METHODS: PubMed, Embase, Web of Science, and Cochrane Library were systematically searched for all relevant follow up studies until July 2019. Multivariable-adjusted relative risks (RRs) and corresponding 95% confidence intervals (CIs) from individual studies were used to calculate the overall summary estimates. The dose-response relationship was assessed using generalized least-squares trend estimation.

    RESULTS: Six prospective cohort studies, involving 19 173 cases in 6.2-12.1y follow up of 171 620 participants, were included in the analysis. Increased physical activity was significantly associated with reduced risk of ARC by 10% (RR: 0.90; 95%CI: 0.81, 0.99, P=0.04). Stratified analysis by assessment method for physical activity suggest that studies using metabolic equivalent (MET) per day tended to report a slightly stronger association with ARC (RR: 0.85; 95%CI: 0.81, 0.90, P<0.001) than studies which assessed activity by weekly activity (RR: 0.96; 95%CI: 0.89, 1.03, P=0.24). Dose-response analysis indicated that the risk of ARC decreased by 2% (RR: 0.98; 95%CI: 0.98, 0.99, P<0.001) for every 6 METs per day increase in activity.

    CONCLUSION: The findings from this Meta-analysis provide additional evidence that increased physical activity is inversely associated with ARC risk dose-responsively.