Seasonal variation in the distribution of daily stepping in 11-13 year old school children.

PURPOSE Seasonality studies in adolescent's physical activity (PA) tend to report total PA (e.g. steps/day) rather than more specific detail such as steps/hour. This study compared the detailed changes in PA between seasons. METHODS Thirty three adolescents (baseline age 12.2 ± 0.3y) wore the activPAL activity monitor for 8 days on two occasions. RESULTS Steps/day were higher in summer (Mdn = 12,879) than winter (Mdn = 10,512), p<.001. Steps/hour were significantly higher in summer compared to winter between 17:00 and 21:00 (p<. 044). No steps/day differences were found between boys and girls at either time point (p>.05), however, boys had significantly higher step counts in summer between '13:00-14:00' (p=.023), '19:00-20:00' (p=.032) and '20:00-21:00' (p=.023). CONCLUSION Total steps/day masked sex differences within specific hours of the day, particularly evening times. Detailed daily patterns of PA are required to fully understand differences between sexes and across seasons.