CHICAGO (AP) â€” Women who get 30 minutes of vigorous exercise every day, even just a brisk walk, can reduce their chances of having a stroke by as much as 30 percent, a study says.
The findings, published in Wednesday's Journal of the American Medical Association, were based on six years of data from 72,488 women, ages 40 to 65, who participated in the Harvard-based Nurses Health Study.
The researchers said it is the first large-scale study to link exercise to reducing the risk of stroke, which is the third-leading cause of death in men and women.
Previous studies, such as the surgeon general's 1996 report on exercise, concluded it was unclear whether physical activity protects against stroke.
The new study found that doing 30 minutes of moderate to vigorous exercise almost every day cut the risk of having an ischemic stroke, the most common type, by 30 percent. The risk of other types of stroke was cut by 20 percent.
The benefits were the same whether the women took a brisk walk or did more intense exercise such as jogging or aerobics.
``The major public health problem in this nation is sedentary lifestyle,'' said Dr. JoAnn Manson, one of the study's authors and chief of preventive medicine at Brigham and Women's Hospital. ``Walking is the most popular and common form of exercise in middle-age and older women, so it's great news from a public health perspective.''
The benefits from exercise are seen rather quickly, so a woman who doesn't start exercising until later in life still has a chance to cut her risk of stroke, Manson said.
``The earlier you develop good habits, the better,'' she said. ``But it's an important public health point that it's never too late. Someone shouldn't think if they are 60, 70, 80 years old they won't get the health benefits.''
Manson stressed that in order to get the stroke-reduction benefits from walking, women must maintain a brisk pace â€” a mile in no more than 20 minutes, or fast enough to elevate the heart rate and breathing.
One way exercise cuts the risk of stroke is by lowering blood pressure and the chance of clotting, Manson said. An ischemic stroke is caused when blood vessels are constricted and then finally cut off by a clot.