Lieberman on foot strike and injuries on Harvard’s XC team


As of September 2017, new Sweat Science columns are being published at Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)


Does how you run cause (or prevent) injuries? Everyone has a theory, but no one has much data. Into the breach steps Dan Lieberman, with a new Vibram-funded study of injury rates on Harvard’s cross-country team between 2006 and 2011, just published online at Medicine & Science in Sports & Exercise. He looks at 52 runners — 36 rearfoot strikers and 16 forefoot strikers — all of whom recorded their daily training on an online running log during the study, and whose injuries were precisely recorded by the team’s trainers.

The results?

Approximately 74% of runners experienced a moderate or severe injury each year, but those who habitually rearfoot strike had approximately twice the rate of repetitive stress injuries than individuals who habitually forefoot strike.

Now, this is a very interesting and significant result. It also has limitations, which the authors take great pains to detail in their discussion. Probably the most important: this is a retrospective, non-randomized study. That means, for example, that it doesn’t address what happens if a habitual, lifelong rearfoot striker switches to a forefoot strike, which requires stronger calf and foot muscles.

Another point that the authors make is the presence of considerable individual variation. Here’s some of the data:

(The caption reads “Repetitive injuries/10,000 miles; moderate and severe.” Not sure why Harvard is apparently using a Commodore 64 hooked up to a dot-matrix printer to generate its graphics!) Anyway, the point is that some people seem to do just fine with their rearfoot strike, while others are frequently injured with their forefoot strike:

[M]any runners who [rearfoot strike] in shoes do not get injured or get injured rarely even when they train at high intensity. We predict that these runners have better form than those who do get injured: they probably land with less overstride and more compliant limbs that generate less severe impact loading and generate less extreme joint moments… These predictions are supported by several recent studies, and they emphasize the hypothesis that running style is probably a more important determinant of injury than footwear (with the caveat that footwear probably influences one’s running style).

So there you have it. The study’s not perfect, and it doesn’t settle these debates once and for all. But it takes us closer by offering some straightforward data — and that’s how science should work.

Actual data on foot strike patterns


As of September 2017, new Sweat Science columns are being published at Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)


The debate rages on about how your foot should land when you’re running — but we still know remarkably little about how people’s feet are currently landing in the real world, outside of biomechanics laboratories. Pete Larson (of Runblogger fame) has a new paper in the Journal of Sports Sciences that offers some interesting data. It’s a very straightforward study: he (and his undergrad researchers) hung out at the 10K and 32K marks of the 2009 Manchester City Marathon with a high-speed camera, and filmed the runners going past. Then they went back and classified the foot strikes into three categories as illustrated here:

At the 10K mark, he got data for 936 runners who were doing either the half or full marathon. The results:

  • rearfoot: 88.9%
  • midfoot: 3.4%
  • forefoot: 1.8%
  • asymmetrical (i.e. different with right and left foot): 5.9%

It’s worth noting that virtually none of the runners were barefoot or wearing Vibrams — this was 2009, before the frenzy really started. Larson collected more data this year, so it will be interesting to see what (if anything) changes when that data is analyzed.

At the 32K mark, it was just marathoners, and Larson was able to positively identify 286 runners at both the 10K and 32K marks. Of these runners, 87.8% were rearfoot striking at 10K, and 93.0% were rearfoot striking at 32K. Basically, some of the runners who weren’t rearfoot striking initially got tired and settled into a rearfoot gait. There were no forefoot strikers left at 32K. To me, this is the most interesting avenue for further research: can people who switch to a forefoot strike maintain it all the way through a marathon? Do you have to grow up barefoot to develop that strength, or can it be acquired in a few years?

One last point: no significant relationship between race times and foot strike (though the number of non-rearfoot strikers was so small that any relationship would have been hard to find). Anyway, great to see some hard data, and I’m sure we’ll see a lot more like this in the years to come.

If the 100-up isn’t the secret, what is?


As of September 2017, new Sweat Science columns are being published at Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)


I’ve had some interesting e-mail exchanges over the last few days after I expressed my skepticism about the merits of the sudden enthusiasm for the 100-up exercise. Basically, my position was (a) sure, it’s a perfectly good form and/or conditioning drill, which is why it has been in pretty much continuous use for decades, but (b) I didn’t see any reason to think it was “the secret,” or any more useful than other form drills, simply because Walter George said he used it. The mere fact that someone is fast and does a particular drill is a pretty slender reed to build a training program on — and if that’s the yardstick, I pointed out to one person with tongue firmly in cheek, then I should be considered more qualified than Walter George to dispense advice, since I’ve run considerably faster than him.

Well, Justin called my bluff:

Great points all around [he wrote,] so here’s a question for you: if you had to start somewhere to learn running form — and you couldn’t afford a coach — where would you start?  What exercise would advance you the most in the shortest period of time?

That’s an excellent question. And a difficult one. So here’s my attempt to answer — or rather, to explain why I don’t have a simple, easy-to-package-and-sell answer.

The thing is, I’m still not convinced that most people do need to learn running form. I worry that all these articles about the necessity of learning the “one true way” to run are convincing people that they shouldn’t risk heading out the door in an untrained state to try this enormously complex activity.

Of course, some people definitely do need help with form. I watched the New York Marathon last weekend, and yes, there were some funky strides going past after the leaders were gone. So how do we fix those strides? Well, that depends on what’s wrong with them. Some people are leaning too far forward, others are leaning too far back. Many are overstriding, but a few are understriding. Some people are flapping their arms around like birds, others are barely moving them at all. It’s not the same fix for all of them.

Now, what Justin’s looking for isn’t a fix for a particular problem; he’s looking for a way to build the ideal stride from the ground up. And for that, maybe the 100-up is as good a place to start as any. I don’t have another exercise that I think is a “better” way to start developing a perfect stride, because I’m skeptical of the value of this perfect stride. In a sense, I’m just like Walter George in that I’m captive to my own experience and development. The way I learned to run was by heading out the door and trying it, then gradually adjusting along the way based on what felt good. That’s also how most of the people I know learned to run. Would we have been better if we’d been taught the “right” way to run right from the start? It’s possible.

By no means am I dismissing the benefits of optimizing running form. As I’ve written elsewhere, I think the single most common mistake people make is overstriding, which can often be addressed by quickening your cadence. I just have a nagging sense that form work has acquired enormous importance that is out of proportion to its value, when the real barrier for most beginning runners is still aerobic fitness. It reminds me of one of the most famous passages from Once a Runner:

And too there were the questions: What did he eat? Did he believe in isometrics? Isotonics? Ice and heat? How about aerobics, est, ESP, STP? What did he have to say about yoga, yogurt, Yogi Berra? What was his pulse rate, his blood pressure, his time for the 100-yard dash? What was the secret, they wanted to know; in a thousand different ways they wanted to know The Secret.

Chris McDougall responds


As of September 2017, new Sweat Science columns are being published at Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)


[UPDATE: After a few further e-mails, it’s become clear that Chris misspoke in his original interview with me, and said he’d been struggling with plantar fasciitis for “two years” when he meant to say “two months.” This certainly makes a difference in my general sense of the extent to which it was misleading to write that he hadn’t lost a day of running to injury since then.]

I got an e-mail from Chris McDougall earlier today, asking that I correct what he sees as the errors in my post from a few days ago. Here’s his account of my errors:

there are several mistakes in your post about me. i’ve told the story of my bout with PF publically and often, as in the outside magazine interview below. your version is incorrect.

1/  i wasn’t “felled” by PF. in fact, i never missed a day of running because of it.during that period, i ran with many sources, including amby burfoot, matt carpenter, scott jurek, tony kupricka, david horton — all of them tough runners, most of the runs on hard trails.

2/ I didn’t have it for two years; it bothered me for a few months.

3/ i wasn’t ‘stressed out’ about it because the publication date was nearing; on the contrary, i was still researching and writing. i considered it a formative learning experience, which is why i’ve spoken and written about it many times.

4/ my training in 2006 was vastly greater than 2010/2011. in 2006, i hit 100 miles a week, including two 50-mile runs and several weeks of high altitude in leadville. last year, i averaged maybe 30 miles a week. i was traveling nearly non-stop, squeezing in whatever workouts i could manage.

Here’s an excerpt from the transcript of our interview in 2009:

Imagine the situation I’m in. Because two years ago, I start researching this book. And the whole purpose of the book, premise of the book is that I’ve discovered the secret of lifelong injury-free running. And in the middle of writing the book, I come down with this ailment. And I can’t shake it. And I’m thinking, you know, I’m about to go out and promote a book. And I got this stinking injury. And I spent two years [UPDATE: Chris misspoke and meant to say “two months”] trying to get rid of it.

His points number 2 and 3 are directly contradicted by that quote. Obviously I’m not inside his head (or his foot), so I don’t know which version is more accurate. But I think my original blog entry was a fair account of what he told me.

As for point number 1, I’m happy to believe him if he says he hasn’t missed a day of running due to injury since then. And I never said he did. But I certainly felt (and still feel) that the impression left by writing “I haven’t lost a day of running to injury since” is at odds with the fact that, during that period, he travelled (again, according to his 2009 interview with me) to see “doctors in Germany, in London, in Detroit, in Indianapolis, in California… all kinds of different people” in unsuccessful attempts to get rid of the injury. If that’s not being “felled” by an injury, I don’t know what is.

Finally, I’m not sure why he’s calling point number 4 an “error.” He suggested that his improvement from 2006 to 2010/2011 could be explained by his use of the 100-up. I suggested that an alternate (and in my opinion more likely) explanation was that he had four years of consistent running behind him, instead of one year of high mileage. Running is cumulative, and many runners experience episodes like this. Obviously I’m just speculating, as is he himself.

Ultimately, I’m disappointed by this exchange. As I said in the initial post, I think McDougall has a great story to tell that has resonated with a lot people. That story is strong enough on its own merits; it doesn’t need to be made better than it already is.

Chris McDougall on “the one true way” to run


As of September 2017, new Sweat Science columns are being published at Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)


[UPDATE Nov. 8 : Chris McDougall sent me an e-mail asking that I correct several errors in this blog entry. His description of the errors, along with my response, is here.]

I’ve had a few e-mails asking what I thought of Chris McDougall’s piece “The Once and Future Way to Run” in this weekend’s New York Times Magazine, so I figure I might as well share those thoughts here.

1. Chris is a great storyteller and an engaging writer. I really enjoyed Born to Run, and I enjoyed this piece too. I think the running world is better off now that there’s greater awareness of the potential benefits of running barefoot or in minimalist shoes, and people have another option in the search for a running approach that works for them. I’d go so far as to say that McDougall has done more than anyone else in the world over the past two years to bring new people to running and create excitement about its possibilities.

2. What about the science in the article? I can’t really critique it, because there isn’t any science there — it’s all anecdote. For a thorough and balanced take on what the science does (or, more accurately, doesn’t) tell us about the quest for running perfection, read Pete Larson’s response to the article. He’s the evolutionary biologist quoted in the opening scene of McDougall’s article. Larson’s cautious middle ground is probably not what you’d expect if you’d just read McDougall’s article without knowing anything else about Larson.

3. What about W. G. George’s 100-up exercise, a century-old drill that McDougall suggests may be the “one true way” to develop perfect running form? This is where I start rolling my eyes, when he attributes a series of personal best performances to this magic drill:

“I don’t get it,” [he says at one point in the article,] “I’m four years older. I’m pretty sure I’m heavier. I’m not doing real workouts, just whatever I feel like each day. The only difference is I’ve been 100-Upping.”

Oh, please. For one thing, four years ago was, by his own account, roughly when he finally “learned to run” for the first time. If he’d been unable to run for years, and then learned to run, his improvement now compared to four years ago is likely due to something we call “training.”

Incidentally, the 100-up is a drill that modern runners call the “running A.” Virtually every competitive runner I know has done it at some point, and it’s a basic staple of every elementary school track camp. I was first introduced to it more than 20 years ago. So does that mean that McDougall is right, that it’s the secret that makes good runners fast? Of course not. It’s one of the many, many tiny ingredients that can add up to running success. There’s no secret, and no short cut.

4. The one part of the article that made me kind of angry was this passage, about McDougall’s visit to the Copper Canyon in Mexico that led to Born to Run:

I was a broken-down, middle-aged, ex-runner when I arrived. Nine months later, I was transformed. After getting rid of my cushioned shoes and adopting the Tarahumaras’ whisper-soft stride, I was able to join them for a 50-mile race through the canyons. I haven’t lost a day of running to injury since.

I actually interviewed McDougall back in 2009, shortly before Born to Run came out. And that’s not the story he told me. Here’s what I wrote then:

Long plagued by an endless series of running injuries, he set out to remake his running form under the guidance of expert mentors, doctors and gurus. He adjusted to flimsier and flimsier shoes, learning to avoid crashing down on his heel with each stride and landing more gently on his midfoot. It was initially successful, and after nine months of blissful training, he achieved the once-unthinkable goal of completing a 50-mile race with the Tarahumara. But soon afterwards, he was felled by a persistent case of plantar fasciitis that lingered for two years. “I thought my technique was Tarahumara pure,” he recalls ruefully, “but I had regressed to my old form.” Now, having re-corrected the “errors” in his running form, he is once again running pain-free.

I’m in New York right now, and won’t be back home until Monday night, otherwise I’d see if I can dig up my actual notes from the interview. But I remember McDougall telling how stressed out he’d been, because he’d spent all this time working on a book about the “right” way to run — but as the publication date loomed ever nearer, he’d been chronically injured for two years. It was only shortly before publication that he was able to get over the injuries and start running again.

So does this prove that barefoot running is a sham? Of course not. Injuries happen, with or without shoes. But it points to a fundamental dishonesty in the way the story is being told. He’s not disinterestedly sharing with us the results of an experiment he performed on himself; he’s deploying all his rhetoric to make as convincing a case as possible for one side of an argument that (as Pete Larson explains) is much more nuanced than he pretends. I’m not a big fan of “science by anecdote” under any circumstances — but if you’re making up the anecdotes, then what have you got left?