OBJECTIVETo find out the current situation of physical activity and its influencing factors among Chinese primary and middle school students.

METHODSA total of 166 812 students aged 9 - 18 finished the questionnaires of physical activities and lifestyle behaviors who were selected from "2010 National Physical Fitness and Health Surveillance". The subjects were sampled by stratified cluster sampling method in 30 provinces (autonomous regions, municipalities) except Tibet. The physical activity for a total of at least 60 minutes per day, attitudes on physical activity, parents' supports toward physical activity of children, development of school physical education, the schoolwork burden and sedentary lifestyle were all analyzed. Logistic regression was used to analyze the association between the physical activity for a total of at least 60 minutes per day and individual, family, school and sedentary behavior.

RESULTSA total of 22.7% (37 867/166 757) of primary and middle school students aged 9 - 18 had been physically active doing any kind of physical activity for a total of 60 minutes or more per day, the prevalence was higher among male (25.4%, 21 086/83 159) than female (20.1%, 16 781/83 598) students (P < 0.05). In the 9 - 12 age group, the prevalence was higher among urban (37.6%, 5 980/15 912) than rural (32.0%, 4 917/15 375) students (P < 0.05), but in the 16 - 18 age group, the case was opposite. The prevalence of doing physical activity for a total of 60 minutes or more per day among students who liked physical education (23.7%, 11 866/50 073), were willing to participate in the extracurricular sports activities (23.2%, 13 460/57 907), and were willing to participate long running exercise (26.9%, 9 185/34 153) was higher than those who dislike physical education (15.9%, 589/3705), were not willing to participate in the extracurricular sports activities (15.9%, 567/3565), and were not willing to participate long running exercise (12.1%, 2 246/18 493), respectively. The prevalence was higher among students whose parents supported their physical activity (20.4%, 15 148/74 312) than those students without parents' support (17.5%, 1626/9270) (P < 0.05). And the prevalence was higher among students whose parents often took part in the physical activity (22.7%, 12 864/56 769) than those students whose parents did not (14.6%, 3 906/26 780) (P < 0.05). Logistic regression analysis (adjusted sex, age and urban or not) demonstrated that variables associated with physical activity for a total of 60 minutes or more per day were the initiative will on the physical activity and parental physical activity (OR: 1.478, 95%CI: 1.398 - 1.562). The students without adequate physical education class in school were less likely to do physical activity for a total of 60 minutes or more per day than those who with adequate physical education class in school (OR: 0.536, 95%CI: 0.523 - 0.550), and the students in the school with the phenomenon of "crowding out" or "no" physical education were less likely to do physical activity for a total of 60 minutes or more per day than those whose school without these with phenomenon (OR: 0.712, 95%CI: 0.666 - 0.761). The heavy homework burden (OR: 0.926, 95%CI: 0.899 - 0.953) and long homework time (OR: 0.879, 95%CI: 0.853 - 0.906) were reversely related to the physical activity.

CONCLUSIONThe prevalence of having been physically active for a total of 60 minutes per day in Chinese students is still low. The strong initiative will on the physical activity, parental physical activity, and better school sports atmosphere are good for students to carry out physical activity, and the students with the heavy homework burden and long homework time are less likely to take part in the physical activity.