running – Page 6 – Sweat Science

February 20, 2011

What do we actually KNOW about running injuries?

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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I’m a couple of weeks behind the curve on this, but I just wanted to highlight an excellent post by Pete Larson of Runblogger. He recently attended a conference/course on running injuries taught primarily by Blaise Dubois, and took the opportunity to write up a succinct list of 16 things we know about running injuries, ranging from the very basic to the fairly technical.

Part of the reason I liked it so much was that it was very balanced — not promoting big shoes, little shoes, or no shoes as the panacea that will cure everything. In fact, his fourth point is:

Most running injuries are overuse injuries that can be attributed to stubborn and obsessive runners doing too much too soon. In doing this, runners exceed their body’s stress threshold and something gives. The end result is an injury.

Just for kicks, though, I’ll quibble with one point. He writes:

One of the things that also came through loud and clear is that barefoot running is our default. It is how we evolved, and modern shoes are a change from that default. Thus, the burden of proof should be to prove that we are better off running in big, bulky shoes. People often seem to think that the notion that we should run in a way that emulates the barefoot gait is radical (whether actually barefoot or in minimal shoes), but in reality it’s what our species has done for nearly 2 million years prior to about 1970.

I understand the point, of course. But let me make a competing point: in the U.S. alone, according to Running USA, there were 25.559 million people who ran at least 50 times in 2009. Some 10.29 million of them finished a road race. They bought a total of 39.76 million pairs of running shoes. How many of those people went barefoot, or in minimalist shoes? I really don’t know — I wish I had the data. But I think it’s fair to say that the overwhelming majority of people who have grown up in a modern, western, convenience-filled, concrete-covered society and have taken up running without having relied on it as a primary form of transport throughout their childhood have done so wearing conventional running shoes. Does that mean barefooting or minimalism or forefoot striking is bad? Definitely not. But since we don’t have any answers yet, let’s be circumspect about applying the “burden of proof.”

Anyway, I’m just quibbling here. Pete’s post is great, and a must-read for anyone interested in the topic!

February 17, 2011

New explanations for runner’s high

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- Alex Hutchinson (@sweatscience)

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Gretchen Reynolds has an article in the New York Times about recent research into the origins of “runner’s high,” suggesting that endocannabinoids rather than endorphins might be responsible — in other words, the body’s internal version of marijuana instead of morphine:

But perhaps the most telling experiment was published last year by researchers in France who had bred mice with no functioning endocannabinoid receptors. Mice usually love to run, but the genetically modified animals, given free access to running wheels, ran about half as much as usual.

Reynolds is usually an excellent reporter, but I was a bit disappointed in the lack of context offered in this article. She dismisses the role of endorphins as follows:

Endorphins, however, are composed of relatively large molecules, “which are unable to pass the blood-brain barrier,” said Matthew Hill, a postdoctoral fellow at Rockefeller University in New York. Finding endorphins in the bloodstream after exercise could not, in other words, constitute proof that the substance was having an effect on the mind.

This is true, but German researchers published a study back in 2008 that was very widely reported (including in the Times by Reynolds’s colleague Gina Kolata) that directly measured the increase of endorphins in the brain after a two-hour run. Both Reynolds and Hill are undoubtedly familiar with this study, so it seems disingenuous to pretend that we don’t know anything about the link between exercise and endorphins in the brain.

Ultimately, the runner’s high is such a nebulous, ill-defined thing, meaning different things to different people, that it’s probably a combination of several different effects — endorphins, endocannabinoids, and perhaps other factors, including some straightforward psychological ones. So it seems silly to dismiss the “old” theory in favour of a new one when there’s no reason the two can’t coexist.

February 16, 2011February 16, 2011

Stride rate, running speed, and “cruise control” for runners

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- Alex Hutchinson (@sweatscience)

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A press release from Simon Fraser University in Vancouver reported a few days ago that a pair of biomedical physiologists have invented a “cruise control” device for runners. As far as I can tell, it’s basically a metronome that provides a beat for you to synchronize your strides with; it measures your speed (presumably via GPS) and increases the cadence if you’re going slower than your desired speed, and slows it down if you’re going too fast. Right now, it’s basically a clunky backpack prototype, but future versions might be, say, an iPhone app that provides music with a “sliding tempo” to keep you on pace.

Okay, so not a device I’d feel much need for, but I can see a potential market. One hesitation, though. The entire device is predicated on the following assumption:

“We know that for higher running speeds humans prefer higher step frequencies,” says Snaterse. “This relationship can be inverted – for higher step frequencies, humans prefer higher speeds. The cruise control for runners uses this principle.”

Is that really true? There’s a lot of dogma floating around the running world that running speed is essentially independent of stride rate — if you go for a jog and gradually pick up speed until you’re nearly sprinting, your stride length will get longer and longer but your stride rate will stay essentially unchanged. For example, check out this recent post from Amby Burfoot’s blog about the potential benefits of shortening your stride:

Most of us, when we increase pace, increase stride length much more than stride rate. So our stride rate stays roughly the same at different paces, slow and fast.

Now, that doesn’t necessarily mean the reverse is true. It’s possible that when you increase speed, your stride rate stays the same, but when you increase stride rate, you speed up. And there’s some evidence that other effects might crop up when people exercise while listening to music — for example, I wrote about a study where British researchers secretly sped up and slowed down workout music by 10% and people on exercise bikes sped up and slowed down without realizing what was happening. If we’re dealing with a cruise control that, by design, is intended to make only small corrections to your pace, maybe a small effect like that is sufficient.

What does the actual research say? It’s harder to dig up than I expected, partly because it’s such an “old” question that some of the relevant studies aren’t online. Here a description of an older (1974) study from a 2009 paper:

Saito et al. [27] showed that trained runners increased their speed to 7 m/s [2:22/km, 3:50/mile] by lengthening their stride, whereas untrained runners increased stride length only up to 5.5 m/s [3:02/km, 4:53/mile]; any further increase in running speed was achieved primarily by increasing stride rate.

In other words, you have to be sprinting pretty darn fast before you start increasing stride rate instead of stride length. Still there must be some better and more recent data out that show the typical relationship between speed and stride rate — if anyone knows where I should be looking, please let me know!

February 11, 2011February 13, 2011

Manipulating muscle tension to run faster

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- Alex Hutchinson (@sweatscience)

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[UPDATE Feb. 13: more detailed info on muscle tension research in this post.]

Steve Magness has an article in next month’s Running Times magazine called “Managing Running Tension,” in which he argues that we should aim to have loose, floppy muscles during easy runs to enhance recovery, and tight, tense muscles during hard workouts and races to get more “pop” in the legs. He suggests several ways to increase tension (sprinting, ice baths, running on hard surfaces, etc.) and several ways to decrease it (jogging, massage, warm baths, running on soft surfaces, etc.).

Runner’s World’s Amby Burfoot offers his take on the article on his Peak Performance blog: the take-away message, he believes, is that when you’re tapering before before a race, you should be wary of doing all your runs on soft surfaces lest you’re left with sub-par tension, and thus dead legs on race day.

It’s an interesting idea. Certainly, I’ve always marvelled at how incredibly dead my legs tend to feel on race mornings — a reaction I’ve always assumed was mental rather than physical, as my brain becomes hypersensitive to sensations of effort in anticipation of the supreme effort to come. Could muscle tension have something to do with it? I don’t know. I’d like to see some evidence to support the story. Do we know how to objectively measure muscle tension? Has anyone measured how it changes in response to things like running surface? I’d welcome pointers if anyone knows — because it sure would be nice to learn how to avoid that dead-leg feeling!

December 13, 2010

“Moderate” amounts of booze slow muscle recovery

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- Alex Hutchinson (@sweatscience)

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My latest column in the Globe takes on a topic of seasonal significance: alcohol and exercise. Researchers at Massey University in New Zealand have been doing some very interesting research about the links between alcohol and recovery from DOMS; and there are some other factors like glycogen replenishment and dehydration that come into play:

Earlier this year, researchers in New Zealand published a surprising study that found significant delays in muscle recovery when the subjects drank a “moderate” amount of alcohol after a strenuous workout. The findings join a little-known body of research suggesting that alcohol can sap your morning-after strength even if you’re not hung over.

The subjects in the new study did a series of leg exercises, then had 90 minutes to drink either straight orange juice or a mix of vodka and orange juice before going to bed. Over the next three days, the alcohol group didn’t report feeling any additional leg soreness compared to the OJ group – but their loss of strength in a series of tests was 1.4 to 2.8 times greater.[READ THE REST OF THE ARTICLE…]

(So that I don’t get accused of being a Scrooge, let me give away one of the article’s conclusions: truly moderate consumption, i.e. of a drink or two, shouldn’t have any effects on your recovery.)