alex – Page 19 – Sweat Science

October 5, 2011

Knee bends make you smarter?

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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The best way to improve your cognitive function is to… strengthen your quadriceps muscles?! That (sort of) is the message of a new study in the European Journal of Applied Physiology by researchers in Japan.

In brief: they measured cognitive function in a group of 39 older men (average age 69) using the “Mini-Mental State Exam” (MMSE), and compared to results to measures of elbow, knee and ankle strength. They found that knee extensor strength (i.e. quadriceps) was significantly correlated with MMSE scores, but elbow and ankle strength weren’t. To some extent, this isn’t surprising: cognitive decline is often linked to declining ability to carry out everyday tasks, though it’s not entirely clear which is the cause and which is the effect. (Does physical weakness condemn you to sit helplessly in your chair, causing your mental faculties to atrophy? Or is it mental decline that stops you from doing your usual activities, causing your muscles to weaken?)

But this doesn’t explain why knee strength predicted cognitive function while elbow and ankle strength didn’t. One possibility is that the knee is more significant because it’s a larger muscle mass, so it’s more capable of affecting the levels of hormones like insulin-like growth factor 1 circulating in your body, which in turn affect brain health. This is pretty speculative. A simpler possibility is that knee strength is more important to mobility (e.g. getting in and out of chairs) than ankles or elbows. (And a third possibility is that the result is simply a fluke due to small sample size.)

Anyway, this raises the question: can you get smarter by doing deep knee bends? The study tried this, putting 27 of the subjects through a three-month, six-day-a-week home training program involving simple things like sitting in a chair then standing up. The results were a little unclear because the changes were very small after such a light training program — but the increases in MMSE score were indeed correlated (with p<0.05) with increases in knee extensor strength. In other words, those who achieved the biggest gains in knee strength also saw the biggest gains in MMSE score.

So what does this mean? I don’t think it’s anything earth-shatteringly new. To keep your wits about you, you have to stay active; to stay active, you need to have the physical ability to get around. Most previous studies on exercise and cognition have focused on aerobic exercise, which produces very strong effects on the brain. The message here is that you can’t neglect your muscles — particularly the big ones that get you out of your chair and walk you down the street.

October 4, 2011

The Streetlight Effect

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- Alex Hutchinson (@sweatscience)

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This came up in the comments of a previous post, but I thought it was worth a post of its own. I was trying to explain the dangers of the “Streetlight Effect,” and came across this article from Discover magazine by David Freedman, the author of Wrong, which does a very nice job of explaining it:

The fundamental error here is summed up in an old joke scientists love to tell. Late at night, a police officer finds a drunk man crawling around on his hands and knees under a streetlight. The drunk man tells the officer he’s looking for his wallet. When the officer asks if he’s sure this is where he dropped the wallet, the man replies that he thinks he more likely dropped it across the street. Then why are you looking over here? the befuddled officer asks. Because the light’s better here, explains the drunk man.

How does this relate to scientific research? It points out that researchers are always likely to focus on quantities they can measure (i.e. where the light is good), regardless of whether they’re the most important. An example:

A bolt of excitement ran through the field of cardiology in the early 1980s when anti-arrhythmia drugs burst onto the scene. Researchers knew that heart-attack victims with steady heartbeats had the best odds of survival, so a medication that could tamp down irregularities seemed like a no-brainer. The drugs became the standard of care for heart-attack patients and were soon smoothing out heartbeats in intensive care wards across the United States.

But in the early 1990s, cardiologists realized that the drugs were also doing something else: killing about 56,000 heart-attack patients a year. Yes, hearts were beating more regularly on the drugs than off, but their owners were, on average, one-third as likely to pull through. Cardiologists had been so focused on immediately measurable arrhythmias that they had overlooked the longer-term but far more important variable of death.

This particular example brings to mind last month’s discussion about the increased incidence of arrhythmias among elite cross-country skiers. Should we be worried about those arrhythmias? Or should we focus on the “more important variable of death,” since studies of the same skiers found that more skiing led to longer life?

More generally, the Streetlight Effect is one of the key reasons why extrapolating “real world advice” from lab studies has such a low batting average. Last week, I blogged about an interview with Asker Jeukendrup, a sports scientist who I have a tremendous amount of respect for. But I disagreed with one of his comments: “I think if the physiological changes are there, the performance must ultimately follow.” All it takes is a stroll down the supplements aisle of a pharmacy or health-food store to remind me that promising physiological changes don’t always translate into measurable health or performance benefits.

October 3, 2011

Beet juice vs. nitrate supplements

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- Alex Hutchinson (@sweatscience)

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The story so far: beet juice improves endurance performance. We’re pretty sure it’s because of the nitrate in beets. But we’re not sure whether you can get the same effects by simply taking nitrate supplements directly.

Enter a study in this month’s Medicine & Science in Sports & Exercise, from researchers in Spain. They administered either a placebo or a dose of sodium nitrate (10 mg per kg of body weight) to 11 well-trained cyclists and triathletes. Then, three hours later, the athletes did a series of sub-maximal cycling bouts and a progressive VO2max test to exhaustion. The results: well, this is where it gets confusing:

[W]e found that the VO2peak was significantly reduced when athletes ingested nitrate. These in vivo data were found without any changes in cardiorespiratory and performance parameters, which suggests that nitrate and its reaction products could play an important role in oxygen consumption at maximal intensity of exercise in well-trained athletes.

So basically, in the progressive test to exhaustion, the athletes lasted the same amount of time with or without nitrate (416 seconds with nitrate, 409 seconds with placebo, a nonsignificant difference) — but they reached failure while using less oxygen. So the good news is that nitrate did somehow make the cyclists more efficient at converting oxygen into power. But the bad news is that this didn’t improve their performance — they just used less oxygen.

What to make of this? I’m not sure. That’s partly because the paper is fairly confusing, but I think it’s also because researchers simply don’t know what exactly is going on yet! For practical purposes, my conclusion would be that if you’re looking for a boost, stick with real beet juice rather than sodium nitrate for now. There may be other differences between this study and previous successful performance-boosting studies (e.g. in the training of the subjects, their typical dietary habits and usual nitrate levels, etc.) — but until further studies sort this out, the only thing we know for sure is that beet juice, in some circumstances, works.

October 1, 2011

Running stride: speed vs. injury-proofing

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- Alex Hutchinson (@sweatscience)

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Another great post on Amby Burfoot’s Peak Performance blog explores an important wrinkle in the ongoing debates about optimal running form. We tend to think that “better” running form is better in all relevant respects: we’ll be faster and less likely to be injured. But that’s not necessarily the case. Amby takes a look at a study from a couple of years ago that analyzed the gait of an ultrarunner who ran from Paris to Beijing in 161 days, averaging 53 km per day. As Amby writes:

You would think that 161 days of a marathon-plus per day would turn you into a lean, mean running machine. But that doesn’t happen, at least not when it comes to running economy… His stride became shorter and “smoother,” the word used by the physiologists to describe his decrease in aerial time with each stride… He reduced his landing force and also his loading rate. But his oxygen efficiency, or running economy, decreased by six percent.

This illustrates one of the conundrums faced by those attempting to run with shorter strides. It may in fact reduce your injury rates. It won’t necessarily make you faster.

The adaptations that this runner’s body made over the course of this epic run make perfect sense: after all, his top priority was to survive each day without breaking down. But it’s a good reminder that, when we talk about “improving” running form, we have to think carefully about what, exactly, we’re hoping to improve.

September 30, 2011

Toning shoes: a $25 million scam

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- Alex Hutchinson (@sweatscience)

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It has been a very long couple of days for me, packing up and moving out of my apartment, and getting ready to catch a trans-Pacific flight — so I was very happy to see some good news to brighten my evening. As Julie Deardorff of the Chicago Tribune notes, Reebok has apparently agreed to refund $25 million to consumers who bought their toning shoes because of misleading advertising claims:

According to the FTC complaint, Reebok falsely asserted specific numerical claims, saying, for example, that walking in EasyTone shoes had been proven to lead to 11 percent greater strength and tone in hamstring muscles than regular walking shoes.

Over the last year or two, I’ve had quite a few requests from readers (or disgusted skeptics) to write a column on the “science” (yes, those are sarcastic quote marks!) behind toning shoes. The problem is that it’s very hard to write a science-of-exercise column on something so devoid of science. (Or to look at it another way, it’s very easy, but the column ends up being two sentences long — and I get paid by the word!) 🙂

Anyway, as it turns out, there has been some critical scientific analysis of toning shoes: Christian Finn does a good job of summing up the topic here, including a link to a (non-peer-reviewed) study by some very well respected University of Wisconsin researchers that compared Reebok EasyTone, Skechers Shape-Ups and MBT shoes to ordinary running shoes, and found no worthwhile differences.

The one thing that surprises me is: why Reebok, in particular? Because ads for athletic apparel are generally so ridiculous and misleading that I’ve always assumed they just operate in a truth-free zone. Will similar suits follow against Skechers and other brands? Anyway, regardless of what follows, it’s always good to see the occasional victory for common sense. With PowerBalance earlier this year and now EasyTone, it’s been a pretty good year for the good guys.