Diurnal variation of adolescents physical activity / 中国学校卫生

ABSTRACT

Objective@#To analyze diurnal variation of moderate to vigorous physical activity (MVPA) and sedentary time among adolescents, to further explore the possible factors associated with diurnal variation of adolescents physical activity and to provide reference for appropriate intervention strategies.@*Methods@#A total of 148 middle school and high school students in Beijing were assessed for daily MVPA and sedentary time by wrist worn ActiGraph GT3X three axis accelerometers for one week. Height and weight were measured. @*Results@#The MVPA [(49.39±30.36)min/d] on weekdays was higher than that on weekends[(34.24± 30.30 )min/d]( t=6.61, P <0.05). The MVPA of boys on weekdays and weekends was higher than that of girls( t=4.42, 2.18 , P <0.05). The sedentary time on weekdays and weekends was(566.48±156.84) and (588.55±152.93)min/d, respectively, and the difference was not statistically significant( t=-0.21, P >0.05). The sedentary time of boys was lower than that of girls( t=-8.20, -2.51 , P <0.05). The coefficient of variation of adolescent MVPA was lower on weekdays(0.39±0.17) than on weekends(0.59± 0.46 ), and the difference was statistically significant( t=-3.23, P <0.01). There was no significant difference in the coefficient of variation between weekdays (0.17±0.08) and weekends(0.15±0.13)( t=1.10, P >0.05). The coefficient of variation(0.52±0.18) of MVPA in adolescents was higher than that of sitting(0.18±0.07)( t=14.43, P <0.01).@*Conclusion@#Adolescents have higher level of physical activity on weekdays, and high level of physical inactivity on weekends. MVPA time variation is higher within a week, especially on weekends, sedentary time is steadily at a high level. The finding suggests that in addition to the active measures taken by schools to increase the physical activity of students, interventions for girls and weekends are particularly important to increase the overall level of physical activity for adolescents.