Working Up a Sweat May Help Reduce Stroke Risk
To investigate the relationship between physical activity and stroke, a team led by Dr. Michelle N. McDonnell from the University of South Australia and Dr. Virginia Howard of the University of Alabama at Birmingham analyzed data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. The dataset included information on more than 27,000 black and white participants, both men and women, from across the country. They were at least 45 years old at the time of recruitment and had no prior history of stroke.
The participants were asked how many times per week they exercised to the point of sweating. They were then contacted every 6 months to see if they had experienced a stroke or a mini-stroke known as a transient ischemic attack. Participants were followed for an average of 5.7 years. Medical records confirmed their responses. The study was funded by NIH’s National Institute of Neurological Disorders and Stroke (NINDS). It appeared online on July 18, 2013, in the journal Stroke.
Participants who were inactive (exercising less than once a week) were 20% more likely to have a stroke or transient ischemic attack than those who exercised at least 4 times a week. After adjusting for traditional stroke risk factors (diabetes, hypertension, body mass index, alcohol use and smoking) exercise was not a significant independent predictor of stroke risk, suggesting that the effect of physical activity is mediated through its association with obesity, hypertension and diabetes.
“Physical inactivity is a major modifiable risk factor for stroke,” Howard says. “This should be emphasized in routine physician checkups.”
“Exercise reduces blood pressure, weight and diabetes. If exercise was a pill, you'd be taking one pill to treat 4 or 5 different conditions,” McDonnell says.
One limitation of the study is that it included self-reported data on the frequency of exercise, but not on the duration of activity. Official guidelines recommend that healthy adults (ages 18 to 64) get at least 2.5 hours of moderate aerobic physical activity each week. Activity should be done for at least 10 minutes at a time.
REGARDS will continue to assess stroke risk factors to look for long-term patterns in the study population. The findings will ultimately help researchers develop interventions aimed at preventing stroke and its consequences.
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Funding: NIH’s National Institute of Neurological Disorders and Stroke (NINDS).