Archive

Archive for November, 2009

New Zealand-bound

November 29th, 2009

Just a heads-up that I’m about to catch a flight to New Zealand, to do some hiking on the Routeburn Track, and then some kayaking on Doubtful Sound. Back in a week!

Group dynamics in cycling, and “half-wheeling”

November 29th, 2009

phil-alpe-d-huezA few months ago, I wrote about the physiology of spinning, and how it’s different from cycling alone. I also wondered whether spinning is different from cycling in a group outdoors. I recently had an interesting e-mail exchanged with Toronto cyclist Philip Koop [right] on the topic. Here’s some of what he had to say:

In my experience, a road ride has the same psychological benefits as described for spinning – provided I am riding with people who are better than me. In that case, my effort is dictated by factors outside my control: the wind, the gradient, and the whims of those making the pace. I often find myself working harder than I thought possible.

The effects of riding with people of my own ability are more variable; they depend on the group size, pace and length of turns on the front. This type of ride is characterized by brief intervals of hard work on the front followed by longer intervals at lower intensity. At a given level of average power, this is harder work than maintaining a steady power output. But generally, one can maintain higher average power on one’s own. Under different circumstances, one effect can win out over the other. The psychological aspect of the group is diluted because at the points of highest effort one is making the pace oneself instead of striving to match that of another. Read more…

NYT: hiking the Larapinta Trail in the Australian outback

November 28th, 2009

Another slightly off-topic post… An article describing my recent hike along the Larapinta Trail, a fantastic route through the empty desert west of Alice Springs in Australia’s “Red Centre,” will run in this Sunday’s New York Times travel section. Actually, it’s not that off-topic — for this hike, we had to pay very close attention to factors like hydration (a frequent Sweat Science topic), since there was literally not a drop of water available other than occasional rainwater tanks. Along some sections of the trail, the distance between tanks was a nine- or ten-hour hike at a pretty fast clip. We met some hikers who couldn’t make it that far in a single day, and were thus forced to carry enough water for two full days with them (and that includes cooking water).

Anyway, it was a great hike — a chance to see some unique and inaccessible landscape, and a real test of endurance. The story is online here.

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Jockology:exercising while you’re sick, and boosting your immune system

November 26th, 2009

This week’s Jockology column takes a look at how exercise affects your chances of staying healthy during the cold and flu season, and what happens if you exercise when you’re already sick:

The question

Will working out help me beat the flu?

The answer

As cold and flu season kicks into high gear, so too does the search for an immunity edge.

Recent studies offer plenty of evidence that regular exercise really does strengthen immune function – a claim that can’t be made for most of the pills and potions whose sales spike at about this time of year. But like any powerful medicine, exercise also carries the risk of an overdose.

“It’s what experts call the ‘J-curve’ hypothesis,” says Brian Timmons, a researcher at McMaster University’s Children’s Exercise and Nutrition Centre. “Moderate intensity is good, but too much exercise is not so good.”

Exercise also turns out to be a mixed blessing if you do get sick: harmless and possibly even helpful for some symptoms, but not recommended for others.[read more...]

An important point made by a commenter on the Globe site: if you’re contagious, you definitely shouldn’t head to the gym and infect other people!

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How exercise helps relieve stress

November 24th, 2009

It’s pretty commonly accepted folk wisdom that a good workout helps blow off steam and reduce anxiety. Now there are some interesting new studies suggesting that exercise may play a much deeper role in making our brains “stress-proof.” In an experiment with rats, Princeton University researchers found that the new neurons that grow in response to exercise are less likely to react to stress than regular neurons:

The “cells born from running,” the researchers concluded, appeared to have been “specifically buffered from exposure to a stressful experience.” The rats had created, through running, a brain that seemed biochemically, molecularly, calm.

Gretchen Reynolds does a nice job describing this research in the New York Times. In another experiment, rats that exercised for three weeks didn’t show signs of a calmer brain, but those who exercised for six weeks did. It’s not clear how long humans need to exercise to see these changes, but the lesson is pretty clear:

Keep running or cycling or swimming. (Animal experiments have focused exclusively on aerobic, endurance-type activities.) You may not feel a magical reduction of stress after your first jog, if you haven’t been exercising. But the molecular biochemical changes will begin, Dr. Greenwood says. And eventually, he says, they become “profound.”

More on magic beets for endurance

November 22nd, 2009

A few months ago, I wrote about a new study claiming that beet juice would allow you to exercise for up to 16 percent longer. I was somewhat skeptical: “Don’t look for Tour de France riders or Olympic runners to be downing beet juice anytime soon,” I wrote.

Well, I was wrong in one respect. From Amby Burfoot’s Peak Performance blog:

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.”

So Paula has tried beet juice. And Amby himself, it turns out, has just bought his first bottle of beet juice, hoping to reap the benefits of nitrates. Here’s his blog on the topic (with progress reports promised over the next few weeks).

Stress fractures: reducing stride length and the role of muscle

November 18th, 2009

A couple of interesting studies about stress fractures in the December issue of Medicine & Science in Sports & Exercise.

First, researchers from Iowa State University looked at the effect of stride length. Basically, the idea is that if you shorten your stride, you’ll have more footstrikes per mile (and thus more impact jarring your bones) but each footstrike will be a little gentler. So which effect predominates? The researchers had 10 runners run at their normal stride length, and with a 10 percent reduction in stride length, measuring the relevant forces with motion-capture cameras and force plates. They then used a computer model based on bone damage and repair mechanisms to estimate the risk of stress fracture for both groups. The conclusion: shortening your stride length by 10 percent reduces stress fracture risk by three to six percent!

The clinical implications for these results are clear [they write]. Those runners wanting to decrease their likelihood for stress fracture can do so by reducing their stride length by 10%. This reduction would also allow for runners to run an additional 2 miles [per day] and maintain the same [fracture risk].

In general, I’m not a big fan of trying to meddle with your running form, thanks in part to studies like the one I wrote about here. But overstriding is apparently a pretty common issue, and prominent coaches like Jack Daniels have advocated increased cadence (and thus shorter stride) as a way of running more efficiently. So maybe there’s something here…

In the same issue of MSSE, researchers from the University of Minnesota examined the bone strength and body composition of 39 female distance runners, (slightly less than) half of whom had a history of stress fractures. To nobody’s surprise, the tibia bones in the stress fracture group were smaller by seven to eight percent, and weaker by nine to 10 percent. What’s interesting, though, it that the bone differences were exactly in proportion to the size of the muscles in the same area, and there was no difference in bone mineral density. What this suggests is that the best way to avoid stress fractures is to make sure you have enough muscle on your legs — presumably by doing weights and (it goes without saying) eating enough.

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Jockology: How music (and TV) helps (or hurts) your workout

November 12th, 2009

Over the past few months, I’ve posted a few links to interesting studies about the potential positive and negative effects of distractions on your workout. I decided to take a deeper look at the literature in this field, and put together a Jockology column that appears in today’s Globe and Mail on the topic.

The question

I love listening to music or watching TV when I exercise. How does that affect my workout?

The answer

In a forthcoming study, British researchers secretly sped up or slowed down music by 10 per cent and observed the effect on subjects riding exercise bikes. Sure enough, like marionettes on musical strings, the riders unconsciously sped up or slowed down.

The results add to a complex body of research on how distractions influence our exercise performance, extending far beyond the simple psych-up provided by motivational lyrics. Instead of just hitting shuffle next time you’re at the gym, you might be able to harness these benefits by taking control of your playlist to enhance your workout. [read on...]

Ultimately, it’s a pretty complicated stew of different (and sometimes conflicting) effects. You might be listening to a tune whose motivational lyrics urge you forward, but also distract you from the physical cues you might otherwise rely on to maintain your intensity. And you might find your breathing or stride rate locking in sync with the music — which could be good or bad, depending on the tempo. And all of those factors might be overridden by the simple question of how much you like the tune that’s playing. So for now, I think optimizing a playlist remains a matter of personal preference.

(And I almost hesitate to say this, because I realize I’m in a shrinking minority, but my own inclination is to exercise in silence. If I’m outside, I like hearing my surroundings, particularly if I’m in a nice forest or park. And in general, I like to let my thoughts wander aimlessly and free-associate. The problem with music, I find, is that I tend to really listen to it, so it guides and anesthetizes my thoughts. For the same reason, I can’t write with music on in the background — it grabs my attention too forcefully.)

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Brown is the new red? Chocolate milk clears arteries just like wine

November 11th, 2009

It was surprising enough when chocolate milk started being touted as a perfect post-exercise recovery drink, thanks to its 4-to-1 ratio of carbohydrates to protein. Now a study in the American Journal of Clinical Nutrition suggests that the flavonoids in cocoa may slow or even prevent the development of atherosclerosis, the hardening of the arteries:

Scientists in Barcelona, Spain, recruited 47 volunteers ages 55 and older who were at risk for heart disease. Half were given 20-gram sachets of soluble cocoa powder to drink with skim milk twice a day, while the rest drank plain skim milk. After one month, the groups were switched. Blood tests found that after participants drank chocolate milk twice a day for four weeks, they had significantly lower levels of several inflammatory biomarkers, though some markers of cellular inflammation remained unchanged. Participants also had significantly higher levels of good HDL cholesterol after completing the chocolate milk regimen… [New York Times]

Needless to say, chocolate milk — like wine — should be consumed in moderation.

The right way to warm up: go neuromuscular

November 9th, 2009

The best way to warm up before exercise is a pretty controversial topic. Most people still think of stretching as the best thing to do — despite the fact that plenty of research suggests it’s among the worst pre-exercise options. Researchers these days are advocating a “dynamic” or “neuromuscular” warm-up that starts with very gentle cardio exercise and progresses to increasingly specific use of the muscles and motions that your workout will involve.

I recently noticed a study by some Finnish researchers, due to appear in an upcoming issue of the British Journal of Sports Medicine, in which they study the effect of a neuromuscular warm-up program on “floorball” players. (Search me, I’d never heard of it either. Apparently it’s “a fast and intensive indoor team sport that is played on a court (20x40m) surrounded by a low board.”)

The neuromuscular warm-up programme consisted of four different types of exercises: 1) running technique exercises, 2) balance and body control exercises, 3) jumping exercises, and 4) strengthening exercises to the lower limbs and trunk. The neuromuscular training was carried out like a warm-up session just before floorball exercises, with low-to-moderate intensity for each exercise type. One warm-up session lasted 20-30 minutes, each exercise type taking about five to seven minutes.

So no stretching, just a series of drills that mimic the movements and use the muscles required in floorball. A companion study had already found that, after six months of this warm-up program, the 119 players using it had fewer lower-leg injuries compared to the 103 controls who were just doing their usual warm-up. This study followed that up by showing that the group doing the new warm-up was also better at jumping over a bar (power) and standing on a bar (balance).

Unless you’re a floorball player, the precise details of the warm-up routine probably aren’t that important. But it is interesting to note that this approach produced measurable good results — something that pre-exercise stretching has repeatedly failed to do. I think this is an important topic, so I’ll keep my eyes out for good warm-up studies that may be more applicable to sports I’ve actually heard of. (If anyone has any suggestions, please let me know.)