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Archive for September, 2010

Antioxidants and cancer: questions about quercetin

September 11th, 2010

Another development in the continuing saga of confusion about the benefits and hazards of antioxidant supplements. Despite recent suggestions that certain antioxidant supplements may slow or counteract some of the benefits of exercise, there’s still great interest in whether plant-based antioxidants like quercetin can boost endurance. A new study in the Journal of Agricultural and Food Sciences should make you think twice about whether you really want to pursue that avenue.

Kuan-Chou Chen, Robert Peng, and colleagues note that vegetables, fruits, and other plant-based foods are rich in antioxidants that appear to fight cancer, diabetes, heart disease, and other disorders. Among those antioxidants is quercetin, especially abundant in onions and black tea, and ferulic acid, found in corn, tomatoes, and rice bran…

They found that diabetic laboratory rats fed either quercetin or ferulic acid developed more advanced forms of kidney cancer, and concluded the two antioxidants appear to aggravate or possibly cause kidney cancer.

I generally try to avoid putting too much emphasis on single studies like this one (especially when they’re conducted on “diabetic laboratory rats” instead of humans), since it’s very frustrating to be bombarded by messages that bounce back and forth between “X is great for you” and “X is bad for you” and “No wait, X will make you stronger” and “Oops, sorry, X will kill you.” I definitely don’t view this as anywhere near definitive evidence that quercetin will kill you.

That being said, this study does fit into a larger pattern of research over the past few years that leaves me with the conclusion that we’re much better off getting our micronutrients from whole foods than from supplements. I know, I know, that’s difficult. In fact, after I blogged about Juice Plus+ last month, I got an e-mail from a promoter of the product who made that argument:

If you are like me, you probably love eating the real thing, and nothing beats the flavour of fresh produce. I just had some corn, peaches and grapes! But it’s practically impossible to eat 13-17 servings every day, especially fresh, vine ripened and raw.

I don’t know — “impossible” seems like a bit of an overstatement. And I’m not sure where “fresh, vine ripened and raw” came from. Frozen and canned fruit and vegetables still seem like a far better option to me than supplements. Here’s what Lauren and I picked up in two trips to the fruit and vegetable market in Sydney last summer, for ridiculously low prices ($5 for 12 baskets of strawberries, $5 for that entire crate of plums, etc.). Most of it ended up in our freezer — which was pretty awesome over the winter!

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Sarcopenia redux: running preserves “motor units”

September 9th, 2010

I posted a few thoughts last week about an article on sarcopenia — the gradual loss of muscle with age — and new attempts to find drugs that will slow it down. I’d be remiss if I didn’t point out some of the research on the obvious drug-free ways to avoid withering away to nothingness. For instance, I just noticed an article in the current issue of Medicine & Science in Sports & Exercise that compares the number of “motor units” in the muscles of masters runners (average age 65) with age-matched controls, and with a younger group (average age 25). The news is good.

First off, a motor unit is “a single alpha-motor neuron and all of the corresponding muscle fibers it innervates.” Losing motor units is one of the several mechanisms that combine to produce the muscle loss grouped as sarcopenia. In this case, it’s not the muscle fibres themselves that die; rather, it’s the motor neurons that control them. When you’re young, the orphaned neurons often sprout new axons that connect them to other motor neurons — so the number of motor units decreases, but the amount of muscle you can use stays the same. This can hide the problem until your 60s or 70s, at which point you’re no longer able to reinnervate orphaned fibres as well, and motor unit loss becomes a serious issue.

Anyway, the study itself was quite simple. Testing the tibialis anterior (shin) muscle, they found that the masters runners had 140 motor units on average, compared with 150 for the young group but just 91 for the old non-runner group. So there it is: consistent training preserves muscle — not the muscle fibres, in this case, but the motor neurons that control them. As the researchers put it:

The significance of the (…) findings centers on providing an improved understanding of the neuromuscular system through ‘‘elite aging’’ and provides support into the favorable value of long-term physical activity and exercise for protecting neural function.

How to run hills, part 2

September 7th, 2010

So much for the theory of hill running – now I have some practical wisdom to impart, after participating in my first World Mountain Running Championships on Sunday. For instance, sometimes walking is better than running…

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The race was in Slovenia, just outside the town of Kamnik, on a course that climbed more than 1,200 metres in 12 kilometres. With the exception of a few hundred metres of steep downhill about two thirds of the way up, it was pretty much relentlessly uphill from the outskirts of town to a rocky peak at the top. It took just under an hour for the winners to climb (and definitely over an hour for me!)

I’m still not entirely sure what my limiting factor was. There’s no doubt that my legs were burning as we climbed, but I was also breathing very heavily. After about four kilometres, I slowed to walk a particularly steep section – and found, to my surprise, that I didn’t lose any ground to the competitors around me who were still trying to run. After that, I mixed in quite a few short stretches of walking. Not something I’d anticipated or am particularly proud of, but it just seemed like the fastest way to the top. I ended up in 91st place out of about 150 competitors – not quite what I was hoping for, but a good first attempt at the discipline. The Canadian men’s team placed 13th out of 24 teams, led by a fantastic 30th place finish by Kris Swanson. Maria Zambrano led the Canadian women with a 23rd place.

The next day, my teammates and I hiked up Mount Triglav, the highest peak in Slovenia (and one that, apparently, all Slovenians “must” climb at some point in their lives). We ended up jogging up (and down) a significant portion of the route, allowing us to finish what would otherwise be quite a long hike in under eight hours and get back to the cars in daylight. Surprisingly, my legs felt absolutely fine – which tells me that it was (lack of) aerobic fitness that was holding me back during the race, not my legs.

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How to pace yourself on hills

September 3rd, 2010

I’m posting from a little town in the Julian Alps in Slovenia, where I’m preparing for this weekend’s World Mountain Running Championships (more on that later). Not entirely by coincidence, this week’s Jockology column in the Globe and Mail is about how to pace yourself on hills:

… Fortunately, a group of Australian researchers used the latest technology to investigate this question, sending a group of runners out on a hilly 10-kilometre course while wired with a portable gas analyzer to measure oxygen consumption, a GPS receiver to measure speed and acceleration, a heart-rate monitor and an “activity monitor” to measure stride rate and stride length. The results, published this year in Medicine & Science in Sports & Exercise, suggest that most runners make two key mistakes: They try to run too fast uphill and don’t run fast enough downhill… [READ THE WHOLE ARTICLE]

I did the course tour this morning — 12km, with a steady climb of about 1,200m. I suspect that whatever pace I start out at, it will feel “too fast” by the time I get to halfway!

The same gene makes you fast… and inflexible

September 1st, 2010

This is a really neat study (tweeted about by @stevemagness). I’ve been writing a bunch lately about the fact that being inflexible seems to be associated with higher running economy (i.e. better “gas mileage,” so it takes less energy to run at a given pace). A new study from the guys at the University of Cape Town adds a very interesting wrinkle to this discussion: the same gene that makes people inflexible also makes them run fast.

The study focuses on a gene called COL5A1, which has recently been shown to be linked to your hereditary level of flexibility (about 64-72% of your flexibility is determined by genes, with the rest by environment, the paper says). One version of the gene means you’re quite flexible (and stay more flexible as you age), the other means you’re stiff.

So, in light of all these studies linking inflexibility and running economy, the UCT researchers decided to see if this same gene is also linked to endurance running performance. They analyzed results from the 2006 and 2007 South African Ironman triathlon for 313 athletes who agreed to genetic testing. Sure enough, those with the inflexible gene ran significantly faster than those with the flexible version (4:54 versus 5:07 for the marathon). But the two groups were indistinguishable in the swim and the bike — so this gene doesn’t make you a better endurance athlete, or improve your oxygen transport or anything like that. It just seems to make you run more efficiently.

Now, a study like this leaves a lot of dots to be connected. It’s possible that the effect on running performance is mediated by some completely different pathway other than flexibility that we don’t even expect. Genetic studies don’t lend themselves to simple conclusions.

But it’s certainly very suggestive, and it offers a convincing explanation for one of the enduring mysteries of running: why so many runners are so remarkably inflexible despite decades of indoctrination about the benefits of flexibility. We’ve always assumed that lots of running makes you inflexible — but maybe we’ve (once again) mistaken correlation for causation.