Women who regularly take a brisk walk or who walk at a more moderate pace for more than two hours a week can help cut their risk of stroke by more than a third, researchers say.

The findings come in a study that observed the fitness habits of more than 39,000 female health professionals. Their average age was 54. The study found that compared to women who didn't walk:

  • Women who usually walk at a pace of at least 3 miles per hour (4.8 km/h) have a 37 per cent lower risk of suffering any type of stroke.
  • Women who walk two or more hours a week at any pace have a 30 per cent reduced risk of any type of stroke.

The risks were lower for all kinds of stroke, including the more common clot-related (ischemic) stroke, and bleeding (hemorrhagic) strokes, researchers said, though the reductions in risk were more significant with hemorrhagic stroke.

It‘s no secret that people who are more physically active generally have a lower risk of stroke than those who are the least active. But it hasn't been clear how vigorous the exercise needed to be to reduce the risk. Nor has it been clear what kinds of stroke were affected by regular exercise.

Interestingly, the researchers say they're not ready to say that walking provides the same benefits to men.

"In previous studies, the relation between walking and stroke risk among men has been inconsistent," said Jacob R. Sattelmair, the study's lead author and doctoral candidate in epidemiology at Harvard School of Public Health in Boston.

"The exact relation between walking and stroke risk identified in this study is not directly generalizable to men."

The study, published in Stroke: the Journal of the American Heart Association, comes as the AHA's Start! initiative launches National Start Walking Day to encourage people to get moving.

For the study, researchers followed 39,315 U.S. women participating in the massive Women's Health Study. Every two to three years, participants report their leisure-time fitness activities during the past year.

Among the women who said they walked for exercise, they reported their usual walking pace as either:

  • casual (about 2 mph or 3.2 km/h)
  • normal (2.9 mph or 4.7 km/h)
  • brisk (3.9 mph or 6.3 km/h)
  • or very brisk (4 mph or 6.4 km/h)

During almost 12 years of follow-up, 579 women had a stroke (473 were ischemic, 102 were hemorrhagic and four were of unknown type).

The women who were most active in their leisure time activities were 17 per cent less likely to have any type of stroke compared to the least-active women.

The link to reduced stroke was clear with women who walked at a moderate pace, but less clear with vigorous activity.

"It is not entirely clear why we observed an association between walking, a moderate-intensity activity, and stroke risk, but not association with vigorous-intensity activity," the authors wrote.

The researchers suspect that too few women reported vigorous activity in the study to get an accurate picture. Or it might be that moderate-intensity activity may be more effective at lowering blood pressure, as some previous research has suggested.

The AHA notes that walking provides other health benefits beyond lowering stroke risk. Walking for as little as 30 minutes a day will improve circulation, lower cholesterol and blood pressure, and promote weight loss.