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Introduction Physical activity can improve academic performance; however, much less is known about the specific association between sport participation and academic performance, and this evidence has not been synthesized. Our aim was to systematically review and combine via meta-analyses evidence of the association between sport participation and academic performance in children and adolescents. Methods We conducted searches of five electronic databases using sport and academic performance related terms. We combined evidence from eligible studies using a structural equation modeling approach to multilevel meta-analysis. Results From 115 eligible studies, most of which had a high risk of bias (k = 87), we meta-analyzed 298 effect sizes. Overall, sport participation had a small positive effect on academic performance (d = 0.26, 95% confidence interval = 0.09, 0.42). Moderator analyses indicated that sports participation was most beneficial for academic performance when it was at a moderate dose (i.e. 1–2 h·wk−1), compared with no sport or a high dose of sport (3+ h·wk−1). Conclusions Sports participation during school hours was more beneficial for academic performance compared with sport participation outside school hours. Based on mostly low-quality studies, we found some evidence that sport could positively affect academic performance in children and adolescents. It appears that sport participation of a moderate dose and at school could be used to promote academic performance. However, if this field were to inform policy, high-quality studies are needed that provide insight into the effect of dose and sport characteristics on academic performance. [ABSTRACT FROM AUTHOR]

Background: The UK Biobank (UKB) has been used widely to examine associations between lifestyle risk factors and mortality outcomes. It is unknown whether the extremely low UKB response rate (5.5%) and lack of representativeness materially affects the magnitude and direction of effect estimates.Methods: We used poststratification to match the UKB sample to the target population in terms of sociodemographic characteristics and prevalence of lifestyle risk factors (physical inactivity, alcohol intake, smoking, and poor diet). We compared unweighted and poststratified associations between each lifestyle risk factor and a lifestyle index score with all-cause, cardiovascular disease (CVD), and cancer mortality. We also calculated the unweighted to poststratified ratio of HR (RHR) and 95% confidence interval as a marker of effect-size difference.Results: Of 371,974 UKB participants with no missing data, 302,009 had no history of CVD or cancer, corresponding to 3,298,958 person years of follow-up. Protective associations between alcohol use and CVD mortality observed in the unweighted UKB were substantially altered after poststratification, for example, from a hazard ratio (HR) of 0.63 (0.45-0.87) unweighted to 0.99 (0.65-1.50) poststratified for drinking ≥5 times/week versus never drinking. The magnitude of the poststratified all-cause mortality hazard ratio comparing least healthy with healthiest tertile of lifestyle risk factor index was 9% higher (95% confidence interval: 4%, 14%) than the unweighted estimates.Conclusions: Lack of representativeness may distort the associations of alcohol with CVD mortality, and may underestimate health hazards among those with cumulatively the least healthy lifestyles. [ABSTRACT FROM AUTHOR]