An older woman’s walking speed may help predict her risk of suffering stroke, over and above traditional risk factors, a new study suggests.

Researchers found that among 13,000 postmenopausal women, those with the slowest walking speeds were 69 percent more likely to suffer a stroke over the next five years than women with the quickest gait.

Even when the researchers excluded women with health conditions that might slow their walking speed, the higher stroke risk persisted. Traditional stroke risk factors - like diabetes, high blood pressure and smoking - did not explain away the link between walking speed and stroke.

“This research has shown that slow walking speed is a predictor of ischemic stroke independent of known stroke risk factors,” said lead researcher Dr. Aileen McGinn, of Albert Einstein College of Medicine in New York.

Ischemic strokes are those caused by a blockage in a blood vessel supplying the brain, which starves the brain tissue of oxygen. This is the most common type of stroke.

Based on the current findings, McGinn told Reuters Health, future studies should look at whether tests of walking speed can help predict older adults’ risk of ischemic stroke.

The study, published in the medical journal Stroke, is based on data from the Women’s Health Initiative (WHI), a major U.S. government study that began following more than 160,000 postmenopausal women ages 50 to 79 in the early 1990s.

McGinn’s team focused on 13,048 women who had no history of stroke when they entered the WHI. All of the women underwent a walking speed test that measured how long it took them to walk 6 meters, or roughly 20 feet.

The researchers found that the one third of women with the slowest walking speeds were 69 percent more likely to suffer a stroke during the study period than the one third with the quickest speeds.

Walking speed is considered a good reflection of people’s overall physical function as they age. But slower speeds may also be a proxy for subtle, “subclinical” dysfunction in the brain, McGinn and her colleagues speculate.

Otherwise healthy older adults who are slow walkers may, for instance, have small areas of brain tissue damage where blood flow was impaired - but not severely enough to cause clear symptoms of a stroke.

In this study, the slowest walkers moved at a rate of 1.06 meters per second or less, while the quickest walkers had a pace of at least 1.25 meters per second. Those cut-points, however, were arbitrary, McGinn noted, and more research is needed to determine the speeds that best predict stroke risk.

SOURCE: Stroke, April 2008.