July 19, 2013
Stroke Risk Can Be Reduced If You Just Break A Sweat
Lawrence LeBlond for redOrbit.com - Your Universe Online
In a study of some 27,000 Americans 45 years of age and older who were followed for 5.7 years on average, researchers, led by Michelle McDonnell, PhD, of University of South Australia's School of Health Sciences, found some surprising results.
McDonnell and her colleagues found in their data a third of the participants in the study reported being inactive, exercising less than once per week. The data also showed that those inactive individuals were 20 percent more likely to experience a stroke than those who exercised at moderate to vigorous intensity at least four times per week. In men, those who exercised at moderate to vigorous intensity four or more times per week had a lower stroke risk. In women, the relationship between stroke and activity level was not as clear.
The data was obtained from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, which looked at the reasons behind higher rates of stroke mortality among African-Americans and other residents living in the Southeastern United States. REGARDS is funded by the NIH National Institute of Neurological Disorders and Stroke (NINDS).
"Epidemiological studies such as REGARDS provide an important opportunity to explore race, genetics, environmental and lifestyle choices as stroke risk factors," said Claudia Moy, PhD, program director at NINDS.
For the study, the researchers initially interviewed more than 30,000 participants over the phone and subsequent visits to get data on their medical histories and to take vitals, such as blood pressure and body mass index (BMI). During the study the research team contacted participants every six months to see if they had experienced a stroke or transient ischemic attack (TIA). Responses were confirmed by reviewing medical records of the participants.
"Our results confirm other research findings but our study has the distinct advantage of including larger numbers, especially larger numbers of women as well as blacks, in a national population sample so these provide somewhat more generalizable results than other studies," said Virginia Howard, PhD, senior author of the study from the School of Public Health, University of Alabama at Birmingham.
"The stroke-lowering benefits of physical activity are related to its impact on other risk factors," said McDonnell. "Exercise reduces blood pressure, weight and diabetes. If exercise was a pill, you'd be taking one pill to treat four or five different conditions."
"[Currently,] we can tell you how much your stroke risk improves for each cigarette you cut out or every point you reduce your blood pressure, but we still need good studies on the amount you can reduce your risk of stroke by taking up exercise," McDonnell said.
Dr. Howard noted the results of this study should encourage doctors to stress the importance of exercise when discussing stroke risks with their patients. "Physical inactivity is a major modifiable risk factor for stroke. This should be emphasized in routine physician check-ups along with general education about the benefits of exercise on stroke risk factors including high blood pressure, diabetes and being overweight or obese," she said.
The study findings make a good suggestion to men that exercise should be moderate to vigorous at least four times per week, where they break a sweat. Despite the weak relationship between physical activity and stroke risk observed in women, it wouldn't hurt for women to follow similar activity patterns. McDonnell did note, however, women may get the same benefit as men with less vigorous exercise such as walking.
The AHA recommends healthy adults (ages 18-65) get at least 30 minutes of moderate-intensity physical activity at least five days per week, or at least 20 minutes of vigorous-intensity physical activity at least three days per week.
"Findings from this study, including the current physical activity results, will ultimately help us to identify potential targets for immediate intervention as well as for future clinical trials aimed at preventing stroke and its consequences," said Dr. Moy, adding that the REGARDS study will continue to assess stroke risk factors.