When you finally get off the couch and experience your first runner’s high, you may want to run forever, but is it possible to get too much exercise?
The answer is yes, according to a recent review of research by a team led by cardiologist Dr. James O’Keefe. In some ways, exercise is like a medication that can be used to prevent and treat many chronic diseases. As with prescription drugs, though, it’s possible to “overdose” on exercise.
The researchers, who published their work in the Mayo Clinic Proceedings, looked at studies of people who competed in marathons, iron man triathlons, ultramarathons, and long distance bicycle races.
Overall, these endurance athletes fared better than sedentary couch potatoes—living seven years longer, on average. However, when the researchers focused only on people who took endurance training to its extreme, not only did the benefits of exercise diminish, but the excessive activity started to take its toll.
During an extreme workout like a marathon, the heart has to pump five times the amount of blood that it does while someone is at rest. This excessive exertion can cause short-term changes in the heart and large arteries.
Without additional training, the body usually returns to normal within one week. Repeated exercise at an extreme level, however, can cause scarring of the heart that increases the risk of irregular heartbeats. This can lead to more serious conditions later on.
The researchers are quick to point out that exercise is still important, especially if you want to feel better and live longer. Most of the benefits of exercise, however, happen at a moderate level—30 to 60 minutes a day.
If you are a runner, that’s about 10 to 15 miles a week, plenty of miles to get a runner’s high, but not so much that you start to lose your healthy edge.