Exercise and risk of stroke in male physicians

Background and Purpose-From a physiological perspective, physical activity might be expected to decrease the risk of developing stroke. However, epide miological studies of physical activity and stroke risk have yielded diverg ent findings. We therefore sought to examine the association between exerci se and stroke risk. Methods-This was a prospective cohort study of 21 823 men, followed up for an average of 11.1 years. Participants were from the Physicians' Health Stu dy, a randomized trial of low-dose aspirin and beta carotene. Men, aged 40 to 84 years at baseline, were free of self-reported myocardial infarction, stroke, transient ischemic attack, and cancer. At baseline, they reported o n the frequency of exercise vigorous enough to work up a sweat. Stroke occu rrence was reported by participants and confirmed after medical record revi ew (n = 533). We used Cox proportional hazards regression to analyze the da ta. Results-With adjustment for age, treatment assignment, smoking, alcohol int ake, history of angina, and parental history of myocardial infarction, the relative risks of total stroke associated with vigorous exercise <1 time, 1 time, 2 to 4 times, and greater than or equal to 5 times per week at basel ine were 1.00 (referent), 0.79 (95% confidence interval [CI], 0.61 to 1.03) , 0.80 (95% CI, 0.65 to 0.99), and 0.79 (95% CI, 0.61 to 1.03), respectivel y; P for trend = 0.04. in subgroup analyses, the inverse association appear ed stronger with hemorrhagic than ischemic stroke. When we additionally adj usted for body mass index, history of hypertension, high cholesterol, and d iabetes mellitus, corresponding relative risks for total stroke were 1.00 ( referent), 0.81 (95% CI, 0.61 to 1.07), 0.88 (95% CI, 0.70 to 1.10), and 0. 86 (95% CI, 0.65 to 1.13), respectively; P for trend = 0.25. Conclusions-Exercise vigorous enough to work up a sweat is associated with decreased stroke risk in men. In the present study, the inverse association with physical activity appeared to be mediated through beneficial effects on body weight, blood pressure, serum cholesterol, and glucose tolerance. A part from its favorable influences on these variables, physical activity ha d no significant residual association with stroke incidence.