Data from 133,479 women in the California Teachers Study has found that those who reported doing moderate physical activity (such as brisk walking) in the three years before enrolling in the study were 20% less likely to suffer a stroke than women who reported no activity. More strenuous activity didn’t further reduce risk.
Postmenopausal women taking menopausal hormone therapy had more than a 30% higher risk of stroke than women who never used menopausal hormone therapy, but this risk started diminishing after they stopped taking hormones. Moderate exercise helped offset the increased stroke risk.
http://www.eurekalert.org/pub_releases/2014-02/aha-mec020414.php