Relationship Between Body Mass Index, Body Composition And Aerobic Fitness In Greek Primary School Students

Introduction
The prevalence of child obesity is increasing rapidly worldwide [1]. Child obesity may be a precursor of adult obesity
and is associated with several risk factors for chronic diseases such as hyperlipidaemia, hyperinsulinaemia, and early
atherosclerosis. According to surveys in many European, Asian and American countries the prevalence of obesity in
young boys and girls has increased to about 10%-20% over the last decade [1,2]. In the cases where obesity is combined
with inactivity, then the harmful effects to health may be greater. The purpose of the present study was to examine the
relationship between obesity estimated by body mass index (BMI), body composition and aerobic fitness in young
Greek boys and girls.

Methods
One hundred and one children aged 10-12 y took part in this study (55 boys and 46 girls, age: 11.3±0.6 y, Ht: 151.0±6.0
cm, Wt: 46.0±9.8 Kg, mean±SD). Body composition (%fat and lean mass) was estimated from the triceps and
subscapular skinfolds using age and sex specific equations [4]. BMI was calculated (weight/height2) and then converted
to a percentile value adjusted for age and sex according to the LMS method [1]. BMI values between the 85th and 95th
percentile were taken to indicate risk of overweight, while a BMI greater than the 95th percentile was considered to
indicate obesity [1,2]. Aerobic fitness was evaluated using the 20 m shuttle run test from which VO2max values were
calculated according to the level accomplished. Means were compared using unpaired t-tests.

Results
There was no significant difference between boys and girls in height (151.8±5.5 vs 150.0±6.4 cm), weight (47.2±10.4
vs 44.6.0±8.9 Kg), BMI (47.2±10.4 vs 44.6±8.9 Kg/m2) and percent body fat (20.3±8.0% vs 19.0±5.4%). However,
VO2max relative to body weight, as estimated from the shuttle run test, was higher in boys compared to the girls
(47.4±4.1 vs 45.5±2.9 ml/Kg/min, P<0.02). Percentile and BMI values were strongly associated with percent body fat
(Graph 1), and fat mass (r2=0.85, P<0.01), while a negative correlation between BMI and VO2max was observed (r=-
0.54, P<0.01). Similarly, percent body fat was negatively correlated with VO2max (Graph 1). The percentage of girls
characterized as overweight was 13%, while for boys this value was almost twice as high (23.6%).

Discussion/Conclusions
The results of this study support the use of BMI and percentile ratings as a measure of fatness in children aged 10-12
years [3]. The negative correlations between all estimates of body fatness and VO2max suggest that child obesity may
be accompanied by decreased aerobic fitness. The percentage of overweight children, especially boys, was high
compared to international surveys [1,2].

References
[1]. Cole et al. (2000) B.M.J. 320: 1-6
[2]. Goran (2001) Am. J. Clin. Nutr. 73: 158-171
[3]. Pietrobelli et al. (1998) J. Pediatr 132: 204-210
[4]. Slaughter et al. (1988) Human Biol. 60: 709-723

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