Sorry if this has already been discussed here. I was wondering what other runners thought about this.
Even though the heart disease risk factors couldn't explain the shorter longevity of high-mileage runners, there do seem to be potentially life-shortening ill effects from that amount of running, said Dr. James O'Keefe, director of preventive cardiology at the Mid-American Heart Institute in Kansas City.
O'Keefe, who reviewed the findings, believes there may simply be "too much wear and tear" on the bodies of high-mileage runners. He has researched the issue and is an advocate of moderate running for the best health benefits. Chronic extreme exercise, O'Keefe said, may induce a "remodeling" of the heart, and that could undermine some of the benefits that moderate activity provides.
In O'Keefe's view, the "sweet spot" for jogging for health benefits is a slow to moderate pace, about two or three times per week, for a total of one to 2.5 hours.
"If you want to run a marathon," he said, "run one and cross it off your bucket list." But as a general rule, O'Keefe advises runners to avoid strenuous exercise for more than an hour at a time.