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Archive for May, 2010

Training without breakfast boosts glycogen stores

May 9th, 2010

I posted last month about the “train low, compete high” concept, in which you do a depletion workout to empty your glycogen stores, then do a hard workout while running on empty. The idea is basically the nutritional equivalent of running with a weighted vest — it makes training harder, and perhaps forces your body to adapt to the tougher conditions so that when you do fuel up properly, you get an extra boost. But results so far have been ambiguous: your body does respond in several ways, including learning to burn more fat instead of carbohydrate, but there’s no good evidence that it actually improves performance. And it’s very hard and makes you feel like crap.

A kinder, gentler version of “training low” is doing your workout before breakfast, without restocking the glycogen that you’ve burned overnight (your liver glycogen stores drop by about 50% while you sleep). There have been a few studies on this regime, and the most recent is now in press at the Journal of Science and Medicine in Sport. Researchers in New Zealand had 14 cyclists perform a four-week training program, five mornings a week, starting with 25 minutes per session at 65% of VO2max and building up to 100 minutes per session. Half of them had a “standard cereal breakfast” an hour before working out, while the other half had the same breakfast shortly after working out.

The results were pretty striking. The fasted group increased the amount of glycogen stored in their muscles by 54.7%, while the breakfast group increased by just 2.9%. The fasted group also increased their VO2max by 9.7%, compared to 2.5% in the breakfast group. The other interesting finding is that men and women responded differently to some of the training adaptations: men seemed to benefit more from the fasted training, while women seemed to benefit more from the fed training.

Some caveats: First, it’s a small study, so the margins of error are high. Second, the subjects were untrained — athletes who are already training definitely won’t boost their glycogen stores by 50% or their VO2max by 10%, so it’s possible that the differences may disappear entirely. Third, actual exercise performance wasn’t measured as an experimental outcome. The literature is full of bright ideas that change some parameter in lab tests but don’t actually make you faster when the chips are down. Finally, the training program isn’t one that anyone would implement in the real world. It’s highly unlikely that doing ALL your training in a fasted state is the optimal approach.

Still, the results are interesting. They raise the possibility that mixing in an occasional fasted workout, perhaps once or twice a week, could provide your body with a different sort of stimulus that might prompt some useful adaptations. And this no-breakfast approach seems a lot more realistic to me than the idea of doing a one-hour depletion run before a hard workout.

(Thanks to Steve Magness for pointing out the study.)

Staying fuelled while cycling helps bone density

May 9th, 2010
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I’m not sure if my headline is misleading. There’s a new press release from the University of Missouri titled “Maintaining Energy Balance During Stage Races May Protect Cyclists’ Bones, MU Researcher Says,” but the description of the research is a little confusing (and the journal paper in Applied Physiology, Nutrition and Metabolism has yet to appear).

The new study is by Pam Hinton, who I interviewed last year for a piece on exercise and bone density. That previous study compared running, cycling and weightlifting, and concluded that running was good because of the jarring impacts, weightlifting was good because the added muscle puts stress on bones, but cycling had neither of those benefits.

The new study monitored cyclists during the Tour of Sutherland, a six-day, 10-stage race:

Hinton found significant increases in markers of bone formation and bone breakdown among the athletes whose energy intake matched their energy expenditure throughout the race.

Fortunately, bone formation increased more than bone breakdown, which suggests that everything is fine for those who take in enough calories.

“The findings suggest that participation in stage races might not have negative effects on bone turnover if energy intake matches the energy cost of high-intensity racing over several days,” said Pam Hinton, associate professor in the Department of Nutrition and Exercise Physiology. “The results are consistent with the practical recommendation that elite cyclists should match their energy intake to the high energy demands of stage racing.”

What’s unclear from the press release is whether she actually observed enhanced rates of breakdown in cyclists who weren’t getting enough calories during the race. If so, you’d think they’d mention it. If not, then I’m not sure how the study proves anything about adequate energy intake (though it’s obviously a good idea with or without this study!). I’ll follow up on this when I see the full study.

Anyway, uncertainty aside, the message seems to be: hauling ass during a brutal multi-day stage race won’t have any negative effect on your bones, assuming you’re taking in enough calories.

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National Magazine Award nominations

May 6th, 2010

If you’ll pardon a little self-promotion, the nominations for this year’s National Magazine Awards were announced last night, and I was thrilled to pick up three. Two of them were for my piece in The Walrus about the neuroscience of navigation and how using GPS may be affecting our brains.

The third was for a piece in Canadian Running on evolution, barefoot running and injuries, including some interesting thoughts from Chris McDougall, the author of the bestseller Born to Run. (The piece was written last spring, before McDougall’s book was released and rocketed the topic into the public conversation.) I included a brief excerpt from the piece in a blog entry last summer, but now the full piece is available online for the first time here:

The giant screen at the front of the lecture theatre shows, in gruesome detail, a dissected bare foot connected through tendons to ten different muscles in the lower leg, all pulling in slightly different directions. Benno Nigg, a renowned professor of biomechanics who co-directs the University of Calgary’s Human Performance Laboratory, is leading an audience of Australian academics gathered at the University of Sydney through a presentation titled “The Future of Footwear.” During almost four decades as one of the world’s leading athletic shoe researchers, Nigg has worked closely with major companies such as Adidas, Nike and Mizuno. But plotting the future of the running shoe, he now believes, may require a look to the past, at what worked for our ancestors.

“Look at all these muscles here,” he says, gesturing at the dissected ankle. He asks the audience to guess which of the muscles we need in order to walk while wearing a typical shoe. Only two of the ten are needed, it turns out: the tibialis anterior (shin) and the triceps surae (calf). “And all the other ones, you don’t need, because the shoes take over.” Nigg pauses to let his audience consider this piece of trivia, then poses the central question of his talk: “Is that a problem?” [READ ON…]

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Jockology: does a personal trainer help?

May 3rd, 2010
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A new Jockology column is now posted on the Globe and Mail website, taking a closer look at some of the research into personal trainers (a topic I blogged about a few months ago):

The question

Will I get a better workout if I hire a personal trainer?

The answer

In a famous study at Ball State University in Indiana, researchers put two groups of 10 men through identical 12-week strength-training programs. The groups were evenly matched when they started, and they did the same combination of exercises, the same number of times, with the same amount of rest.

At the end of the experiment, one group had gained 32 per cent more upper-body strength and 47 per cent more lower-body strength than the other. No performance-enhancing pills were involved – the only difference was that the more successful group had a personal trainer watching over their workouts.[READ ON…]

One of the key punchlines: people with personal trainers choose to lift heavier weights, and thus make more progress. Left to their own devices, many people choose weights that are less than 40-50% of their one-rep max, and thus pretty much ineffective for stimulating strength gains.

Two approaches to brain training

May 2nd, 2010
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Two recent items related to what makes your brain work better. First, a study in Nature on the benefits of the current fad for “brain training”:

The largest trial to date of ‘brain-training’ computer games suggests that people who use the software to boost their mental skills are likely to be disappointed…

“There were absolutely no transfer effects” from the training tasks to more general tests of cognition, says Adrian Owen, a neuroscientist at the Medical Research Council (MRC) Cognition and Brian Sciences Unit in Cambridge, UK, who led the study. “I think the expectation that practising a broad range of cognitive tasks to get yourself smarter is completely unsupported.”

One major criticism of the study is that the largest effects of brain training are anticipated in adults over 60, at which point mental sharpness may already be slipping. Also, the total training time in the study averaged just four hours, which may not be enough to offer any benefits.

With that in mind, it was interesting to see this interview with Barbara Strauch, who has just written a book on the “grown-up” brain:

Q. Is there anything you can do to keep your brain healthy and improve the deficits, like memory problems?

A. There’s a lot of hype in this field in terms of brain improvement. I did set out to find out what actually works and what we know. What we do with our bodies has a huge impact on our brains. Our brains are more like our hearts in that everything you do for your heart is thought to be equally as good or better for your brain. Exercise is the best studied thing you can do to your brain. It increases brain volume, produces new baby brain cells in grownup brains. Even when our muscles contract, it produces growth chemicals. Using your body can help your brain.

I’m all in favour of undertaking challenging cognitive tasks to stay sharp (and for fun) — but aerobic exercise is still the best thing you can do for your brain.

Why athletes can’t resist racing in practice

May 1st, 2010

I posted a few times last month about the sometimes irresistible urge to race in practice. In that context, I was interested to see a description of this study, published in PNAS last week by neuroscientists at Washington University in St. Louis:

Whether it’s for money, marbles or chalk, the brains of reward-driven people keep their game faces on, helping them win at every step of the way. Surprisingly, they win most often when there is no reward.

Basically, the researchers used fMRI scans to monitor the brains of people participating in word games with and without monetary rewards. They found that, once an association between activity and reward is established, the pattern of brain activity shifts to automatic mode so that the actual presence of the reward is irrelevant.

The research has important implications for understanding the nature of persistent motivation, how the brain creates such states, and why some people seem to be able to use motivation more effectively than others.

They suspect the mechanism has to do with dopamine:

“It would be like the dopamine neurons recognize a cup of Ben & Jerry’s ice cream and tell the lateral PFC the right action strategy to get the reward — to grab a spoon and bring the ice cream to your mouth,” Braver says. “We think that the dopamine neurons fires to the cue rather than the reward itself, especially after the brain learns the relationship between the two. We’d like to explore that some more.”

So in an athletic context, maybe that means the cues surrounding a hard training session are sufficient to spark some of the same brain chemistry that takes over in a race with big rewards on the line, even though the practice doesn’t have any rewards of its own.

Hot peppers for weight loss

May 1st, 2010

UCLA researchers are reporting a study on how one of the ingredients in hot peppers can enhance calorie burn and fat oxidation for several hours after a meal. That’s sort of old news — what’s new is that instead of capsaicin they’re using another substance called dihydrocapsiate (DCT), which is like capsaicin but doesn’t make smoke come out your ears when you eat too much. So in other words, they’re saying: “Look, we can get all the benefits without the downside!” I don’t even have to read the study to know that’s not going to work out as promised. (Or maybe that’s just my Puritan streak emerging!)