How much will I slow down in my late 30s?

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- Alex Hutchinson (@sweatscience)

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While I’m clearing out my mailbag… I got a question from a 800-metre runner in his mid 30s asking about how quickly he should expect his (and his competitors’) times to decline. It’s an interesting question that can be approached in a number of different ways — age-group records, which obviously depend on outliers; population-level cross-sectional studies; individual longitudinal studies — and all give different answers.

I cover this in a fair amount of detail in my book, but a couple brief points: numerous studies over the past three decades have found that cross-sectional declines tend to be steeper than longitudinal declines. That makes sense: the cross-sectional data gets weaker and weaker as you get to higher ages because there are more injuries and fewer people interested. (The latter factor is interesting in its own right: there’s evidence, albeit in mice, that the “impulse to exercise” declines with age. So it’s not just that people get busy or bored with competition, they may also have less intrinsic drive to compete.) Anyway, the point is: if you remain healthy and continue training at the same relative intensity (big “ifs” in both cases), you should expect to be able to beat the “average” decline represented by data like age-graded tables.

Speaking of which, here’s some data. The WMA age-graded table expect that you don’t start slowing down at all until you hit 35. At that point, the decline until your 40 appears to be linear. For comparison, I’ve plotted the times put up by the inimitable Johnny “Twilight Zone” Gray:

Gray was obviously a one-of-a-kind performer in many respects. The question is: was he a freak because he was still capable of running 1:45 as a 39-year-old? Or was he a freak because he was still interesting and willing to train at the level required to run 1:45 when he was 39? How many other 1:42 guys could have done the same if they’d tried? We don’t really know the answer to these questions, but the general feeling among researchers that I’ve spoken with is that the fundamental physical decline is much less steep than we previously believed. It’s more about training and motivation (and, of course, injuries).