A moderate level of aerobic fitness can significantly reduce stroke risk in men and women, according to a new study.

The study shows that 30 minutes or more of brisk walking, or an equivalent aerobic activity, five days a week could lower stroke risk by about 40 percent.

Researchers at the University of South Carolina Arnold School of Public Health analyzed data on more than 60,000 people -- 46,405men and 15,282 women -- who participated in a long-term study between 1970 and 2001.

The participants, aged 18 to 100 and free of known cardiovascular disease when they entered the study, were followed for an average of 18 years. During that time, 863 people -- 692 men and 171 women -- had strokes.

Upon entering the study, each participant took a test to measure cardiorespiratory fitness in which they walked on a treadmill at an increasing grade and/or speed until they reached their maximalaerobic capacity.

Men in the highest quartile (25 percent) of CRF had a 40 percent lower relative risk of stroke compared with men in the lowest quartile.

Among women, those with a higher cardiorespiratory fitness level had a 43 percent lower relative risk than those in the lowest fitness level.

The overall stroke risk dropped substantially at the moderate CRF level, with the protective effect persisting almost unchanged through higher fitness levels.

That difference stayed constant even after adjusting for other factors such as smoking, alcohol intake, family history of cardiovascular disease, body-mass index (an estimation of body fatness), high blood pressure, diabetes and high cholesterol levels, study author Steven Hooker said in a statement.

This study, presented at the on-going American Stroke Association's International Stroke Conference in New Orleans on Friday, was the first to suggest there may be a significant independent association between cardio respiratory fitness (CRF) and fatal and nonfatal stroke in men and nonfatal stroke in women.

(Xinhua News Agency February 25, 2008)