Variability in school children's activity occurs in the recess and before-school periods

BackgroundAn accurate description of physical activity (PA) at school is required for appropriate health interventions. We examined PA patterns in children, and identified the time periods that influenced them. MethodsForty students in five Japanese primary schools were asked to wear triaxial accelerometers for 7days. We obtained coefficients of variance (CV) at 15min intervals, and conducted factor analysis of the school periods. A questionnaire was used to investigate where students spent time before school, and during recess. ResultsThe amount of PA, and its CV were higher around 8a.m. (before-school period), 10a.m. (morning recess), 1p.m. (lunch recess), and 4p.m. (commuting home from school). Moderate-vigorous PA (MVPA; 3.0 metabolic equivalent units [MET]) was highest during lunch recess and the after-school period (12.9 7.4min and 12.6 +/- 6.2min, respectively). The percentage of MVPA time was high (>15%) in the before-school period and morning and lunch recesses, but low (10%) in the after-school period. On factor analysis there were differences in PA patterns between the school period and the after-school period. The students who spent their time in the playground logged more MVPA time and less sedentary time (1.5 MET) than those who did not spend their time in the playground. ConclusionActivities before school, and in the morning and lunch recesses influenced daily PA, and were different from after-school PA. Close attention to these periods may help in defining PA parameters during free time at school for PA interventions in children.