Investigating children’s short-term responses to imposed or restricted physical activity

Background: Little is known about whether physical activity compensation occurs. This study experimentally explored the activitystat hypothesis by investigating children’s short-term responses to imposed or restricted physical activity. Methods: A total of 156 children (46 boys; mean age = 11.3 y) from 9 schools wore an ActiGraph accelerometer for 5 days (Monday-Friday) across 2 consecutive weeks. In addition, 145 children (49% boys) simultaneously wore a SenseWear Armband. Schools were randomized to participate in 1 of the 3 experimental conditions that took place on 1 occasion: additional moderate- to vigorous-intensity physical activity (3 schools), additional light-intensity physical activity (3 schools), or restriction of light-intensity physical activity and moderate- to vigorous-intensity physical activity (3 schools). Multilevel linear regression models were conducted to examine associations between the day the condition took place and the following day and week (baseline and experiment) for each condition. Results: There was no evidence of a difference between children’s activity levels on the day after the experiment condition compared with their usual activity for that day. Conclusion: The findings suggest that children do not compensate their sedentary time and/or physical activity levels following imposed or restricted physical activity in the short term.