More than one road leads to Rome: A narrative review and meta-analysis of physical activity intervention effects on cognition in youth.

A growing body of research indicates that physical activity (PA) positively impacts cognitive function in youth. However, not all forms of PA benefit cognition equally. The purpose of this review was to determine the effect of different types of chronic PA interventions on cognition in children and adolescents. A systematic search of electronic databases and examination of the reference lists of relevant studies resulted in the identification of 28 studies. Seven categories of PA were identified, based on all possible combinations of three types of PA (aerobic, motor skill, cognitively engaging), and four comparison groups (no treatment, academic, traditional physical education, aerobic). Effect sizes were calculated based on means and SDs at the post-test using Hedge's g formula, which includes a correction for small sample bias. Each study was only entered once in each intervention-comparator category. Full data were provided from 21 studies (28 effect sizes; n=2042 intervention; n=2002 comparison group). Overall, chronic PA interventions had a significant small-to-moderate effect on cognition (0.46). Moderate significant positive effects were identified when PA interventions were compared to no treatment (0.86) or academic content (0.57). A non-significant effect was noted when PA interventions were compared to traditional physical education (0.09) or aerobic group (0.80). However, high heterogeneity in pooled effect sizes suggests that important differences in the qualitative characteristics of the PA intervention and comparison interventions may exist. Effect sizes based on comparisons between different types of PA interventions and comparison groups are discussed in order to identify possible directions for future investigations. We conclude that chronic PA interventions have a positive impact on cognitive function in youth, but more systematic research is needed in this area.