Regular, Vigorous Exercise May Lower Stroke Risk
Direct effect not shown in study, but experts say physical activity's impact is clear
But that number dipped to 14 percent -- considered to be statistically insignificant -- once the researchers did more adjusting. In other words, the extra exercise appeared to have no effect after taking into account for traditional stroke risk factors such as diabetes, high blood pressure, overweight, alcohol use and smoking.
However, this may be because the further adjustments eliminated the indirect influence of exercise on stroke -- its effect on risk factors like high blood pressure, for example.
The research also suggested men got more benefit from exercise than women on the stroke front. "There has been some research to suggest that women perhaps benefit from less intense exercise, like walking, but seeing as we didn't ask this question in our study we really can't speculate any more than that," McDonnell said.
Steven Blair, a professor who studies exercise at the University of South Carolina, praised the study and said a 20 percent reduction in stroke risk is "a reasonably big deal," especially in comparison with medical treatments for some conditions that may have the same effect.
The message "is simply that everyone should strive to meet our Health and Human Services physical activity guidelines -- all adults should get 150 minutes of moderate intensity physical activity per week, 75 minutes of vigorous intensity activity, or mix and match with one minute of vigorous being equal to two minutes of moderate," Blair said. "The exercise bouts should be at least 10 minutes in duration. So if everyone took three 10-minute walks a day on at least five days of the week, this would have a dramatic effect on disease rates in the U.S. population."
The study appears online July 18 in the journal Stroke.