Burning calories without stimulating appetite

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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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I’ve posted a few times recently on the challenges of losing weight — in particular, the homeostatic mechanisms that your body uses to fight against any attempt to burn more calories than you consume. For instance, exercising stimulates appetite hormones that prompt you to eat more. So I found the following tidbit in the New York Times interesting:

In a completed but unpublished study conducted in his energy-metabolism lab, [Barry] Braun [of UMass-Amherst] and his colleagues had a group of volunteers spend an entire day sitting. If they needed to visit the bathroom or any other location, they spun over in a wheelchair. Meanwhile, in a second session, the same volunteers stood all day, “not doing anything in particular,” Braun says, “just standing.” The difference in energy expenditure was remarkable, representing “hundreds of calories,” Braun says, but with no increase among the upright in their blood levels of ghrelin or other appetite hormones. Standing, for both men and women, burned multiple calories but did not ignite hunger. One thing is going to become clear in the coming years, Braun says: if you want to lose weight, you don’t necessarily have to go for a long run. “Just get rid of your chair.”

This suggest that all those people trying to work at “stand-up” desks may be onto something. On the other hand, I’m still not completely sold on the general message about exercise and weight loss that is more or less accepted as fact in this article:

“In general, exercise by itself is pretty useless for weight loss,” says Eric Ravussin, a professor at the Pennington Biomedical Research Center in Baton Rouge, La., and an expert on weight loss.

The article then describes one of Ravussin’s studies (which I blogged about back in December) in which one group of subjects lost nearly 10% of their bodyweight, or a pound a week, through exercise alone — which seems to contradict the assertion that exercise is useless for weight loss.

But in the exercising group, the dose of exercise required was nearly an hour a day of moderate-intensity activity, what the federal government currently recommends for weight loss but “a lot more than what many people would be able or willing to do,” Ravussin says.

Oh, now I get it. It’s not that exercise is useless for weight loss — it’s doing a little bit of exercise at a low intensity that is useless. Those are two very different statements. I understand that an hour a day of moderate-intensity exercise is a tall order for people in today’s busy, convenience-driven, nutritionally bankrupt society etc. etc. But that doesn’t mean exercise is useless, it just means that it takes a lot of exercise — more, perhaps, than most people are willing to do — to see appreciable changes.

Convincing people to climb stairs

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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In light of the Jockology column on stair climbing that I just posted, I found this post on the Obesity Panacea blog really interesting:

In this new study, Megan Grimstvedt and colleagues placed signs near the elevators of 4 university buildings in San Antonio. The sign said simply “Walking up stairs burns almost 5 times as many calories as riding an elevator” and included an arrow directing people to the nearest staircase, as well as a cartoon of the school mascot walking up a flight of stairs…

At baseline, only 13% of people used hidden staircases, while 43% of people used visible staircases. Even more interesting is that overall stair use increased 34% as a result of the intervention, an increase which persisted 4 weeks after the signs had been removed.

There’s more data and analysis in the original post. Time to make some signs!

Jockology: taking the stairs actually makes a difference

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)

***

This weekend, about 7,000 people will tackle the 1,776 steps of the CN Tower in support of the World Wildlife Fund. Meanwhile, in Calgary, people will be climbing the Calgary Tower in support of the Alberta Wilderness Association. Also this weekend in Germany, there’s the Mt. Everest Stair Marathon, in which competitors go up and down a 397-step staircase 100 times, climbing the equivalent of sea level to the top of Everest and covering the distance of two marathons along the way.

Seriously.

So, all in all, it seemed like a good time to take a look at research into the health benefits of stair climbing for this week’s Jockology column. If you choose the stairs instead of the escalator or elevator a few times a day, does it really make any difference to your health?

Researchers in Ireland have been studying the benefits of dashing up the stairs periodically over the course of a workday, and they’ve observed surprising fitness gains.

“I think the key thing here,” says Colin Boreham, a professor at the University College Dublin Institute for Sport and Health, “is that stair-climbing is one of the few everyday activities at a moderate to high intensity that one can do surreptitiously without having to change, use special equipment or look foolish.” [read the rest of the column…]

As an aside, that’s the Colin Boreham who once held the British high-jump record and represented Britain in the 1984 Olympics as a decathlete alongside Daley Thompson.

Perceived exertion, not muscle failure, determines “exhaustion”

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)

***

There’s an interesting preprint available online from the European Journal of Applied Physiology, by Samuele Marcora and a colleague from Bangor University in Wales. Its title is “The limit to exercise tolerance in humans: mind over muscle?,” so you might think it’s another paper supporting Tim Noakes’s “central governor” theory. It is, and it isn’t — but either way, it’s interesting.

Marcora took 10 elite rugby players and (after various preliminary testing and so on) had them do a five-second “maximum voluntary cycling power” (MVCP) test. Then they did a very intense cycling trial to exhaustion which took about 10 minutes (they offered cash prizes to the top performers and circulated the results publicly to stimulate competition and make sure the subjects went all-out), followed immediately (within one second) by another MVCP test.

Now, if you subscribe to traditional exercise physiology, you’d say that the subjects stopped the test-to-exhaustion when they were no longer physically able to generate enough power to continue. Possible reasons for their failure would include “limited oxygen delivery, metabolic and ionic changes within the active muscles, supraspinal reflex inhibition from muscle afferents sensitive to these changes, and altered cerebral blood flow and metabolism.” But that’s not what Marcora saw. The subjects had to maintain an output of (on average) 242 watts in the test to exhaustion. But as soon as they stopped, one second later, they were able to output (on average) 731 watts in a five-second burst — nearly triple the required power! Clearly the subjects didn’t stop the test because their couldn’t physically produce the needed power:

These results challenge the long-standing assumption that muscle fatigue causes exhaustion during high-intensity aerobic exercise, and suggest that exercise tolerance in highly motivated subjects is ultimately limited by perception of effort.

The interpretation of these results gets a little tangled. Marcora is an advocate of something he calls the “psychobiological model of exercise tolerance,” which seems to basically mean that we stop exercising when it gets hard. He says this is different from — and much simpler than — Noakes’s central governor theory. I’m not sure I really a see a difference that extends beyond semantics, but perhaps that’s because I haven’t given it enough thought. I downloaded a couple of Marcora’s other papers where he explains the theory in more detail, so I’ll be interested to see what he has to say. Either way, these results are certainly interesting in that they once again support the notion that, when we collapse from exhaustion, we’re generally running up against barriers imposed by our brain rather than absolute physical limits imposed by our body.

Staying healthy after 153,300 miles

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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Runner’s World has an interesting interview by Amby Burfoot with marathoning legend Ron Hill, now most famous for the daily running streak he’s kept alive since 1964. A passage I liked:

I saw a woman who said, “Running’s not good for your knees.” I said: “Okay, but I’ve got 150,000 miles on these knees and they’re working quite well.” She said: “That’s only because you’re so slim.” I said: “Well, how do you think I got this slim, and stay this slim?”

He has a good point (as I discussed in a Jockology column a few years ago). On the other hand, I have to admit that the picture accompanying the interview does look like a guy who hasn’t taken a day off in the last 45 years.