Running long distance week after week, year after year, could do more harm to your heart than good, a new editorial published in the British journal Heart says.
The key to exercising for heart health, researchers argue, is limiting intense endurance activity to between 30 and 50 minutes a day.
The editorial's authors point to accumulating evidence of heart damage in marathon runners tested right after races. Backing up this finding, wrote lead author James O'Keefe, M.D., head of preventive cardiology at the Mid America Heart Institute at Saint Luke’s Health System, is the famous "Iron Mouse" study, which found scarring in the hearts of mice forced to run long distances every day for four months. However, the mice's hearts returned to normal after they stopped running.
But the issue, according to the editorial, is that distance runners don't take enough time off from the sport to allow their hearts to heal, especially as they age.
Up to 30 percent of marathons have elevated levels of troponin, which is the marker of heart damage that usually indicates a heart attack. Even though the troponin level in marathoners isn't nearly as high as in a person who has had a heart attack, the damage and scarring from running can add up over time -- possibly shortening a runner's life.
In one study in which researchers followed 52,600 people, including nearly 14,000 runners, for 30 years, the runners as a group had a 10 percent lower risk of death from any cause than non-runners. But those who ran more than 20 or 25 miles per week had the same mortality risk as the sedentary people in the study, O'Keefe said.
The Copenhagen City Heart Study, which followed 20,000 Danes for 35 years, found that slow and steady joggers live about six years longer than non-joggers. Jogging at a slow pace for one to two and a half hours a week provided the most significant benefits, researchers found, comparing running to drinking alcohol -- mortality is lower among moderate drinkers and moderate runners, but at either end of the spectrum, the life-extending benefits disappear.
The authors of the Heart editorial agreed, writing "a routine of moderate physical activity will add life to your years, as well as years to your life. In contrast, running too far, too fast, and for too many years may speed life’s progress towards the finish line of life."
Will this research cause you to change your running routine?
"Running Farther, Faster Could Shorten Your Life" originally appeared on Everyday Health