Older men who regularly jog, swim or engage in other moderate- to high-intensity exercise may have a lower risk of suffering a stroke than their less-active counterparts, according to research published Monday.

The study, which followed 3,300 older adults for 9 years, found that men who got moderate- to high-intensity exercise were almost two-thirds less likely than sedentary men to suffer a stroke caused by a blood clot - the most common form of stroke.

Lighter exercise, such as walking, did not show a similar benefit. Nor was exercise protective for women - though, the researchers say, this was possibly because so few women in the study were active that it may not have been possible to detect a benefit.

The findings are published in the online edition of the journal Neurology.

Regular exercise is a well established way to control body weight, blood pressure, type 2 diabetes and other risk factors for stroke; some studies have found that physical activity may also lower stroke risk independent of those benefits.

Still, as compared with heart disease, research has been less consistent in showing that exercise can prevent strokes.

These latest findings suggest that more-vigorous exercise may be particularly protective when it comes to stroke, at least in men.

“It was the intensity of the exercise that seemed to be important rather than the amount of energy (calories) you burned,” lead researcher Dr. Joshua Z. Willey, of Columbia University Medical Center in New York, told Reuters Health.

As for why women did not see the same benefit as men, the reasons are unclear. One possibility is that some unmeasured factor was involved.

For instance, Willey said, the study lacked information on the women’s use of hormone replacement therapy (HRT), which is related to an increased risk of stroke; women who were more active may have been more likely to use HRT.

“We found no benefit (of exercise) for women in this study,” Willey said. “But we can’t say that there is no benefit.”

He also stressed that older women should not be discouraged by the findings. Whatever the effects of exercise on stroke risk, there are plenty of other health benefits, including a lower risk of heart disease, Willey pointed out.

The same advice applies to older adults who can manage only lighter activity, like brisk walking, which studies show can improve heart health.

The study included 3,298 older adults living in Northern Manhattan; more than half were Hispanic, one-quarter were black and 20 percent white.

Overall, only a minority of men and women - 20 percent - reported any moderate- to high-intensity activities, like jogging, swimming, bicycling or tennis. Almost 41 percent were completely sedentary.

“The alarming finding,” Willey noted, “is that a large percentage were not exercising at all.”

That, he said, highlights a need to find ways to encourage more older urban adults to stay regularly active.

SOURCE: Neurology, online November 23, 2009.