Weekly patterns of physical activity and sleep, and overweight in adolescents

Introduction: This study examined weekly patterns of physical activity and sleep, and their associations with overweight among adolescents in Hong Kong.

Methods: 740 adolescents aged 11-18 years were recruited from 15 secondary schools. They were instructed to wear an activPALTM inclinometer continuously throughout eight days. Time spent MVPA and sleep were calculated every day. Number of days meeting the PA and sleep guidelines (9-11 hours for 11-13 years and 8-10 hours for 14-18 years) was quantified and recorded into three groups, i.e. fail to meet (0 day), irregularly meet (1-4 days), and regularly meet (≥5 days) the guidelines. The relationships between the three behaviour categories and the risk for being overweight were tested using linear mixed models.

Results: Approximately 6% of the adolescents meet the PA or sleep guidelines regularly (≥5 days a week). Adolescents who regularly meet the PA guidelines achieved an average of 68 minutes/day of MVPA. Regularly meeting the PA guidelines was associated with 76% reduced risk (OR: 0.24, 95%CI: 0.06-0.94), while irregularly meet the PA guidelines led to 32% lower risk (OR: 0.58, 95%CI: 0.35-0.97), of being overweight. No associations were found between weekly patterns of sleep duration and being overweight.

Conclusions: Regularly sufficient PA and sleep duration was rare among adolescents in Hong Kong. The findings support the current evidence for adults that “some is better than none” for PA participation. However, youth may gain maximal health benefits from a regular active lifestyle.