Background: There has never been a dose-response meta-analysis of the relationship between physical activity and the risk of depression. Hence, we aimed to explore the dose-response relationship between leisure-time physical activity (LTPA) and the risk of depression through a meta-analysis to provide a basis for the prevention of depression.Methods: PubMed and Web of Science databases were searched using a computer to collect prospective cohort studies on the relationship between LTPA and depression between January 1997 and July 2021. A dose-response meta-analysis was performed using the Stata 14 software to calculate the combined effect size relative risk (RR and 95% confidence interval CI).Results: Twelve cohort studies included 310,359 subjects who met the inclusion criteria. The categorical dose-response analysis results showed that the risk of incident depression was 27%, 17%, and 8% lower for the light, moderate, and highest dose LTPA participants, respectively (RR: 0.73, 95% CI: 0.64-0.82; RR: 0.83, 95% CI: 0.78-0.87; RR: 0.92, 95% CI: 0.86-0.99), compared with the lowest LTPA category. Continuous dose-response analysis showed a nonlinear relationship between LTPA and the risk of incident depression (P = .04). The risk of incident depression was reduced by 3% (RR: 0.97, 95% CI: 0.95-0.98) for every 5 MET-h/week increase in LTPA < 25 MET-h/week; when LTPA was higher than 25 MET-h/week, a 4% increase in the risk of depression for every 5 MET-h/week increase was observed (RR: 1.04, 95% CI: 1.02-1.05).Conclusions: There was a nonlinear relationship between LTPA and the risk of incident depression. Moderate and low doses of LTPA were protective factors in preventing the risk of incident depression, while high doses of LTPA may increase the risk of incident depression.Abbreviations: LPA = light intensity physical activity, LTPA = leisure-time physical activity, MET = total dose of sports, MPA = moderate-intensity physical activity, MVPA = moderate-to-vigorous physical activity, VPA = vigorous-intensity physical activity.

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Background: Many people have experienced a high burden due to the spread of the coronavirus disease (COVID-19) and its serious consequences for health and everyday life. Prior studies have reported that physical activity (PA) may lower the risk of COVID-19 hospitalization. The present meta-analysis explored the dose–response relationship between PA and the risk of COVID-19 hospitalization. Methods: Epidemiological observational studies on the relationship between PA and the risk of COVID-19 hospitalization were included. Categorical dose–response relationships between PA and the risk of COVID-19 hospitalization were assessed using random effect models. Robust error meta-regression models assessed the continuous relationship between PA (metabolic equivalent [Met]-h/wk) and COVID-19 hospitalization risk across studies reporting quantitative PA estimates. Results: Seventeen observational studies (cohort\case–control\cross-section) met the criteria for inclusion in the meta-analysis. Categorical dose-relationship analysis showed a 40% (risk ratio [RR] 0.60, 95% confidence interval [CI]: 0.48–0.71) reduction in the risk of COVID-19 hospitalization compared to the lowest dose of PA. The results of the continuous dose–response relationship showed a non-linear inverse relationship (Pnon-linearity < .05) between PA and the risk of COVID-19 hospitalization. When total PA was < or >10 Met-h/wk, an increase of 4 Met-h/wk was associated with a 14% (RR = 0.83, 95% CI: 0.85–0.87) and 11% (RR = 0.89, 95% CI: 0.87–0.90) reduction in the risk of COVID-19 hospitalization, respectively. Conclusions: There was an inverse non-linear dose–response relationship between PA level and the risk of COVID-19 hospitalization. Doses of the guideline-recommended minimum PA levels by the World Health Organization may be required for more substantial reductions in the COVID-19 hospitalization risk.