Relationship between Moderate-to-Vigorous Physical Activity and Sedentary Behavior on School and Non-School Days in Japanese Children

抄録

Background: Ensuring moderate-to-vigorous intensity physical activity (MVPA) and reducing sedentary behavior (SB) are beneficial to children’s health. Although previous studies have pointed out that MVPA was associated with SB, little is known about the relationship between these two outcomes when objectively measured separately on both school and non-school days. Determining whether MVPA can replace SB for children can help in identifying targets and opportunities for intervention.

Objective: This study aimed to examine the relationship between objectively measured MVPA and SB among boys and girls on school and non-school days.

Methods: In this cross-sectional study, data were collected annually from 2015 through 2017, in February and March. A total of 278 children (grades 4–6) participated in the study and wore a triaxial accelerometer to monitor their activities. Children were asked to wear the accelerometer on their waist, for at least 7 consecutive days during all the waking hours, removing it during water-based activities such as showering, bathing, or swimming. A partial Spearman’s rank correlation analysis was performed, and the correlation coefficient was calculated to assess the relationship between MVPA and SB controlled grade and wearing time for both sexes on school and non-school days. The correlation coefficients were compared using the Fisher’s z-transformation.

Results: Total 225 (108boys, 117girls) and 227 (105boys, 122girls) children met the criteria for wearing the accelerometer on school days and non-school days, respectively. Objectively measured MVPA and SB showed sex-based differences. Boys engaged in daily MVPA time longer than girls on both school and non-school days. In addition, daily SB time of boys was less than those of girls on school day. Significant inverse relationships were observed between MVPA and SB in both boys (−0.63 and −0.67) and girls (−0.64 and −0.72) on school and non-school days. The correlation coefficients were no significant sex differences in the z-scores. Additionally, the correlation coefficients for school days were comparable with those for non-school days regardless of sex.

Conclusion: This study has shown that there is dependent relationship between MVPA and SB in children regardless of the day. Namely, these findings suggest that targeted health education program that increases MVPA and reduces SB can promote a physically active lifestyle among children.