Physical Activity, Screen Time and Body Composition in Adolescents: A Population-based Prospective Cohort Study

Abstract

Abstract Background Physical activity and sedentary behaviors have been shown to have varying health benefits. Nevertheless, it is unclear how physical activity and screen time affect body composition during adolescence. This study examined the associations of physical activity and screen time with overall and abdominal fat depositions in general pediatric population. Methods In a population-based prospective cohort study, among 3.258 adolescents aged 13 years, physical activity and screen time were assessed via self-report questionnaires. Body mass index, dual-energy X-ray absorptiometry-based measures (i.e., fat mass index (FMI), lean body mass index and android/gynoid fat mass ratio (A/G ratio)), and magnetic resonance imaging-based measures (i.e., abdominal subcutaneous fat index, abdominal visceral fat index and abdominal visceral/subcutaneous fat mass ratio) were obtained. Results After adjusting for social-demographic and growth-related factors, a change of per additional hour per day spent in physical activity was associated with lower FMI (Z score difference, -0.08; 95% CI, -0.14 to 0.01), A/G ratio (-0.10 [-0.18; -0.03]) and abdominal visceral fat index (-0.11 [0.20; -0.02]), and higher lean body mass index (0.15 [0.08; 0.22]). A change of per additional hour per day spent in screen time was also associated with higher body mass index (0.02 [0.01; 0.04]), FMI (0.02 [0.01; 0.03]), A/G ratio (0.03 [0.02; 0.04]), abdominal subcutaneous fat index (0.03 [0.02; 0.05]) and abdominal visceral fat index (0.03 [0.01; 0.05]), and lower abdominal visceral/subcutaneous fat mass ratio (-0.02 [-0.04; -0.01]). Conclusion Adolescents with higher physical activity and lower screen time had lower levels of adiposity both at the general and visceral levels. This information may be used for future work to develop targeted intervention strategies that improve body composition among adolescents.