Research continues to emerge that physical exercise is one of the best ways to tap into the fountain of youth. But there’s also some research emerging that suggests participating in strenuous exercises such as long-distance running too much exercise as you reach middle-age and beyond may actually take a terrible toll on your body.

In a recent story in The Wall Street Journal, reporter Kevin Helliker points to a study of 52,600 people over a 30-year period.  In that study, runners had a 19 percent lower death rate; however, runners who ran for extended distances of more than 20 miles a week were more likely to die. Another study suggested that people who ran slower than eight miles per hour were less likely to die than their faster colleagues.

 “Chronic extreme exercise appears to cause excessive ‘wear-and-tear’ on the heart, inducing adverse structural and electrical remodelling, which offsets some of the CV  (cardiovascular) benefits and longevity improvements conferred by moderate physical activity,” Dr. James O’Keefe of Saint Luke’s Mid America Heart Institute and the University of Missouri-Kansas City School of Medicine and Dr. Carl J. Lavie of The University of Queensland School of Medicine and the Pennington Biomedical Research Center write in an editorial in the journal Heart. “Thus, even though chronic extreme exercise may not kill you, it may erase many of the health advantages of regular moderate exercise.”

Earlier this year, CNN reported on similar findings from a meta-analysis of 50 different studies focused on athletes who participated in extreme endurance events, including marathons, ultra marathons, Ironman triathlons and long-distance bicycle races. The researchers’ analysis found that that “excessive training and competing can cause cardiovascular damage such as scarring and enlargement of the heart and blood vessels, as well as irregular heart beating,” the CNN story stated. The story quoted Dr. O’Keefe, who stated, “"It’s definitely not good for your heart in the long run. If you want to do it, train up for it, and cross it off your bucket list. This is not a healthy, long-term exercise pattern.” He instead suggests people do less intense exercises such as walking, jogging and swimming.

A paper by Hans Larsen for The AFIB Report also points to multiple studies that have found that older people who participate in continuous endurance exercises have the potential for heart issues. He also suggested that the body is placed at risk because this type of exercise “profoundly affects the body’s physiology.” Those changes include reducing the heart rate and testosterone levels and increasing the risk of inflammation. Furthermore, he points to research that found that long-term endurance training actually changes the structure of the heart by often increasing the size of the left atrium.

However, there are some benefits of endurance exercise training. For instance, a 2010 study out of Italy looked at how endurance exercise training affects cognitive decline in healthy older adults. These researchers followed 120 people between the ages of 65-74 years of age. They were divided into two groups, one of which participated in 12 months of supervised endurance exercise training in a community gym for three hours a week.  (Note that this study did not mention whether the participants also exercised on their own for extended periods of time.) These researchers found that the participants who were involved in the endurance exercise training group did better on the Mini Mental State Examination.