All exercise performances are sub-maximal

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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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Another interesting pacing study, with many similarities to the one I blogged about last week, published once again in Medicine & Science in Sports & Exercise. Cyclists are asked to do a series of 2,000-metre time trials in a pseudo-virtual reality set-up. Most of them they perform solo, but in one of the trials they race against a virtual competitor (who, unbeknownst to them, is actually programmed to exactly mimic their own previous trial). The result is obvious: competition improves performance, so they’re able to beat their doppelganger and race significantly faster.

What’s interesting is how they manage to beat their previous performance. Throughout the race, the power generated from aerobic sources is exactly identical in all the different trials. But the power from anaerobic sources is significantly higher in the “racing” scenario during the second half of the race (during the last 90 seconds or so, in other words).

What does this mean?

Consequently, it has been argued that all exercise performances are sub-maximal, since they are terminated before there is a catastrophic metabolic or cardio-respiratory failure, and that a physiological ‘reserve’ capacity will always remain. The ergogenic effects of the [head-to-head] competition might therefore result from the central influence of some motivational or dissociative effect enabling the use of a greater degree of the physiologic ‘reserve’ capacity.

That’s actually quite a powerful statement: “all exercise performances are sub-maximal.” If the stakes are raised sufficiently, you can always squeeze out a little extra. I think most of us grow up knowing this intuitively, but at some point — after we start learning about VO2max and lactate threshold and so on — it’s often forgotten.

Jonah Lehrer on marshmallows and executive function

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 the comments section of last week’s post on delayed gratification and the Marshmallow Test, Seth Leon pointed out a really interesting article by Jonah Lehrer (first published in the Wall Street Journal but mirrored on his excellent blog, Frontal Cortex) that discusses ways in which you can improve your focus and impulse control — how to boost your performance on the Marshmallow Test, in other words:

The key is strengthening what psychologists call “executive function,” a collection of cognitive skills that allow us to exert control over our thoughts and impulses. When we resist the allure of a sweet treat, or do homework instead of watch television, or concentrate for hours on a difficult problem, we are relying on these lofty mental talents. What we want to do in the moment, and what we want to want, are often very different things. Executive function helps to narrow the gap. […]

But here’s the good news: Executive function can be significantly improved, especially if interventions begin at an early age. In the current issue of Science, Adele Diamond, a neuroscientist at the University of British Columbia, reviews the activities that can reliably boost these essential mental skills. The list is surprisingly varied, revolving around activities that are both engaging and challenging, such as computer exercises involving short-term memory, tae-kwon-do, yoga and difficult board games.

The whole article (which isn’t very long) is worth a read, as is Lehrer’s previous post, which describes in considerably more detail the history and implications of the marshmallow studies.

The finishing kick is in your head, not your legs

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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Another cool study showing that your brain always holds back a little energy even during “maximal” effort — and that you can access this reserve during your finishing kick. This one comes from Northumbria University in the UK, published in Medicine & Science in Sports & Exercise, and it’s fairly straightforward. Nine trained cyclists each do three 4,000-metre time trials on a stationary bike hooked up to pseudo-virtual-reality computer system:

  1. a baseline trial where they go as fast as they can;
  2. a “race” where they compete against an avatar representing their baseline performance;
  3. another “race” where they compete against an avatar which they’re told represents their baseline performance, but is actually going 2% faster (the second and third trials were given in random order to avoid learning effects).

The results: as you might expect, when racing against their previous performance, the cyclists were able to eke out a little extra energy, finishing 1.0% faster on average. But crucially, when they were deceived into competing against a faster avatar, they managed an even bigger boost, improving their time by 1.7%! Interestingly, an earlier study that tried something similar but gave feedback that was off by 5% produced the opposite result, because the cyclists were tricked into going out too fast and eventually crashed — so this isn’t an unlimited technique that will allow you to travel at the speed of light.

On the surface, these results aren’t really that surprising. Knowing how the human body (and mind) work, that’s pretty much what we’d expect. But it’s important to realize that this conflicts with the conventional understanding of how physiological constraints limit our performance. Whatever factors determined the baseline finishing times, they clearly weren’t absolute physiological limits, because the cyclists were able to beat them a few days later.

Further analysis of the data shows that in the deception trial, the cyclists had to start supplying more anaerobic power in the final 10 percent of the race in a desperate attempt to keep up with their supercharged rival. Here’s the graph of aerobic and anaerobic power contributions in the three trials (baseline, accurate and deception):

This graph sheds some interesting light on a longstanding debate about the origins of the “finishing kick,” which is a pretty much universal phenomenon in endurance races lasting longer than a few minutes. Why are we able to accelerate at the end, when we should be at our most tired? The conventional answer is that we’ve been relying primarily on aerobic energy throughout the race, but as the finish line approaches, we can mobilize anaerobic sources — the same ones we’d use to sprint 100 metres — and exhaust them just as we cross the line. The “alternate” explanation is that the brain has been limiting exertion in order to preserve homeostasis, but permits us to access some of those reserves as we approach the finish line (with the implicit promise that we’ll then stop and allow the body to recover).

It’s certainly true that the extra power needed for the finishing kick comes from anaerobic energy sources. But it’s also clear that, in the baseline trial and even in the “accurate” competition trial, the cyclists didn’t fully exhaust their anaerobic energy stores. Why not? The answer can lie only in the brain.

So what’s the practical takeaway? Well, I suppose if you can convince your real-life competitors to run 2% faster than normal without telling you, that would help! But realistically, I think this is a situation where knowledge is, literally, power. When you approach the finish of a race, you DO have energy remaining, despite what your mind and body are telling you. Believing that beyond a shadow of a doubt is, I believe, the first step to accessing it.

Mental fatigue and “armchair marathon training”

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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As I mentioned earlier, I went to a conference called “The Future of Fatigue in Exercise” a few weeks ago. One of the researchers I was most interested in hearing from was Samuele Marcora, now at the University of Kent, who has produced a bunch of interesting results on the role of mental fatigue in physical performance over the past few years. For this week’s Jockology column in the Globe and Mail, I wrote about Marcora’s theories and his latest research:

“Improve your marathon time while sitting at your computer” is the kind of claim you expect from an infomercial or a spam e-mail, not from the keynote speaker at an academic gathering.

“It sounds crazy,” Samuele Marcora admitted during his talk at a conference on fatigue at Charles Sturt University in Australia last month, “but it’s actually not.”

Dr. Marcora, a professor at the University of Kent’s Centre for Sports Studies in Britain, has spent the past few years unravelling the surprising links between tired brains and physical performance. His initial results suggest that what we perceive as physical limits are actually highly dependent on our levels of motivation and mental fatigue – and that we may be able to use this fact to our advantage. […]

READ THE WHOLE ARTICLE HERE.

Decision fatigue and workout planning

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)

***

John Tierney has an interesting article in New York Times Magazine about the concepts of “decision fatigue” and “ego depletion” — the idea that the simple act of making decisions, no matter how seemingly trivial, uses of a finite store of willpower. The idea seems intuitively obvious, but the studies he describes are fascinating and unexpected.

For example, prisoners appearing before Israeli parole boards have a 70 percent chance of getting parole if they appear first thing in the morning, but just a 10 percent chance if they appear late in the day: the judges are tired of making decisions, and react unconsciously by sticking to the default option. Lots of different factors affect decision fatigue, including glucose levels in the brain — so the chance of parole drops to 20 percent by midmorning, then rises to 65 percent after the midmorning break, during which sandwich and fruit is served to the judges. Just before lunch, probability is back down to 10 percent, then back up to 60 percent immediately after lunch, and so on.

It’s a long article, and I don’t want to oversimplify by summing up — but this is the passage, near the end, that I found interesting in the context of exercise:

“Good decision making is not a trait of the person, in the sense that it’s always there,” Baumeister says. “It’s a state that fluctuates.” His studies show that people with the best self-control are the ones who structure their lives so as to conserve willpower. They don’t schedule endless back-to-back meetings. They avoid temptations like all-you-can-eat buffets, and they establish habits that eliminate the mental effort of making choices. Instead of deciding every morning whether or not to force themselves to exercise, they set up regular appointments to work out with a friend. Instead of counting on willpower to remain robust all day, they conserve it so that it’s available for emergencies and important decisions.

I think this is a really important point. Strangely, I’ve found it’s much easier for me to stick to a routine where I run every day than to run six or five or four days a week. In terms of my current fitness goals, six days would be plenty and possibly even preferable to seven — but as soon as you introduce that element of choice, every morning suddenly gets much more complicated. Should I take my day off this morning? How tired am I? Is it going to rain? How do I expect to feel later in the week?

When I was training more seriously, a periodic rest day was much more important in order to get adequate recovery — but even then, I found it much easier to schedule a regular rest day (I took every second Monday off) than to make those decisions on a day-to-day basis. It wasn’t a question of being too obsessive to take an unplanned day off — it was simply too much mental effort to have to decide every morning “Am I running today?” There’s a great passage in Once a Runner about that idea (unfortunately I don’t have my copy here, or I’d quote it), how you have to make the decision about what you’re going to do, then close the book and just do it, rather than revisiting the decision every time it gets hard, or every time you wake up in the morning. (Of course, you still have to allow a certain amount of flexibility: sometimes it really is smarter to take an unplanned day off — but that’s different from having a regular weekly day off that can be taken any day of the week.)

When people ask me for advice about planning an exercise program, that’s one of the things I emphasize. Being flexible and fitting in exercise when it’s convenient may sound good in theory. But for me, at least, my will power isn’t strong enough to do that on a regular basis. Better to make the decision in advance, then just follow my own orders when it’s time to workout.