Background: Cycling has been suggested to be related to risk of all-cause and cardiovascular disease (CVD) mortality. However, a quantitative comprehensive assessment of the dose-response association of cycling with risk of all-cause and CVD mortality has not been reported. We performed a meta-analysis of cohort studies assessing the risk of all-cause and CVD mortality with cycling.
Methods: PubMed and Embase databases were searched for relevant articles published up to December 13, 2019. Random-effects models were used to estimate the summary relative risk (RR) of all-cause and CVD mortality with cycling. Restricted cubic splines were used to evaluate the dose-response association.
Results: We included 9 articles (17 studies) with 478,847 participants and 27,860 cases (22,415 from all-cause mortality and 5445 from CVD mortality) in the meta-analysis. Risk of all-cause mortality was reduced 23% with the highest versus lowest cycling level [RR 0.77, 95% confidence interval (CI) 0.67-0.88], and CVD mortality was reduced 24% (RR 0.76, 95% CI 0.65-0.89). We found a linear association between cycling and all-cause mortality (Pnon-linearity = 0.208); the risk was reduced by 9% (RR 0.91, 95% CI 0.86-0.96) with each five metabolic equivalent of task (MET)-h/week increase in cycling. We found an approximately U-shaped association between cycling and CVD mortality (Pnon-linearity = 0.034), with the lowest risk at approximately 15 MET-h/week of cycling.
Conclusions: Our findings based on quantitative data suggest that any level of cycling is better than none for all-cause mortality. However, for CVD mortality, one must choose an appropriate level of cycling, with an approximate optimum of 15 MET-h/week (equal to 130 min/week at 6.8 MET).