Habitual physical activity in children and adolescents during school and free days

PURPOSE: The purpose of this study was to analyze habitual physical activity (HPA) of boys and girls from primary school to high school. METHODS: One hundred eighty-two schoolchildren and teenagers (6-20 yr) were studied at primary school (PS, N= 64), junior high school (JHS, N= 67), and senior high school (SHS, N= 51). HR was continuously monitored during the whole week to assess HPA during school days and free days. Total physical activity (TPA), low physical activity (LPA), moderate physical activity (MPA), and vigorous physical activity (VPA) were evaluated from the time spent each day above 50%HR reserve (HRR), below 50%HRR, between 50% and 70%HRR, and above 70%HRR, respectively. RESULTS: During school days, TPA decreased by 69% in male subjects (P< 0.05) and by 36% in female subjects (N= 0.058) from PS to SHS. In contrast, TPA did not vary significantly during free days (male subjects, PS: 62 +/- 37 min x d, SHS: 63 +/- 67 min x d; female subjects, PS: 75 +/- 59 min x d, SHS: 62 +/- 44 min x d ). Gender differences were only observed during school days at PS for TPA (male subjects: 121 +/- 37 min x d vs female subjects: 92 +/- 44 min x d, P< 0.05) and VPA (male subjects: 38 +/- 21 min x d vs female subjects: 18 +/- 12 min x d, P< 0.05). Male and female subjects were more inactive during free days than during school days at PS (P< 0.05). No effect of the type of day and gender was observed for all indices of HPA at high schools. CONCLUSIONS: Our results highlight the importance of taking into account the type of day (school day vs free day) in the analysis of children and adolescents' HPA.