Physical Activity and Stroke Incidence Among Post-Menopausal Women: Insights from the Women's Health Initiative.

Introduction: Stroke is a leading cause of morbidity and mortality, particularly in older adults. Identifying lifestyle factors, such as physical activity (PA), that mitigate stroke risk is critical for stroke prevention, especially in postmenopausal women. We sought to determine the association between levels and types of recreational PA and risk of total, ischemic, and hemorrhagic stroke in postmenopausal women.

Methods: We performed a prospective cohort study conducted within the Women's Health Initiative from 1993 to 1998 with a mean follow up of 8.5 years. We studied a total of 139,871 postmenopausal women aged 50-79 years without prior cardiovascular disease or stroke at enrollment. Cox regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI). Recreational PA assessed via questionnaire, including total, light, moderate, and vigorous activities and walking. Incident total, ischemic, and hemorrhagic stroke. HRs and 95% CIs were adjusted for sociodemographic, lifestyle, and clinical factors.

Results: During follow up, 4,642 stroke occurred (3,496 ischemic and 728 hemorrhagic). Higher levels of total PA (per 1-SD MET-hr/wk: HR=0.90, 95% CI: 0.87-0.93), walking (HR=0.93, 95% CI: 0.90-0.96), and moderate PA (HR=0.91, 95% CI: 0.88-0.94) were associated with reduced total stroke risk. Similar inverse associations were found for ischemic stroke. Vigorous PA demonstrated a J-shaped association with ischemic stroke, while light PA was not significantly associated with stroke risk. Total (HR=0.90, 95% CI: 0.83-0.97) and vigorous PA (HR=0.88, 95% CI: 0.81-0.96) were inversely associated with hemorrhagic stroke. Associations were consistent across subgroups defined by age, race/ethnicity, blood pressure, hormone therapy use, BMI, and dietary intake.

Conclusion: Increased recreational PA, particularly moderate, with cautious interpretation of vigorous activity due to its J-shaped association and potential risks, is associated with reduced risks of total and ischemic stroke in postmenopausal women. Our findings support promoting PA as a key strategy for stroke prevention in this population.