Though some view exercise as an abstraction, many Americans engage in binge exercising in an all-or-nothing ethos of running, jumping, and lifting.

Now scientists say the answer to good health might lie somewhere between all and nothing, with extreme runners sharing something in common with the couch potato: a shortened longevity. Despite numerous health benefits to running, new research suggests that high-milers may die sooner than people who run in moderation.

“Our study didn’t find any differences that could explain these longevity differences,” Martin Matsumura, co-director of the Cardiovascular Research Institute at the Lehigh Valley Health Network, told CBS News. “What we still don’t understand is defining the optimal dose of running for health and longevity.”

Matsumura and his colleagues reviewed study data on 3,800 men and women who participated in the Masters Running Study, a web-based self-reporting survey for runners over the age of 35. Some 70 percent of the study participants logged more than 20 miles per week, at an average age of 42. In the analysis, the researchers compared total running exercise time to self-reported

The researchers found the link after considering such factors as the use of prescription medication and painkillers, hypertension and heart disease risk, diabetes and family history of chronic sickness. Interestingly, the researchers found that average runners were more likely to use painkillers, popping a few Ibuprofens as a warmup. Such nonsteroidal anti-inflammatory medications as ibuprofen and naproxen have been linked to heart problems, while aspirin has been known to confer protective benefits to the cardiovascular system.

James O’Keefe, director of preventive cardiology at the Mid-American Heart Institute, said excessive running might bring the body “too much wear and tear.” By contrast, O’Keefe says he runs moderately at a slow to medium pace for two to three 2.5-hour sessions per week. “I certainly don’t tell patients ‘Don’t run,’” Matsumura told CBS. Yet, “if you want to run a marathon, run one and cross it off your bucket list,” he added.

The good doctor even tells his patients to avoid strenuous exercise for more than an hour at a time.