The incredible unaging triathlete

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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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Here’s a pretty graphic illustration, from a recent paper by Dr. Vonda Wright and her colleagues (hat tip to Laura McIntyre for the forward), of the importance of lifelong physical activity:

It’s from a new study freely available at The Physician and Sportsmedicine that took detailed measurements of 40 masters athletes between the ages of 40 and 81, and found a surprising lack of age-related muscle loss:

This study contradicts the common observation that muscle mass and strength decline as a function of aging alone. Instead, these declines may signal the effect of chronic disuse rather than muscle aging.

 

Marathon heart attacks: new data

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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There’s a big new study out in the New England Journal of Medicine that takes a comprehensive look at every case of cardiac arrest during every marathon or half-marathon in the U.S. with more than 100 participants between 2000 and 2010. It’s being widely covered in the press; you can read a good summary in the New York Times or in the Globe and Mail, among other places. The primary message: these events are rare. There 59 cases of cardiac arrest, of which 42 were fatal. That translates to a 1 in 259,000 chance of dying, which is much lower than previous reports and than many other sports.

I’m actually in Houston right now for the U.S. Olympic Marathon Trials, and it happens that Aaron Baggish of Mass General, the senior author of the study, was giving a talk this morning to the members of the World Road Race Medical Society — so I popped in to hear what he had to say. A couple points he made that I found interesting:

Weather wasn’t a factor. The average starting temperature during events where someone suffered a heart attack was almost identical to the 10-year average (55.9 vs. 55.5 F), and the average deviation was just 0.3 degrees.

For 31 of the cases, they were able to track down either the survivor or the next-of-kin and get full medical records, autopsy results, and running history — so this allowed them to really look at the causes of death in detail. One of the surprises is that none of the runners died from a ruptured plaque producing a blood clot, which is (or at least was) thought to be one of the possible mechanisms of sudden death in athletes. The problem with ruptured plaques is that they’re hard to predict in advance. But if underlying coronary artery disease is the real problem (more on that in a sec), then pre-exercise cardiac screening should be able to pick some of that up, Baggish argues.

The average age of the people who survived cardiac events was 53; the average age of the people who died was 34. There are two distinct groups here. One is young people with thick hearts (“hypertrophic cardiomyopathy”), an underlying genetic conditionl; when they collapse, they’re very hard to revive and tend to die. The other is older men with narrowed arteries (coronary artery disease) due to the usual risk factors; when they collapse, they can often be revived if someone gets to them soon enough.

That brings me to one of Baggish’s key point: the absolute best predictor of whether someone would survive cardiac arrest during a race was simple: did a bystander start CPR immediately, before paramedics got there? The lesson is simple: we should all — runners, family members, spectators, heck, everyone in society — have basic CPR training. It could make all the difference to someone, including you.

Baggish’s overall message: running (and by extension, other aerobic activity) is generally safe — but it doesn’t give you immunity from heart disease. That means that everyone, and particularly older males, should be alert for warning signs and not ignore them. Some key ones:

  • a burning sensation in the chest (could be confused with acid reflux) that comes on when you start running then gradually fades away, and keeps recurring;
  • breathing more heavily than you’d expect given your effort;
  • persistent, unusual fatigue.

None of these risk factors necessarily mean something is wrong, but they can be a signal that it’s worth checking in with your doctor to see is you’ve got coronary artery disease that needs to be addressed before racing a marathon.

Last point. Previous studies have shown that most marathon race deaths occur in the final mile or at the finish; this study confirms that. The implication: if you have reason to worry about your heart’s health and want to minimize that risk, think twice about your final sprint. Here’s the data, broken down by race quartile:

The more you eat, the faster you go (in ultraendurance)

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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A few months ago, I blogged about a study that observed correlation between in-race carb intake and race time in Ironman triathletes. What was significant about that paper is that it looked at a topic that has been studied to death in the lab, and took it out into the real world. There are a lot of “problems” with the real world that make it hard to nail down causes and effects — but ultimately, the whole point of this type of research is to understand what’s happening in the real world. So these observational studies, despite their challenges, are very important.

That’s by way of intro for another small study, just published in the International Journal of Sport Nutrition and Exercise Metabolism, from researchers in New Zealand. They looked at the nutritional intake of participants in a brutal cycling race, the K4, which covers 384K and includes 4,600 metres of climbing. The average finishing time of the 18 study participants was 16 hours and 21 minutes! The key points:

  • The estimated calorie burn for the race was about 6,000 calories; the average intake was just 4,500 calories, so there was a big caloric deficit.
  • There was a significant inverse relationship (p=0.023) between number of calories consumed and finishing time. The more calories you managed to cram down your gullet, the faster you finished!

Is this a surprise? Given that the race was so long, it makes sense that taking in enough energy was a significant challenge. Obviously the same thing doesn’t apply during, say, a 100-metre sprint. The question is: where’s the breakpoint, beyond which energy intake becomes a significant independent predictor of performance? I think the general assumption is that it’s probably a bit below marathon distance — so it would be really interesting to see a study like this, with a very large number of participants, at a marathon.

Five tips for cold-weather workouts

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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My Jockology column in today’s Globe and Mail gets seasonal and looks at five bits of research related to exercising outdoors in the winter. For example:

The challenge: Going bareheaded in the winter is like leaving the lid off your thermos. Classic studies in the 1950s showed that if you wear winter clothes but no hat at 4 C, you lose about 50 per cent of your body heat through your head.

The research: A U.S. Army study published in early 2011 showed that your face is almost as important as the top of your head for heat loss. Volunteers spent an hour in a cold chamber with a wind chill of -20 C; those who wore a balaclava had measurably warmer fingers and toes than those wearing a normal hat. Your body tries valiantly to keep your brain warm by shunting blood away from your extremities toward your head.

Read the whole column here.

Maternal exercise lowers fetal heart rate

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)

***

A new study in Medicine & Science in Sports & Exercise, from the same group in Kansas City that previously found lower fetal heart rates when mothers exercised during pregnancy. This time, they were looking for a dose-response effect — the more exercise, the lower the heart rate — which would strengthen the case for causality rather than correlation. Here’s what they found:

“A” is “active” and “Q” is “quiet (as in whether the fetus is moving around or lying still). The Q results weren’t statistically significant, but for the A results, greater intensity did indeed lead to lower heart rates. But perhaps most significant is what they didn’t find:

Interestingly, maternal factors (i.e. maternal age, maternal resting HR, maternal weight gain, pre-pregnant BMI) did not influence the associations between physical activity and fetal parameters. Fetal cardiac autonomic control was enhanced in mothers who participated in physical activity regardless of the amount of weight they gained, their weight status prior to pregnancy, resting HR or age.

In other words, they’re not saying that fit mothers have fit babies; they’re saying that active mothers have fit babies.