July 18, 2013
Science Daily/University of Alabama at Birmingham
A new study from researchers at the University of Alabama at Birmingham (UAB) is one of the first to study the relationship between exercise and stroke in a large biracial cohort of men and women in the United States. The findings are published in the American Heart Association Journal Stroke.
Using 27,000 stroke-free blacks and whites ages 45 and older in the United States from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study cohort, researchers examined the association of self-reported physical activity with incident of stroke.
Participants were classified at baseline as being in active (i.e., no workouts in a typical week), moderately active (workouts one to three times per week) or vigorously active (workouts more than four times per week), and they were followed for an average of 5.7 years.
The results showed that physical inactivity was reported by 33 percent of participants and was associated with a 20 percent increased risk of stroke. Those who reported they exercised at least four times a week were less likely to experience a stroke or mini-stroke. Among men, only those who exercised four or more times a week had a lower stroke risk. Among women, the relationship between stroke and frequency of activity was less clear.
"The protective effect of intense physical activity may be through its impact on traditional risk factors such as hypertension and diabetes," explained Virginia Howard, Ph.D., UAB professor of epidemiology and senior study author.
"These findings confirm past results of studies done in only men or only women in limited geographical areas," Howard said. "By using the REGARDS cohort, our study was able to use a larger and more diverse population to show that participating in regular physical activity is associated with lower stroke risk."
Howard added that stroke is preventable, and physical activity is a major modifiable risk factor for stroke. "This should be emphasized more in routine physician check-ups, along with general education on the proven health benefits of regular physical activity on other stroke-risk factors including high blood pressure, diabetes and obesity," Howard said.
Study limitations highlighted include that the results are based on self-reported levels of physical activity, and self-reported data may not be a reflection of the truth. Also, investigators did not have data on the type or duration of the exercise in which people engaged, nor the number of sessions. Howard suggested future studies should consider different ways to measure physical activity through: use of more questions; devices such as accelerometers and heart monitors that can provide more objective data; and capturing information on other dimensions of physical activity such as frequency, intensity and duration.