i.e. in vitro studies with various tissues of laboratory animals, revealed that adaptation to increased exercise obviously modified the metabolic activity of fat and muscle tissue (bioptic studies in growing normal humans were of course not possible). Adipose tissue, which was always reduced in animals adapted to increased exercise compared with control and/or hypokinetic laboratory rats, released in vitro a higher amount of nonesterified, free fatty acids (FFA) both spontaneously and/or after adrenaline. Lipolytic activity of skeletal and cardiac muscles of exercised animals also increased and the inflow rate of labeled FFA (with ^!4C) to them was higher, indicating their higher utilization even under rest conditions. In contrast, lipolytic activity and inflow rate of labeled FFA to cardiac and skeletal muscles was especially reduced in animals adapted to hypokinesia living in a limited small space. Adaptation to reduced physical activity was especially negatively effective in growing but not in adult and/or older animals (1, 10, 12).

Obesity as a result of energy imbalance

The problem of obesity during growth started to appear more markedly in the middle of the last century, even when it was not yet so frequent and urgent as at present time. Obese children and adolescents were followed up in the pediatric clinic in Prague, where the outpatient department for the obese participants finally separated from the endocrinological outpatient department in the late 1950s. Clinical follow-ups revealed that obesity in growing participants very rarely resulted from endocrinological abnormalities but mostly from energy imbalance caused by reduced physical activity and lack of exercise along with inadequate food intake. Usual clinical symptoms such as increased blood pressure, dyslipoproteinemia, impaired glucose tolerance, insulin resistance, orthopedic, and psychological problems mostly appeared as a consequence of obesity.

Not only an increased amount of fat but also its impaired distribution (indicating metabolic risks) was apparent and, when accompanied by reduced aerobic power (max O₂ related to total and lean body weight) and a lower level of physical performance, especially of a dynamic character (body weight-lifting activities), resulted in reduced interest in exercise. Muscle strength, however, was often higher due to greater lean body mass, and skills of smaller muscle groups were not impaired.

Morphological and functional differences between normal weight, overweight, and/or obese participants that appeared during growth were always significantly negative and undesirable in terms of body composition, physical fitness level, and health status during later life (1, 12).

The effect of reduction treatment through monitored diet and exercise.

Obese children were followed up longitudinally during reduction treatment in the above-mentioned pediatric clinic. This took place both during the school year and especially during summer camps for the obese, where the best results could be achieved. Reaction to reduction treatment, monitored diet, increased exercise, and behavioral and psychological interventions was assessed before and after the summer camps. Morphological evaluations were always supplemented by functional and biochemical assessments, which showed significant positive improvements of functional capacity and physical fitness accompanying the reduction of fat. Reduction treatments have been implemented regularly up to the present, especially in spas, which specialized in these procedures in children and adolescents. The effects of the combined treatment always resulted in positive changes of BMI, fat ratio, increase of physical performance, reduction of blood pressure, and improvement of biochemical and hormonal variables (e.g. reduced level of leptin) (12,15,16).

However, during the following school year, the positive results of summer reduction treatment mostly deteriorated. Along with further growth, body fat again markedly increased, its distribution also changed negatively, and physical fitness levels decreased. The best results were achieved after repeated summer camp treatments for several years, which was not always possible for all children. Repeated studies in the same group of treated obese children for 4 y revealed that the reaction of such treatment was mostly successful when introduced during younger periods of development such as the prepubertal period rather than during and after puberty (12).

The way to improve: early start of treatment and prevention of obesity.

As shown in regularly exercising children, desirable body composition and physical fitness level can be achieved and maintained as a result of an optimal regime of systematic, adequately intense, and ongoing physical activity and exercise. This always prevented, even under conditions of a higher food intake (including some undesirable items like sweets and fatty foods), greater deposition of fat. Energy balance can be maintained on a desirable level without increasing BMI and fat deposition more easily when both energy intake and output are at a high level. The obese individual, on the contrary, is mostly characterized by low activity with a resulting low level of fitness, which is considered as one of the most important causes of increased adiposity and which is not always accompanied by markedly increased energy intake. An important aspect is when to start with such an adaptation. The comparison of energy balance and turnover indicates that successful adaptation should start as early as possible in life when it corresponds to actual ontogenetical trends (1,4,12).

The effect of nutrition and physical activity already in the fetal and weaning periods can manifest itself as delayed consequences in adult offspring, as shown especially in models with laboratory animals, which made all-life follow-ups possible (10).

The prognosis of obesity can result from the dietary and physical activity regime of the mother during pregnancy through her eventually modified nutritional and metabolic status (10). Parents with higher BMI usually have heavier children (which is not only the result of genetic, but also environmental factors in the family such as nutrition and activity) and children born heavier remain overweight also later on (10). The size and speed of weight gain during a child´s first months and early years characterized by crossing-up BMI percentile development and earlier AR can facilitate present and later development of overweight and obesity. These factors also depend, e.g., on the duration of breast-feeding (which mostly reduces the risk of later obesity), which is related to the mother’s education level (7). Repeated assessments revealed mostly an increased food intake during later periods of preschool age (10).

As repeatedly assessed, spontaneous physical activity in preschool children is on a high level and decreases from the beginning of school age. This results not only from the changed lifestyle due to spending more time sitting at school but also concerns how free time is used during weekends (17,18). Acquiring proper motor habits and adapting to higher levels of physical activity during an adequate regime at preschool age facilitates the development of positive interest and involvement in exercise also in later life. Cross-sectional and longitudinal observations of preschool children indicate that both spontaneous and induced exercise result in desirable changes of body composition, fitness level, and serum lipid level. Physical performance in areas such as coordination or strength of certain muscle groups (e.g. ball throw or broad jump) is also improved, especially in children participating in special kinds of physical education classes or exercise of preschoolers with one of the parents. In the Czech Republic, such programs have been organized on a mass scale since the 1960s. It has been included in mass gymnastic displays that take place regularly in several year intervals up to this day. Exercise of children at this age is a special pedagogical problem and must be spontaneous like natural games. The participation of mothers, fathers, or any other close person is a guarantee that exercise will be safe and well accepted. Children like to take part, including children who are handicapped (10).

Discussion, Conclusions, and Recommendations

To guarantee the optimal development of a fit child with a desirable health prognosis, an early introduction of adequate nutrition accompanied and balanced with proper physical activity and adequate exercise is necessary. BMI development should follow the optimal percentile and AR should not start earlier than recommended, i.e. at ∼5.5–6 y of age. At present, in addition to genetic factors, an adequate nutritional and physical activity regime should start already with that of the pregnant mother and also with the child during the first months and years of life (19). This can be decisive for the optimal development and prevention of obesity as a predisposition for later optimal health, performance, and life expectancy. Family environment is essential; the best management of obesity is to not let it develop at all during early childhood.

Adequate physical activity and exercise, however, should be an ongoing part of a person´s lifestyle without longer interruption. This has not often been guaranteed and the role of both activity and adequate nutrition often has been underestimated. Regulation of energy balance and body composition due to the increase of energy expenditure by increasing activity enables higher food intake, which prevents eventual deficiencies of selected items in a reduction diet, which is more difficult to define and preserve. Unfortunately, such a regime is at present very difficult to adhere to, especially in large urban areas, along with the simultaneous effects of commercials and advertising of unsuitable nutrition (too much saturated fat, simple sugars, salt) and reduction of activity due to television programs and videogames. Lack of suitable and safe areas and playgrounds for exercise and games also have a negative impact on physical activity. As early as possible, the introduction of a proper regime of diet and exercise can facilitate the adherence to such a lifestyle when the participant accepts and makes this his/her spontaneous personal desire. Education and family members as role models also play an essential role. The way to desirable results is lifelong and starts at its very beginning. This especially applies to children with genetic predispositions (obese parents or siblings) who are already at risk to becoming overweight and/or obese and who need adequate intervention and treatment (20).

These recommendations repeat mostly old and well known truths since past centuries (21). A continuing increase in obesity prevalence shows that this is still necessary. Changing life conditions require new, innovative approaches and actualized recommendations corresponding to the present lifestyle, which is incomparable to that of not long ago (22). The task is difficult, but worth the effort.