Regularly Breaking a Sweat May Protect Against Stroke
Failing to regularly work up a sweat through exercise may raise risks for a stroke or transient ischemic attack (TIA), a new study confirms.
The study found that participants who were inactive had a 20% increased risk for stroke compared with those who exercised 4 or more times per week, and that those who were active 1 to 3 times a week were 16% more likely to suffer a stroke.
“The point here is that you should be exercising 4 times a week at least and doing it hard enough so that you’re getting a bit of a sweat,” lead author Michelle N. McDonnell, PhD, lecturer, rehabilitation, University of South Australia, Adelaide, told Medscape Medical News.
The study was published online July 18 in Stroke.
Sweat Question
The Reasons for Geographic and Racial Differences in Stroke (REGARDS) is a population-based, longitudinal study of 30,239 Americans aged 45 years or older, with oversampling of blacks and residents of the Stroke Belt, an area in the southeastern United States that has a relatively higher stroke mortality rate.
The question about exercise-related sweating is easy to answer, and responses correlate well with fitness level, said Dr. McDonnell. “It’s really biasing towards more vigorous activity, which we know is important.”
Researchers verified strokes through medical records and classified them into ischemic or hemorrhagic. The 27,348 participants, who were stroke free at the start of the study, were followed for a mean of 5.7 years.
The study found that compared with those who hit the gym, biked to work, or were similarly active at least 4 times a week, the hazard ratio (HR) for stroke/TIA for those undertaking no physical activity was 1.20 (95% confidence interval [CI], 1.02 – 1.42) after adjustment for age, sex, race, and age-race interaction. For 1 to 3 times per week, the HR was 1.16 (95% CI, 0.98 – 1.42).
Risk Factors
This tells us that exercise seems to be working by reducing blood pressure and reducing obesity and perhaps helping with controlling diabetes, so exercise is working on lots of things all at the same time.
Those in the study who were more physically active were generally more fit, had lower blood pressure; and were less overweight or obese judging from body mass index (BMI) data, although, unexpectedly according to the authors, they tended to drink more alcohol.
Physical activity also has direct biological effects that could be protective against stroke. It improves circulation and endothelial function, and reduces platelet activity to help prevent formation of blood clots, in addition to enhancing brain function.
When looking at the effects of sex, the authors found that men who took part in physical activity 1 to 3 times per week had a greater incidence of stroke compared with those who exercised 4 or more times per week (HR for demographic model, 1.30; HR for socioeconomic status model, 1.26).
In men, those who exercise 3 times a week didn’t have the same benefits as those who exercised 4 or more times a week, suggesting that for men in particular it’s that 4 times a week, rigorous activity that is really important.
In contrast, there was no significant association between physical activity and incident stroke in women, although there was a trend to a similar reduced risk for those who exercised at least some compared with none.
The study results should encourage doctors to stress the importance of exercise when speaking with patients.
Physical inactivity is a major modifiable risk factor for stroke. This should be emphasized in routine physical 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.
Accounting for Sedentary Behavior
Stroke. Published online July 18, 2013. Abstract
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