Marathons, heart damage, MRIs and VO2max

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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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The issue of heart damage in marathons has been a hot one lately, in the news most recently because of a study presented at the Canadian Cardiovascular Conference in Montreal last week. Laval University researchers did an MRI study of runners before and after a marathon, and concluded the less-fit runners sustain heart damage that can last for up to three months. They suggest that runners should get a VO2max test to determine whether they’re ready for a marathon.

Three points. First, do marathons “damage” hearts? This is the second MRI study to come out in the past year or so. The previous one, at last year’s Manitoba Marathon, found damage that disappeared within a week after the race. In the new study, they’re saying three months (note: since it’s just a conference presentation, I haven’t seen the details of the study yet). So it seems clear that marathon DO damage hearts — in the same way that they damage leg muscles, neuromuscular firing patterns, and probably even motivation to run, i.e. temporarily. As far as I know, there were no lasting negative outcomes in the Laval study.

Second, are runners who train less more susceptible to damage? This is the “novel” finding of this study, though it’s pretty obvious on an intuitive level. Personally, I think it’s a pretty good message: marathons are a big endeavour, and it’s worth training properly for them for all sorts of reasons. Do I think that those who persist in jumping into marathons with inadequate preparation are tempting fate? Not really — the statistics show that marathons as a mass participation event are still overwhelmingly safe compared to the baseline risk of other activities.

Third is this warning that prospective marathoners should get a VO2max test to figure out whether their heart can handle a marathon. I’ll have to wait until the full study is published to evaluate this more fully, but I’m a little skeptical. They initially point out that the heart is divided into 17 segments, and when one segment is injured/stressed the other segments can compensate, hiding the problem:

It also makes it practically impossible for physicians to arrive at an accurate assessment of the heart health of the marathoner when only considering the whole heart.

That’s why MRI is useful, because it can look at the segments individually. But then they turn around and suggest VO2max, which is an overall measure of cardiac function (not to mention all the controversies about what peripheral factors may also play into VO2max).

It just seems to me that VO2max is a pretty blunt instrument for figuring out who’s okay to run a marathon. It’s also a difficult, time-consuming and inconvenient test to run — so I’d like to see some assessment of what negative outcomes, exactly, we’d be hoping to avoid in exchange for the time and expense of hundreds and thousands of VO2max tests. Is it the handful of yearly deaths in major marathons (many of which would NOT be predicted by screening programs like this)? Or is it to prevent the temporary, invisible heart damage that marathoners have apparently been suffering with no ill effects for years?

Cryotherapy: the latest miracle money-waster

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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cryosauna

At the risk of sounding a bit cranky, I’m going to complain about another piece of new-fangled sports technology. Doug Binder of TrackFocus has an interesting article about Alberto Salazar’s Nike group in Oregon using a “Space Cabin” for cryotheraphy to cool down after workouts:

Step inside this metallic cylinder and liquid nitrogen-cooled air (say, 170 degrees below zero) rushes in and cools your skin to a chilly 30 degrees, yet penetrates just a half millimeter. You slowly rotate for two and a half minutes, holding your hands up and out of the freeze, wearing socks on your toes, and at least some underwear to cover your privates.

Okay, I’m down with ice baths, and maybe this is a super-ice-bath – though I’m certainly curious about how much one of these gadgets costs, and whether it’s actually any better than a simple ice bath. What got me cranky was the manufacturer’s website, which claims that the benefits of this device include (but are not limited to):

* Decreased fatigue
* Decreased muscle soreness
* Decreased injury recovery time
* Quicker surgical recovery
* Psychological competitive edge [okay, this one I believe]
* Decreased anxiety
* Decreased depression
* Decreased incidence of colds and flu
* Tighter, healthier skin
* Cellulite reduction
* Stronger, fuller hair
* Stronger nails
* Fewer skin blemishes
* Increased libido
* Increased sexual stamina

And of course, “it f-ing prints money!” I mean, seriously. They must have lots of evidence to back up those claims, right? Why yes, FAQ no. 17 is “Are there any studies regarding Whole Body Cryotherapy (WBA) in the USA?” The answer is:

Yes, there is. We recently installed cryosauna in the office of Dr. Jonas Kuehne in Beverly Hills, Los Angeles, California. During a six month study, Dr. Kuehne successfully served his clients with cryoprocedures. HERE you can find a video clip with some results of his studies.

Click on the link and, if you don’t poke your eyes out with a fork, you can watch a lame infomercial by some doctor who makes no mention of a “study” and who simply reasserts that these machines can do everything including your taxes.

Anyway, perhaps I’m being premature in my scorn. Maybe the studies demonstrating all these wonderful effects just haven’t been published yet. After all, it’s fancy new technology, right? As FAQ no. 1 says:

The process was originally developed in Japan in 1978, and the benefits have been studied and refined in Europe since that time.

Silly North Americans, ignoring all these wonderful benefits for the last 32 years!

(Okay, so what’s my real message here? When I first read the story, I was interested to find out more about this technology. But what really turned me off was the wildly inflated claims on the website with a complete lack of evidence. It’s entirely possible that this technique will have some benefits for Salazar’s athletes, but the snake-oil website lowers my confidence in it dramatically.)

Phantom epidemic: salt intake hasn’t changed in 50 years

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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One of the health topics I’ve been curious about recently is the question of salt intake. It seems that everyone — governments, scientists, heart institutes — agrees that we eat way too much salt, and it’s leading to an epidemic of hypertension.

But there are skeptical voices — the much-maligned Gary Taubes is one, but there are many others (like my wife!) who argue that (a) sodium levels in the body are very tightly regulated, so any excess in a healthy individual is simply excreted out in the urine, and (b) dramatic reductions in salt produce only a minor blood pressure change of a few mmHg, and not in everyone, so blanket recommendations for the whole population to cut salt make little sense.

So I was interested to see a study from Walter Willett at Harvard in the current issue of the American Journal of Clinical Nutrition (full text here). He and a colleague reviewed studies between 1957 and 2003 that measured sodium excretion in urine — a very accurate way of determining salt intake that gets around the difficulties in figuring out exactly how much salt is in your food. They found two main things: (a) sodium intake averaged about 3,700 mg per person per day, which is way higher than the upper recommended limit of 2,300; and (b) it essentially hasn’t changed in the half-century studied.

Interestingly, these results agree almost exactly with similar reviews of studies from 33 different countries: salt intake is high, and it hasn’t changed in recent memory.

Now, here’s the question that Willett dances around in his discussion: If hypertension is a rising epidemic in the U.S. (and elsewhere), and if salt intake hasn’t changed in 50 years, how can salt possibly be the culprit? He points out that hypertension has “multiple etiologic factors,” and suggests that obesity may be a more important determinant.

The article is accompanied by a fairly strident editorial by David McCarron titled “Science trumps politics: urinary sodium data challenge US dietary sodium guidelines” (full text here). McCarron is a familiar figure in the salt wars, and is often maligned because he has consulted with the Salt Institute in the past. Lots of money sloshing around in this debate. What’s so interesting about this study is the involvement of Willett, a public health titan who normally lines up on the other side. Here’s what Willett had to say in a debate about New York City’s proposed salt rules on the New York Times website earlier this year:

The evidence is solid, based on many years of research, that reducing sodium intake from the high amounts now consumed in the U.S. will reduce the risks of these conditions [hypertension, stroke, heart disease].

His own study now tells us that the amounts now consumed in the U.S. are not at all “high,” historically speaking. Will this lead him to change his views? I’m not counting on it — but it’s at least encouraging that he’s interested in looking at the data.

More on the banned basketball shoes

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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I wrote about the bogus ban on APL’s basketball shoes a few days ago, and the bad science behind it. I just noticed that the New York Times, of all places, actually wrote about the shoes. The piece has some very interesting nuggets in it — and some very sloppy reporting. The key point to note is a statement from the NBA:

“No player has asked to wear these shoes, so it’s a nonissue,” the N.B.A. spokeswoman Kristin Conte said. “However, we determined that they don’t conform to our rules, based on the company’s representation of what they do.”

The key part is in bold here. In other words, the NBA has no idea whether the shoes enhance vertical jump. APL called up the NBA and said, “We have shoes that will make players instantly jump 3.5 inches higher using special technology in the toes, will players be allowed to wear them?” Of course the answer was no — but that says nothing about whether they work.

The other passage that caught my attention is here:

The Goldstons have compared the spring embedded in the front part of the sole to a diving board; the more pressure that is pushed down on it, the more spring it will provide. They claim it increases vertical leap by an average of about three and a half inches.

Lucky break for the company here. Even they don’t make that claim, although that’s exactly the impression they’re trying to give when they repeatedly mention increases of “up to 3.5 inches.” The Times reporter fell for it without checking the fine print. As I pointed out in my initial post, only one of 12 test subjects increased by anywhere close to 3.5 inches, under test conditions that the company won’t even disclose.

The more I read, the more unimpressed I am by how sleazily dishonest this whole campaign is. On the other hand, it’s a very successful campaign — the surge in sales after the “ban” shut down their servers. Perhaps we shouldn’t be surprised: apparently the 23-year-old twins running company are the sons of Reebok’s former chief marketing officer — the guy who came up with the famously stupid but commercially successful Reebok Pump.

Hiking in Papua New Guinea on the Kokoda Track

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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That’s a pic from Papua New Guinea, where Lauren and I went hiking a couple of months ago. It was a fantastic trip, and my article about it is now available on the New York Times website:

[…] We had been warned over and over to prepare ourselves for two things: mud and hills; hills and mud. While the highest point on the trail is a modest 7,000 feet, the accordionlike ridges and gullies mean you climb and descend more than 20,000 feet in total.

But it’s not the vertical that can break your spirit, we soon realized, it’s the horizontal — seeing the trail almost within arm’s reach in front of you, then realizing that you have to clamber 200 feet down a steep and muddy decline, wade through a stream or tiptoe across a slender log, then haul yourself back up the other side on wet clay. [READ THE WHOLE ARTICLE]

A few more pics from the trip:

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