Pacing and cognitive development

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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 bit of a loaded question: does your pacing strategy — even? positive splits? negative splits? — reveal something about your cognitive development? I blogged a few weeks ago about the perennial question of 1,500-metre tactics and whether going out a fast pace is smart or stupid, so I was interested (and amused) to see a new study from Dominic Micklewright at the University of Essex, just posted online in Medicine & Science in Sports & Exercise, called “Pacing Strategy in Schoolchildren Differs With Age and Cognitive Development.”

It’s actually a really neat and thought-provoking study. Here’s the gist: the researchers studied four groups of children (aged 5-6, 8-9, 11-12, and 14). Each group was asked to run a time trial over a distance that took them about four minutes to finish — so similar to the demands of a 1,500-metre race in adults, actually. Here’s what the pacing for each group looked like:

The basic conclusion from this data:

Younger schoolchildren with less advanced cognitive development exhibited a negative pacing strategy indicating an inability to anticipate exercise demand. Older schoolchildren at a more advanced stage of cognitive development exhibited a more conservative U-shaped pacing strategy characterised by faster running speeds during the first 15% and last 20% of the run.

In other words, young kids go out very fast and fade from the front, while older kids understand the pain that awaits them and hold some energy back until they’re sure they’ll make it to the finish. But there’s more to it than that. The researchers also administered tests to determine where the kids fit into Piaget’s four stages of cognitive development — and they saw roughly the same pattern: kids with a lower stage of cognitive development went out hard and got progressively slower, while the kids with more advanced cognitive development had the U-shaped curve — which, I should point, is exactly the pacing strategy adopted by world-record-setters at distances from 1,500 to 10,000 metres ever since the IAAF started keeping records.

I should clarify (before Rob Watson kicks my ass) that the link between pacing between cognitive development and pacing is mostly related to age. Once you’re a grown-up (and in particular, once you’re racing against other people rather than just against the clock), there are many different reasons to adopt different pacing strategies. Let me repeat: I’m not saying that going hard means you’re dumb!

What this research is really about is “anticipatory regulation of effort” — which is basically just a rebranding of what’s sometimes called the central governor theory. (Debate about the central governor has become so personal that many scientists seem unable to actually read new studies about it, instead criticizing the ideas that were proposed 10 years ago.) Here’s how the authors of the new study put the idea into evolutionary context:

The survival of certain animals is contingent upon the successful deployment of energy conservation strategies such as the regulation of feeding, physical exertion and rest. Such energy conservation strategies are imperative to successfully completing predetermined survival activities within biological and environmental constraints. Humans use similar energy regulation strategies to successfully conduct their daily living activities albeit with less emphasis than other animals on survival. This is particularly apparent in the way humans pace themselves during athletic activity to avoid premature fatigue.

What’s fascinating is that this anticipatory pacing strategy appears to be hardwired into us. By the time we reach the third Piaget stage, we’re already pacing ourselves in exactly the same (much-debated) way that the runners who set distance-running world records do: a fast start, a slower middle, then a fast finish.

Jockology: how much exercise is too much?

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 look at the debate about whether too much exercise is actually bad rather than good for you, drawing on recent studies about cardiac fibrosis in elite endurance athletes, epidemiological data from the National Runners’ Health Study, and — to be topical — Tour de France riders:

Given the number of cyclists in this year’s Tour de France who have skidded off mountain passes, been sideswiped by passing cars or catapulted into barbed-wire fences, it’s obvious that riding in the Tour can be hazardous to your health.

But what about the riders who make it to the finish line in Paris, having covered 3,430.5 heart-pounding, leg-draining kilometres in three weeks? Does their gruelling training regimen make them healthier, or does too much of a good thing leave them worse off? Medical opinion has flip-flopped over the years as our understanding of the heart’s response to exercise has increased, but a new study on the most important outcome of all – staying alive – suggests that Tour riders do better than average. [READ THE ARTICLE…]

 

Ice baths for recovery: 15 minutes at 10 C

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)

***

Post-workout ice baths are one of those things that everyone believes in, no matter what the science says. There have been a bunch of ice bath studies, but they’ve used lots of different water temperatures, immersion times, and outcome measures, and the results have been very mixed. This month’s European Journal of Applied Physiology has a study from France’s National Institute of Sport that looks like the strongest evidence yet in favour of ice baths — and offering some concrete advice on water temperature and immersion time.

One key difference from previous studies: they used elite athletes — 41 football, rugby and volleyball players — whose recovery might be expected to be faster than untrained volunteers. They tested four different protocols:

  • TWI: body-temperature water (36 C) for 15 minutes;
  • CWI: cold water (10 C) for 15 minutes;
  • CWT: contrast water (10 C and 42 C), alternating 90-second bouts for 15 minutes;
  • PAS: no water — just sitting there for 15 minutes.

The exercise they used to induce fatigue and muscle damage was alternating bouts of hard rowing and counter-movement jumps. They took blood samples and tested muscle strength (MVC), jump height, and power produced during 30 seconds of rowing — and they did those tests before and immediately after the exercise, then again one hour and 24 hours later.

As you can imagine, with all those different test groups and protocols, the results are a bit of a jumble. The key result, as far as I’m concerned, is right here:

This is the data for creatine kinase, which is a commonly measured marker related to muscle damage. Its exact significance is often debated, but the authors of this study suggest it’s a sign of “reduced passive leakage from disrupted skeletal muscle, which may result in the increase in force production during ensuing bouts of exercise.” The key: the ice bath outperforms all the other interventions, including the contrast bath.

Of course, nothing is quite that simple. If we look at the performance measures, the picture gets muddier:

What we’re interested in here is the cases where performance returns to “normal” quickly. The asterisks indicate where performance is reduced from the first bout by a statistically significant amount. The broad conclusion we can draw is that both the ice bath and the contrast bath seem to offer some advantages compared to room temperature water or not bath. The main reason I included this data is to show that it’s not a simple, magical effect. It’s complicated. But for practical purposes, this data gives me more confidence than any previous study to support the very strong anecdotal evidence that a sustained cold-water bath — in this case, 15 minutes at 10 C — helps to speed up recovery after hard workouts.

Vitamin D and muscle injuries

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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)

***

I’m on the record as a bit of a vitamin D skeptic. Not a total skeptic, mind you — it’s actually the only supplement of any kind that I take on a regular basis these days. But the claims that vitamin D enhances athletic performance have seemed pretty weak to me so far. However, I’ll dutifully pass along this press release from the American Orthopaedic Society for Sports Medicine, which describes some new research linking vitamin D levels with muscle injuries in NFL football players.

The study: 89 players from one NFL team were tested for vitamin D levels in spring 2010, during pre-season. Not surprisingly, the levels were generally low compared to what’s considered desirable (which seems to be true for pretty much every population group in the developed world):

Twenty-seven players had deficient levels (< 20 ng/ML) and an additional 45 had levels consistent with insufficiency (20-31.9 ng/mL). Seventeen players had values within normal limits (>32 ng/mL).

The team then provided data on time missed due to injuries during the season. Sure enough, players who suffered muscle injuries has “significantly lower levels” of vitamin D. How much lower? It’s not clear: this is conference data, so not yet published in a journal, and unfortunately the press release release doesn’t do a very good job of presenting the data. The average level for players with a muscle injury was 19.9, but it doesn’t tell us what the average for uninjured players was.

First thing to wonder: is it this cause or correlation? Do the players with crappy diets also neglect their strength, flexbility and warm-up routine? Second thing: if it is causal, what’s the mechanism? Why does this work?

Leaving that aside, I’ll just reiterate my hair-splitting distinction between a “performance-enhancing” substance and one that hurts performance if you’re deficient in it. Water helps your performance if you’re dehydrated, but we don’t consider it an ergogenic aid. As far as I can tell, vitamin D falls into the same category: something that you shouldn’t be deficient in, whether you’re an athlete or not. But I’m still not convinced that more is better if you’re in a healthy range.

To clinch victory, shoot for the left side of the net

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)

***

Interesting press release about an upcoming study in Psychological Science. In an analysis of every World Cup penalty shoot-out from 1982 to 2010, researchers from the University of Amsterdam found that goalies tend to dive to the right when their team is down and the game is on the line. (In other situations, they were equally likely to go right or left.)

Many studies have found that people and animals that want something tend to go to the right. When dogs see their owners, they wag their tails more to the right; toads strike to the right when they’re going for prey; and humans are more likely to turn their heads to the right to smooch their sweeties…

In an experiment, the team found that people who are told to divide a line in half tend to aim a bit to the right when they are both thinking about a positive goal and under time pressure—just like the goalies.

So how will this affect strategy in the next World Cup? Now the goalies know about this innate tendency; but the shooters know that the goalies know; but the goalies know that the shooters know that the goalies know…

[Minor gripe: the press release doesn’t actually reveal what the split in the data was — i.e. 51:49? 70:30? And the paper itself isn’t yet available online. A rather crucial detail, I’d have thought.]