Sweat Science

You’ve seen the news stories about races up various tall buildings like the C.N. Tower and Empire State Building… Now, in an upcoming issue of the Scandinavian Journal of Medicine and Science in Sports, you can finally learn all about the physiology of these races!

It’s actually a pretty interesting paper. The researchers (from the University of Milan) do a general analysis of 36 world stair-climbing records for buildings ranging from 48 to 421 metres high. They also collected a bunch of data from a specific race in Milan (up the Pirelli Building, a model of which is shown on the right), and compare their results to a mathematical model of stair-climbing.

The reason the sport is so well-suited to this kind of analysis is that stair-climbing is fairly simple, biomechanically speaking. We don’t store elastic energy in our legs with each stride — our main task is simply raising our centre of mass from the bottom of the building to the top. (To be precise, the researchers calculate that 80.4% of the energy expended by racers goes directly into counteracting gravity. Just 4.5% goes to accelerating limbs with respect to the body, and the remaining 15.1% goes into the turns between flights of stairs.)

So what’s the take-away message from this research? I’m not sure. Certainly this conclusion doesn’t sound too earth-shattering:

Our studies suggest that the best athletes are those who do not show any sudden speed change, and therefore that athletes must wisely dose their initial effort in order not to jeopardize the rest of the performance.

Still, reading the paper made me want to try one of these races. Apparently they demand a mix of aerobic and anaerobic energy, much like middle-distance running. And then there’s this:

Another attractive aspect relates to the presence, in most skyscrapers, of handrails that maximize the muscle mass involved and, consequently, the mechanical/metabolic power of the ascent, conferring the race with a feel of a global, maximal effort as in rowing.

“Global, maximal effort” — sounds like fun!

stair climbing

I’ve spent quite a bit of time reading the research on supplements over the past few years — and frankly, the more I read, the less inclined I am to use any. But there is one supplement I’m taking right now (having started a few months ago), and that’s vitamin D. I’ve heard enough enthusiasm from researchers I trust, and seen enough suggestive results, to decide that it’s worth a try — especially during the depths of a Canadian winter.

So why should I expect vitamin D to turn out any differently from all the other “miracle vitamins” that have preceded it and then been debunked? That’s the question that Tara Parker-Pope tackles in this entry on her Well blog. Her main point:

Although numerous studies have been promising, there are scant data from randomized clinical trials. Little is known about what the ideal level of vitamin D really is, whether raising it can improve health, and what potential side effects are caused by high doses.

And since most of the data on vitamin D comes from observational research, it may be that high doses of the nutrient don’t really make people healthier, but that healthy people simply do the sorts of things that happen to raise vitamin D.

Obviously, we need to figure these things out — which is where a new study comes in. The VITAL study is currently enrolling 20,000 older adults to take part in a five-year, placebo-controlled trial of vitamin D and omega-3 fatty acids. They’re looking for people all over the U.S. (no clinic visits are required, and all the pills will be mailed). If you’re interested, the details are here.

For now, I’ll keep taking vitamin D. But it’s worth remembering where the current research stands — and that many previous “miracle vitamins” have failed to pass the hurdle represented by the VITAL study.

supplements

I have to admit, I was very, very skeptical when I read this report in the New York Times about “performance mouthpieces” that would instantly boost strength, power, endurance, flexibility, reaction time and so on. Alarm bells ring for me when a researcher offers evidence like this:

Previously she “had been happy with running 10-minute miles,” she said, but wearing the mouthpiece, she consistently ran a mile in as little as 8 minutes. “It was pretty astounding to me,” she said. “I didn’t feel as tired as when I ran the 10-minute-per-mile pace.”

So I figured I’d look into the research behind the claims for a Jockology column, which appears today.

What I found was a surprise — in both directions. There was some surprisingly good research that suggests there may be a real effect here. And there was some surprisingly bad research that any company should be embarrassed to promote. The main research cited by Under Armour to back up the claims for its mouthpiece come from a special issue of the far-from-prestigious Compendium of Continuing Education in Dentistry. And not just any special issue — every article in the issue is written by someone who is either an employee or paid consultant of Bite Tech, the company that developed Under Armour’s mouthpieces. This is not research, it’s advertorial.

Here’s an example of what this means, as I describe in the Jockology piece:

The results are interpreted rather generously. What’s described as “a definite trend for lower cortisol” turns out to mean that cortisol levels dropped in only 11 of the 21 cyclists in the study – barely more than half. A follow-up study of runners in 2009 also failed to find any statistically significant change in cortisol.

On the other hand, there is a placebo-controlled, double-blinded crossover study, funded by Makkar Athletics, that found an increase in vertical jump and power in a 30-second cycling test. So, despite my skepticism, there may be something there after all…

sports technology

This is going to make a big splash. A paper by Dan Lieberman — the Harvard anthropologist who made headlines with the argument that long-distance running was a key evolutionary driver in humans — in tomorrow’s issue of Nature argues that barefoot running is better than modern running shoes. Here’s how the Associated Press is reporting this story:

Harvard biologist and runner Daniel Lieberman had a simple question: “How did people run without shoes?”

The answer he got is: Much better.

At least running barefoot seems better for the feet, producing far less impact stress compared to feet shod in fancy, expensive running shoes, according to a study by Lieberman in Thursday’s issue of the journal Nature. The study concludes that people seem to be born to run—barefoot…

What great timing, you might think. After all, it was just last week that I blogged about Mark Plaatjes’ thoughts on barefoot running — and two of his key statements, which I agreed with, were:

4. There are no clinical trials that show an effect of barefoot/minimalist running for a prolonged period of time.
5. There are no research studies that prove that wearing traditional running shoes increases injuries or that barefoot/minimalist running reduces injuries.

So does Lieberman’s study fill this gap? No. What he found is that his subjects strike the ground with three times more force when they’re wearing cushioned running shoes compared to running barefoot. This is reminiscent of the study that made waves a few weeks ago (which I blogged about here) that made the convoluted claim that running shoes are worse than high heels. What we’re dealing with in both cases is very indirect measures that may or may not have some connections to the outcomes that matter to us — i.e. pain and injury. I really don’t care how many Newtons of torque my patella is feeling if it doesn’t result in any injury or discomfort.

Now, I haven’t seen the study, so I’ll be very interested to read it when it comes out tomorrow. But given the current wave of popularity surrounding barefoot running, I have a sinking feeling that this is just the beginning of the storm — we’re going to see a whole bunch of studies coming out, accompanied by press releases and news stories, that capitalize on this interest without really telling us what we want to know. Hopefully there are also people doing the long, painstaking, prospective research that would really shed new light on this question.

I don’t mean to sound too skeptical here. I think a lot of what’s said about barefoot running makes very good intuitive sense. If I was growing a batch of test-tube babies to create a distance-running army, I’d probably have them avoid shoes during their formative years to develop the stride we see in Kenyan runners.

But most would-be runners in the Western world are not starting from scratch — and the question of what shoe makes the most sense for a middle-aged, overweight neophyte is still very much open. Even staunch minimalists would acknowledge that running barefoot isn’t an instant miracle cure. (”If you change the way you run quickly ‘you have a high probability of injuring yourself,’ Lieberman says. In general, changes either in running shoes or distance should be no more than 10 percent a week.”)

That may well be true. My feeling, though, is that most people who are REALLY cautious and patient enough that they never change their weekly running distance by more than 10 percent a week will find that they’re able to run successfully in almost anything. It’s like (bear with me here) buying a house to get the financial advantages. We can debate until we’re blue in the face whether owning or renting makes more sense — but for many people, buying acts as a “forced savings” mechanism, since they no longer have any disposable income to waste. Maybe barefoot running acts in a similar way: it forces runners to be cautious and build up very gradually — precisely the approach that works best no matter what you’re wearing.

barefoot running

To the scientist in me, this is a really interesting study. But to the athlete and fan in me, it seems like bad news. British researchers fed highly trained cyclists acetominophen (Tylenol, as it’s known around here) before a 10-mile time trial. It was a double-blind, placebo-controlled trial. The riders who were fed Tylenol cycled about 2% faster, and had higher heart rate and lactate production (i.e. they were working harder) — but their perceived exertion was identical to the placebo group’s.

To read more about the study and its implications, read this entry in Amby Burfoot’s Peak Performance blog, which includes a Q&A with one of the researchers. The basic interpretation is simple: Tylenol blocks pain, and pain is what makes us slow down during long races. This is an important scientific result, because it sheds light on a red-hot debate about the nature and origins of fatigue. The authors of the study view their results as supporting the “central governor” theory, which argues that our brain subconsciously makes sure that we never let our body get too close to its absolute limits.

This, of course, is not the main message that many athletes will take from the study. A 2% performance boost is nothing to sneeze at for the well-trained athlete, so I expect that many athletes will start experimenting with Tylenol in training and racing. Is this dangerous? I don’t really know. (Gretchen Reynolds wrote an interesting article last summer about the risks athletes incur by overuse of NSAIDs like ibuprofen; Tylenol is a different class of drug.) But I have to admit: whenever I see a study of a potentially performance-enhancing pill, I cheer when the results come up negative, because (in my view) it keeps the sport a little simpler.

cycling, supplements

Last fall, an excellent University of Georgia study failed to confirm the endurance-boosting effects of the supplement quercetin that earlier mouse studies had suggested. Now there’s a new study on quercetin from David Nieman’s highly respected lab at Appalachian State University, in the February issue of Medicine & Science in Sports & Exercise — and the news is mixed.

Reading the abstract, you might conclude the double-blinded crossover study was a success: they found “a small but significant improvement in 12-minute treadmill time trial performance” after two weeks of 1,000 mg of quercetin a day. Quercetin is a flavonoid that is thought to enhance the growth of new mitochondria, which is the most significant adaptation resulting from endurance training. So they also performed muscle biopsies, but these didn’t show a significant effect (though there were “insignificant increases”).

When you read the study closely, even the treadmill improvement is a disappointing result. An earlier study from the same lab had failed to find any improvement for well-trained cyclists in 5-, 10-, and 20-km time trials. So they hypothesized that the benefits of quercetin wouldn’t show up for well-trained athletes, who already have a high density of mitochondria. This study specifically enrolled sedentary young adults: the maximal exercise level permitted was 20 minutes, twice a week.

In other words, these were subjects ripe for LARGE improvements. What they found was an improvement of 2.9% in treadmill distance, while the placebo group actually got 1.1% worse. It is statistically significant (barely: P=0.038), but it’s hard to argue that it’s practically significant. For people this sedentary, an occasional walk around the block would have done more. An improvement of a percent of two is only really significant for elite athletes — precisely who this study wasn’t aimed at.

The authors acknowledge that the effect is far smaller than that seen in mouse studies, and they conclude that further research is needed with higher doses and longer study periods. This sounds like a good idea — but until those studies come in, the logical assumption is that quercetin doesn’t offer any practical benefit for people of any fitness level.

supplements

[1/27: For more on this debate, see here.]

Mark Plaatjes, the marathon gold medalist at the 1993 world championships and longtime physical therapist to running stars in Boulder, has posted his thoughts about the current fad for barefoot/minimalist running on Facebook. It’s an interesting read. He starts with five facts that (he says) no one would dispute:

1. Running barefoot/minimalist strengthens the intrinsic or postural muscles in the feet and lower leg.
2. Running barefoot/minimalist increases proprioceptive awareness and balance.
3. Running barefoot/minimalist forces a change in mechanics to adapt to the forces on the feet.
4. There are no clinical trials that show an effect of barefoot/minimalist running for a prolonged period of time.
5. There are no research studies that prove that wearing traditional running shoes increases injuries or that barefoot/minimalist running reduces injuries.

I’d agree with these statements.

He then discusses the distinction between “good” and “bad” heel-striking. People who overstride come crashing down on their heels, braking with each stride. This is bad. But it doesn’t necessarily follow that ALL heel-striking is bad — if you’re running with a short enough stride, so that your centre of gravity is above your heel when you land, that’s a perfectly good stride, Plaatjes says. In other words, not everybody has to become a forefoot striker, despite the claims made by minimalist advocates.

After that, the article starts to ramble a bit, and I’m less clear what his point is. He does make an interesting claim: that 65 to 75% of people are unable to run barefoot because they have inadequate foot structure and mechanics (and he can tell by looking at their feet). He starts to lose me here, since he doesn’t back up this statistic. But I think his first five points (which I quoted above) are a good starting point for any discussion of this issue — because if you disagree (particularly with points 4 and 5), you’ve probably bought some snake oil.

barefoot running, running

A belated note that the Jan.-Feb. issue of Canadian Running magazine is on newsstands now. My top picks for this issue: a hilarious back-page essay by Canadian miling legend Harvey Mitro on runners’ obsession with stopping their watches, and an interesting piece by nutrionist Matthew Kadey on which foods it’s worth paying more for, and which you can skimp on. (For example, he argues in favour of dark poultry meat — a policy I’ve long advocated in order to save $1.19 at Swiss Chalet!)

And, of course, there’s my regular Science of Running column, tackling hyponatremia, deep-water pool-running, “dynamic compression” technology, and other topics.

Canadian Running mag, nutrition

Ever since the sun-baked fiasco of the 2007 Chicago Marathon, there’s been renewed discussion about how to figure out when it’s unsafe to hold a major road race. In the February issue of Medicine & Science in Sports & Exercise, the medical director of the Twin Cities Marathon, University of Minnesota med school prof William O. Roberts, has an interesting analysis of this question — and he ends up with pretty conservative recommendations.

What’s interesting about his analysis is that he takes a population-level approach: instead of sticking a few representative subjects on a treadmill, he analyzes two large data sets. First, he looks at eight unexpectedly hot races that results in either mid-race cancellations or “mass casualty events” (where the number of patients overwhelms the medical resources available in a community), and calculates the “wet bulb globe temperature” (WBGT) at start time. He finds that WBGT above about 21 C (70 F) is an indicator of serious trouble for marathons at northern latitudes with participants who haven’t acclimatized to the unexpectedly hot weather.

Then he does a more specific analysis for the Twin Cities marathon, plotting the percentage of marathon starters who were either unable to finish or required medical attention as a function of WBGT. (The graph, along with the full text of the paper, is available here.) In this case, he finds that a start WBGT above 20.5 C (69 F) is trouble.

These conclusions contrast with American College of Sports Medicine guidelines allowing starts with WBGT up to 28-30 C (82-86 F) — guidelines based on tests of young military recruits. The key problems are (a) the average recreational marathon runner is not G.I. Joe, and (b) the participants in a northern (latitude greater than 40 degrees) marathon will be less prepared for a hot day than people who live in hot places.

This probably isn’t welcome news for race directors — no matter how hot it is, few participants are going to take kindly to a decision to cancel something they’ve spent months training for. But knowledge is good — and even if a race isn’t cancelled, this is the kind of information that runners themselves should take into account when they’re facing adverse weather conditions.

(A note on WBGT: it’s a scale that takes into account the effects of humidity and solar radiation, as well as air temperature, on humans. As a very rough rule of thumb, if humidity is above about 50%, WBGT will be higher than air temperature; if humidity is below 50%, WBGT will be less than air temperature.)

running

When you kick a soccer ball, it tends to go where you’re looking. The problem is that when you’re anxious, you tend to fixate on threats — the goalkeeper, in this case — and consequently kick it straight at him. That’s the message from an interesting University of Exeter study published last month, which I just noticed thanks to Dan Peterson’s blog.

The players wore special glasses which enabled the researchers to record precise eye movements and analyse the focus of each footballer’s gaze and the amount of time spent looking at different locations in the goal. The results showed that when anxious, the footballers looked at the goalkeeper significantly earlier and for longer. This change in eye behaviour made players more likely to shoot towards the centre of the goal, making it easier for the keeper to save.

The solution? “Research shows that the optimum strategy for penalty takers to use is to pick a spot and shoot to it, ignoring the goalkeeper in the process,” the study’s author says. And to do that, you need to practice, so that the skill becomes so ingrained it no longer requires conscious control, as discussed in this Jockology column.

mental, sports psych