Changes in Moderate-to-Vigorous Physical Activity Among Older Adolescents

OBJECTIVES: Examined patterns and determinants of objectively measured moderate-to-vigorous physical activity (MVPA) over 4 years in US emerging adults. METHODS: Waves 1 through 4 (W1 [10th grade] to W4 data of a national cohort starting in 2010 (N = 561; 16.19 +/- 0.51 years) were used. MVPA was assessed annually from accelerometers; BMI calculated from measured height/weight; and surveys ascertained self-reported physical activity (PA) planning, peer PA, family support, W1 sociodemographics, W4 school status, W4 residence, and W4 employment. Latent growth modeling estimated trajectories in log-transformed duration (minutes/day) of MVPA and associations with covariates. RESULTS: Less than 9% of participants met the recommended 60+ minutes/day MVPA across W1 through W4. W1 MVPA was greater in males versus females (B = 0.46, P < .001) and Hispanic versus White (B = 0.34, P < .001) participants. Increased BMI change (W1 to W4 slope) was associated with decreased MVPA. MVPA was positively associated with PA planning (W1-W3: B = 0.10, B = 0.06, B = 0.08, Ps < .05), but not with peer PA or family support. Participants attending 4-year college versus not-attending school (B = 0.52, P < .001), and college students living on campus versus at home (B = 0.37, P < .001) were more likely to engage in MVPA at W4. Weekend MVPA remained relatively constant from W1 through W4. CONCLUSIONS: High-school students engaged in little MVPA and maintained this low level through the transition to adulthood. Emerging adults' MVPA engagement may vary according to social contexts. Those with high BMI may benefit most from interventions to promote MVPA.