Accelerometry-measured Physical Activity and Determinants in PE classes of Fourth-Grade Primary school students in China

Purpose Physical education (PE) classes provide opportunities for students to meet recommended daily moderate-to-vigorous physical activity (MVPA). This study aimed to explore PA levels and determinants in PE among Chinese fourth-grade primary school students. Methods This cross-sectional study recruited 195 Grade 4 children (49.2% boys; aged 12 to 13 years). Accelerometers (ActiGraph GT3X) were used to measure PA in PE. Physical fitness (PF) was measured by professional PE teachers during PE lessons from October 10 to October 20, 2020, following the Chinese National Student Physical Fitness Standard (CNSPFS) guidelines, as established by the Ministry of Education. Students' body mass index (BMI) and fitness scores were calculated and evaluated from their PF test. We observed 10 PE lessons and recorded lesson contents. Independent samples t-tests and analysis of variance (ANOVA) were applied to compare the differences in PA between genders, weight statuses, and PF scores among the students. The multiple linear regression model (MLR) was developed to identify the influencing factors that influence the PA levels of boys and girls enrolled in PE classes. Results Within 40 minutes of each PE class, children averagely accumulated 6.69 ± 4.05 minutes MVPA, equaling 16.73% of PE time. Boys were more active than girls ( %MVPA : Boys 18.95%, Girls 14.56%; %Sedentary Behaviour : Boys 42.44%, Girls 49.29%; P  < 0.01). MVPA was significantly affected by teaching content (Boys β  = 0.613, P  < 0.001; Girls β  = 0.837, P  < 0.001). PF (Boys β  = 0.113, P =  0.246; Girls β  = 0.093, P =  0.196) and BMI (Boys β =-0.069, P =  0.474; Girls β =-0.029, P =  0.690) did not significantly affect MVPA in PE. Conclusion The percentage of MVPA in PE was much lower than the proposed standards (50%). Teaching content significantly affects the MVPA level of elementary school students, especially for girls. PF and BMI did not significantly affect MVPA in PE. In China, there is an urgent need to design contents for improving MVPA in PE.