Elderly individuals who engage in strenuous exercise, such as jogging, are at increased risk for developing blood clots, which can have serious consequences, according to the results of a new study. Still, the authors assert, the benefits of moderate or strenuous exercise in elderly individuals likely outweigh this risk.

Prior studies have yielded conflicting results regarding the impact of exercise on the risk of blood clots, technically known as venous thrombosis, according to the report in the Journal of the American Geriatrics Society. However, the main studies investigating this topic did not provide a detailed analysis of exercise or careful control of outside factors that may have influenced the results.

The current investigation by Dr. Susan R. Heckbert of the University of Washington, Seattle, and colleagues involved an analysis of data for 5,534 subjects, 65 years or older, without a history of venous thrombosis who were enrolled in the Cardiovascular Health Study and were followed for around 11 years.

The subjects were questioned about exercise activities two or three times during follow-up. Activities were classified as low intensity (walking), moderate intensity (gymnastics) or strenuous (jogging).

During follow-up, 171 patients developed a venous thrombosis, the report indicates.

After accounting for gender, age, race, self-reported health, body mass index, the researchers found that, in general, exercise did not significantly influence the risk of venous thrombosis.

However, on further analysis, there was some evidence that mild-intensity exercise may have slightly reduced the risk. Strenuous exercise, by contrast, was definitely shown to increase the risk.

Despite these findings, Heckbert and colleagues conclude: “The overall benefits of exercise likely outweigh the possible higher risks of venous thrombosis or injuries, but more research is needed to investigate this unexpected higher risk of venous thrombosis in elderly people associated with strenuous-intensity exercise.”

SOURCE: Journal of the American Geriatrics Society, March 2008.