The Effect Of Chronotype On The Cognitive Benefits Of Acute Physical Activity In Children

A single bout of acute physical activity has been shown to benefit cognition. Evidence also supports superior cognitive performance when aligned with chronotype. What remains unclear is how the cognitive benefits of acute physical activity vary with chronotype alignment. PURPOSE: This study investigated the effect of physical activity on cognitive performance in children, and how this varied with chronotype alignment. METHODS: 34 primary school pupils (9.53 ± 1.13 years old, 41 % female) underwent 30 minutes of physical activity and a poster-making control session, both either at the start or end of the school day, in a cross-over randomised order. For half the pupils, the sessions were aligned with their chronotype. Before and after each session, pupils completed cognitive tasks (simple reaction time, sustained attention, inhibition) and the Lark-Owl Questionnaire for Children to determine chronotype. For each session, the residuals of percentage change in task performance were calculated. Within-subject t-tests and Wilcoxon tests were used to compare the change in cognitive performance between control and intervention sessions. Between-subject t-tests and Wilcoxon tests were used to compare the change after sessions aligned and unaligned with chronotype. RESULTS: Pupils had significantly greater improvements in simple reaction time (p = .02), sustained attention Stay errors (p < .01) and inhibition NoGo errors (p = .02) following physical activity sessions compared to control. In addition, there was a significantly greater reduction in commission errors in the inhibition (p = .03) and sustained attention tasks (p = .04) following chronotype-aligned physical activity sessions compared to unaligned. CONCLUSIONS: Participants had significantly faster reaction times and made significantly fewer errors following acute physical activity compared to a sedentary but cognitively engaging activity. In addition, results showed greater cognitive benefits of acute physical activity when aligned with chronotype. This has important implications, for example on the timings and role of physical activity during the school day. Further research with a larger sample is required to support these findings. Funding was received from Greenhouse Sports (registered charity number: 1098744) and Impact on Urban Health (part of Guy's & St Thomas' Foundation, registered charity number: 1160316).