Physical activity fat mass gain in Mexican school age children: a cohort study

Abstract

Background: In México, the prevalence of unhealthy weight increased from 24% at 6 y to 33% at 12 y of age, opening a window of opportunity to better underst the pathogenesis of obesity. The objective of this study was to explore the association between time spent on medium, vigorous physical activity (MVPA) concurrent gains in BMI, fat mass (FM) fat free mass (FFM), alternately, in a cohort of Mexican children followed from kindergarten (baseline) to 2nd grade elementary school (endline). Methods: The MVPA (5 d accelerometry), BMI, FM FFM (air displacement plethysmography) were measured at baseline endline. Associations between gains in BMI, FM FFM changes in MVPA were examined using lagged dynamic regression models, controlling for energy intake and demographic variables. Results: A total of 205 children were analyzed. Gender affected the effect of MVPA on FM gain. In girls, a high baseline MVPA predicted a lower FM gain ( 0.96 kg, p=0.025) compared to low/medium MVPA. Increasing, decreasing or having a persistently high MVPA predicted a lower FM gain (range 1.6 to 1.03 kg, p<0.05) compared to persistently low MVPA. In boys, increases in MVPA were associated with higher gains in BMI (+0.76 kg/m2, p=0.04) FFM (+1.1 kg, p=0.01) compared to persistently low MVPA. Conclusion: These results support a protective role of MVPA on FM gain in girls, suggesting that it may play a crucial role in the development of obesity. Further research on the gender effect of MVPA is warranted to better understand its role in the prevention control of overweight obesity.