Daily Total Physical Activity and Incident Stroke: The Japan Public Health Center–Based Prospective Study

BACKGROUND AND PURPOSE—There is limited evidence on the association between total physical activity and stroke in Asian populations experiencing a greater burden of hemorrhagic stroke than Western populations. We aimed to understand their optimal level of physical activity for stroke prevention. METHODS—A total of 74 913 Japanese people 50 to 79 years of age without histories of cardiovascular disease or cancer were followed from 2000 to 2012. RESULTS—During the 698 946 person-years of follow-up, we documented a total of 2738 incident cases of stroke, including 1007 hemorrhagic strokes (747 intraparenchymal and 260 subarachnoid hemorrhages) and 1721 ischemic strokes (1206 nonembolic and 515 embolic infarctions). Individuals in the second or third metabolic equivalents of task–hours per day quartile had the lowest risks of total stroke (hazard ratio [HR], 0.83; 95% confidence interval [CI], 0.75–0.93), intraparenchymal hemorrhage (HR, 0.79; 95% CI, 0.64–0.97), subarachnoid hemorrhage (HR, 0.78; CI, 0.55–1.11), and nonembolic infarction (HR, 0.78; CI, 0.67–0.92), whereas those in the fourth quartile had the lowest risk of embolic infarction (HR, 0.76; CI, 0.59–0.97). Cubic spline graphs revealed a steep decrease in stroke risk (30% risk reduction) from the lowest level to a plateau at 5 to 10 metabolic equivalents of task–hours per day (50th percentile). The associations of total physical activity level with hemorrhage stroke showed U or J shape, which were because of vigorous-intensity activities, whereas the association with ischemic stroke showed L shape. CONCLUSIONS—For Japanese people, moderate levels of total physical activity, particularly achieved by moderate-intensity activities, may be optimal for stroke prevention because excessive vigorous-intensity activities might not be beneficial or even disadvantageous for prevention of hemorrhagic stroke.