Running regularly has always been linked to health benefits, such as weight control, better blood pressure, stress reduction and cholesterol.

However, recent research suggests there may be a point of diminishing returns with running, reports webmd.com.

The researchers behind the newest study on the issue say people who get either no exercise or high-mileage runners both tend to have shorter lifespans than moderate runners. But the reasons why remain unclear, they added.

Dr. Martin Matsumura, co-director of the Cardiovascular Research Institute at the Lehigh Valley Health Network in Allentown, Pa. and his colleagues evaluated data from more than 3,800 men and women runners, average age 46. They were involved in the Masters Running Study, a web-based study of training and health information on runners aged 35 and above. 

The runners supplied information on their use of common painkillers called NSAIDs (nonsteroidal anti-inflammatory medications such as ibuprofen and naproxen/Aleve), which have been linked with heart problems, as well as aspirin, known to be heart-protective. The runners also reported on known heart risk factors such as high blood pressure, high cholesterol, diabetes, family history of heart disease and smoking history.

Dr. James O'Keefe, director of preventive cardiology at the Mid-American Heart Institute in Kansas City, who reviewed the findings, believes there may simply be "too much wear and tear" on the bodies of high-mileage runners. He has researched the issue and is an advocate of moderate running for the best health benefits.