[Behavior and knowledge on physical activity among urban junior students in Hangzhou]

To study the status of physical activity (PA) and sedentary behaviors and relevant knowledge to it among junior students.

In a cross-sectional study, a self-administered questionnaire was used to assess the PA, sedentary behaviors and relevant knowledge on 4549 eligible urban junior students.

Among the 4549 junior students, only 7.50% engaged in ≥ 60 minutes of PA, per day. Those junior students spending 2 hours on weekdays, 3 hours on weekends in doing homework and those spending ≥ 30 min on weekdays, 2 hours on weekends in doing other sedentary activities, accounted for the highest proportion of the subjects respectively. The awareness rate of spending at least 60 minutes each day on PA to stay fit and healthy was 24.63%. Differences in gender and grade at school were significantly on 'understanding of health benefits regarding PA' (P < 0.05).

Urban junior students were lack of awareness and appropriate behavior on physical activities so the related intervention should be taken actively to improve the current situation among the adolescents at school.