Chart by Jens Jakob Anderson and Ivanka Andreeva Nikolova, runrepeat.com
When it comes to running, I live in a bubble. I spend some part of every day running, or coaching, or writing, or thinking about running. My social life revolves around running. I frequent running websites. I stream obscure races and meets from around the world to my laptop at odd hours of the day and night. I am writing this in my dorm room at a running camp.
All of this makes it hard for me to see the big picture: to see that people like me represent a very small fraction of the running population of this country. Vastly more people run for health or recreation than for prizes, and those people likely do not obsess over intervals, tempo runs, and weekly mileage.
The fact that I have spent a lot of my life trying to get better at running, and trying to help others do the same, also makes it hard for me to understand the following recent phenomenon: American runners are slowing down. Or, to put it more precisely, average race times across a variety of standard race distances have been slowing steadily for at least two decades.
Two weeks ago, Amby Burfoot penned an article for the Washington Post under the melancholy headline “’American runners have never been slower,’ a new study says – but why?”
The study in question, with the depressing but direct title, “American Runners have never been slower,” was led by statistician Jens Jakob Anderson of the Copenhagen Business School and assisted by mathematician Ivanka Andreeva Nikolova. It looked at a massive amount of data from races over the past twenty years, some 34 million road race results from 1996 to 2016.
The major findings of the study:
- Average times have gotten steadily slower, with 2016 being the slowest year on record
- The effect is stable across race distances from 5K to the marathon
- Although some of the slowdown reflects greater participation by female runners over that time, the effect cannot be explained solely by that shift.
- Likewise, the slowdown cannot be explained by an increase in the number of walkers, or very slow runners.
My first instinct on reading the Washington Post article was to regard the findings skeptically. After all, I reasoned, there isn’t any such person as the average American runner. There are only runners, and some of them are getting faster and some of them slower. New runners are entering the population and old ones are dropping out. And a lot of them, like me, are aging. If the average is slowing down, it’s probably because of some such statistical fluctuation overlooked by the authors, like having more of us hanging on into our 50s and 60s.
I considered leaving it at that, but the question of age kept bothering me, so I decided to reach out to the authors of the study to see if they had any thoughts about whether an aging population of runners could account for the decline in performance. If so, the study would still be interesting, but there would be no mystery. To my surprise, I received a prompt and extremely helpful response from Jens Anderson acknowledging the question and providing additional data that had not been in the published study. They had considered the question of age. Specifically, they found that — although the average age of participants had increased from age 37 to age 41 over the past 20 years — the data showed that, like the other demographic trends they had examined, an aging population of runners could not explain all the slowdown. Basically, all age cohorts were slowing down.
So, what could be the explanation? Is the slowdown the sum of many more-or-less benign demographic effects, or is it something else?
In the published study, Anderson notes that the slowdown correlates well with several measures of declining health in the American population as a whole — for example, obesity rates — but he stops short of claiming causation. While it’s possible that runners are, on average, heavier than before, the data cannot prove this.
In the Washington Post article, Burfoot considers other explanations, which he gathers from various experts and prominent figures in the wider running community. Most of the explanations offered suggest that the average runner “these days” is less motivated to train hard and race fast. For example, statistician Ken Young writes:
“Average [race] times are slowing because more and more races are emphasizing their social aspects…They seek to attract recreational runners and walkers. Look at the race websites. You can find all sorts of social media links, party details and merchandise for sale, but it’s hard to find the race results.”
And here’s Tom Grilk, chief executive of the BAA, which organizes the Boston Marathon:
“In recent years, the general emphasis among marathoners has shifted from performance to participation… If that means more people are running for their long-term health and fitness, it’s a trend I applaud. I think it’s healthy that fitness ‘sustainability’ is more important than speed.”
But don’t these explanations beg the question? If the average runner today is slower today than the average runner of 1996 because today’s runner is not as interested in being faster, why is there declining interest in trying to be faster? And is that a good thing (as Grilk suggests) or a bad thing?
I still can’t completely shake the idea that I’m missing something that’s in the data – some change or combination of changes that account for the near universal slowing of the broader running population (except for the very elite, who seem to be holding their own). Or maybe because I live in the bubble, I’m missing something far more obvious, an attitudinal shift like the ones offered by Young and Grilk. I remain skeptical that there’s a medical explanation, but perhaps that, too, plays some part.
What I do know, is that if you hang around older runners, the ones who have been racing since the 1970s and somehow continue to drag their aching bones to road races today, you’re bound to hear some variation of “…it was different in my day…” And if you dig through musty archives for race results that pre-date web sites, you’ll find typewritten lists of names and times that evoke a world where 5Ks were virtually unknown, and a surprising number of runners were what we would call fast.
“In my day,” the old runner grumbles, “we were all running high volume, and hammering each other. You’d show up to a 10K or a 10-miler (no 5K fun runs for us) and run 5:00 pace and you’d be lucky to be in the top 10.”
You wouldn’t think that being fast would fall out of fashion, but then again, I live in a bubble, focused on my own little world, so maybe I was just out of touch.
In a last attempt to get clarity for myself, I reached out to a former work colleague, Mike Newman. Mike earned his Ph.D. in physics, and does quantitative research for a living. He is on of the smartest people I know, and also happens to be a runner approaching his 50th birthday. Surely, he would provide insight that had escaped me.
I shared with Mike the link to the Anderson/Nikolova study and asked him whether he thought it proved that Americans were getting slower. His one-sentence response:
“Well, I’m getting slower, so it must be true.”