Cardiorespiratory fitness as a quantitative predictor of the risk of stroke: a dose-response meta-analysis

Background and purpose Cardiorespiratory fitness (CRF) is closely related to our health, but whether high cardiorespiratory fitness could reduce stroke risk remains controversial. We used a meta-analysis to examine the overall association between cardiorespiratory fitness and stroke incidence. Methods A systematic search was performed in PubMed, EMBASE, and Web of science. We estimated the overall relative risk (RR) of stroke incidence for high levels of CRF individuals versus individuals with low levels of CRF. Meanwhile, we made a quantitative analysis of the association between CRF and the risk of stroke. Results 14 cohort studies containing 1,409,340 participants were included in this meta-analysis, and 23,894 stroke patients were observed. The meta-analysis documented that the high-CRF individuals had a 42% lower risk of stroke (RR_0.58; 95% CI 0.51-0.66) compared with low-CRF individuals. Besides, subgroup analysis showed that the inverse association of CRF with the risk of stroke was consistent. There are 29% lower risk of ischemic stroke (RR_0.71; 95% CI 0.54-0.93) and 31% lower risk of hemorrhagic stroke (RR_0.69; 95% CI 0.47-1.00). Dose-response analysis showed that every "unit-dose" increment of five metabolic equivalents (METs) reduced a 15% lower risk of stroke (RR_0.85; 95% CI 0.79-0.91). Conclusion This meta-analysis provides the evidence that better CRF was with a lower risk of stroke incidence.