Month: September 2011

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Sports medicine: evidence-based or sales-based?

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- Alex Hutchinson (@sweatscience)

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Great article by Gina Kolata in the New York Times on the challenges facing sports medicine doctors, and lack of evidence-based medicine that sometimes results:

[…] Patients “see a high-profile athlete and say, ‘I want you to do it exactly the same way their doctor did it,’ ” said Dr. Edward McDevitt, an orthopedist in Arnold, Md., who specializes in sports medicine.

The result is therapies that are unproven, possibly worthless or even harmful. There is surgery, like a popular operation that shaves the hip bone to prevent arthritis, that may not work. There are treatments, like steroid injections for injured tendons or taping a sprained ankle, that can slow the healing process. And there are fads, like one of Ms. Basle’s treatments, P.R.P., that soar in popularity while experts debate whether they help.

All this leads Dr. Andrew Green, a shoulder orthopedist at Brown University, to ask, “Is sports medicine a science, something that really pays attention to evidence? Or is it a boutique industry where you have a product and sell it?”

“For a lot of people it is a boutique business,” he said. “But are you still a doctor if you do that?”

The article focuses on platelet-rich plasma (PRP) therapy, since it’s a perfect example of the hype-before-evidence phenomenon that’s so common in sports medicine. Kolata discusses the mishmash of conflicting evidence, and the reasons the treatment seems plausible. But she also points out the inevitable conflicts of interest from some of the scientists whose evidence is used to support PRP:

They included Dr. Allan Mishra, an orthopedist in private practice in Menlo Park, Calif., who is supported by and gets royalties from one of the P.R.P. equipment makers, Biomet, and is on the board of directors and owns stock in another company, BioParadox, which is exploring the treatment for cardiovascular disease.

Dr. Mishra says more research is needed but offers the treatment for a variety of injuries. His Web page includes a TV news video that claims P.R.P. cured a Stanford football player, James McGillicuddy, with a torn knee tendon. On the program, Dr. Mishra says that, in general, 90 percent of the patients he treats “get better and stay better” after the treatment.

Wow, 90 percent success rate! Too bad he didn’t publish those results, because that’s not what any of the studies say. It sounds more like he “has a product and is selling it” — and unfortunately, that’s all too common with “breakthroughs” in sports medicine and physiotherapy.

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Mental fatigue and “armchair marathon training”

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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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As I mentioned earlier, I went to a conference called “The Future of Fatigue in Exercise” a few weeks ago. One of the researchers I was most interested in hearing from was Samuele Marcora, now at the University of Kent, who has produced a bunch of interesting results on the role of mental fatigue in physical performance over the past few years. For this week’s Jockology column in the Globe and Mail, I wrote about Marcora’s theories and his latest research:

“Improve your marathon time while sitting at your computer” is the kind of claim you expect from an infomercial or a spam e-mail, not from the keynote speaker at an academic gathering.

“It sounds crazy,” Samuele Marcora admitted during his talk at a conference on fatigue at Charles Sturt University in Australia last month, “but it’s actually not.”

Dr. Marcora, a professor at the University of Kent’s Centre for Sports Studies in Britain, has spent the past few years unravelling the surprising links between tired brains and physical performance. His initial results suggest that what we perceive as physical limits are actually highly dependent on our levels of motivation and mental fatigue – and that we may be able to use this fact to our advantage. […]

READ THE WHOLE ARTICLE HERE.

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How long does jetlag affect physical performance?

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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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Athletes have to fly to competitions — it’s an inevitable part of international sport. But flying long distances can hurt performance. There are lots of “rules of thumb” that people use to plan travel and competition (e.g. allow one day of recovery for each time zone crossed), but not a lot of hard evidence. Australian researchers have just published a neat study in the European Journal of Applied Physiology that sheds a little light on this question.

The study looked at five members of the Australian skeleton team before and after a flight to a training camp in Canada that took 24 hours and involved four different flights (so a pretty brutal travel schedule, but not that rare for athletes). Two days before they left, they did a bunch of power tests: box drop jumps, squat jumps, and countermovement jumps. Once they arrived in Canada, they repeated these measurements daily for 11 days. Some Canadian skeleton athletes (who didn’t have to fly) also did some of the tests as a control.

The data, frankly, is pretty messy. Performance clearly drops after the flight, but the various measurements aren’t perfectly consistent about when the biggest drops come and how quickly performance returns. Here’s a bit of sample data, showing the squat jump height. The two squares (instead of circles) are the Canadian controls — they basically just show that there’s not much day-to-day variation in the measurements for non-jetlagged athletes:

So what’s going on? The researchers believe that it’s not just being cooped up in a plane for a day that causes the problems:

We would contend that a symptom of jet lag is circadian misalignment and as such the performance declines that we are reporting are the result of circadian misalignment due to trans-meridian flight.

Seems fairly reasonable. The solution:

This research highlights that where possible, athletes performing explosive short duration efforts as part of a competitive environment should time their arrival in the destination country following long haul travel at least five days prior to the competition.

This I’m a little more skeptical about. Looking at the data, it’s hard to see any particular break point after five days. That being said, in the balance between leaving too little time to recover versus arriving too early and being out of your element for too long, five days does seem like pretty good common sense.

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Exercise intensity is more important than duration

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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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This is a really interesting graph:

It comes from a study called the Copenhagen City Heart Study, which followed a random sample of about 12,000 people in Copenhagen for 21 years. This particular data (which was presented at the European Society of Cardiology conference last week) looked at the cycling habits of the subjects, teasing out the separate effects of how hard they typically cycle and how long they spend cycling on a typical day. What you see is that it’s all about intensity: men who typically cycled “fast” (as subjectively determined by self-report) lived 5.3 years longer than those who cycled “slow,” whereas duration had no significant effect.

Since this is just a conference presentation, I don’t have full details on the data and analysis. Obviously there are likely to be some correlations in action — people who are unhealthy for whatever reason are likely to cycle slower and die earlier. That being said, the results were corrected for “age, gender, number of other sports activities, BMI, systolic blood pressure (including antihypertensive medication), HDL-cholesterol, smoking, income, alcohol-intake and diabetes”. Here’s the comparable data for women:

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Heart arrhythmias and endurance sports

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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)

***

I’m starting to really dislike these jerks who keep studying Swedish cross-country skiers and producing findings that conflict with my worldview… First it was arthritis; now, the researchers studied 47,000 people who participated in the 90-km Vasaloppet ski race in Sweden between 1989 and 1998, looking for associations between the number of times they participated in the race and the odds that they were subsequently diagnosed with arrhythmias (a task made possible by Sweden’s comprehensive national health records). The result (according to a press release describing a conference presentation; the findings haven’t yet appeared in a peer-reviewed journal):

Compared to those who had completed one single race, those who had completed 7 or more races had 29% higher risk of a subsequent arrhythmia. Further, elite athletes finishing at 100-160% of the winning time had 37% higher risk of arrhythmias than recreational athletes finishing at more than 241% of the winning time.

Leaving aside the quibble that “elite” is a bit generous for someone finishing at 160% of the winning time, the findings seem to suggest pretty clearly that extensive endurance training increases the chances of arrhythmia. The biggest differences were found in subjects under 45, and were exclusively associated with atrial fibrillation and bradyarrhythmias, which are considered less serious than the “potentially lethal” ventricular arrhythmias, according to the researchers:

Dr. Andersen summarizes: “Basically, this study shows, that even though physical activity is generally healthy, athletes committed to endurance sports at elite level have higher risk of suffering from a heart rhythm disorder… We emphasize that we do not find any increased incidence of potential lethal heart rhythm disorders. However, this study only compares athletes at different levels and a future large scale study comparing athletes against the normal population would be very interesting.”

The last point is interesting. It does seem increasingly clear that training as an elite endurance athlete is more likely to have an impact on the heart than training at a recreational level — but what about compared to sedentary life? Is this a linear relationship, or a “U-curve” where moderate training produces the best results?

Bottom line: although the press release skips some relevant details (like how common were these arrhythmias in absolute terms?!), I don’t think this changes my risk-benefit assessment. It’s like the well-known trade-off for exercise of any sort: your chance of a heart attack rises temporarily during extreme exertion, but your overall odds of heart attack decline with exercise. In this case, it’s worth bearing in mind the findings from previous studies of the same race: the more Vasaloppets you do, the longer you live. So whatever the downsides of arrhythmias, they’re evidently outweighed by other benefits.