Physical activity, screen time and body composition in 13-year-old adolescents: The Generation R Study.

BACKGROUND: Body composition between prepubertal children and adolescents varies, and it is unclear how physical activity and sedentary behaviour affect adolescent body composition.

OBJECTIVES: This study aimed to examine the associations of physical activity and screen time with overall and specific fat depots in the general adolescent population.

METHODS: In a population-based prospective cohort study, among 3258 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 and lean body mass) and magnetic resonance imaging-based measures (i.e. abdominal subcutaneous and visceral fat mass) were obtained.

RESULTS: After adjusting for social-demographic and growth-related factors, each additional hour of daily physical activity was associated with lower fat mass, abdominal visceral fat mass and higher lean body mass (all p < 0.05). However, these associations were not observed in the longitudinal analyses. Each additional hour of daily screen time was associated with higher body mass index, fat mass, abdominal subcutaneous and visceral fat mass (all p < 0.05), which were consistent with the longitudinal analyses.

CONCLUSION: Adolescents with higher physical activity and lower screen time had lower levels of adiposity both at the general and visceral levels.