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Archive for August, 2010

Sarcopenia: muscle loss is the new bone loss?

August 31st, 2010

For an article I’m working on, I’ve been digging through the literature on sarcopenia, the age-related loss of muscle mass that most of us face starting in our 30s. I’ve found several conflicting estimates of how much muscle you can expect to lose, with a high end of 1-2% per year starting in your fourth decade (from this paper). That’s a lot more aggressive than I’d expected. I get the sense that it’s one of those problems whose implications we’re just now beginning to grasp — so I was interested to see this article by Andrew Pollack in the New York Times, which offers a good introduction to the topic:

Bears emerge from months of hibernation with their muscles largely intact. Not so for people, who, if bedridden that long, would lose so much muscle they would have trouble standing.

(Nice lede!)

Why muscles wither with age is captivating a growing number of scientists, drug and food companies, let alone aging baby boomers who, despite having spent years sweating in the gym, are confronting the body’s natural loss of muscle tone over time.

Comparisons between age groups underline the muscle disparity: An 80-year-old might have 30 percent less muscle mass than a 20-year-old. And strength declines even more than mass…

Much of the article focuses on attempts to agree on a clinical definition of the condition — which would then make it possible for drugmakers to win approval from regulators for drugs to treat it. But the key point for me is:

Researchers involved in the effort say doctors and patients need to be more aware that muscle deterioration is a major reason the elderly lose mobility and cannot live independently.

In other words, I need to start doing my push-ups again. Soon.

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Beyond beet juice: L-arginine also boosts endurance

August 27th, 2010

Andrew Jones, the man behind the beet juice fad of 2009, has more performance-enhancing revelations in a study just released online in the Journal of Applied Physiology. He found that taking the supplement L-arginine produced very similar effects to beet juice: by reducing the “oxygen cost of exercise,” it allowed subjects to last 20% longer in a ~10-minute cycle to exhaustion (11:47 versus 9:22 for controls) in a placebo-controlled double-blind trial. They estimate that’s equivalent to a boost of 1-2% in a fixed-distance race. (Abstract here, press release here.)

What’s significant here is that L-arginine acts in basically the same way as beet juice. Beet juice contains nitrate, which the body converts to nitric oxide, which has a number of effects such as dilating blood vessels and lowering blood pressure, ultimately allowing the body to perform more work from the same amount of oxygen. L-arginine is also converted by an enzyme to nitric oxide, producing the same cascade of effects — and, as the researchers note, the performance boosts observed in the two studies are very similar, giving them confidence that they really do understand what’s happening inside the body.

This is by no means the first L-arginine study — there have been a number of attempts to use it for performance enhancement, with conflicting results. Previous studies have generally given the supplement on a chronic basis — a little bit each day, or even several times a day. In this case, the researchers opted for one big dose, taken an hour before exercise, to make sure that nitric oxide availability really was elevated during the exercise bout. (They used 500mL of a drink called Ark 1, containing 6 g of L-arginine. There are no disclosures in the paper about who paid for the study.) This change may explain why they saw such a clear result compared to earlier studies.

So what’s next? According to the press release, “the researchers are hoping to find out whether combining the two methods could bring an even greater improvement in athletic performance.” In the meantime, perhaps L-arginine will prove to be a more user-friendly option than beet juice. Here’s what Amby Burfoot reported about one world-record-holder’s abortive try:

Two days before the ING New York City Marathon, I asked Paula Radcliffe if she actually drank beet juice. This moved her to stage one: silly giggles. And an embarrassing response. “I tried it once,” she said, “but most of it came out the other end.

Is exercising with your iPod making you stupid?

August 25th, 2010

Just read an interesting article by Matt Richtel in the New York Times. The nut: Researchers believe that our brains need downtime in order properly assimilate new information and memories, but we now have so many devices to fill every moment with distraction and titillation that we may be compromising our ability to learn.

It’s 1 p.m. on a Thursday and Dianne Bates, 40, juggles three screens. She listens to a few songs on her iPod, then taps out a quick e-mail on her iPhone and turns her attention to the high-definition television. Just another day at the gym…

But scientists point to an unanticipated side effect: when people keep their brains busy with digital input, they are forfeiting downtime that could allow them to better learn and remember information, or come up with new ideas. Ms. Bates, for example, might be clearer-headed if she went for a run outside, away from her devices, research suggests.

This is a new wrinkle in a very familiar debate about the pros and cons of exercising with headphones or other electronic devices. I have to confess that, though I’ve read all the literature about how music can pump you up and so on, I’m in the shrinking minority that prefers their exercise unwired. And my reasons, on an intuitive level, fit with what Richtel describes in this article. My life is pretty hectic, and I’m bombarded by a constant stream of information and stimulus. Most of us are these days, I think. I’d love to say that, when I head out for a run, it gives me a chance to think in peace, to have those deep insights that require uninterrupted meditation. But really, I usually just space out. If these researchers are right, though, that period of mental blankness could play a key role in the epiphanies I have later on, since my brain has been busy consolidating and organizing information.

Of course, there’s a flip side. It’s undeniable that lots of people really like exercising with music and/or TV. And that’s got to be better than not exercising at all, as Richtel’s article also acknowledges:

Some researchers say that whatever downside there is to not resting the brain, it pales in comparison to the benefits technology can bring in motivating people to sweat.

“Exercise needs to be part of our lives in the sedentary world we’re immersed in. Anything that helps us move is beneficial,” said John J. Ratey, associate clinical professor of psychiatry at the Harvard Medical School and author of “Spark: The Revolutionary New Science of Exercise and the Brain.”

But all things being equal, Mr. Ratey said, he would prefer to see people do their workouts away from their devices: “There is more bang for your buck doing it outside, for your mood and working memory.”

The trouble with acupuncture studies

August 24th, 2010

Tara Parker-Pope has an interesting article in the New York Times about a recent study on acupuncture for pain relief, and more generally about the difficulties in testing acupuncture (and other forms of “traditional” or “integrative” medicine) using standard Western research methods.

The study tested acupuncture versus a sham treatment (that also involved needles, but inserted in the “wrong” places and not as deeply) in 455 patients suffering from knee arthritis. Both groups experienced relief — their pain decreased by one point on a scale of 1 to 7 compared to controls who received no treatment at all. This is consistent with a series of earlier studies suggesting that “inserting needles in or around an area of pain may have caused a ‘super placebo’ effect, touching off a series of reactions that changed the way the body experienced pain.”

The NYT article is worth reading for the discussion of what can and can’t be tested with traditional blinded clinical trials. And then there’s the even harder question: if the effects of acupuncture are essentially a placebo, but a powerful one, then what do we do? After all, the results — pain relief — are surely more important than the mechanism. But what if we establish once and for all that it’s a placebo. Does that mean its effectiveness will disappear? Is it better to remain ignorant so that treatments like acupuncture will work?

Pre-run stretching doesn’t affect injury rate

August 23rd, 2010

In the “I didn’t know they did research” department, U.S.A. Track and Field just released the results of a study on pre-run stretching. They recruited 1,400 runners through their website for a randomized, prospective study in which half the volunteers stretched before running and the other half didn’t. Over the next three months, 16% of the runners got injured, with no difference whatsoever between the stretching and non-stretching groups.

You can’t read too much into a volunteer, self-reported study like this, but if you drill a little further into the data, there are some interesting wrinkles. Age, sex, weekly mileage, flexibility and level of competition all had no effect on injury rates. High BMI and previous history of injury, on the other hand, both led to a higher probability of injury.

Most interestingly, people who normally stretch before runs but were assigned to the non-stretching group actually doubled their risk of injury. There’s not really enough detail in the study to understand why this happened, but it underscores an important message that applies not only stretching, but to other hot topics like running shoes: If you’re running happily without injury problems, don’t change what you’re doing!

Shortening your stride mimics the effects of running barefoot

August 23rd, 2010

Just got back from a fantastic canoe trip in Quebec (and yes, I caught more pickerel, along with a pike and a whitefish). While I was away, my Jockology column on how shortening your stride can mimic some of the effects of barefoot running ran in the Globe and Mail:

…a forthcoming study from researchers at the University of Wisconsin suggests that many of the benefits promised by barefoot running, including a reduction of the forces acting on knees and hips, can be obtained simply by taking shorter, quicker steps.

“We found very similar loading patterns,” says Bryan Heiderscheit, the senior author of the study, which will appear in a forthcoming issue of Medicine & Science in Sports & Exercise, “and you don’t have to go all the way to the extreme of getting rid of your shoes. [READ THE REST OF THE ARTICLE...]

I initially blogged about this study last month, but I subsequently had a really interesting interview with Dr. Heiderscheit. Obviously, this is a very controversial topic these days, and it sometimes seems as if everybody has a biomechanical study that supports their point of view. So I was happy to hear that the Wisconsin team is undertaking a proper randomized, controlled clinical trial that will follow runners for a year or two as they alter their stride length, to see whether it actually affects injury rates as opposed to just joint forces.

Mission: pickerel

August 15th, 2010

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I’m heading out in about half an hour for my annual canoe trip, this time on the Lievre River in the Laurentians. My mission: catch at least one delicious pickerel like this one I caught last year on the Noire. (That’s “walleye” for you Americans out there.) Also, try not to add any scars to the big one on my hip that I picked up last year while navigating a 200-metre-long rapids a few metres behind my upside-down canoe. At least this year I’m bringing a helmet! I’ll be back in a week…

Fruit and vegetables in a pill: does it work?

August 15th, 2010

The more we study antioxidants, the more it looks like — despite the hype — popping big doses of vitamin C and so on doesn’t do much to help your muscles recover from strenuous exercise. In fact, some researchers now suggest popping antioxidants might actually hurt your recovery.

On the other hand, no one doubts that eating lots of fruit and vegetables is just about the best thing you can do, nutritionally speaking. So how about taking a supplement that is, essentially, concentrated fruit and vegetable, like Juice Plus+, which is “whole food based nutrition, including juice powder concentrates from 17 different fruits, vegetables and grains“? That’s what researchers from the University of North Carolina Greensboro decided to test, in a study now appearing online in Medicine & Science in Sports & Exercise (funded, needless to say, by the makers of Juice Plus+).

The 41 volunteers in the study took Juice Plus+ (or a placebo) for four weeks  prior to an intense, muscle-damaging workout. They continued taking it for another four days after, while various measures of antioxidant status, muscle soreness, strength, and range of motion were recorded at intervals. The conclusion:

This study reports that 4 weeks of pretreatment with [Juice Plus+] can attenuate blood oxidative stress markers induced by [eccentric exercise] but had no significant impact on the functional changes related to pain and muscle damage.

So what does this tell us? Yes, fruit and vegetable concentrates supply antioxidants (along with, presumably, other interesting ingredients). These substances may have some health benefits — though whether the benefits are greater or less than taking pure vitamins, we don’t know. But, as far as exercise and recovery goes, antioxidants don’t seem to have anything to do with it.

So for now, my feeling is: why take a powder that might have some benefits when you can take the actual fruits and vegetables that definitely have benefits, and taste better anyway? That being said, I’ll give some credit to Juice Plus+. I’m sure they didn’t get the results they were hoping for, but at least they’re making the effort to fund independent studies — which is a lot more than can be said for most of the products on health-food store shelves!

Building muscle with light weights

August 11th, 2010

Another interesting strength-training study just popped up, this one published in PLoS One. The claim in the press release is quite eye-catching: “Building muscle doesn’t require lifting heavy weights.” This is a leap of logic that isn’t quite supported by the paper itself, whose claims centre on “stimulating muscle protein synthesis ” and “inducing acute muscle anabolism” rather than actually demonstrating big muscles. Still, it’s a very surprising study, from a well-respected group (Stuart Phillips at McMaster University).

The study compared three different weights routines:

(1) lift at 90% of one-rep max until failure;

(2) lift at 30% of one-rep max until you’ve lifted as much as you did in the first routine;

(3) lift at 30% of one-rep max until failure.

Deeply entrenched dogma tells us that the best way to build big muscles is to lift heavy weights — option (1) in the workout routine. But the researchers injected tracers and took muscle biopsies four and 24 hours after each workout to find out what was happening on a cellular level. They found that the first and third routines were the same on most measures of protein synthesis, and the third routine was even better on some measures. Those new proteins being synthesized are what accumulate, over time, to produce bigger muscles. So as long as you’re lifting until can’t lift anymore, you’ll do as well or better with light weights as you would with heavy weights.

This is some serious heresy being proposed, and it’s important to note that they didn’t actually observe bigger muscles, just cellular markers. The researchers themselves note that “a training study in which these distinctly different exercise loads are utilized is clearly warranted to confirm our speculation.”

Whatever the training study eventually shows, it’s hard to imagine that this will affect how serious muscle-builders train. However, the researchers believe it could have important implications for “people with compromised skeletal muscle mass, such as the elderly, patients with cancer, or those who are recovering from trauma, surgery or even stroke,” since it minimizes the risk of orthopedic and soft-tissue injury. I’d generalize that even further — there are many, many people who are intimidated by the prospect of trying to lift heavy weights, but might be willing to lift a lighter weight 20 or 30 times until they can’t lift it anymore. Of course, that’s the crux: the method only works if you reach failure, so it’s still going to hurt. You’re just less likely to cause a scene at the gym by dropping the weight on your foot.

Ballistic power vs. strength training for athletic performance

August 11th, 2010

If you’re trying to step up your basketball (or tennis or soccer or whatever) game, which weights routine is better:

(1) three sets of three back squats at 90% of one-rep max; or

(2) seven sets of six jump squats at less than 30% of one-rep max?

The conventional wisdom is that ballistic power training carries more bang for your performance buck, since it simulates the movements you’ll be making at realistic speeds. Other than in sports like weightlifting and football, it seldom matters what your absolute maximum strength is, especially if you can’t summon it instantly.

Certainly, if you’re Roger Federer, you’ve got a custom-tailored, periodized training plan that incorporates both pure strength and ballistic work. But what if you’re an average, non-professional athlete? A study by New Zealand researchers in the current issue of Medicine & Science in Sports & Exercise pits these two workout regimens against each other in a group of 24 “relatively weak” volunteers, measuring functional outcomes like maximal power output, jump height, movement velocity and sprint performance. The result: after 10 weeks, the two groups were pretty much identical (and significantly better than untrained controls in all measures).

In both cases, the adaptations were primarily neuromuscular — signals from the brain to the muscles were transmitted and executed more effectively. (The precise neuromuscular changes were different in the two groups: the ballistic group was able to produce force more quickly, while the strength group increased the magnitude of their contractions, but the performance results were the same.) These neuromuscular adaptations are precisely the point of ballistic training — to some extent, that’s all you get from it. The surprising result in this study was that, for “weak” people who haven’t already done a lot of weightlifting, ordinary strength training produces comparable neuromuscular benefits. But if you keep at it, strength training will eventually also produce significant structural changes — i.e. bigger muscles — that provide further performance benefits.

So the moral of the story, according to the researchers, is that recreational athletes who’d like to improve their performance should choose strength training. It’ll give them all the benefits of neuromuscular training, with the possibility of additional muscle growth if they keep at it.

From my point of view, there’s another moral we can draw from it, which is that, if you haven’t been lifting any weights, pretty much anything you do is going to trigger those neuromuscular gains and improve your performance — so don’t get hung up on the details, just do it.