Physical Activity and Sedentary Behaviors of Urban Chinese Children: Grade Level Prevalence and Academic Burden Associations.

The objectives of this study were (a) to report grade level prevalence in physical activity and sedentary behaviors and (b) to examine academic burden associations with these behaviors. School-aged children (n = 48,118) reported their physical activity, perception of physical activity sufficiency, factors for activity insufficiency, homework hours, and screen time in a typical week. Data were analyzed using general linear models and logistic regression models of Complex Samples. Prevalence results showed that children had lower physical activity and lower screen viewing time, but higher homework time during transition grades (6th, 9th, and 12th) and high school years. Academic burden was cited as the primary reason for not having sufficient physical activity (76.6%). Compared to those citing academic burden, students who did not report academic burden were significantly more likely to meet physical activity guidelines (Odds Ratio (OR) = 5.38, 95% CI = 4.74-6.11), but less likely to meet screen time guidelines (OR = 0.78, 95% CI = 0.72-0.84), controlling for body mass index, gender, and grade level. Additionally, children who reported academic burdens had significantly longer average daily homework time than those who did not (p < 0.01). Policy makers should promote physical activity and help children find a balance between homework and physical activity time particularly among the educational transition grades.