Relationship between activity energy expenditure and body composition in school-age children / 中华临床营养杂志

ABSTRACT

Objective To investigate the association between activity energy expenditure ( AEE ) and body composition in school-age children.Methods A total of 62 students ( Grades 3 and 4, aged 8 -10 years) from a primary school in Shanghai were enrolled in this study .AEE was estimated with a metabolic cart (energy metabolism determination system ).Body composition (body mass, body mass index, fat percentage, fat mass, fat-free mass, fat mass index, fat-free mass index, obesity degree) was evaluated by bioelectrical im-pedance analysis .The above indicators were compared between obese and non-obese students .Results There were no statistically significant differences in exercise time , total AEE and relative AEE between obese and non-obese boys [ (9.70 ±1.91) min vs.(10.00 ±1.97) min, t=0.336, P=0.739; (198.74 ±53.33) kJ vs.(171.54 ±41.75) kJ, t =-1.422, P =0.165; (0.46 ±0.09) kJ/(min· kg) vs.(0.51 ± 0.04) kJ/(min· kg), t=2.043, P=0.051], while obese boys had higher absolute AEE than non-obese boys [(20.06 ±3.14) kJ/min vs.(16.93 ±1.85) kJ/min, t=-2.910, P=0.007].Obese girls had shor-ter exercise time and lower relative AEE than non-obese girls [ (7.35 ±3.05) min vs.(9.98 ±1.82) min, t=2.509, P=0.027;(0.41 ±0.09) kJ/(min· kg) vs.(0.51 ±0.07) kJ/(min· kg), t=3.244, P=0.003 ] , whereas there were no statistically significant differences in total AEE and absolute AEE between obese and non-obese girls [ (129.29 ±71.13) kJ vs.(161.50 ±35.38) kJ, t =1.351, P =0.203; (16.82 ± 3.26) kJ/min vs.(16.17 ±2.00) kJ/min, t=-0.676, P=0.504].After controlling for age and gender, absolute AEE was significantly positively correlated with body mass index ( P=0.015 ) , obesity degree ( P=0.010), fat mass (P=0.047), fat-free mass (P=0.010), and fat-free mass index (P=0.003) in boys, but not in girls.Relative AEE was significantly negatively correlated with body mass index ( boys: P =0.000, girls: P=0.000), obesity degree (boys: P=0.002, girls: P=0.000), fat percentage (boys:P=0.000, girls:P=0.001), fat mass (boys:P=0.000, girls:P=0.000), fat-free mass (boys: P=0.002 , girls: P=0.022 ) , and fat mass index ( boys: P=0.000 , girls: P =0.000 ) in both boys and girls.Conclusions In obese children, AEE is correlated with body composition, with relative AEE reducing as obesity degree increasing.There may be complex relationships among body size , body composition, and energy metabolism in children.