Posts Tagged ‘barefoot running’

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

January 5th, 2012

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

December 6th, 2011

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?

November 11th, 2011

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

November 8th, 2011

[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

November 5th, 2011

[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?

Why neither “normal” nor minimalist running shoes will disappear

September 15th, 2011

Which is better: a pill that 75% of the population can take, which produces wonderful benefits for 25% of those who take it; or a pill that 25% of the population can take, which produces wonderful benefits for 75% of those who take it? I was pondering this question while re-reading Peter Vigneron’s long, thoughtful piece about running form, from the June issue of Runner’s World. This passage, in particular, made me think:

Perhaps—and this, too, is speculative—the modern cushioned running shoe makes running easy for the modern runner. This seems like a good thing. Should millions of runners suddenly decide to change their form and then find that running is no longer a manageable activity, it would be a tragedy. The solution to an imperfect state of affairs ought not make things worse—it should not produce more injured, unhappy runners.

One of the common narratives you hear a lot these days is that modern running shoes are the product of an insidious corporate campaign to sell us useless shoes that effectively enslave us by weakening our feet. I find this conspiracy-theory stuff quite tiresome — shoes may or may not be good for us, and of course shoe companies want to sell us anything they can, but I have no doubt that the origin of what Pete Larson calls the “pronation paradigm” was well-intentioned. The simple but often overlooked point is that the shoes caught on. I’d bet that, in 10 years, the recent fad for “toning shoes” will be all but forgotten since they simply don’t work. But running shoes have had remarkable staying power — perhaps because, as Vigneron says, “the modern cushioned running shoe makes running easy for the modern runner.” Or at least some modern runners, some of the time.

Let’s say we accept that, in a perfect world, the barefoot running style is optimal for humans. What if in our postlapsarian modern society, a large proportion of us are simply not equipped to make that transition after decades of sedentary, shod living? Or we can make the transition, but it requires the careful, patient, dedicated, slightly obsessive six-month transition period that barefoot advocates scrupulously recommend? Given the staggeringly high numbers of people who can’t be bothered to do any physical activity, even so much as a brisk walk, despite the overwhelming evidence that it’s the single best thing they could do for all aspects of their physical and mental health, I suspect that the barriers to successful barefoot running will always limit it to a fairly small subset of population.

So that’s what my opening question was about: what if barefoot running is fantastic for a small segment of the population, while running shoes are hit-and-miss but accessible to a much larger portion of the population? What’s the “right” answer to how we proceed? Obviously I chose my sample numbers carefully (so that both versions of the pill help 18.75% of the population, if anyone’s checking the math), but I wonder what those numbers are in reality. How many people can barefoot running reach? How “bad” are normal shoes? In the end, the numbers don’t really matter — because there will always be some part of the population that can succeed with one approach but not the other.

Minimalism: three perspectives

June 6th, 2011

Three interesting blog posts that anyone interested in the ongoing debate over minimalist shoes will be interested in:

First, Amby Burfoot had a brief Q&A with Irene Davis, a top researcher and barefoot advocate formerly at Delaware and now at Harvard, in advance of last week’s ACSM meeting. She discusses a few bits of upcoming research, and the freshest wrinkle from my perspective was a study on balance with and without socks:

It was determined that a thin pair of socks causes a statistically significant reduction in balance, suggesting that they filtered out important sensory information.

We often talk about barefoot running and minimalist shoes like Vibrams as essentially the same thing — but maybe there’s something intrinsically superior about going totally barefoot in terms of “dynamic stability.”

Second, Ross Tucker at the Science of Sport has a lengthy post that sums up his take on the barefoot debate starting with a very basic intro — perfect for those who want to get up to speed but haven’t been following the debate closely. This post sums up my own positions on the pros and possible cons of barefoot running absolutely perfectly, so I highly recommend it!

One interesting point that Ross makes is the difference between running and training for high performance. As he points out, it’s highly unlikely that our caveman forebears ever tried running 120 to 200K per week at relatively high speeds. At those training levels, muscle fatigue may become a limiting factor:

The third presentation in the symposium showed some really interesting evidence that the loading on the joints and bones was HIGHER as muscles fatigued.  This stands to reason, of course – muscle absorbs much of the impact force, and so tired muscle loses that ability, exposing the joints.

So those who are training for performance may struggle because of a muscle fatigue issue – the muscle is working differently, and harder in certain muscles, when barefoot, and that may be limiting.

Finally, Pete Larson at Runblogger has an epic post where he takes on the outspoken Asics researcher Simon Bartold (who I interviewed a few years ago for this article), with the discussion continuing in the comments section. What’s funny to me here is that I think the two of them are in pretty close agreement about the current state of evidence for (and against) normal and minimalist shoes — which is to say, there’s some suggestive biomechanical data but a complete dearth of convincing epidemiological or interventional data in either case.

The difference is in where they see the burden of proof. Bartold seems to hold minimalist advocates to a higher standard of evidence than he holds “current state of the art” shoes with a raised heel. Pete takes the opposite view:

Since evidence seems to be a popular word in this discussion, what evidence is there that this [shoes with raised heels] is safe? Shouldn’t the burden of proof be on the company making the product to show that it’s safe for the consumer? Isn’t this what drug companies have to do?

This is similar to what Blaise Dubois told me when I spoke to him a few months ago. But I’m not sure I fully buy that. Even if you accept all the evolutionary arguments marshalled in favour of barefoot running, I don’t think it necessarily trumps the experience of recent decades. Say you claim that sleeping in stuffy, poorly ventilated houses leads to respiratory infections, so we should sleep in the trees the way our ancestors evolved to do over hundreds of thousands of years. It might be true. But I’m not going to immediately give priority to a claim based on evolution (even if backed by logic and anecdotal support) and ignore the practical experience over the past few decades of people with whom I have a lot more in common than cavemen. These “modern” running shoes have been out there for the past ~20-30 years — and in that time, I’d bet that more people have run more miles successfully than in the previous couple of millennia cumulatively.

That doesn’t mean the shoes are “good,” or that we shouldn’t be eagerly and actively pursuing alternatives — just that they’ve earned a position as the default option, to be supplanted when something else is shown to be demonstrably better. If we’re using the lingo of drug trials, they’re the current “standard of care” that experimental treatments need to exceed in order to be adopted.

The priming effect: how a hard warm-up can help performance

May 9th, 2011

Most people who do hard interval sessions will have noticed this mystery: why does the second or third interval usually feel easier than the first one? I always figured it had to do with “getting into the rhythm” or something along those lines. Whatever the reason, Pete Sherry — my main training partner for 2002-2004 — and I eventually decided that we’d run 2x400m in ~72 sec a few minutes before every workout, in the hopes of making the first interval feel easier. Our impression was that it worked, and we started doing it before races too.

It turns out there’s plenty of physiology behind this. If you suddenly start running at a hard pace, with no warm-up, it takes a while before your body can adjust to start delivering oxygen to your muscles at its maximum possible rate. That’s one of the reasons VO2max tests take 10-12 minutes, rather than simply involving a short, all-out sprint. It takes time for the blood flow to your muscles to increase, and for the enzymes that extract oxygen from the blood and oxidize fuel to ramp up their activity levels. A good warm-up gets this ramp-up process over with, allowing your body up to deliver more oxygen to muscles right from the start of the workout or race, and reducing the temporary oxygen debt.

Still, most people warm up with gentle jogging, flexibility drills, and some short sprints. But how about including a six-minute “hard” effort (above lactate threshold but below VO2max pace), about ten minutes before the start of your race or workout? Would that “prime” your oxygen kinetics even more? The challenge is as follows: a sustained burst of hard exercise (above threshold) definitely improves how quickly your body can process oxygen once the actual race starts; this effect can last for a half-hour or more. If you exercise too hard, on the other hand, you deplete your anaerobic energy stores (phosphocreatine), and metabolites build up in your muscles that may slow you down. Numerous experiments over the past decade have found conflicting results: depending on the precise details of the duration, intensity and recovery time following the “priming” burst, performance either increases, decreases, or stays the same.

A new cycling study just posted online at Medicine & Science in Sports & Exercise, from Mark Burnley’s group at Aberystwyth, adds some more data on finding the right balance. They used a six-minute priming bout, 10 minutes before the “race” — a formula that other studies have found to be effective. For intensity, they compared “heavy” (about 25% of the way between threshold and VO2max power) and “severe” (about 63%) priming bouts. The findings: “heavy” priming boosted oxygen kinetics and significantly increased time-to-exhaustion in tests ranging from ~2-10 minutes. “Severe” priming also boosted oxygen kinetics, but didn’t increase time-to-exhaustion, suggesting that the downside of depleted anaerobic reserves outweighed the benefits of more aerobic energy available early in the test.

So what does this mean in practical terms? It’s hard to know how generalizable this protocol is, but I’d say it’s worth experimenting with some sort of extended surge ~10 minutes before the end of your warm-up. If you’re doing a six-minute effort, it looks like you should aim just above your threshold. I know quite a few runners who have incorporated similar but shorter surges of ~1-2 minutes into their warm-up routine. There may be a good argument for runners to stick to shorter surges, since the impact of leg-pounding is a bigger factor than it is in cycling. In that case, you may be able to get away with a higher intensity. But so far I don’t think the research has answered that question — for now, it’s trial and error.


Running stride analysis of top marathoners at Boston

May 6th, 2011

Just got around to reading Pete Larson’s very cool analysis of the strides of the top four men and top four women from this year’s now-legendary Boston Marathon, using high-speed (300 fps) video. He looks at a bunch of parameters, including footstrike and cadence. The “secret” to running 2:03 isn’t, unfortunately, revealed — but there are some very interesting nuggets. For example, Ryan Hall has the slowest cadence of the eight runners, at 174 steps per minute, while Desiree Davila has the fastest, at about 195. The post is definitely worth a read, as are Amby Burfoot’s thoughts on Pete’s data.

And analysis aside, the videos themselves are pretty neat to watch. Kudos to elvin314!

What’s the ideal running stride to avoid injury?

March 27th, 2011

This week’s Jockology column in the Globe revisits a familiar question:

The question

Is there an ideal running stride, and can I learn it?

The answer

You may think running has more in common with day-to-day functions like breathing and eating than with more technical sports like golf or swimming: As kids, we learn how to run with no special instruction, just as our ancestors have for millennia. The result?

“Most people run very badly,” says Blaise Dubois, a Quebec City physiotherapist whose multi-day course on the prevention of running injuries has been drawing sellout crowds of health professionals, coaches and running enthusiasts around the world… [READ THE REST OF THE COLUMN]

I had a really interesting interview with Blaise Dubois for this article. We spoke for nearly 90 minutes — so of course, only a tiny fraction of the discussion made it into this article. Hopefully I’ll have time at some point in the next few weeks to go through my notes and write a blog post about some of the other things we talked about. Hat tip once again to this post from Pete Larson’s blog that convinced me to get in touch with Blaise.