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Archive for September, 2010

Vitamin C, not D, helps acute-care hospital patients

September 28th, 2010

Over the past few years, I’ve become increasingly skeptical about the benefits of taking vitamin C (and other antioxidant) supplements. On the other hand, vitamin D research has looked increasingly promising. So here’s a study from Montreal’s Jewish General Hospital that suggests I should keep my mind open:

In a double-blind clinical trial, patients admitted to the JGH were randomly assigned to receive either vitamin C or vitamin D supplements for seven to ten days. Patients administered vitamin C had a rapid and statistically and clinically significant improvement in mood state, but no significant change in mood occurred with vitamin D, the researchers discovered.

Now, this is a fairly specific population being studied, so the results aren’t generalizable. Apparently about 20% of the acute-care patients in that hospital “have vitamin C levels so low as to be compatible with scurvy,” so it’s not surprising that vitamin C helped. Ultimately, this is simply more evidence that supplements are useful for treating deficiencies; it doesn’t say anything about whether supplements provide any benefits for healthy people.

Your neighbourhood affects your BMI — in unexpected ways

September 28th, 2010

Researchers at the University of Alberta just published some interesting data from a six-year longitudinal study looking at links between neighbourhoods, physical activity and body-mass index. Of the people who moved during the study, those who chose new neighbourhoods based in part on walkability maintained their weight (as expected), while those who chose locations based on proximity to outdoor recreation opportunities (surprisingly) gained weight.

This is by no means a perfectly controlled experiement — for example, as the researchers point out, it could be that the subjects choosing to live near outdoor recreation were doing so primarily for their kids. But it certainly fits with other data, like the fact that New York City — highly walkable but terrible for outdoor recreation opportunities –  is among the thinnest cities in the U.S. (42% of people there were overweight, compared to 67% nationally, according to a 2009 study). And it underlines the point that a healthy lifestyle is more dependent on the little things you do on a daily basis, rather than the big excursions you make on weekends.

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Circadian rhythms and athletic performance

September 25th, 2010

The latest Jockology column is posted on the Globe and Mail site (it won’t actually appear in the paper until this coming Thursday due to a schedule change, so you’re getting a sneak peak online!). The topic is circadian rhythms — how they affect physical performance, and how you can alter them. An excerpt:

[...] A 2007 study by Tunisian and French researchers found that power in an all-out 30-second cycling test was lowest at 6 a.m., then increased steadily through the day until it was about 10 per cent higher at 6 p.m., then fell steadily. A long list of earlier studies had found similar effects in back and arm strength, vertical and broad jump, and also in sports ranging from swimming to badminton, with the peak time always within a few hours of 6 p.m.

This effect may be partly a function of time awake (you’re groggy early in the day and tired later in the evening) and eating patterns (you won’t be at your best before breakfast or immediately after lunch).

But more subtle circadian rhythms, such as the daily change in core body temperature, also play a role, Dr. Sleivert says. Studies have found that body temperature rises by about 1 C between early morning and late afternoon, which may help loosen muscles and swell blood vessels in the same way a pre-exercise warm-up does… [READ THE WHOLE ARTICLE]

A related topic is how athletes deal with jet-lag, which is covered in an info-graphic that accompanies the piece (but doesn’t seem to be included online). I looked into some of the research on melatonin (the hormone that basically tells the body that it’s nighttime), and found it convincing enough that I decided to give it a try. By coincidence, I flew to London last night/this morning, so I’ll have a chance to give a try when I go to bed in a few hours. Here’s hoping for a melatonin miracle and a good night’s sleep!

Being a sports fan in the Internet age

September 25th, 2010

A quick plug for my cover story in the new issue of Maisonneuve magazine, a 5,500-word essay on how the relationship between sports fans and their heroes is changing in the Internet age. It’s a piece that I started developing as a writer-in-residence at the Banff Centre, which gave me the luxury of time to think about and research this idea in depth. The article itself isn’t available online, though the opening paragraph is posted — along with a YouTube clip of the 1500m final at the 1996 Canadian Olympic Trials, which was a pretty embarrassing moment for me but significant in terms of the ideas I look at in the article. You’ll have to read the article (in the paper version of the mag) to find out why!

Massage lowers stress hormones

September 24th, 2010

Massage is a multi-billion dollar industry these days, as a new study in the Journal of Alternative and Complementary Medicine points out. Apparently 8.3% of adults in the U.S. got at least one massage in 2007, “as a treatment for a myriad of conditions ranging from muscle aches, back pain, headaches, and insomnia, to psychologic stress, anxiety, and depression.” But does it actually do anything? It’s a very difficult topic to study, though a few researchers have started to make headway.

The new study, by researchers at Cedars-Sinai Medical Center in Los Angeles, is an interesting one. They gave 53 volunteers either a standard 45-minute Swedish massage (using the “core massage techniques of effleurage, petrissage, kneading, tapotement, and thumb friction”), or 45 minutes of “light touch” therapy using the back of the hand. The hypothesis was that massage would lower stress hormones such as cortisol by increasing levels of oxytocin, the “cuddle hormone” that is involved in bonding, maternal behaviour and a host of other behaviours.

What they found was that cortisol did drop, by 32% in the massage group and 21% in the touch group — so massage was “better.” But oxytocin couldn’t explain the change — it fact, it increased more in the touch group (12%) than the massage group (9%). So the conclusion (in press reports, at least) is that “massage benefits are more than skin deep“; the paper itself concludes that “these findings may have implications for managing inflammatory and autoimmune conditions,” but not through the mechanism they originally expected.

My take: this is not surprising. I would have been astounded if massage didn’t lower cortisol levels. After all, listening to music or getting a nice compliment can lower your cortisol — but we don’t claim that these things can heal muscle pain! What’s most interesting about this study is that the controls received “light touch” therapy, which likely triggers many of the same bonding responses. This gives us the chance to see how much of the effects of massage are due to the pleasurable social/bonding interaction, and how much is due to “effleurage, petrissage, kneading, tapotement” and so on. And the differences aren’t as big as you might hope.

That being said, this study’s outcomes are mostly about general “wellness” rather than sports-related benefits — there’s nothing that tells us what’s happening to muscle fibres and so on. Still, it is (as the authors note) an important first step to separating the general benefits of having someone rub their hands all over you from the specific benefits of certain massage techniques. Hopefully we’ll see more studies like this in the future.

The psychology of choking

September 21st, 2010

I interviewed University of Chicago psychologist Sian Beilock for this Globe and Mail article about “attentional focus” and athletic performance last year. She’s an exceptional researcher — her name comes up repeatedly when I’m interviewing other researchers, usually along the lines of “You should talk to Sian Beilock, she’s a genius and her research is fascinating.” She’s the one who did the study showing that expert golfers putt better when they’re distracted, while novices putt better when they focus — a finding that has been replicated in a wide variety of tasks.

I mention all this because Beilock’s new book, Choke: What the secrets of the brain reveal about getting it right when you have to, was released today. She’s widely considered the world’s foremost expert on choking — and, needless to say, her research has a lot to say about how not to choke. I’m looking forward to reading the book. And in the meantime, she’s also blogging on the topic for Psychology Today.

“Defensive pessimism” and athletic performance

September 21st, 2010

When I first started competing in running races, I used to look around at the other runners while I was warming up and think, “Oh man, that guy looks fast… and that guy too… and that guy…” Gina Kolata has an article in yesterday’s New York Times about this kind of thinking as she and her husband tried their first ever bike race:

The way we started thinking when we saw the other cyclists is a strategy called defensive pessimism, said John S. Raglin, a sports psychologist at Indiana University. He explained that it consisted of “downplaying your ability and expectations.” That way, if you do poorly you are not crushed, and if you do better than you expected, “you get this payoff,” Dr. Raglin said.

He has done studies of track-and-field college athletes who employ the defensive pessimism strategy, comparing them with optimists who think they’ll do well. The pessimists performed just as well as the optimists.

I’d like to read more about this, because it’s a tactic I’ve made heavy use of (to the point that teammates sometimes didn’t like being around me before big competitions because I was such a downer!). On the other hand, recent research by people like Samuele Marcora emphasizes the role of the brain in determining how far you can push yourself, so you’d think positive thinking would be pretty important.

As Kolata points out, these kinds of thoughts aren’t relevant only in competitive settings:

On the other hand, the type of anxiety we felt when we saw the other riders is also a reason many people steer clear of competitive sports altogether — even a reason many avoid walking into gyms, said Ralph A. Vernacchia, director of the Center for Performance Excellence at Western Washington University.

“What you are looking at is a social comparison,” he said.

Like just about anything, I suspect there’s an optimal level of “defensive pessimism” beyond which it becomes truly counterproductive. These days, when I’m feeling nervous before a race, I try to turn these pessimistic thoughts into a joke to minimize their power — or at least, I say them out loud so that it’s obvious how silly they sound. “That guy looks really fast… and so does that little girl… and so does that old guy pushing his grandchildren in the jogging stroller…”

(I realize, of course, that there are many little girls and old guys pushing their grandchildren in strollers who really are very fast. My point is just that it’s silly to judge and get scared based on appearances alone. And the true peace of mind, especially in a recreational setting, comes when you understand that it’s okay if the little girl does beat you — the point is to go as fast as you can, and not worry about what others are doing. But that’s sometimes easier said than done.)

Climbing stairs: every step, or every other step?

September 19th, 2010

The age-old question: is it more efficient to climb stairs one at a time or two at a time? Fortunately, researchers at Penn State have tackled this puzzler in the current issue of the Journal of Strength and Conditioning Research. They start with a helpful diagram of the two options:

stairclimbing

Strangely, the researchers hypothesized that, left to choose their own speeds, the volunteers would take the same amount of time single-stepping and double-stepping, and use mostly about the same level of muscle activation. This isn’t what they observed (is it just me, or is this obvious?): they climbed 22% faster while double-stepping, choosing to take 83 double steps per minute, compared to 109 single steps.

It’s worth noting that these researchers aren’t the first to address this question. A team in Singapore tried a similar experiment back in 2005, but they fixed the step rate (100 per minute for single-stepping, 50 for double-stepping) so that the total time was the same. The conclusion in that case was that single-stepping under these conditions raised heart and breathing rates more, but any calorie difference was negligible.

In the new study, using “natural” stepping rates, the researchers concluded that double-stepping burns about 70 to 90 calories more per hour than single-stepping (678 vs. 592 per hour, on average, for the subjects in the study). Again, this is not surprising: bounding up stairs two a time takes more energy than going up one at a time — if you engage in the activity for the same amount of TIME. But will the time be the same? What if you’re doing a set number of staircases, so that you spend less time double-stepping than you would single-stepping? Which burns more calories that way?

Unfortunately, I can’t find those numbers in the paper. But if my back-of-the-envelope numbers are right, double-stepping burns 15% more calories per hour but takes 22% less time. So if you’re climbing a real staircase (e.g. stadium steps), you’ll get a better workout by single-stepping. But if you’re on a stair machine in the gym, working out for a set amount of time rather than distance, then big steps will burn more calories. Let’s see that diagram again, in case anyone’s confused:

stairclimbing1

Collapsing after a race: dehydration or blood pooling?

September 15th, 2010

Watch the finish line at big endurance races, and you’ll see plenty of people staggering to a halt and then wobbling, looking dizzy, and perhaps even collapsing if race volunteers don’t get there in time to usher them to the medical tent. What’s going on here? Why are they collapsing after the race, and how should they be treated? A new paper posted online at the British Journal of Sports Medicine takes a look at the two leading theories: (1) they’re dehydrated and overheated, or (2) the blood vessels in their extremities are dilated, so when they stop exerting themselves, the blood pools there and leads to shortage of blood going to the brain.

The right treatment depends on which of those theories you believe. If it’s dehydration, you give IV fluids. If it’s blood pooling, you put the athlete in the “Trendelenburg position” (lying down with legs elevated above heart) and let them drink as much as they want. Researchers from the University of Cape Town conducted a randomized clinical trial at the 2006 and 2007 South African Ironman Triathlons and the 2006 Comrades Marathon, randomly assigning 28 collapsed athletes to the two treatment protocols based on whether they had an even or odd race number.

The results: no statistically significant difference between the protocols: 52 minutes before discharge for the IV group, 58 minutes for the non-IV group, with a standard deviation of 18 to 23 minutes. So this doesn’t really settle the debate about what’s causing it — but, applying the “simple is better” principle, it suggests that you don’t really need an IV if you’re dizzy at the end of a race (but don’t have, say, a temperature above 40C).

How to pedal efficiently: “dead centre size”

September 13th, 2010

[UPDATE 9/17: Check out reader Phil Koop's analysis of the paper in the Comments section of this post. Definitely worth a click.]

An interesting Norwegian study on pedalling efficiency has been posted online at Medicine & Science in Sports & Exercise, proposing a new measurement to determine whether cyclists are getting the most out of their pedal strokes.

The basic goal of cycling, obviously, is to convert your effort into forward motion of the bike. To do that, experts have long believed that a quantity called “force effectiveness ratio” (FE) should be optimized. FE basically tells you how much of the force you’re applying with your foot at any given moment is directed perpendicular to the crank. For example, when the crank is parallel to the ground and you’re pushing straight down, FE is very high. But when the pedal is at the very bottom of the cycle, if you’re still pushing down instead of back, your FE will be lower. Averaged over the whole pedal stroke, a typical FE might be about 50%.

This makes sense in theory, but no one has been able to show that better cyclists have higher FE (at least if you’re comparing elite and sub-elite, as opposed to complete novices):

From an energetic-mechanical point of view, this should be the best “technique” parameter because the energy used for producing the ineffective, static component of force will not contribute to external power. However, it is not necessarily so that man is able to produce the highest FE at the lowest metabolic cost: the coordinative challenge of generating power while creating a rotation of the crank by extending the lower extremity may require additional, apparently ineffective, energy expenditure.

The Norwegian researchers propose instead a parameter called “dead centre size” (DC). They look at the two weakest parts of the pedal stroke — the top and bottom — and compare how much useful force you’re generating to the average useful force over the whole pedal stroke. A typical value is about 25%. The idea is that the better these “low points” in the stroke are, the smoother your overall stroke must be, so you’ll avoid wasting energy accelerating and decelerating and so on.

So they did a study with 21 competitive cyclists, using force-sensitive pedals and high-speed video and so on, and sure enough found that DC was much better at predicting the overall efficiency of the cyclists than FE. So what does this mean? Well, it’s consistent with the idea that you shouldn’t worry too much about trying to generate power on the upstroke, since that’s a hopeless task. Instead, focus on keeping the whole cycle smooth, not letting power dip too far at the top and bottom. One thing I couldn’t tell was whether it’s possible for anyone without a high-tech laboratory to get a measurement of DC, in order to see whether they’re improving their form over time. It would be pretty cool if local bike shops were able to offer the service.