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Posts Tagged ‘injuries’

Can biomechanical analysis cure Dathan Ritzenhein’s injuries?

July 21st, 2010

Dathan Ritzenhein just announced that he’ll be running the New York City Marathon this November, joining a stacked field that already includes Haile Gebrselassie and Canadian hope Simon Bairu. One thing that jumped out at me from the press conference (as reported by Letsrun) was his coach Alberto Salazar’s assertion that Ritz’s injury problems are a thing of the past thanks to some high-tech analysis:

“Gordon Valiant – the head of biomechanics for Nike – did an evaluation of Dathan and was able to find some things that are unique to Dathan with the way he runs and strikes his foot. With that (study completed), we now have some modified inserts. I wouldn’t call them orthotics – just an insert into the shoe where he has an abnormal amount of force near his third metatarsal. It seems to have alleviated his symptoms completely and we’ve retested him in the lab and shown those forces have been lessened tremendously.”

For those who’ve been following the barefoot running debate, this should raise some flags. For years, critics of the big shoe companies have pointed out that measuring forces in a lab setting doesn’t necessarily equate to a change in injury rates. Australian minimalist advocate Craig Richards said as much in an article I wrote back in 2008:

“Shoe researchers and manufacturers will try and bamboozle you with the results of hundreds of biomechanical studies,” [Richards said]. While these studies tell you how your stride is affected by the shoe, “they cannot currently tell you what this means for either the injury risk or performance of the wearer.”

Fair point — though, as I pointed out last month, minimalists are suddenly more enthusiastic about biomechanical studies now that Dan Lieberman and others have provided them with some studies of their own.

Anyway, we now have a study (with n=1) in which the manipulation of biomechanical forces in the foot is hypothesized to solve a longstanding injury problem. The outcome measure: whether Ritz makes it to New York in one piece, with an uninterrupted build-up. Here’s hoping!

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Platelet-rich plasma for muscle injuries

July 15th, 2010
Comments Off on Platelet-rich plasma for muscle injuries

The current issue of the British Journal of Sports Medicine has a couple of articles on platelet-rich plasma therapy, the experimental treatment that made headlines thanks to the Anthony Galea scandal and its links to Tiger Woods and other famous athletes. It’s most commonly used (in sports circles) for tendon injuries, but Kimberley Harmon of the University of Washington takes a look at the evidence for its use in muscle injuries (the full article is available for free at the BJSM site). Her conclusions are pretty much what you’d expect:

There is theory and preliminary evidence regarding the effectiveness of PRP, but its use is still investigational. It is incumbent upon physicians using this treatment to disclose its experimental status and to follow outcomes in a structured way. Further studies are needed to establish the effectiveness, indications and protocols for using PRP in the treatment of acute muscle injuries.

In other words, nobody really knows yet — but if you’re a pro athlete whose livelihood depends on getting that muscle or tendon fixed, it’s probably worth a try.

What I actually found most useful in the article was that it starts with a clear, detailed description of our current understanding of how muscles heal on a cellular level — the carefully choreographed sequence of platelets, growth factors, cytokines, neutrophils, and so on. This is a topic I was looking into recently during the research for another article, and I would have loved to find such a clear explanation.

(As an aside, she discusses the role of prostaglandin E2, which is affected by non-steroidal anti-inflammatory drugs like ibuprofen: “Recent studies have shown that NSAIDs likely tip the delicate balance of regeneration versus fibrosis toward fibrosis (scar).”)

Shorter strides are easier on your knees and hips

July 12th, 2010

Yet another study advocating shorter, quicker strides when you run has just been posted on the Medicine & Science in Sports & Exercise site. In this one, researchers at the University of Wisconsin had 45 recreational runners run on a treadmill at their preferred stride rate, then increased or decreased the stride rate by 5% and 10% (keeping speed constant, so a faster stride rate resulted in shorter strides and vice versa).

The results aren’t that surprising: Increasing stride rate by 5% or 10% reduced the mechanical energy absorbed by the knee joint by 20% or 34% for each stride. The ankle joint didn’t change much, while the hip absorbed significantly less energy only when the stride rate was increased by 10%.

Of note, the researchers point out:

[M]any of the biomechanical changes we found when step rate increased are similar to those observed when running barefoot or with minimalist footwear.

So you could read this as an argument for minimalism — or, alternately, you could conclude that you can get the benefits of going barefoot simply by shortening your stride.

Three caveats. First, if you shorten your stride, you’ll take more steps to cover the same distance. Last year, researchers from Iowa State used a computer model to predict that, for a 10% increase in stride rate, the benefits of gentler foot-strike outweigh the downside of taking more strides in reducing your stress fracture risk. Still, it’s hard to know whether this conclusion is generalizable to other injuries. Second, studies have found that deviating from your preferred stride rate makes running feel harder, though there’s conflicting evidence about whether it actually makes you burn more energy. So this tactic might be most appropriate, the researchers suggest, when you’re returning from an injury and reduced load is more important than efficiency. And third, the study — as with virtually all the studies in the ongoing Shoe Debate — is a kinematic one that makes big assumptions about the connections between joint forces measured in the lab and ultimate injury rates. No one really knows whether “a more flexed knee at initial contact with less peak knee flexion during stance” will translate into a lower injury rate.

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Weak hips cause runner’s knee

June 8th, 2010

I’m looking forward to going through the research presented last weekend at this year’s ACSM meeting. For starters, a study presented by researchers from the Indiana University found that hip strengthening exercises reduce or eliminate “patellofemoral pain” (“runner’s knee”) in female runners. This is an idea that has been gaining momentum over the past few years — I first heard about it back in 2007 from Reed Ferber of the University of Calgary’s Running Injury Clinic (and wrote about it here).

The Indiana study is pretty small — just nine runners, with the five who did the hip strengthening exercises lowering their pain score from 7 to 2 or lower (on a scale of 0 to 10) after six weeks of twice-a-week strengthening. The researchers are hoping to try the same program on a larger group of runners. Normally I wouldn’t get too excited about such a small study, but given that the idea is also being developed elsewhere (such as this study about hips strength and knee arthritis that I blogged about last year), it’s starting to look pretty interesting. I suffered through an extremely persistent case of runner’s knee a decade ago that kept me out of competition for almost two years, so I certainly wish I’d known about the possibility that hip exercises might help.

If you want to give them a try, here are Reed Ferber’s suggested hip exercises [pdf, 2 MB].

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National Magazine Award nominations

May 6th, 2010

If you’ll pardon a little self-promotion, the nominations for this year’s National Magazine Awards were announced last night, and I was thrilled to pick up three. Two of them were for my piece in The Walrus about the neuroscience of navigation and how using GPS may be affecting our brains.

The third was for a piece in Canadian Running on evolution, barefoot running and injuries, including some interesting thoughts from Chris McDougall, the author of the bestseller Born to Run. (The piece was written last spring, before McDougall’s book was released and rocketed the topic into the public conversation.) I included a brief excerpt from the piece in a blog entry last summer, but now the full piece is available online for the first time here:

The giant screen at the front of the lecture theatre shows, in gruesome detail, a dissected bare foot connected through tendons to ten different muscles in the lower leg, all pulling in slightly different directions. Benno Nigg, a renowned professor of biomechanics who co-directs the University of Calgary’s Human Performance Laboratory, is leading an audience of Australian academics gathered at the University of Sydney through a presentation titled “The Future of Footwear.” During almost four decades as one of the world’s leading athletic shoe researchers, Nigg has worked closely with major companies such as Adidas, Nike and Mizuno. But plotting the future of the running shoe, he now believes, may require a look to the past, at what worked for our ancestors.

“Look at all these muscles here,” he says, gesturing at the dissected ankle. He asks the audience to guess which of the muscles we need in order to walk while wearing a typical shoe. Only two of the ten are needed, it turns out: the tibialis anterior (shin) and the triceps surae (calf). “And all the other ones, you don’t need, because the shoes take over.” Nigg pauses to let his audience consider this piece of trivia, then poses the central question of his talk: “Is that a problem?” [READ ON…]

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Stretching is bad for power… and endurance running

February 11th, 2010

[UPDATE – March 24, 2010: for further info on this study, including an interview with the author, see this post.]

Among the latest batch of papers accepted for future publication in the Journal of Strength and Conditioning Research is one on the effect static stretching during warm-up on jumping performance, by researchers from the University of Milan. It shows that stretching before exercise makes you jump lower, more slowly, and with less force. Ho-hum, right? Anyone who cares about this stuff has seen these studies before.

(For the record, what’s new in this latest study is that it looks at different joint angles. We already knew that power from full knee extension — e.g. in sprinting from starting blocks or playing football — was reduced. Now we know other angles, like you might encounter in swimming, basketball, soccer and so on, are also compromised.)

But for many people, these studies don’t carry much weight. The typical attitude is summed up by running guru Steve Boyd on his excellent blog:

Although I hedge my bets by not making a religion of stretching, I count myself among those millions who are convinced on the pure level of “feel” that flexibility work enables them to run further and faster, and cope with injuries better. And I think one day science will discover the secret of what many runners “know” deep in their fibers.

And to be fair, most of the existing studies look at explosive power rather than endurance. So I was definitely interested to see another study on the JSCR site that, for the first time, focuses on the effect of static stretching on endurance performance. (There was a study last year that found that less-flexible runners tend to have higher running economy, but it didn’t look explicitly at stretching.)

Lo and behold, stretching before a run makes you run more slowly and less efficiently.

The basic details of the study, which comes from Florida State University: 10 trained distance runners performed two one-hour runs, once with stretching before (four 30-second reps of five basic stretching exercises) and once without. The one-hour runs consisted of 30 minutes at a set pace (65% of VO2max) during which running economy was measured, then 30 minutes going as fast as they could to see how much distance they could cover. The non-stretchers burned ~5% fewer calories in the first part of the experiment, and ran 3.4% farther in the second part of the experiment.

I won’t get into the debate about what causes this. It may have to do with the energy storage abilities of floppy tendons, or the torque-producing capabilities of stretched muscles fibres; this study doesn’t address that. I’m also not making any pronouncements about the role of stretching in general — after all, it’s still very possible (though highly controversial) that a regular stretching program might reduce injury rates.

But I will say this. Static stretching may feel good (possibly in part because so many of us were brought up believing in it), but given the steady accumulation of evidence, you’d be a fool to keep it as part of your warm-up routine before a race. Or any type of athletic competition, for that matter, other that those where range of motion is a key factor, like gymnastics or hockey goaltending.

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Platelet-rich plasma therapy: just another placebo?

January 17th, 2010

“Platelet-rich plasma therapy” is a pretty hot topic these days, what with sports doc Anthony Galea (who has performed the technique on countless professional athletes) under the microscope because of a criminal investigation, and recreational athletes getting in on the action too. It’s a pretty simple concept: extract the patient’s blood, spin it in a centrifuge to concentrate the platelets (and ditch the red blood cells), then re-inject the platelets at the injury site (e.g. Achilles tendon, tennis elbow, other tendon injuries).

There have been some encouraging studies over the past few years, but a discordant note has just emerged in the Journal of the American Medical Association. Dutch researchers injected 54 patients with Achilles tendon problems, and followed up with them over the course of 24 weeks. Sure enough, the patients improved on measures of pain and activity level — the problem is, half of them were injected with a placebo, and there were no statistical differences between the two groups.

Needless to say, this doesn’t prove that the procedure doesn’t work. But it should throw a bit of cold water on hopes that it would be a miracle treatment.

Is physiotherapy useless?

January 9th, 2010

Gina Kolata has another debunking-conventional-wisdom Personal Best column in the New York Times, this time taking on physical therapy (or physiotherapy, as it’s known here in Canada). I’ve really appreciated some of her previous articles on stretching, cool-downs, massage, lactic acid, and so on. This one, I was less impressed by. She writes:

When I’ve gone to physical therapy, the treatments I’ve had — ice and heat, massage, ultrasound — always seemed like a waste of time. I usually went once or twice before stopping.

To me, this is sort of like saying “Yeah, I’ve tried antibiotics several times, but it never seems to work for me, so I always just take the pills for a day or two and then throw the rest away.” Any successes I’ve had with physical therapy tend not to be the “fix pain in two weeks” category, but more like “spend six months correcting some subtle weaknesses and imbalances in order to avoid repeating the injury you just had.” It’s a long-term investment.

That being said, the article has some interesting information about which treatment and recovery modalities actually have solid evidence behind them (not many). I’ve written about heat and ice and massage before — the fact is, if we limited ourselves to the modalities that have solid peer-reviewed evidence, we’d all just be lying in bed for a few weeks every time we got injured. So much as I like evidence-based medicine, I think we have to be realistic about the current state of knowledge.

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Running shoes are worse than high heels (unless you actually read the study)

January 8th, 2010

In the comments section of yesterday’s post, John Lofranco raised the topic of a subject that has been popping online and in newspapers over the past few days. You may have seen the headlines: “Running shoes are more dangerous than high heels” and so on. Here’s the press release, and here’s the full text of the study itself, “The Effect of Running Shoes on Lower Extremity Joint Torques,” by researchers at the University of Virginia. Here’s the key part of the press release:

In a study published in the December 2009 issue of PM&R: The journal of injury, function and rehabilitation, researchers compared the effects on knee, hip and ankle joint motions of running barefoot versus running in modern running shoes. They concluded that running shoes exerted more stress on these joints compared to running barefoot or walking in high-heeled shoes.

From what I can tell, this is solid research that suffered from the “broken telephone” effect, being successively distorted at each step. First, there’s the data they measured — useful stuff that sheds light on how our legs work. Then there’s the scientific paper, which in my opinion stretches the conclusions a little farther than the data currently warrant. Then there’s the press release, written by a PR person at the journal, which stretches things even further (the study, for instance, did not include any high-heeled shoes, and no direct comparisons between running shoes and high-heeled shoes were possible). Then there are the press articles, which rely on the press release… (There’s also this: “In July, [Kerrigan] left the University of Virginia to start her own company, JKM Technologies LLC, which will focus on developing her shoe in coming years.”)

Amby Burfoot of Runner’s World, in his Peak Performance blog, has written an excellent post in response to this study that is essential reading for anyone interested in running injuries and the role of shoes. As usual, it’s a nuanced point of view that neither praises nor buries the research. He points some of the leaps — the difference between measured torque in the knee and observing arthritis, the mismatched comparison between walking and running forces, the downplaying of the role of stride length. His main message is that this is a very complex field of research where little is known, so we should be open to new results but avoid gratuitous oversimplification. It’s definitely worth a read.

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Stress fractures: reducing stride length and the role of muscle

November 18th, 2009

A couple of interesting studies about stress fractures in the December issue of Medicine & Science in Sports & Exercise.

First, researchers from Iowa State University looked at the effect of stride length. Basically, the idea is that if you shorten your stride, you’ll have more footstrikes per mile (and thus more impact jarring your bones) but each footstrike will be a little gentler. So which effect predominates? The researchers had 10 runners run at their normal stride length, and with a 10 percent reduction in stride length, measuring the relevant forces with motion-capture cameras and force plates. They then used a computer model based on bone damage and repair mechanisms to estimate the risk of stress fracture for both groups. The conclusion: shortening your stride length by 10 percent reduces stress fracture risk by three to six percent!

The clinical implications for these results are clear [they write]. Those runners wanting to decrease their likelihood for stress fracture can do so by reducing their stride length by 10%. This reduction would also allow for runners to run an additional 2 miles [per day] and maintain the same [fracture risk].

In general, I’m not a big fan of trying to meddle with your running form, thanks in part to studies like the one I wrote about here. But overstriding is apparently a pretty common issue, and prominent coaches like Jack Daniels have advocated increased cadence (and thus shorter stride) as a way of running more efficiently. So maybe there’s something here…

In the same issue of MSSE, researchers from the University of Minnesota examined the bone strength and body composition of 39 female distance runners, (slightly less than) half of whom had a history of stress fractures. To nobody’s surprise, the tibia bones in the stress fracture group were smaller by seven to eight percent, and weaker by nine to 10 percent. What’s interesting, though, it that the bone differences were exactly in proportion to the size of the muscles in the same area, and there was no difference in bone mineral density. What this suggests is that the best way to avoid stress fractures is to make sure you have enough muscle on your legs — presumably by doing weights and (it goes without saying) eating enough.

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