US adolescents at risk for not meeting physical activity recommendations by season.

ABSTRACT

BACKGROUND: We sought to identify regional and seasonal variation in not meeting physical activity (PA) recommendations of ≥60 min a day of moderate-to-vigorous PA (MVPA) and 3 h of vigorous PA per week (VPA) in a longitudinal cohort of United States (US) adolescents. METHODS: Participants in the Growing Up Today Study 2, a prospective study of 10,918 adolescents, self-reported season-specific weekly hours of MVPA and VPA from 2004 through 2011. To assess variation in PA by climate, we grouped the contiguous US into nine climatically consistent geographic regions. We also examined MVPA and VPA by season, sex, ethnicity, weight status, and age group. RESULTS: The majority (85%) of adolescents did not meet the MVPA recommendation, and 91% did not meet the VPA recommendation, for one or more seasons over the four study years. Across all climate regions, adolescents were two times more likely to not meet the MVPA recommendation during the winter compared to summer (odds ratio 2.02, 95% confidence interval 1.96-2.08). CONCLUSION: Regardless of climate region, gender, ethnicity, or age group, adolescents were more likely not to meet MVPA or VPA recommendations in the winter than the summer. Adolescents may benefit from interventions aimed at increasing PA in the winter.