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SAN DIEGO – Moderate exercise significantly reduced the risk of stroke in women and seemed to offset much but not all of the increased stroke risk in postmenopausal women on hormone therapy, a large retrospective study found.
A self-reported history of moderate-to-strenuous physical activity in the prior 3 years was associated with a roughly 20%-30% lower risk for stroke in an analysis of data on 133,479 women in the California Teachers Study who had been followed every 4-5 years since 1995 by questionnaire, Sophia S. Wang, Ph.D., and her associates reported.
Sophia S. Wang, Ph.D.
They linked the data set with hospitalization data during 1996-2010 to identify 2,416 ischemic strokes and 710 hemorrhagic strokes in the cohort that were validated by a review of medical records.
The strongest reduction in stroke risk was seen in women who reported moderate physical activity such as brisk walking, recreational tennis, golf, volleyball, or cycling on level streets. Women who reported in 1995-1996 questionnaires that they had engaged in moderate activity in the prior 3 years were 12%-22% less likely to develop a stroke, depending on the amount of activity each week, compared with inactive women who reported less than a half-hour per week of moderate activity.
"You don’t have to climb a mountain" to gain the stroke-reducing benefits of exercise, Dr. Wang said in an interview at the International Stroke Conference. And the fact that people tend to overreport how much they exercise when surveyed makes the findings "particularly robust," she said.
Indeed, reports of strenuous activity were not significantly associated with lower stroke risk. Strenuous activity included swimming laps, aerobics, running, calisthenics, jogging, basketball, racquetball, or cycling on hills. Risk levels ranged from an increase of 3% to a reduction of 18% with strenuous activity, compared with inactive women.
Because most women who exercised strenuously also reported moderate activity, the investigators combined those two activity categories and again found approximately a 20% reduction in stroke risk that clearly was being driven by the benefits of moderate activity, said Dr. Wang of Beckman Research Institute at the City of Hope, Duarte, Calif. Stroke risk reductions ranged from 15%-23% in the combined activity analysis for the 1995-1996 surveys.
Surveyed again in 2005-2006, women who reported moderate or strenuous activity in the prior 3 years were 12%-20% less likely to develop a stroke, compared with inactive women, she said at the meeting, sponsored by the American Heart Association.
More than 5 hours of activity wasn’t more beneficial than fewer hours, she added. Stroke reduction benefits seemed greatest with 3.5-5 hours of activity per week, which was associated with a 23% risk reduction in the earlier survey and a 29% reduction in the later survey. With more than 5 hours, the risk reduction was 17% and 27%, respectively.
In inactive postmenopausal women, current hormone use was associated with a 59% higher risk for stroke and former hormone use was associated with a 16% increased risk, compared with postmenopausal women who didn’t use hormones, Dr. Wang said. However, the elevated stroke risk with hormone use fell in women who exercised, compared with those who didn’t.
In current hormone users, stroke risk was 37% higher in women who reported 0.51-3.5 hours of moderate or strenuous activity per week and 29% higher in women who reported more than 3.5 hours of activity per week, compared with non-hormone users. In former hormone users, stroke risk was 15% higher in those who reported 0.51-3.5 hours of activity per week and 5% higher in those who exercised more than 3.5 hours per week, compared with non-hormone users.
Because of smaller numbers of women in the subset analyses of postmenopausal hormone use, these differences between groups did not reach statistical significance, Dr. Wang said.
She and her associates plan further studies related to these findings, including whether or not activity levels may help prevent stroke in women who’ve already had a stroke, she said.
Dr. Wang and her colleagues reported having no financial disclosures. The National Institute of Neurological Disorders and Stroke funded the study.
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