Can walking help guard against stroke?

NEW YORK (Reuters Health) - Walking may be an important weapon for women in the fight against stroke, a new study hints.

The study found that women who walked for two or more hours a week had a lower risk of stroke than those who walked for less than two hours a week.

It’s well known that physical activity is good for heart health, including reducing the risk of stroke. “More active people generally demonstrate a 25 to 30 percent lower risk of stroke,” Jacob Sattelmair, the study’s lead researcher and a doctoral candidate in epidemiology at Harvard School of Public Health in Boston noted in a telephone interview with Reuters Health.

To investigate further, Sattelmair’s team studied more than 39,000 healthy women aged 45 or older enrolled in the Women’s Health Study. The women reported their leisure-time physical activity at the start of the study (1992-1995) and periodically during the study.

During an average follow-up of nearly 12 years, 579 women suffered a stroke. There were 473 ischemic strokes - the most common type caused by a blockage or blood clot supplying blood to the brain -- and 102 hemorrhagic, or “bleeding,” strokes. Four strokes were of an undetermined type.

Overall, the most active women in the study were 17 percent less apt to suffer a stroke during follow up than the least active women, the researchers found.

Compared with women who didn’t walk, women who walked two or more hours a week at any pace cut their risk of any type of stroke by 30 percent.

Women who walked at a pace of 3 miles per hour or faster had a 37 percent lower risk of suffering any type of stroke compared to those who walked at a slower pace. Walking appeared to primarily lower the risk of ischemic stroke.

These observations “certainly add to the evidence that even moderate-intensity activity such as brisk walking is beneficial to the reduction of risk of strokes,” Dr. Frank Hu, of the Harvard School of Public Health, who was not involved in the study, told Reuters Health by phone.

Hu published a study in 2000 in the Journal of the American Medical Association showing that physical activity, including walking, provided a significant reduction in stroke risk.

The current study is “observational,” Hu pointed out, with self-reported data. But the research team controlled well for other risk factors for stroke, he said, such as smoking. A connection between more vigorous forms of physical activity and reduced stroke risk couldn’t be properly examined in the study, he added, because there weren’t a sufficient number of vigorous exercisers; walking was a more popular activity for the study participants.

Sattelmair and colleagues note that their study primarily looked at well-educated, middle-aged white women, although there is no particular reason to believe that the results can’t be generalized across the wider population of American women, according to the researchers.

Men were also not included in the study; exercise has generally been shown to reduce stroke risk in men as well, but there isn’t yet clear data on how walking specifically affects risk for them.

Hu said this study is clinically important because of the devastating side effects of stroke, which include reduced mobility, speech difficulties and memory loss. Stroke is the third leading cause of death in the United States, after heart disease and cancer.

“The bottom line,” Hu said, “is that this study provides another piece of evidence for why people should move and get off the couch.”

SOURCE: Stroke: The Journal of the American Heart Association, online April 6, 2010.