Archive

Archive for July, 2009

The bare facts about heat stroke

July 30th, 2009

In case summer ever decides to start, here’s an article on heat stroke from Gretchen Reynolds of the New York Times. The best line, relating to how heavy clothing can increase risk:

“I’m all in favor of naked practice sessions,” [University of Connecticut researcher Douglas] Casa says. Unfortunately, sunburn also is thought to have an impact on your abilitity to dissipate heat.

Other than that, nothing particularly surprising in the article — unfortunately, there’s no quick fix or miracle cure for heat stroke. It’s a matter of caution, acclimating to hot weather (especially if, say, an unusually cold and wet summer has limited your exposure to hot days), and looking out for warning signs like dizziness and confusion. Another interesting point: while hydration is important, it’s perfectly possible to get heat stroke even if you’re fully hydrated.

VO2max (and lactate threshold) testing: what is it and why get it?

July 30th, 2009

This week’s Jockology column in the Globe and Mail compares the benefits of VO2max and lactate threshold testing:

The question

What is VO2max and should I have mine tested?

The answer

VO2max is a term that surfaces whenever feats of great endurance are in the news, such as the gruelling Tour de France that wrapped up last weekend. It refers to “maximum oxygen uptake,” the amount of oxygen you’re able to deliver to your muscles when you’re exercising at your hardest.[read on...]

I’ve been tested a couple of times, once as part of an exercise physiology study and once purely for interest because a friend of mine, Dr. Gerald Zavorsky, offered to test me. But I’m not sure how many people take advantage of the commercial services offering testing. I’d be interested to hear from anyone who’s done it — why they did it, what they got out of it and so on.

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Preventing knee injuries with mental training

July 30th, 2009

A pair of new studies from the University of Michigan offers an interesting take on how to prevent knee injuries like the ever-common ACL (anterior cruciate ligament) tears. What they’ve found is that the “wrong move” that leads to the injury may result as much from fatigue in your central nervous system as from physical fatigue in the knee or joint itself. That means we may want to change the kinds of preventive exercises we do to focus more on our brains and reflexes. Read more…

How to swim fast pt. 2: Train, because Jaked and LZR are banned

July 26th, 2009

The big news in swimming is that the buoyant polyurethane suits that have made a mockery of world records for the past 17 months — first Speedo’s LZR, and more recently the Jaked suit — have finally been banned by international authorities, effective starting in 2010. To put this in context:

In the Olympic individual events, only four world records remain from the pre-2008, pre-polyurethane era: the men’s 400- [UPDATE: uh, scratch that: Ian Thorpe's record just went down] and 1,500-meter freestyles, and the women’s 100 breaststroke [that one's gone too] and 100 butterfly [and so's that one].

This is the right decision, and a big relief for anyone who wants the competition to be among athletes rather than the R&D arms of big companies.

[T]hey enabled swimmers without an ideal physique or impeccable conditioning to be more competitive. Squeezed into the corset-like suit, a muscled and stocky body is as streamlined as a long and lean one; a soft abdomen as effective as six-pack abs. “The thing that’s really hurt more than anything else is the whole suit situation has devalued athleticism,” [U.S. swim coach Dave] Salo said. “A lot of kids who aren’t in very good shape can put on one of these suits and be streamlined like seals.”

Of course, that doesn’t prevent some whining from athletes who like the suits:

“Basically, when we roll back, racers are going to hurt a lot more than they hurt currently, which is not something I’m looking forward to,” [U.S. swimmer Matt] Grevers said.

The big question now: what to do about the world records that have been set over the pact few years. After all, it could take a long time to eradicate them with normal suits.

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How many calories in that brownie: Why food labels are wrong

July 21st, 2009

Fascinating article in New Scientist about the “calorie delusion.” Turns out that the number of calories listed on food labels can be very misleading, depending on the type of food:

[A]ccording to a small band of researchers, using the information on food labels to estimate calorie intake could be a very bad idea. They argue that calorie estimates on food labels are based on flawed and outdated science, and provide misleading information on how much energy your body will actually get from a food. Some food labels may over or underestimate this figure by as much as 25 per cent, enough to foil any diet, and over time even lead to obesity.

The standard figures assume that we get about 4 calories per gram of carbohydrate and protein, and 9 calories per gram of fat. But because of the way we digest food, more recent research suggests that’s an overestimate by about 20 percent for protein, and 25 percent for dietary fibre. Other factors like the texture of the food, whether it’s cooked, and even whether it’s chopped or ground up, also make a big difference.

In a study published in 2003, for example, a team led by Kyoko Oka at Kyushu University in Fukuoka, Japan, investigated the effect of food texture on weight gain. They fed one group of rats their usual hard food pellets, while a second group received a softer version. Both pellets had exactly the same calorie content and flavour. The only difference was that softer ones were easier to chew. After 22 weeks, the rats on the soft food diet were obese and had more abdominal fat. “Food texture might be as important a factor for preventing obesity as taste or food nutrients,” Oka and his colleagues concluded (Journal of Dental Research, vol 82, p 491).

The bottom line, as the article points out: don’t pick a brownie full of refined flour and sugar over a granola bar full of nuts and whole grains just because the label says the brownie has fewer calories.

Stronger hips for pain-free knees

July 20th, 2009

Last year, I had an interesting conversation with Dr. Reed Ferber, who runs the Running Injury Clinic at the University of Calgary. He’s a big believer in the role of hip strength in promoting proper biomechanics — in one seven-month study he performed, 92 percent of the injured runners who reported to his clinic had abnormally weak hip muscles, and 89 percent of them improved with a four- to six-week hip strengthening program. (Read more about his research, and the exercises he recommends, in this Jockology column.)

I mention this in light of a study that researchers at Rush University Medical Center in Chicago are conducting, trying to see if strengthening hip muscles can relieve pain and slow the progression of arthritis in the knees.

The exercises focus on strengthening the hip abductor muscles, such as the gluteus medius, a broad, thick, radiating muscle that helps to stabilize the pelvis during ambulation. In patients with osteoarthritis in the knees, these muscles tend to be weak, causing the pelvis to tilt toward the side of the swing leg when walking, instead of remaining level with the ground, which increases the load on the knee joints. Strengthening these muscles helps the pelvis and the knee remain in better alignment, and thereby lessens the load.

Sounds like the same principles at work — I’m sure Dr. Ferber will be watching carefully to see the results of this study.

Ghrelin and leptin: how sleep affects your appetite

July 20th, 2009

Very interesting article by Jackie Dikos in Running Times about the relationship between sleep and appetite:

There are two hormones associated with sleep that influence eating behaviors: ghrelin and leptin. Ghrelin is the hormone that lets your body know you’re hungry. Leptin’s role is to send a message to stop eating when your body has had enough. When you’re sleep-deprived, your ghrelin level increases. At the same time leptin levels decrease. So you crave additional food while simultaneously not getting the proper message to stop eating.

Seems like a pretty straightforward connection, and explains the well-documented links between getting too little sleep and gaining weight. I’ve posted before about how sleep aids athletic performance, and it’s worth adding Dikos’s conclusion:

Sleep is another way to nourish your body, just like a high-quality food choice is.

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Size matters in running and swimming: some data

July 20th, 2009

It’s not just Usain Bolt — elite athletes have been getting bigger for the past century at a faster rate than the general population, according to researchers from Duke University in North Carolina. Yeah, I think we already knew that. But…

Futhermore, the researchers said, this pattern of growth can be predicted by the constructal theory, a Duke-inspired theory of design in nature that explains such diverse phenomena as river basin formation and the capillary structure of tree branches and roots. (www.constructal.org).

Apparently, the size of athletes illustrates some deep underlying truths about patterns in nature, as described in this Journal of Experimental Biology paper. Maybe, maybe not — it didn’t make a lot of sense to me. What I did find interesting was the data set they dug up for 100-metre world-record setters in swimming and running:

Specifically, while the average human has gained about 1.9 inches in height since 1900, Charles’ research showed that the fastest swimmers have grown 4.5 inches and the swiftest runners have grown 6.4 inches.

There’s been a lot of talk about how Usain Bolt’s otherworldly sprint times might be explained by the fact that he’s one of the first very tall men (6’5″, according to the JEP paper) to master sprinting. The second-tallest world-record holder is, not coincidentally, the second-fastest man, Asafa Powell, at 6’3″. This paper makes some interesting arguments about why this should be so, based on the scaling of horizontal and vertical forces in locomotion. It’s obvious to everyone why basketball players are almost all enormously tall — but the same forces appear to be in play, though less obviously, for runners and swimmers.

The authors also suggest that we may need to introduce size classifications, as in boxing and wrestling, to other sports. It’s an interesting idea — but I’m not sure that the genetic advantage of height is really any different from the genetic advantage of having a huge oxygen capacity or lots of fast-twitch muscle fibres.

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Why you should swear for a better workout or race

July 17th, 2009

A friend forwarded me this Newsweek article about a British experiment on swearing and pain tolerance:

In a study published in this month’s issue of NeuroReport, [Richard Stephens of Keele University and his colleagues] asked participants to submerge their nondominant hand in ice-cold water for as long as possible (or for a maximum of 10 minutes) while either repeating a swear word or a neutral word (one that describes a table). The volume and pace used for swear words and neutral words were kept similar. Then, the researchers compared those who swore and those who didn’t to determine the effect on the length of time that participants were able to keep their hands submerged.

Subjects who swore managed an average of 40 seconds, or about a third longer than those who didn’t—evidence that a few well-placed word bombs of your choosing actually has a protective effect. [read on...]

So next time you’re trying to hit one last rep in the weight room, or hang on for one more kilometre at your maximum pace, take a look around — and if there are no children in sight, try swearing a blue streak to success!

[Thanks for the forward, Jay.]

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Jockology: exercising in pollution

July 16th, 2009

We all know that exercising outdoors with lots of air pollution is bad. But we also know that not exercising for the summer is pretty bad too. How do we balance the two? And is biking to work really any worse that sitting in a car in a traffic jam on the way to work? That’s the topic I tackle in the latest Jockology column in the Globe, which has just been posted:

The question

How harmful is it to exercise outside on a polluted day?

The answer

There’s no doubt that the air pollution in cities is bad for us. And exercise makes it worse, since we breathe in a greater volume of air and bypass the natural filtering of the nasal passages by inhaling through the mouth.

Exercising indoors, where the air tends be better during smoggy periods, is much healthier than slacking off for the summer.

But if you have to head outside anyway – to get to work, for example – the choice is trickier. Depending on when you go and what route you take, you may be better off running or biking to the office than sitting in rush-hour traffic. [READ ON...]