People who break a sweat while exercising may be at a reduced risk of suffering a stroke, a new study indicates.

A stroke occurs when the blood supply to the brain is interrupted, depriving it of oxygen. As a result, some of the brain cells die and others are damaged. Every year, some 10,000 people in Ireland suffer a stroke and 2,000 people die as a result. Thousands more are left with stroke-related disabilities.

Australian researchers decided to look at the protective effects of exercise in relation to stroke. They monitored over 27,000 adults, aged 45 and older, for an average of almost six years.

Among the participants, one in three were found to be inactive - in other words, they exercised less than once a week.

The study found that those who were inactive had a 20% increased risk of suffering a stroke or mini-stroke (transcient ischaemic attack), compared to those who undertook moderate or vigorous intensity exercise at least four times a week. This kind of exercise is enough to break a sweat.

"The stroke-lowering benefits of physical activity are related to its impact on other risk factors. Exercise reduces blood pressure, weight and diabetes. If exercise was a pill, you'd be taking one pill to treat four or five different conditions," explained study author, Dr Michelle McDonnell, of the University of South Australia.

The findings support previous studies which indicate that a lack of exercise is one of the main risk factors for stroke, however more research is needed.

"We can tell you how much your stroke risk improves for each cigarette you cut out or every point you reduce your blood pressure, but we still need good studies on the amount you can reduce your risk of stroke by taking up exercise," Dr McDonnell said.

Details of these findings are published in the journal, Stroke.