Frequent running has always been considered a healthy lifestyle choice, but recent research suggests too much of the activity could be dangerous.
Running has been known to be good for "weight control, stress reduction, better blood pressure and cholesterol," HealthDay reported. Research suggests running for only about two to three hours per week benefits longevity.
The new study suggests both those who do not run at all tend to have a shorter lifespan than moderate runners, but the same is true for high-mileage runners.
"Our study didn't find any differences that could explain these longevity differences," Doctor Martin Matsumura, co-director of the Cardiovascular Research Institute at the Lehigh Valley Health Network told HealthDay.
The researchers looked at 3,800 male and female runners who were an average age of 46; about 70 percent of these study subjects reported running more than 20 miles every week. The participants were members of Masters Running Study.
Factors such as painkiller (NSAID) use were ruled out as contributing factors to the study's findings. Risk factors such as "high blood pressure, high cholesterol, diabetes, family history of heart disease and smoking history" were also ruled out.
"The study negates the theory that excessive use of NSAIDs may be causing this loss of longevity among high-mileage runners," Matsumura said.
"What we still don't understand is defining the optimal dose of running for health and longevity," he said.
Doctor James O'Keefe, director of preventive cardiology at the Mid-American Heart Institute in Kansas City believes "too much wear and tear on the body" could be responsible for the shorter life spans associated with intense running habits. He believes the activity could lead to "remodeling" of the heart that could "undermine" other benefits associated with running.
O'Keefe believes individuals should run no more than 2.5 hours per week.
"If you want to run a marathon," O'Keefe said, "run one and cross it off your bucket list."
