Regular article
Does early physical activity predict body fat change throughout childhood?

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Abstract

Background

Declining levels of physical activity in the population at large may be responsible in part for the rising rates of childhood obesity. Studies to date, however, have not consistently demonstrated such a protective effect. We used longitudinal data from the Framingham Children’s Study (FCS) to address this important question.

Methods

We used 8 years of activity monitoring (Caltrac electronic motion sensors) and repeated anthropometry measures for 103 children to examine the effect of activity on body fat change from preschool to early adolescence. Longitudinal data analysis methods were employed to account for the use of repeated measures on these children.

Results

Children in the highest tertile of average daily activity from ages 4 to 11 years had consistently smaller gains in BMI, triceps, and sum of five skinfolds throughout childhood. By early adolescence (age 11), the sum of five skinfolds was 95.1, 94.5, and 74.1 for the low, middle, and high tertiles of activity, respectively (P for trend = 0.045). This protective effect of activity was evident for both girls and boys.

Conclusion

This longitudinal study adds strong support for the hypothesis that higher levels of physical activity during childhood lead to the acquisition of less body fat by the time of early adolescence.

Introduction

The prevalence of obesity has increased worldwide among people of all ages [1], [2], [3], [4], [5]. Obesity in childhood often persists into adulthood [6], [7], where it has been clearly linked to an increased risk of cardiovascular disease, hypertension, diabetes, and even some cancers [8], [9]. The remarkable rate of change in the prevalence of obesity over the past 30 years suggests that lifestyle rather than genetic factors may be primarily responsible. To develop effective strategies for obesity prevention, it is critical to determine the relative importance of specific obesity-related risk factors.

At a basic level, obesity is a consequence of an imbalance in energy intake and expenditure. Despite this, it has been difficult to demonstrate convincingly that physical activity plays a significant role in the development of excess body fat during childhood. A child’s total energy expenditure (TEE) is the sum of resting metabolic rate, thermogenic effects of food, energy cost of growth, and energy expended as activity. Resting metabolic rate is variable among individuals but it is by far the largest contributor to TEE, accounting for 60–70% of the total. The energy required to metabolize and store food accounts for another 5–10% of TEE. Since the energy needed for growth is small, the principal remaining contributor is physical activity [10].

A number of obesity studies have used a doubly labeled water method for estimating TEE [11] and when used in combination with indirect calorimetry, this approach is designed to estimate the portion of TEE that is attributable to physical activity [12]. The results of studies using doubly labeled water methods (with and without indirect calorimetry) to estimate the effect of energy expenditure on obesity have been conflicting [13], [14], [15], [16], [17], [18], [19], [20], [21], [22]. Most of these studies have been cross-sectional and thus provide limited data on the development of excess body fat since obesity itself alters resting metabolic rate as well as the energy cost of activity [23]. Overall, the consensus seems to be that studies to date have failed to confirm an effect of TEE (or the activity component of TEE) on body fat change in children [12].

Physical activity in children has been estimated by several other methods, including self-report, parent report, direct observation, and activity monitoring [24], [25], [26]. Here too, the cross-sectional epidemiologic study results are variable, with some suggesting that obese children are less physically active than nonobese [27], [28], [29] and others suggesting that energy intake is more important than activity to the development of obesity [10], [30], [31]. Prospective studies of activity and body fat change during childhood are sparse. Some have found little or no effect of activity [32], [33], [34], while others, including our own earlier analyses in preschool children, have shown that more active children acquire less body fat over time than less active children [35], [36], [37], [38], [39]. The majority of these studies had at most a few years of follow-up.

Physical activity may have varying effects on body fat change at different times during childhood, a fact that may explain some of the variability in previous study results. It is possible that there are critical periods of susceptibility for the development of obesity [40]. Adiposity rebound refers to certain developmental periods in which there is a rapid increase in adiposity [41]. At 5 to 6 years of age, body fat typically reaches its lowest point prior to a critical period of increasing adiposity. This seems to be a particularly important time, with studies showing that children who reach the nadir of adiposity at a younger age have a higher risk of obesity as adults [42].

The primary goal of this study is to examine the effects of physical activity on the change in body fat over a period of 8 years, from the preschool years to early adolescence. The secondary goal is to examine whether physical activity has any effect on adiposity rebound in these children.

Section snippets

Methods

The Framingham Children’s Study is a longitudinal study of the early childhood determinants of diet and physical activity. The study began in 1987, when 106 three- to-five-year-old children and their parents were enrolled. The subjects were third and fourth generation offspring of the original Framingham Study cohort. The recruitment and enrollment have been described previously [35]. Briefly, subjects from the original Framingham Study were asked to provide the names and contact information

Results

At baseline (Table 1), the mean Caltrac counts per hour in the low, middle, and high tertiles of activity, respectively, were 8.5, 10.2, and 12.5. The least active children were very slightly older than children with either moderate or high levels of activity. Total energy intake increased with increasing activity, although there were no differences in the mean percentage of calories from fat or the amount of television watched per day at baseline according to activity level. There was no

Discussion

This study confirms a strong protective effect of physical activity on the long-term change in body fat during childhood. Although some earlier studies have also found a protective effect of activity on the development of obesity at various time periods during childhood [35], [36], [37], [38], [39], this is the first study to demonstrate the effects of physical activity on change in body fat from preschool to early adolescence. By age 11, the most active children in this study had lower BMIs

Conclusion

In sum, the results of this study support the belief that the level of physical activity plays a crucial role in the development of obesity for both girls and boys. It also provides new evidence to suggest that high levels of physical activity beginning in the preschool years may delay the onset of the period of rapidly increasing body fat that generally occurs between 4 and 6 years of age. Since physical activity has also been shown to track throughout childhood [52], [53], it is important to

Acknowledgements

This work was supported by Grant 5R01 HL35653-10 from the National Heart, Lung, and Blood Institute.

References (53)

  • R.I. Berkowitz et al.

    Physical activity and adipositya longitudinal study from birth to childhood

    J Pediatr

    (1985)
  • W.H. Dietz

    Periods of risk in childhood for the development of adult obesity—what do we need to learn?

    J Nutr

    (1997)
  • M.F. Rolland-Cachera et al.

    Adiposity rebound in childrena simple indicator for predicting obesity

    Am J Clin Nutr

    (1984)
  • K.M. Flegal et al.

    Overweight and obesity in the United Statesprevalence and trends, 1960–1994

    Int J Obes Relat Metab Disord

    (1998)
  • A.H. Mokdad et al.

    The spread of the obesity epidemic in the United States, 1991–1998

    JAMA

    (1999)
  • R.P. Troiano et al.

    Overweight prevalence and trends for children and adolescents. The National Health and Nutrition Examination Surveys, 1963 to 1991

    Arch Pediatr Adolesc Med

    (1995)
  • C.L. Ogden et al.

    Prevalence of overweight among preschool children in the United States, 1971 through 1994

    Pediatrics

    (1997)
  • World Health Organization. Obesity: preventing and managing the global epidemic. Publication WHO/NUT/NCD/98.1. Geneva:...
  • A. Must et al.

    Risks and consequences of childhood and adolescent obesity

    Int J Obes Relat Metab Disord

    (1999)
  • A. Must et al.

    The disease burden associated with overweight and obesity

    JAMA

    (1999)
  • D. Thompson et al.

    Lifetime health and economic consequences of obesity

    Arch Intern Med

    (1999)
  • J.P. Delany

    Role of energy expenditure in the development of pediatric obesity

    Am J Clin Nutr

    (1998)
  • C. Maffeis et al.

    Total energy expenditure and patterns of activity in 8-10-year-old obese and nonobese children

    J Pediatr Gastroenterol Nutr

    (1996)
  • C. Maffeis et al.

    Energy expenditure during walking and running in obese and nonobese prepubertal children

    J Pediatr

    (1993)
  • S.B. Roberts et al.

    Energy expenditure and intake in infants born to lean and overweight mothers

    N Engl J Med

    (1988)
  • J.P. Delany et al.

    Energy expenditure in lean and obese prepubertal children

    Obes Res

    (1995)
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