Archive for November, 2011

Running “is so prone to these sorts of trends”

November 15th, 2011

I don’t mean to fixate on the topic of running form, but I just want to recommend Gina Kolata’s piece in today’s New York Times, which reads a lot like a response to Chris McDougall’s recent piece (and echoes much of what I wrote a couple of days ago). Her basic point: people are desperate for advice that will “explain” how to run, when in reality the biggest is barrier is simply that running is hard (especially for people who have been inactive for years) and takes more time to adapt to than most people expect.

Researchers who have no financial ties to running programs or shoe manufacturers say that most of those complications are unnecessary and some of the advice is even risky, because it can make running harder and can increase the chance of injury. […]

“There is good evidence that your body is exquisitely lazy and will find the easiest way for you to run,” said Carl Foster, professor of exercise and sports medicine at the University of Wisconsin-La Crosse. […]

Running form is just one example of the confusions buffeting beginning runners. Running, said John Raglin, professor of kinesiology at Indiana University, “is so prone to these sorts of trends.”

People “will latch onto anything,” he added, and an anecdote or two about what is supposed to be an ideal running form often passes for evidence.

Kolata’s articles can sometimes seem a little nihilistic, as she writes about the surprising lack of evidence for very common treatments in sports medicine and physiotherapy, and common practices like warming up. The point isn’t that we shouldn’t do anything that isn’t “evidence-based” — life is complicated, and we inevitably have to make lots of decisions armed only with imperfect knowledge. But we should be aware of that, and not mistake our current guesses and hypotheses for “the one true way.”

Marathons and the female heart

November 15th, 2011

Is marathon running good or bad for your heart? That question has become a hot topic over the past few years thanks to a few studies showing negative effects like heart scarring and artery hardening in veteran marathon runners. One of those studies was a conference presentation last year that looked at 25 male runners who had each completed the Twin Cities marathon 25 years in a row. Compared to matched controls, the runners had greater plaque volume in their coronary arteries.

Now the same group of researchers has followed up with a similar study of 25 female runners who have run a marathon each year for the past 10 years. In this case, the result (as presented at the American Health Association conference) is exactly the opposite: the runners have fewer coronary plaques than matched controls.

So what to make of this? Neither study has been published in a journal yet, so it’s difficult to analyze the results in detail. It’s possible that the conflicting results are simply a result of the fact that the male marathoners were older, on average, that the female marathoners. Or it may be a physiological gender difference. Or it may have something to do with training history. Or it may be a complete fluke: in the male group, the key difference in the plaque volume was 274±176 vs. 169±170. Those are rather large ranges of uncertainty.

But the real question is none of the above: it’s whether these findings about elevated risk factors translate into compromised health. So far, I’m not aware of any study that links marathon running, or any form of endurance exercise, to elevated risk of death (or any other serious ailment) from any cause. That doesn’t mean such risks don’t exist (they could easily be hidden by the overall positive effect of exercise’s other health benefits). Still, as I wrote in the Globe and Mail a few months ago (and probably reflecting my “wishful thinking” bias), I can’t bring myself to get too worried about these apparent risks in the absence of any direct evidence. As Amby Burfoot wrote, “show me the bodies in the streets.”

Exercise -> serotonin -> antidepressant

November 14th, 2011

It’s well-established that exercise can be a powerful tool against depression (as Gretchen Reynolds wrote about in the New York Times a few months ago). What’s less clear is how and why it might help. A new study in  Medicine & Science in Sports & Exercise, from researchers at the University of Sherbrooke, offers some evidence for the theory that exercise can boost serotonin levels in the brain. This, of course, is pretty much the same as what the most common antidepressants (SSRIs: selective serotonin reuptake inhibitors) do.

The study was pretty straightforward. They had 19 men with an average age of 64 perform a 60-minute bout of exercise at moderate intensity (average HR 129 beats per minute, 68% VO2max). Then they measured several proxies of serotonin production, since it’s very difficult to directly measure neurotransmitters in the brain. The result: levels of tryptophan — the key precursor which is converted into serotonin — roughly doubled.

Is this a surprise? There was previous evidence in studies of rodents and younger humans that exercise boosted tryptophan availability, but it wasn’t clear whether the same effect would occur in older adults. This is particularly important because we become increasingly susceptible to depression as we age, suggesting that some of the mechanisms that help us ward off depression stop working quite as well.

Of course, one of the problems with “prescribing” exercise as a depression treatment (as Reynolds notes) is that once you’re depressed, it can be extremely difficult to summon the motivation needed to maintain a regular exercise program. Still, this study suggests that exercise might help to prevent depression in the first place, particularly as you get older.


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.


Asker Jeukendrup on Gatorade and Geb

November 10th, 2011

While I was in New York earlier this week, I had a chance to chat with Asker Jeukendrup, the new “global senior director” of the Gatorade Sports Science Institute. After Amby Burfoot’s wide-ranging interview with him in September, I was curious about what that would mean both for his research and for Gatorade — which, as I wrote about in a Globe article back in 2009, had seemed to be moving away from evidence-based science and toward marketing gimmicks like adding theanine to “improve focus.”

So, after our conversation, I’m now at liberty to reveal… well, nothing. Asker promises that the Gatorade formulas will change, possibly in the short term but certainly in the medium term as new research directions yield results. What those research directions are he wouldn’t reveal, but he emphasized a shift from hydration to the full spectrum of performance nutrition. Two key focuses: energy delivery and recovery. What does this mean? His previous work on “multiple transportable carbs” (which he made famous for PowerBar) showed that the bottleneck for athletes trying to get carbs to their muscles is getting the carbs across the intestinal wall. My totally uninformed guess is that he’s looking at novel ways (different types of carbs? different molecular structures? different ratios?) of getting carbs across that barrier more quickly.

One other interesting nugget. A few months ago, I blogged about a study that included an unverified claim that Haile Gebrselassie lost 10% of his body mass due to dehydration during his world record marathon run. Jeukendrup has worked extensively with Geb — and though that data is confidential, I pressed him a bit about this claim. He confirmed that the 10% figure was reasonable. Geb’s a very small guy who’s capable of working at an inhumanly high work rate for an extended period of time. The result: he generates a huge amount of heat, and thus sweats a lot, likely more than two litres an hour. It’s not practically possible to drink anywhere near this much at world-record marathon pace, so Geb loses a ton of weight.

So the obvious question is: does this rather severe level of fluid loss hurt Geb’s performance? Jeukendrup’s guess: no. The primary mechanism through which dehydration might hurt performance is through reduced blood volume forcing the heart to work harder. But you can compensate for reduced blood volume to some degree: for example, your veins (which return the oxygen-depleted blood to the heart) contract, effectively shortening the circulatory loop. Geb’s example doesn’t prove anything either way — obviously it’s possible that he’d be a 2:02 guy if he drank more. But it’s hard to argue with a world record, unless we have some compelling reason to think that dehydration held him back (and I can’t think of one).


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.

Stats 101: interpreting medical studies

November 8th, 2011

I have a new article over at the Men’s Health website that tries to explain a bit about how the process of “statistical adjustment” works in large observational studies, and what some of the pitfalls are. My favourite example from the piece: a 2009 study of over half a million people that found that red meat intake is associated with increased risk of death — even after “adjusting” for potentially confounding factors like age, education, race, BMI, smoking, exercise, vegetable consumption and so on. Needless to say, that study got lots of press at the time. But when you dig into the study’s stats (as Stanford prof Kristin Sainani pointed out to me), you find out that red meat also increases your risk of sudden accidental death from causes like car crashes and guns!

“Unless red-meat eaters are swerving to avoid cows, that doesn’t make any sense,” Sainani says. Instead, the most likely explanation is that red-meat eaters take more risks in other areas of life. But the study didn’t collect any data on the driving habits and gun collections of its volunteers, so the researchers were unable to adjust for these factors—and as a result, the conclusions were skewed.

Another interesting nugget is a rough estimate of the size of effect needed to be fairly sure you’re not seeing the effects of residual confounding, according to statistical simulations:

Bad data can easily generate an apparent risk increase of up to 60 percent, according to a research paper on statistical adjustment published in the journal PM&R. Effects bigger than that are very difficult to explain without serious errors in the design of the study.

Anyway, check out the whole article for more!

After New York: how did marathoners get so fast?

November 7th, 2011

Another major marathon, another jaw-dropping course record — pretty much what we’ve come to expect in 2011. Geoffrey Mutai’s 2:05:06 at yesterday’s New York Marathon, a course record by 2:37, continues the string of unbelievable performances from Boston, London, Berlin, Frankfurt and so on that have redefined our (or at least my) perceptions about what’s humanly possible at this distance. For a great post-race look at what’s going with the marathon, check out David Epstein’s piece at Sports Illustrated (and for more background, read Ross Tucker’s Science of Sport piece from last week).

Epstein gives a nice overview of the various forces that are converging to give us all these 2:03 marathoners — most obviously money (more of it in marathons, less of it on the track), which is bringing talented runners to 42.2K earlier in their careers. But I just wanted to highlight two quotes from his piece. First:

“I think people are starting to figure out the training and physiology better,” said American Dathan Ritzenhein, who made his marathon debut in New York in 2006 at the age of 23 and finished ninth in the Olympic marathon in ’08.

And second (on the topic of whether all these runners moving to the marathon at a young age will end up having shorter careers than guys like Geb and Tergat, because of the inevitable physical toll of the distance):

Krista Austin, a physiologist who works with pro runners, thinks that this generation of young Kenyan marathoners will have a shot at long careers because “the Kenyans are just starting to do some of the basic [injury prevention] things, like stretching and massage and Pilates.”

The juxtaposition of these two quotes made me smile a bit. One on hand, Ritz saying that marathoners are getting faster in part because of greater understanding of physiology. On the other hand, Austin is correctly pointing out that the runners who are most obviously the fastest (the 20 fastest male marathoners of 2011 are ALL KENYAN) are barely taking advantage of even the most rudimentary suggestions of sports science. If we’re judging by results, we might want to think carefully about which approach we emulate!

Obviously it’s a very complex issue, and I won’t even get into the whole genes/environment question. But in addition to money, I think Epstein (citing Gabriele Nicola, the Italian coach of several of the top Kenyans) nails a vital point:

If one person can run fast, well, dammit, you can train or race with them, and you can, too. As much as we might say this is “in your head,” if it’s in your head, it’s in your body, at least within limits.


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?

Dehydration in the lab vs. the real world

November 3rd, 2011

The “right” amount of hydration during exercise is a hot topic these days. For years, lab studies showed that if you forcibly dehydrate someone and then stick them on a treadmill, their performance suffers. But more recently, “real-world” studies (like the one I blogged about here) have shown that in many cases, the fastest finishers in races tend to be the most dehydrated. The difference, according to researchers like Tim Noakes, is that in the real world your brain is able to make pacing decisions that keep your body in a safe state (using the thirst mechanism); on a treadmill at a fixed pace in a lab, your brain is cut out of the loop.

The result is that there are two bodies of research — lab and field — that appear to be answering the same question (how much should we drink?) but that produce completely different answers. So it’s nice to see a study from the “lab” camp that tries to bridge this gap by doing some experiments on an outdoor trail run. Researchers from the University of Connecticut had 14 runners perform two 12K trails runs, one in a hydrated state and the other in a dehydrated state. Here’s what they found:

Pretty straightforward, right? The runners were slower when they were dehydrated. As expected. Case closed. And we should disregard those inconvenient studies that found that faster runners in real races are more dehydrated, according to the researchers:

Although some field studies have found runners to be extremely successful despite considerable body fluid losses, these runners were not compared with a control condition where these same runners remained more optimally hydrated. Therefore, one cannot conclude that performance in these elite runners may have been enhanced if they had maintained or at least attenuated some of their fluid losses while racing.

But hang on a sec. Does this new study really offer valid “field” conditions? Not quite. It may have been conducted outdoors, on nice trails in a local state park, but it nonetheless managed to reproduce all the usual problems of lab studies. First of all, the runners weren’t freely paced: they were instructed to run at a set heart rate, which imposes a rather arbitrary limitation. So they didn’t go slower because they were unable to keep the pace, but because they weren’t allowed to increase their heart rate. More importantly, the dehydrated runners weren’t allowed to drink or eat “high water content foods” for 22 hours before the test run! The result:

So what can we conclude from these results? If you subject volunteers to a punishing dehydration regimen before your experiment even starts, their performance will suffer. This is very important to bear in mind next time you’re stranded in the desert. But as for how much water you should drink during your next run, this study has basically nothing to say.

(I should point out that the researchers did measure a number of other physiological parameters in the study, like gastrointestinal temperature. This is useful data. They also argue that holding heart rate steady is useful because it’s “similar to how a cross country or track coach may advise their athletes to maintain a certain intensity level during a run.” Sure, I guess. But if that’s what they’re measuring, then why are they using the results to make claims about what happens in real-world marathons, where nobody starts after a full day of dehydration?)