Physical activity and ischemic stroke risk - The Atherosclerosis Risk in Communities Study

Background and Purpose-The relationship between physical activity and strok e is inconclusive according to the 1996 US Surgeon General's Report on Phys ical Activity and Health. Therefore, this study examined the relationship b etween physical activity and ischemic stroke risk among 14 575 Atherosclero sis Risk in Communities Study participants aged 45 to 64 years free of self -reported stroke and coronary heart disease at baseline. Methods-Eligible potential stroke hospitalizations were identified from ong oing hospital surveillance and from hospitalizations reported by the cohort study participants. All strokes were validated by hospitalization records. Physical activity was measured as sport, leisure (nonsport), and work with the use of the Baecke questionnaire. Multivariable Poisson and Cox proport ional hazards models were used to determine the association of differing le vels of physical activity with ischemic stroke incidence. Results-During an average of 7.2 years of follow-up, 189 incident ischemic strokes occurred. Ischemic stroke incidence rates were highest in the lowes t quartile of sport, leisure, and work scores. The hazard rate ratios with 95% Cls for ischemic stroke for the highest quartile compared with the lowe st quartile of activity adjusted for age, sex, race-center, education, and smoking, were sport 0.83 (0.52, 1.32), leisure 0.89 (0.57, 1.37), and work 0.69 (0.47, 1.00). Further adjustment for factors that likely were intermed iate variables (hypertension, diabetes, fibrinogen, and body mass index) be tween physical activity and stroke attenuated the associations. Conclusions-Our findings suggest that physical activity was weakly associat ed with a reduced risk of ischemic stroke among middle-aged adults. The ass ociation may be due to links between physical activity and other risk facto rs or due to chance.