Objective assessment of school-time physical activity of a grade 1-2 junior school students in Beijing

Objective To quantify the physical activity (PA) level during school time, especially in PE class, among Beijing junior school students.

Methods 81 healthy adolescents (37 boys and 44 girls) aged 11-15 were recruited from grade 1-2 of a junior school, and a hip-worn ActiGraph GT3X + accelerometer was used to measure students’ PA. Accelerometer-determined steps, moderate-and vigorous-intensity PA (MVPA), vigorous-intensity PA (VPA) and MET-mins at school time and physical education (PE) class were assessed.

Results During school time, girls spent (47.2 +/- 16.0) mins performing, and boys (67.3 +/- 20.5) mins per day (P < 0.01). Boys also had more steps per day, VPA time and MVPA MET-min than girls (P < 0.001). In PE class, boys spent 53.6% +/- 10.2% of time in MVPA, as compared to girls’ 35.2% +/- 7.2%. Boys with normal BMI had the highest VPA time during PE than other groups (P < 0.05). No significant BMI group differences in PA level were found in girls.

Conclusion PA in school time was objectively qualified in Beijing junior school students. Girls were less active than boys. PE class provided a major portion of the VPA time and MVPA MET-min in school time PA for boys and girls. Boys with normal BMI had the highest PA level during PE classes.