Benefits of physical activity (PA) are well-documented, and sedentary behaviors (SB) are risk factors for disease independent of PA. Applying the concept of the movement continuum, this study characterizes all movement behaviors over the 24-hour day using time-use diary data from adolescents 10-18 years old using the U.S. nationally representative Child Development Supplement of the Panel Study of Income Dynamics (n = 631). We grouped activities and assigned metabolic equivalent of task (MET) values to: sedentary activity (1-1.5 METs), light physical activity (1.5-3.0 METs), and moderate-to-vigorous physical activity (MVPA; >3.0 METs). We calculated total daily energy expenditures (TDEE) and durations of each activity category and used multiple linear regression to examine socio-demographic associations with movement behaviors. Average TDEE was 1,423 MET-minutes on weekdays and 1,457 on weekend days; adolescents spent on average 69 minutes/weekday and 139 minutes/weekend day in MVPA; they engaged in sedentary activities 677 minutes/weekday and 466/weekend day; and slept 540 minutes/weekday and 629/weekend day. Girls spent more time lying down (19.9 vs. 7.9 minutes) and doing activities standing (68.1 vs. 50.7 minutes), and boys spent more time playing computer games (68.3 vs. 16.2 minutes) and sports (28.8 vs. 11 minutes). Black girls had the lowest activity levels. MVPA and SB duration were similar for boys and girls, but there were differences in the activities comprising this time. When taking account of the entire movement continuum, the PA duration of U.S. adolescents was on average closer to recommended levels than other methods have indicated.
Cunningham et al. (Fri,) studied this question.