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Moderate physical activity may lessen stroke risk in women
SAN DIEGO — Physical activity, even of moderate intensity, was associated with a 20% to 30% decreased risk for stroke in women, according to data presented at the International Stroke Conference.
The findings indicate that moderate exercise can compensate for the increased risk for stroke in women taking hormone therapy, Sophia S. Wang, PhD, of City of Hope in Duarte, Calif., said at a press conference.
Wang and colleagues followed 133,479 women from the California Teachers Study for 15 years to investigate the effects of physical activity, hormone therapy and obesity on women’s risk for stroke.
From 1996 to 2010, 3,434 strokes were reported in the study population. Women who reported moderate to strenuous physical activity in the 3 years before enrollment had reduced risk for stroke compared with women who did not report that level of activity (HR=0.79; 95% CI, 0.71-0.98). When moderate and strenuous physical activity were analyzed separately, moderate physical activity was associated with reduced risk for stroke, whereas strenuous physical activity was not, Wang said.
However, she said, “because women who engage in strenuous activity also engage in moderate activity, it made sense to analyze a combination of moderate and strenuous activity.”
Although the risk reduction associated with physical activity was approximately 20% at baseline, it was closer to 30% in those who reported moderate to strenuous physical activity in the 3 years before being surveyed again in 2005 and 2006, Wang said. However, follow-up for this survey is only at 5 years vs. 15 years for the baseline survey.
Women taking hormone therapy had an increased risk for stroke (HR=1.3; 95% CI, 1.03-4.85), but women taking hormone therapy who reported performing moderate to strenuous physical activity had a lower risk for stroke than those taking hormone therapy who were not physically active, Wang said.
“The 42% increased risk in current hormone users is actually a 59% increase in women who exercise less than 0.5 hours per week, but goes down to 29% among women who exercise more than 3.5 hours per week,” she said. “Similarly, for former hormone therapy users, a 16% increase in risk rises to 27% among women who exercise 30 minutes or less per week, but goes down to near 5% among women who exercised more than 3.5 hours per week.”
According to Wang, these data on the hormone associations modified by physical activity are “promising,” but additional research is required. “The bottom line is that our data further support the benefits of physical activity — even moderate physical activity,” she said.
The association between obesity and stroke was largely attenuated when diabetes was considered, as a large proportion of women who were obese also had diabetes, Wang said. – by Erik Swain
For more information:
Wang S. Abstract TMP67. Presented at: International Stroke Conference 2014; Feb. 12-14, 2014; San Diego.
Disclosure: Wang reports no relevant financial disclosures.
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There were two key takeaways from Dr. Wang’s presentation. No. 1, this reinforces the notion that even moderate exercise has an effect in terms of preventing ischemic stroke. No. 2, it mitigates the effect of hormone replacement therapy as well. That’s something that was new for me. The question is: Were there things that these women were also doing that might have contributed to the benefit they had? It’s not clear.
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In this study, Wang et al. have examined obesity, hormone therapy, and physical activity, the three important modifiable risk factors, in the California Teachers Study cohort, a large prospective study comprised of 133,479 women who were enrolled and continuously followed since 1995. They report that in these women, current hormone therapy was associated with a 1.3-fold increased risk for stroke (95% CI, 1.03-4.85), whereas moderate to strenuous physical activity in the 3 years before enrollment (but not lifetime activity) decreased stroke risk by 20% (HR=0.79; 95% CI, 0.71-0.98). Furthermore, the effect of physical activity appeared to counteract the increased risk observed with current hormone therapy use. The authors found no association between obesity and stroke that was independent of diabetes.
This is an important report, as it is focused on stroke prevention in women, the growing proportion of the elderly, who are known to be at a risk of poor outcomes after stroke; thus, necessitating effective preventative strategies. Recent guidelines for the prevention of stroke in women (Bushnell C. Stroke. 2014;doi:10.1161/01.str.0000442009.06663.48) underline several risk factors unique to stroke in women including postmenopausal use of hormonal replacement, which in combinations prescribed in prior studies does not reduce risk for stroke and may increase risk for stroke. In the study by Wang et al., current hormone therapy use was linked to increased risk for stroke, consistent with the prior report; however, this risk was offset by the effect of physical activity.
While physical activity has been repeatedly shown to decrease the risk for CVD, stroke, and mortality, it is combination of healthy lifestyle habits that has been linked to a decrease in stroke risk and an improvement in post-stroke outcomes. In the new guidelines for the prevention of stroke in women, “a healthy lifestyle consisting of regular physical activity, moderate alcohol consumption (<1 drink/day for nonpregnant women), abstention from cigarette smoking, and a diet rich in fruits, vegetables, grains, nuts, olive oil, and low in saturated fat (such as the DASH [Dietary Approaches to Stop Hypertension]diet) is recommended for primary stroke prevention in women with cardiovascular risk factors (Class I; Level of Evidence B)” (Bushnell C. Stroke. 2014).
The biological pathways through which physical exercise may offset the risk of stroke due to current hormonal use is unclear; however, an overall improvement in CV health associated with a healthy lifestyle that includes regular exercise may be implicated. Furthermore, a detailed examination of the hormonal preparations used by women in the California Teachers Study cohort may provide clues for underlying mechanisms of disease that can be modulated by physical activity, or other significantly associated factors.