Women who walk at least three hours every week are less likely to suffer a stroke than women who walk less or not at all, according to research from Spain that looked at thousands of people.
While the current study, which appeared in the journal Stroke, cannot prove that regular walking caused the fewer strokes, it contributes to a small body of evidence for potential relationships between specific kinds of exercise and risk for specific diseases.
Past studies have also linked physical activity to fewer strokes, which can be caused by built-up plaque in arteries or ruptured blood vessels in the brain.
"The message for the general population remains similar: regularly engaging in moderate recreational activity is good for your health," lead author Jose Maria Huerta of the Murcia Regional Health Authority in Spain told Reuters Health.
Women who walked briskly for 210 minutes or more per week had a lower stroke risk than inactive women but also lower than those who cycled and did other higher-intensity workouts for a shorter amount of time.
In all, nearly 33,000 men and women answered a physical activity questionnaire given once in the mid-1990s as part of a larger European cancer project. For their study, Huerta and his team divided participants by gender, exercise type and total time spent exercising each week.
The authors checked in with participants periodically to record any strokes. During the 12-year follow-up period, a total of 442 strokes occurred among the men and women.
The results for women who were regular walkers translated to a 43% reduction in stroke risk compared to the inactive group, Huerta said. There was no reduction seen for men based on exercise type or frequency.
"We have no clear explanation for this," Huerta wrote in an email. He hypothesized that the men may have entered the study in better physical condition than the women, but there was no evidence to support that guess.
Huerta also declined to compare the study participants' risk levels to those of the general population, citing the subjects' unusual characteristics. A majority of men and women in the study were blood donors, for example, and blood donors tend to be in good health.
"I wouldn't make much of the results because they are for a very specific population," said Wilson Cuerva of the University of Chicago, who was not involved with the research.
Cuerva pointed out that the study relied too heavily on subjective measurements, such as the participants' memory of exercise routines, and there was no objective way to measure how much exercise they actually did.
While he noted that it is difficult to draw any conclusions from the Spanish study, he said people should try to follow recommendations for two and a half hours of moderate exercise, such as brisk walking, every week.
"We know that exercise is related to reduced risk of stroke and other diseases," he said.