Think you can never get too much of a good thing? Think again, especially if you are an older athlete, addicted to those long-distance runs.  Such is the disconcerting conclusion of mounting research on the enduring impact of endurance sports as we age.

A recent editorial in the British journal Heart highlighted a study which followed 52,600 people, both runners and non-runners. The good news: Runners were 19% less likely to die than their more sedentary peers over the course of three decades.  The not-so-good news: Among runners — especially those who run more than 20-25 miles a week — the longevity benefits vanish. The authors conclude: “Running too fast, too far and for too long may speed one’s progress toward the finish line of life.”

While it might be hard for compulsive runners to take it easy, the majority of more moderate athletes may draw a deep exhalation of relief.  You don’t have to be an Ironman or woman to reap the rewards of working out. In fact, sometimes a little less may be a lot more.  Seniors who adopt a simple regimen of walking three times a week can improve aerobic ability, which in turn cuts their odds of premature death.  What’s more, regular, brisk walking can increase brain volume as we age — which guards against cognitive decline.

Key takeaway for runners:  Keep your weekly mileage under 20 miles or so, and your average speed under 8 MPH to go the distance in the game of life.

Published February 1, 2014