Archive

Archive for October, 2009

Jockology: running surfaces and injuries

October 29th, 2009

This week’s Jockology column tackles the longstanding question of how different running surfaces affect your risk of injury. The science here is a lot less clear than you might expect.

The question

Will running on hard surfaces like asphalt and concrete increase my risk of injury?

The answer

In a study to be published later this year, Brazilian researchers found that your feet feel about 12 per cent more pressure with each foot strike when running on asphalt compared to grass.
Thanks for that newsflash, Captain Obvious, you might say.
But the findings actually contradict several earlier studies, which – despite what our intuition tells us – have found that we seem to automatically adapt our running stride so that hard and soft surfaces administer roughly the same shock to the body.
In fact, it may be the smoothness of paved surfaces that makes them dangerous to runners, rather than their hardness. And softer, less even surfaces carry their own injury risks, so the best answer may lie somewhere in the middle. [read more...]

(And a random shout-out to Dan Peterson at the Sports Are 80 Percent Mental blog — I think he was the one who introduced me to the prodigious research output of Captain Obvious, though I can’t seem to find the post I’m thinking of anymore!)

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Pay no attention to your form: how to improve running economy

October 29th, 2009

There’s a very interesting article in the current issue of the Journal of Sports Sciences about how your mental focus affects running economy (which is basically the amount of oxygen you use to run at given speed, something that we can’t control consciously). In brief, German researchers had a group of subjects run while focusing either on internal cues (their running form or their breathing) or external cues (a video clip of running through the streets). The running economy was significantly better when the subjects were focusing externally rather than internally, with breathing taking bottom spot.

This result fits in with a large body of research on motor control. The theory is that we have to pay careful attention when we’re learning complex tasks, but they eventually become part of the “procedural knowledge” that we execute automatically. Trying to pay specific attention to one part of a complex action disrupts this automated movement.

For example, Beilock et al. (2002) studied this effect on the motor skills of golf putting and dribbling with a soccer ball. In both sports, they found that for experienced players an internal focus of attention led to a deterioration of performance on behavioural measures (higher number of strokes per hole in golf and slower completion of a dribbling course in soccer).

There are other studies in sports ranging from hockey to dart-throwing. (In the latter case, in addition to differences in accuracy, “heart rate dropped just before the throw in the external condition, whereas it rose in the internal one.”) The basic gist is that thinking too hard about what you’re about to do messes things up.

In endurance running, though, it’s not obvious this would apply. In fact, there’s a fairly long literature arguing that “association” (paying attention to your body’s cues) leads to faster running than “dissociation” (thinking about the weather and last night’s episode of House). The authors of this paper cite a bunch of conflicting papers, making it clear that the topic is an open question right now. One of the tricky things about running studies is that measuring success by how far or fast the subjects run gets skewed by their motivation levels. That’s why they chose to use running economy as the outcome — it’s outside the conscious control of the runners.

For the record, the study used 24 trained runners with a mean 10K best of 36:27 and had them run at 75% of VO2max, a typical brisk training run. The external focus proved to be best in this case, but that may not apply, the authors point out, in racing a marathon or other contexts.

One final note: one of the pieces of advice beginning runners are often given is “pay attention to your breathing.” In this study, those who paid attention to their breathing for some reason slowed down their average breathing rate by almost 20 percent, taking deeper breaths and hurting their running economy.

The results for the breathing condition lead to the assumption that breathing, which is a highly automated process, will adjust most efficiently to the needs of the body when it is not subjected to conscious control.

In other words, you take care of the running, and your subconscious will make sure your muscles get enough oxygen.

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The science of cool-downs after exercise

October 23rd, 2009

The cool-down is another one of those well-established exercise habits, like stretching, that most people swear by without really wondering about the underlying science. And for good reason: it turns out there isn’t really much science there, according to a recent article by Gina Kolata in the New York Times.

Exercise researchers say there is only one agreed-on fact about the possible risk of suddenly stopping intense exercise. When you exercise hard, the blood vessels in your legs are expanded to send more blood to your legs and feet. And your heart is pumping fast. If you suddenly stop, your heart slows down, your blood is pooled in your legs and feet, and you can feel dizzy, even pass out.

So that suggests that, at the very least, you should keep moving, if only at a walk, for a few minutes after vigorous exercise. But there’s no evidence to support the idea that a cool-down will reduce stiffness or muscle soreness the next day, let alone “flush out lactic acid.”

Of course, this may simply be because scientists have yet to do rigorous research into the cool-down. (Kolata does mention a couple of studies that failed to find any benefits.) Based of their personal experiences, many people are firmly convinced that they feel better if they warm down, science or not. And, unlike stretching, there’s no significant evidence that cooling down actually hurts you, so you might as well stick with whatever makes you feel good!

Pump your arms to speed up your legs, thanks to “neural coupling”

October 19th, 2009

“Keep pumping your arms!” That’s one of those canonical pieces of advice that it seems every coach gives to his or her runners. The idea is that, late in a run or race when your legs are burning and you’re starting to slow down, if you keep moving arms briskly, your legs will follow. It’s a nice idea — it’s always good to have some concrete piece of advice that you can hang onto when it seems like the world is about to explode. But does it work?

Unfortunately, I don’t know. But in the course of researching a completely different topic today, I stumbled on an interesting piece of research by Daniel Ferris, a University of Michigan researcher who’s best known for his research into assisted movement using robotic exoskeletons. The paper, which appeared in the journal Exercise and Sport Science Reviews back in 2006, is called “Moving the arms to activate the legs.” The full text is available here.

Ferris’s main focus in the paper is on rehabilitation for patients with spinal cord injuries, helping them learn to walk again. The gist is as follows:

Humans have neural connections between their upper limbs and lower limbs that coordinate muscle activation patterns during locomotor tasks… Recent studies indicate that arm swing may also facilitate lower limb muscle activation via neural coupling. Clinical observations of individuals with spinal cord injury first suggested that rhythmic upper limb movement improved lower limb muscle recruitment during stepping. More recently, studies on neurologically intact subjects have demonstrated an increase in lower limb muscle activation that is proportional to upper limb muscle recruitment during seated recumbent stepping.

The “seated recumbent stepping” he mentions above is a neat set-up. Basically, you sit back in a contraption that you can power with either your arms, your legs, or both. With some careful experiments, Ferris and his colleagues were able to show that when the subjects moved their arms back and forth (opposite to leg motion, as in walking and running), they were able to achieve greater muscle recruitment in their legs. Now, you might assume this is just because it’s easier to get good leverage with your leg if your opposite arm is also moving, but they tried various set-ups with the torso partly or fully strapped to the seat (so you couldn’t twist the torso to get a better angle), and the same results were observed.

The link from this to “Pump your arms when you approach the finish, and your legs will move faster” is still pretty weak. But this idea of “neural coupling” is interesting — so I guess I’ll pump my arms with renewed vigour next time I’m starting to tie up.

Jockology: “active rehab” for pulls and sprains

October 15th, 2009

The latest Jockology column appears in today’s Globe, dealing with the question of when “RICE” (rest, ice, compression, elevation) should turn into “MICE” (movement, ice, compression, elevation). It’s a tricky one, because there’s such a wide range of possible muscle pulls, sprains and tears that it’s difficult to give general advice. But the overall theme is that if you keep protecting and favouring a weak point for too long, you can end up harming the healing process.

The question

Ouch, I think I sprained something. How long should I stay off it?

The answer

Canadian figure skater Anabelle Langlois returned to action last month, earning a bronze medal with partner Cody Hay at a tournament in Germany one year after fracturing her fibula in a training accident. With Olympic dreams on the line, Ms. Langlois’s doctors had pursued every possible avenue in her rehabilitation, including two operations.

One thing they didn’t recommend, though, was a long period of complete rest for the injured leg. [read on...]

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CRM: Science of Running

October 13th, 2009

Forgot to mention in my last post that the latest Science of Running column, from the November-December issue of Canadian Running, is also available online. Among the topics: an 894-kilometre science experiment, running for better vision, and swearing for better performance.

CRM: Ed Whitlock feature

October 11th, 2009

Anyone who follows masters running will have heard the name Ed Whitlock. He’s the man who ran a 2:54 marathon at age 73 back in 2004, the first septuagenarian sub-three. That famous marathon is just the tip of the iceberg when it comes the records he’s set at a ridiculous range of distances over many years, thanks to his famous training regimen of up to three hours of slow, steady running around a local cemetery every day. But all has been quiet on the Whitlock front for the past few years, thanks to knee problems.

That may be about to change, according to a fantastic in-depth feature about Whitlock in the upcoming issue of Canadian Running magazine, by Michal Kapral. Ed is on the comeback trail! Definitely worth a read… (Heck, it’s worth clicking on just to see the photo of Ed racing in 1952 at the Hyde Park Relays — an event I competed in nearly 50 years later!)

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GPS and your brain

October 8th, 2009

This is a little off-topic for this blog, but I just wanted to mention a major feature I wrote that will appear in the November issue of The Walrus, and is now available online. It’s about how using GPS navigation systems can affect the structure of your brain. It was a really interesting piece to report — probably the most interesting thing I’ve done in a few years — so I wanted to share the results.

[UPDATE 10/19: The New York Times picked out this article as its "Idea of the Day" in their "Must Reads From the Week in Review Staff" section.]

Jockology: Triple bill on fitness in your 50s!

October 8th, 2009

The Globe is running a special section on fitness in your 50s, so there are three Jockology columns in today’s paper:

The question

How should I train in my 50s?

The answer

When Ed Whitlock became the first septuagenarian to run a marathon in under three hours in 2003, it was thanks to a simple but gruelling training plan: two- to three-hour runs around a local cemetery, nearly every day.

That regimen presented two key challenges that are familiar to any masters athlete: staying healthy and – just as important but less obvious – staying motivated. In fact, when asked why his race performances in his 50s were less impressive than in the years before and after, Mr. Whitlock points to his motivation…

and

The question

How much will I slow down in my 50s?

The answer

The physical attributes that determine athletic performance – maximal oxygen uptake, as well as muscular strength and power – typically start to decline slowly at about the age of 35, and much more rapidly at about 60…

and

The question

Now that I’m in my 50s, what’s the cumulative effect of all the exercise I’ve done?

The answer

Unless you’ve made a dramatic turnaround after a severely misspent youth, it’s inevitable that some of your body parts don’t work as smoothly as they did a few decades ago. It may be tempting to blame that on the punishment you’ve inflicted on your body during years on playing fields, ice rinks and jogging paths – but the truth is more likely the other way around.

Researchers have a good idea of the average rates of decline you can expect for various systems. And for almost every sign of aging you can think of – muscle loss, weight gain, artery hardening, joint stiffening – there have been studies suggesting exercise slows it down…

There are also some neat graphics there, though the formatting is a bit messed up. Hopefully they’ll get cleaned up as the day goes on.

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Arthritis, exercise and obesity: some unexpected results

October 8th, 2009

A couple of recent studies worth noting, one surprising, the other not.

First, there’s a new Cochrane Systematic Review recommending exercise as a form of treatment for rheumatoid arthritis, to improve “functional ability.” It’s already fairly well-established that exercise is helpful for osteoarthritis, which is the more common (about 1 in 10 people will get it) and better known form of arthritis. But the evidence about exercise and rheumatoid arthritis, which is less common (about 1 in 100 people will get it), is a little thinner on the ground, so the Cochrane review is interesting.

“Based on the evidence in this study, we would recommend aerobic capacity training combined with muscle strength training as routine practice for RA patients,” said lead researcher Emalie Hurkmans of the Leiden University Medical Center in Leiden, Netherlands. “But we need more research to establish the recommended length and type of exercise programs, whether patients need to be supervised and if these programs are cost effective.”

All of this makes the second study a little more surprising. In a mouse study, Duke University researchers found that obesity, on its own, does not cause osteoarthritis. Because of the strong link between arthritis and obesity as a risk factor (one of the reasons exercise is so important), researchers have assumed that the extra weight puts strain on joints, which then leads to degeneration and ultimately arthritis.

But in the new study, researchers used mice that either didn’t have or couldn’t process the hormone leptin, which helps to regulate appetite. No matter how fat these mice got, they didn’t have an elevated rate of arthritis. Mice with normal leptin levels, on the other hand, developed significant knee arthritis when they got just half as fat as the leptin-free mice.

So what’s going on? It’s not clear, since leptin influences factors like body weight, inflammation, sex hormone levels and bone metabolism, all of which could affect the development of arthritis. What it implies is that loading your joints with extra weight isn’t what causes arthritis — the strong link between obesity and arthritis appears to be chemical instead.

“We knew from other studies that obese people got arthritis in their hands, too, which don’t bear weight. This indicated that something besides just body-weight level affected their joints,” [one of the researchers said].

Just to reiterate: the link between arthritis and obesity is as strong as ever. It’s just the mechanism that isn’t as simple as we thought.