Author: alex

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After the Toronto marathon

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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 back online after a very busy three days at the Scotiabank Toronto Waterfront Marathon. I spent Friday and Saturday at the marathon expo, where I gave a couple of Science of Running talks, sold some books, and had a chance to talk to a whole bunch of Sweat Science readers. Those of you who were racing, I hope your day went well and you weren’t too buffeted by the winds!

This morning, I had the opportunity to ride in the truck driving in front of the leaders. My plan was to ride until about 20K, then hop out to follow the Canadians for the rest of the race. As it happened, Reid Coolsaet foiled my plan by hanging with the Kenyan and Ethiopian leaders even though they went out at a sizzling sub-2:07 marathon pace. I figured I’d wait until he blew up — and given the splits of 30:16 (10K), 1:03:58 (21.1K) and 1:31:38 (30K — seven seconds faster than the Canadian 30K record, as it happens), I kept thinking that would happen any minute. But it never did. Despite fighting a brutal headwind for the last 7K or so, Reid held on for third place in 2:10:55, with his teammate Eric Gillis also dipping under the Canadian Olympic standard by exactly one second in 2:11:28.

It was an exciting and inspiring morning. And the best part about it was Reid’s seemingly crazy decision to go out on pace for a five-minute personal best. As Canadian Running magazine’s Scott Leitch recounts, it was a last-minute decision. In fact, he was lying in bed last night, unable to sleep, mulling over the long-established plan to go through halfway in 1:04:40. Finally, he headed downstairs to the hotel bar to find his coach, Dave Scott-Thomas, and said:

I don’t want to sound stupid, but I want to get up front and mix it up. And I want you to tell me if that’s insane or not.

Scott-Thomas asked him how he felt. Reid said, “I feel great.” And that was that. In the end, it was a smart decision given the weather conditions. He was able to shelter in the lead group for nearly the whole race, whereas he would have been all by himself in the wind had he gone out at a more conservative pace. And it leaves Canadian running fans wondering: what will he run when he gets a shot under better conditions?

It was very difficult to get a clear shot from the media truck, but here’s a couple of minutes of footage from the start, the 28K mark, and the finish for Reid, Eric, and Dylan Wykes, whose windy 2:12:57 is a very good sign for his next crack at standard:

 

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Is leisure-time physical activity irrelevant?

THANK YOU FOR VISITING SWEATSCIENCE.COM!

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)

***

Here’s a great example of how two people can look at the same data and reach totally opposite conclusions. Over at Obesity Notes, Arya Sharma just blogged about a new study surveying what types of activities (leisure, occupational, household) burn the most calories for people. The title of the post: “Why Leisure-Time Physical Activity is Irrelevant.” He reaches this conclusion because the study found that leisure-time physical activity accounts for at most 10 percent of total energy expenditure, even for the most active people.

To explain why I find this logic to be a bit strange, let me make an analogy. Let’s say we’re debating why kids these days no longer know how to do long division. A study comes out saying that only 10 percent of elementary schools currently teach long division. Possible conclusions:

  1. So few kids receive long division instruction that teaching is clearly irrelevant to their long-division ability (or lack thereof).
  2. The results are consistent with the theory that the almost total lack of long division instruction may contribute to kids’ observed inability to do long division.

To me, it seems like Dr. Sharma is choosing the first option. Now, there’s plenty in his post that I agree with, particularly the suggestion that we should emphasize things like active transport that use energy in constructive, goal-directed ways. But the blog post has a strong current of antipathy toward the whole concept of exercise that I find surprising. For example:

[W]e have originally evolved the ability to be physically active primarily to hunt, gather, fight, flee and reproduce. The notion that any reasonable person would actually engage in a significant amount of ‘non-utilitarian’ (read: useless) physical activity beyond early childhood… is something that physical education enthusiasts (and governments) would wish for, but nature failed to put into our genes.[…]

Yes, there is a small proportion of the population, who (strangely enough) continues to enjoy leisure-time physical activity well into adulthood. The vast majority, however, prefers to much rather spend their leisure time reading, playing a musical instrument, engaging in arts and crafts, or simply lying on the couch watching professional sports. This is perfectly reasonable and completely normal human behaviour.

I understand that Dr. Sharma is, to an extent, simply counterbalancing the relentless (and misplaced) societal message that tells obese people that they’re abnormal freaks who lack enough self-discipline to take the “simple” steps like exercise that would help them lose weight. But I find it absolutely baffling that he’s arguing, on the one hand, that evolution dictates that we stop physical play after adolescence, but on the other hand suggesting that we’re wired to enjoy mastering a musical instrument (a highly cognitively and sometimes physically demanding task) or watching the very sports that apparently cease to have meaning for us when we become adults. The net result is that, next time I see Dr. Sharma quoted on the question of whether exercise can play a role in preventing weight gain, I won’t be able to avoid the feeling that his answers are coloured by a deep personal dislike of exercise in addition to his reading of the research.

And there’s another point, too. Dr. Sharma talks about “policy changes” and “workplace initiatives” to promote things like active transport, which he views as far superior to  “useless” exercise. But to me, that seems like a false dichotomy. If I have the option of taking the subway to work, but a policy initiative “encourages” me to bike instead, how is that different from voluntary exercise? In both cases, I’m choosing to burn calories that I don’t have to burn, because I believe I will derive a benefit from doing so. Is evolution really wiring me to abhor biking if I head north along the Humber River trail, but to love it if I head east toward downtown along the subway line that could carry me there much more quickly and effortlessly?

And a final thought. Let’s distinguish between what’s “easy” (or what Dr. Sharma would consider “normal”) and what may or may not be causal or contributing factors to obesity. Speaking purely hypothetically here, if a large, well-designed study were to show that two hours of moderately hard daily exercise prevented weight gain in 98% of people, Dr. Sharma might quite rightly say that this finding is irrelevant — after all, how many people will be willing to do that much exercise? But in that case, it would no longer be correct to argue that physical activity can’t prevent weight gain. The current moment in history that we’re living through is precisely the product of our having followed what’s easy/normal at every branch in the road. To move to a different place, we’re going to have to take a path of greater resistance. Whether that means banning cars, restricting processed foods, or exercising more than seems “normal” remains to be seen. But it’s no longer enough to say “I can’t do that, evolution won’t let me” — because that’s what got us here in the first place.

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Do runners get less efficient as they age?

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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)

***

We know that lots of things start to decline as you age — maximal heart rate, VO2max, muscle strength, power, flexibility, etc. But what about running economy? Do you become less efficient (in translating oxygen consumption into forward motion) as you get older, or do you keep the same efficiency while working with a smaller total capacity? Researchers at the University of New Hampshire looked at this question by studying 51 sub-elite runners in three groups: young (18-39), master (40-59) and old (60+), and published the results in the Journal of Strength & Conditioning Research. Here’s what they found:

The graph shows, for each group (A is young, B is master, C is old), measurements of how much oxygen they used (in ml per kg of bodyweight per minute) at different submaximal speeds. What’s of interest is the slope of those lines, which tells you how much oxygen they use per metre. And as it happens, there was no significant difference in the slopes between the three groups, contradicting the researchers’ hypothesis that running economy would decline with age.

This is a surprising result, and one we should look at with considerable suspicion. It’s a fairly small study, and the paces involved were relatively slow in order to make sure that the oldest runners could maintain them comfortably and remain below lactate threshold (which causes the slope to deviate from linear). Still, it does suggest that age-related decline in running economy, even if it does turn out to exist, is a relatively small factor. Instead, other factors like declining aerobic capacity and muscular strength are probably the main reasons we slow down as we age. And that’s kind of good news, because we already know how to fight those particular types of decline: keep training.

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Cognitive bias and the “number needed to treat”

THANK YOU FOR VISITING SWEATSCIENCE.COM!

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 posted a couple of days ago about some famous research showing that the “hot hand” in basketball is (apparently) an illusion. As one of the researchers, Amos Tversky, said:

I’ve been in a thousand arguments over this topic, won them all, but convinced no one.

The reason that story interested me was because I’d been thinking about similar issues in relation to the recent news that a U.S. medical panel has recommended against routine screening for prostate cancer for healthy men. A couple of recent articles in the New York Times have explored the rationale behind this recommendation, and why our minds are ill-equipped to weigh the pros and cons in these cases. As Daniel Levitin wrote in a review of Jerome Groopman and Pamela Hartzband’s new book “Your Medical Mind”:

Yet studies by cognitive psychologists have shown that our brains are not configured to think statistically, whether the question is how to find the best price on paper towels or whether to have back surgery. In one famous study, Amos Tversky [yes, the guy who did the “hot hand” study -AH] and Daniel Kahneman found that even doctors and statisticians made an astonishing number of inference errors in mock cases; if those cases had been real, many people would have died needlessly. The problem is that our brains overestimate the generalizability of anecdotes… The power of modern scientific method comes from random assignment of treatment conditions; some proportion of people will get better by doing nothing, and without a controlled experiment it is impossible to tell whether that homeopathic thistle tea that helped Aunt Marge is really doing anything.

I actually got into a bit of debate at (Canadian!) Thanksgiving dinner a few nights ago about prostate screening. Two of my elder relatives have had prostate cancer, and undergone the whole shebang — surgery, radiation, etc. One of them, in particular, was highly critical of the recommendation not to be screened. It had saved his life, he said. How did he know?, I asked. He just knew — and he knew dozens of other men in his survivors’ support group who had also been saved.

I feel bad about having argued over what is clearly a very emotional topic. Nonetheless, I’m ashamed to admit, I did try to explain the concept of “number needed to treat.” Surely everyone would agree that, say, taking a million men and amputating their legs wouldn’t be worthwhile if it saved one man of dying from foot cancer, right? And if you accept that, then you realize that it’s not a debate about the absolute merit of saving lives — it’s a debate about weighing the relative impact and likelihood of different outcomes. That’s captured very nicely in another NYT piece, by a professor of medicine at Dartmouth, Gilbert Welch, who compared the similarities between breast cancer screening (recommended) and prostate cancer screening (not recommended):

Overall, in breast cancer screening, for every big winner whose life is saved, there are about 5 to 15 losers who are overdiagnosed [i.e. undergo treatments such as surgery, radiation, etc.]. In prostate cancer screening, for every big winner there are about 30 to 100 losers.

So what’s the message here? Is it worth putting 100 men through surgery to extend one man’s life? How about 30 men? (The average extension of life after prostate surgery is six weeks.) Of course, there’s no “right” answer. As Welch writes, reasonable people can reach different conclusions based on the same input data. In the end, you have to assess the odds and the stakes, and choose how you want to gamble. But before you do, you should at least understand what those odds are — and that means taking a good luck at number needed to treat and other ways of assessing treatments.

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Training changes your genetics (or rather, epigenetics)

THANK YOU FOR VISITING SWEATSCIENCE.COM!

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)

***

Just noticed this study published online ahead of print in the journal Drug Testing and Analytics, which suggests that both performance-enhancing drugs and hard training “may alter the expression of specific genes involved in muscle and bone metabolism by epigenetic mechanisms, such as DNA methylation and histone modifications.” Cool, huh? This is why the “genetics versus training” debate is so irreducibly complicated: training can effectively change your genetics.

Recognition of the potential role of epigenetics has been gaining traction over the past few years. Here’s how a review paper on the genetics of elite athletic performance in the Journal of Physiology put it a few months ago:

[F]uture research might determine to what extent the changes that environmental factors can induce in gene expression during critical periods of prenatal and postnatal development (i.e. through epigenetic mechanisms) explain why some individuals reach the elite athletic status. For instance, elite Kenyan runners, who have dominated most distance running events in the last two decades, undergo stringent training regimens since childhood (running ~20 km/day) at high altitude (~2000 m), which might lead to unique environment–gene interactions.

So what are these “epigenetic mechanisms”? This article from Scientific American explains the most common mechanism:

The best-studied form of epigenetic regulation is methylation, the addition of clusters of atoms made of carbon and hydrogen (methyl groups) to DNA. Depending on where they are placed, methyl groups direct the cell to ignore any genes present in a stretch of DNA.

The SciAm article focuses on evidence that overweight mothers may pass the tendency to be overweight on to their children. What’s crucial is that this “inherited” trait isn’t encoded in DNA — instead, it’s how the DNA’s instructions are carried out that is altered. For example, there’s preliminary evidence that children born to an overweight mother before she undergoes gastric bypass surgery are more likely to become overweight when they grow up than their siblings born after the surgery [EDIT: see this AP story or this study for details]. If this was a simple genetic inheritance (i.e. through DNA), the surgery wouldn’t make any difference to inherited traits. Instead, it appears to be an epigenetic phenomenon.

Anyway, this is a topic I’m hoping to learn more about. On the surface, it seems to be a vindication of the old saying “The harder I work, the more talented I get.” I certainly don’t discount the obvious role of genetics in shaping ultimate athletic potential (particularly when we’re talking about the extremes represented by world champions and world record holders), but I do think many people still underestimate how much their body — and even their gene expression — can adapt to the demands they put on it.