Researchers say running too much can be just as unhealthy as being a couch potato.
Scientists say people who run at a fast pace for a total of more than four hours a week have about the same risk of dying as those who are sedentary.
Those with the lowest risk of dying are people who run about an hour and a half a week at a slow to moderate pace -- roughly five miles per hour.
Researchers from Denmark say people who push their bodies too hard may essentially undo the benefit of exercise.
Running too much can be unhealthy, researchers say