Extreme exercise: Tour de France cyclists live longer

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As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

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A little bit of exercise is good for you, but too much is bad for you. That seems to be a fairly widespread societal view — certainly anyone who trains seriously as a runner or cyclist or other endurance athlete is familiar with all the comments about how training so much can’t be good for you. And to be fair, there has been some recent research that raises questions about whether running multiple marathons over an extended period of time can damage your heart.

So I was very interested to see a study, forwarded by Brian Taylor (thanks!), that just appeared in the International Journal of Sports Medicine. Spanish researchers decided to study the records of cyclists who rode the Tour de France between 1930 and 1964 — an example of “extreme” exercise if ever there was one — and see how long they lived compared to the general population. They focused on riders from France, Italy and Belgium (who comprised 834 of the 1229 riders for whom birth records were available), and they compared the longevity of those riders to the general population from their home country in the year of their birth. Here are the aggregate results in graphical form:

The trend is pretty clear. The age by which 50% of the population died was 73.5 for the general cohort, and 81.5 for the Tour de France riders — who, according to the paper, ride about 30,000 to 35,000 km per year (though I’d be surprised in the riders competing in the 1930s were training as hard as modern riders).

So what does this tell us? Well, as in any case-control study, there are plenty of limitations on the conclusions we can draw. First of all, this doesn’t prove that “extreme” exercise is better than “moderate” exercise. It may be that riding 30,000 km/year is significantly better than doing no exercise at all (or than doing the relative pittance that the average modern person does), but is still worse for you than riding, say, 10,000 km/year. But it’s pretty clear that extreme levels of aerobic training don’t shorten your life. As the authors put it:

In our opinion, physicians, health professionals and general population should not hold the impression that strenuous exercise and/or high-level aerobic competitive sports have deleterious effects, are bad for one’s health, and shorten life.

It’s also worth mentioning some potential confounding factors. The paper notes that former athletes tend to smoke less, drink less alcohol and have a healthier diet than the general population. Fair enough: these factors almost certainly contribute to the increased longevity of the riders. Again, the conclusion we can draw isn’t that extreme riding makes you healthier; it’s that it doesn’t make you less healthy.

What about genetics and selection bias? Maybe the Tour de France riders tend to be the type of lucky person with a great metabolism who’s destined to be healthy for his entire life no matter what he does, and it’s those great genetics that predisposed him to become a competitive cyclist. Again, not an unreasonable point. In response, the authors point out a 2010 British Journal of Sports Medicine paper in which researchers in Sweden compared the genetic profiles of 100 world-class male endurance athletes (“Olympic finalists or Europe/World Champions and Tour de France finishers”) with 100 matched controls. They looked at 33 “risk-related mutations and polymorphisms” associated with cardiovascular disease, hypertension, insulin resistance, cancer, and other major causes of mortality — and found no difference:

[T]he overall picture suggests that there is no evidence that elite male world-class endurance athletes are genetically predisposed to have a lower disease risk than non-athletic controls. Thus, the previously documented association between strenuous aerobic exercise undertaken by elite athletes and increased life expectancy is likely not biased by genetic selection.

Bottom line: if the question is “How much exercise is too much?”, I still think the answer is “Way, way more than you think.”

When one twin runs more than the other

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

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Interesting new study from Paul Williams’ National Runners’ Health Study — no, wait, this is a new one, not the one I wrote about a few days ago! This one looks at identical twins to find out the extent to which your body shape is dictated by your genes. Yes, the old nature vs. nurture debate…

Williams has an enormous data set of over 100,000 runners, including 926 identical twins. He explored the relationship between two quantities: the difference in how much a pair of twins ran, and the difference between how much they weighed. Various studies have found that genetic factors account for 40% to 70% of the variation in BMI. But Williams found that the more the active twin exercised, the less genetics seemed to matter. Here’s a graph:

The numbers on the right-hand side represent how much more the active twin runs than the less-active twin. Of course, for some people the results will seem absurdly obvious: the greater the difference in activity levels between two people, the greater the difference in their BMI. Still, it’s a good reminder that genetics isn’t destiny. Here’s what Williams concludes:

Extrapolating the coefficients of Table 3 shows that BMI inheritance might be eliminated completely by running 7.05 km/day (23 mi/wk) in women and 13.51 km/d (60 mi/wk) in men, a projection that is consistent with our previous finding of uncorrelated BMI values in 35 pairs of MZ twins whose running differed by an average of 8 km/d [31], but a projection that should nevertheless be considered with caution.

 

Burfoot, Noakes, and the ultimate workout

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

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Fascinating post on Amby Burfoot’s Peak Performance blog about a recent Yale study on the mind and appetite hormones. Researchers gave subjects either a high-calorie or a low-calorie milkshake (and told them which one they were getting), then measured the change in ghrelin, a key appetite hormone:

As you would expect, the subjects’ ghrelin levels dropped after the indulgent, high-calorie shake. After all, this thing contained more than 600 calories. It would fill up anyone. When the subjects drank the low-cal shake, their ghrelin levels stayed basically the same.

Here comes the twist: The shakes were identical; they were all moderate-calorie.

So what does this mean? Amby goes on to discuss other phenomena like “sham arthroscopy” and the”world’s best running workout.” The whole post is worth a read, but I found his suggestion for a workout particularly interesting: 5 x 1 mile as hard as possible… then when you’re done, your coach makes you do one more at the same pace:

From this workout, you’ll learn forever that you’re capable of much more than you think. It’s the most powerful lesson you can possibly learn in running.

I agree. And it also made me think of something Tim Noakes told me when I interviewed him last summer. I’d asked about the origins of his “central governor” model, and how coaches might actually apply its lessons in practice. Here’s what he said:

I think all the great coaches always work on the brain anyway. And they get you to run faster because they teach you that you can… I remember the compelling moment in my own rowing career was we used to do 6 times 500 metre repetitions. And one afternoon, we did our sixth and turned around rowing back to the boathouse, and the coach says, ‘No, go to the start again. You’re doing another one.’ So we did another 500. And he said go back. And we did another four. And you know, no one would have believed that we could do that, if you’d asked us… That taught us that you have to teach athletes, somewhere in their careers, that they can do more than they think they can.

As Amby points out, the problem is that you can’t prescribe a workout like that to yourself: you need a trusted authority telling you what to do. This is a really interesting and important point. We keep on discovering that the brain is more powerful than we’d suspected in regulating performance (and even appetite hormones) — but it’s still not clear how we can actually harness these powers.

The more you exercise, the less diet matters

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

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This week’s Jockology column in the Globe and Mail takes a closer look at some new results (which I blogged about back in April) from the long-running National Runners’ Health Study:

At a public debate in May on the relative importance of exercise and diet in battling obesity, Yoni Freedhoff began his opening arguments with some basic physics.

“There’s no debate about whether the laws of thermodynamics exist,” said Dr. Freedhoff, the medical director of the Bariatric Medical Institute in Ottawa. Energy can’t be created or destroyed, so weight loss ultimately depends on burning more calories than you consume. But which side of that equation should you focus on? [READ THE FULL ARTICLE]

The basic finding of the new study is that the more you exercise, the weaker the link between diet and weight. I exchanged a few e-mails with Yoni Freedhoff (of Weighty Matters fame) about this idea, and his initial reaction was that the findings could be interpreted as simply the result of calories burned while running. After all, running 8 km per day (as the “top” group in the analysis does) burns quite a few calories. I tend to think that there’s more going on here (as I explain in the article), but I’d certainly be interested in hearing what others think. Am I making too big a deal about something that’s completely obvious?

Vigorous exercise prevents “silent strokes” in older adults

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

***

Just noticed a press release about a study on exercise and brains in older people, reaffirming the well-established idea that there are benefits to more vigorous exercise that you can’t get from mild exercise:

Older people who regularly exercise at a moderate to intense level may be less likely to develop the small brain lesions, sometimes referred to as “silent strokes,” that are the first sign of cerebrovascular disease…”These ‘silent strokes’ are more significant than the name implies, because they have been associated with an increased risk of falls and impaired mobility, memory problems and even dementia, as well as stroke,” said study author Joshua Z. Willey, MD, MS, of Columbia University…

The study involved 1,238 people who had never had a stroke. Participants completed a questionnaire about how often and how intensely they exercised at the beginning of the study and then had MRI scans of their brains an average of six years later, when they were an average of 70 years old.

You can read the press release for more details, but the basic gist is: these lesions are not uncommon (16 percent of participants had them), and those who did moderate to intense exercise were 40 percent less likely to have them than those who did light exercise or no exercise, while controlling for other risk factors like blood pressure, cholesterol and smoking. Just another data point to bear in mind!