Sports Science Update: Run Less To Run Younger?

A new study helps explain why late starters become the fastest older runners.

Written by: Matt Fitzgerald

In Lore of Running, Tim Noakes makes the interesting observation that most of the best runners over age 45 are late starters. Your typical age-group record setter in the older masters divisions only started running in his or her late 20s or early 30s. A classic example of this phenomenon is Kathryn Martin, who started running at 30 and then rewrote the U.S. record book in the 50-54 and 55-59 age groups (she turns 60 this year and will undoubtedly set a new batch of records).

Runners who were the best in the world in their 20s and who keep competing past middle-age are almost never the best in the world in the older age groups. Most are still very good, of course, but they slow down precipitously after age 45 and are eclipsed by later starters like Martin. Bill Rodgers was one of the fastest marathon runners in the world in his prime, but he says that between his 50^th and 60^th birthdays his 10K time slowed by a staggering 10 minutes. Now 62, Rodgers is decidedly not among the fastest 60-plus runners in America.

Tim Noakes speculates that long-term high-mileage training causes the muscles and tendons to lose elasticity. After a certain degenerative tipping point is passed, the legs can no longer capture and reuse as much “free energy” from ground impact and consequently running economy goes down the tubes. It’s not that high-mileage running is inherently bad. Up to a point it is not only good but even downright necessary for performance optimization. All training has both positive and negative physiological effects. It’s the balance that’s important. High-mileage training appears to create a very positive net balance of physiological adaptations for a while, but there comes a point when the positive effects diminish while the negative effects accumulate, and that may be why elite runners slow way down after 45.

A new study by Noakes’ colleagues at the University of Cape Town, South Africa, provides some insight into the nature of this phenomenon. Scientists often measure the length of DNA strands in cells to assess physiological age. Time and stress cause our DNA to progressively shorten. The Cape Town researchers measured the length of DNA strands extracted from the calf muscles of a bunch of experienced runners with an average age of 42 and from a group of sedentary controls with an average age of 39. They found no difference between the two groups, suggesting that years of running had not made the runners’ calf muscle cells physiologically older than those of non-runners. However, there was a significant inverse correlation between running experience and volume and DNA length. In other words, within the group of experienced middle-aged runners, those who had the fewest miles in their legs had the “youngest” DNA.

The practical implications of this study are unclear. I do not take it to suggest that young competitive runners should limit their mileage for the sake of running better when they are older, because doing so would likely make them worse now. Elite running coach Brad Hudson advises runners to transition from a high-mileage approach to a low-mileage cross-training approach when they hit their mid-30s. This makes sense to me, because it gives runners the opportunity to enjoy the full benefits of high mileage and the opportunity to make a speed-preserving change before the costs of high-mileage training really add up.

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FILED UNDER: Features TAGS: American Records / Bill Rodgers / Brad Hudson / Cross Country / High-Mileage Running / Marathon / Masters Running / Running / Sports Science Update / Tim Noakes / Training / Workouts

Matt Fitzgerald

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