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Posts Tagged ‘cycling’

Delhi 2010: WADA’s thoughts on Contador

October 2nd, 2010
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I’ve arrived safely in Delhi, where I’ll be covering the Commonwealth Games for the next two weeks (and my accommodations are just fine, thank you very much!). My main mission will be to gather material for a couple of upcoming stories on cutting-edge sports science and medicine, but I’ll also blog regularly about what I see.

A quick taste before I head to bed: WADA held a press conference today featuring director general David Howman. He danced around a couple of questions about Alberto Contador, but he did say that he’s been happy with how the case has been handled, and hasn’t seen any evidence that cycling authorities have been procrastinating in pursuing the case (despite pointed accusations to the contrary by a German TV station). He also spoke briefly about what dopers are up to now — specifically microdosing (something that could well be relevant to Contador), sample manipulation (e.g. the Russian women caught giving someone else’s pee in 2008), and testosterone patches. Here’s a brief clip of him answering a question about how WADA scientists can hope to stay ahead of the cheaters (in which he demonstrates his high opinion of journalists!):

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.

Do the health benefits of cycling outweigh the risks?

July 18th, 2010

In a Jockology column last summer, I described a few studies about how switching from car to bike for a commute affects your exposure to pollution:

Whether you’re better off inside or outside a vehicle seems to depend on the vehicle and location. A Danish study in 2001 measured pollution exposure while driving or biking along identical routes in Copenhagen. The air inside the cars was bad enough that, even taking into account that cyclists were taking longer and breathing more deeply, the drivers were worse off. On the other hand, an Irish study in 2007 found that the air on buses was worse than the air breathed by cyclists, but that the higher breathing rates led to greater total exposure for cyclists.

It’s one of those issues that might make you think twice about cycling through a busy downtown core to get to work — that, and the risk that you’ll be flattened by an impatient driver. There’s an interesting study that just appeared online in the journal Environmental Health Perspectives weighing the balance between cycling and driving in cities (the full text is freely available here). They make an interesting distinction between what’s good for society and what’s good for you:

Though society may benefit from a shift from private car use to bicycle use (e.g. because of reduced air pollution emission), for the shifting individual disadvantages may occur. While the individual may benefit from increased physical activity, at the same time he/she inhales more pollutants due to an increased breathing rate. The risks of getting involved in traffic accidents may increase as well as the severity of an accident.

To tackle this question, the researchers (from the University of Utrecht) crunch an enormous data set to determine what would happen if 500,000 people switch from car to bike for short trips in the Netherlands (though they argue that the conclusions are widely applicable in other countries). They use demographic information along with studies on air pollution, traffic safety and physical fitness to reach the following encouraging conclusions:

For the individuals who shift from car to bicycle, we estimated that beneficial effects of increased physical activity are substantially larger (3 – 14 months gained) than the potential mortality effect of increased inhaled air pollution doses (0.8 – 40 days lost) and the increase in traffic accidents (5 – 9 days lost). Societal benefits are even larger due to a modest reduction in air pollution and greenhouse gas emissions and traffic accidents.

One of the interesting points that emerges in their discussion of the pollution studies is how big a difference your route choice can make (which I also discussed in the Jockology article linked above). In fact, they cite one study that found “walking close to the kerb in London greatly increased personal exposure”!

(via USA Today and — once again! — Amby Burfoot)

More bad news for cyclists on bone density

July 13th, 2010
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A new study in the Journal of Strength and Conditioning Research follows up with a group of competitive masters cyclists seven years after the original study showing that they had abnormally low bone density. The cyclists now have an average age of 57, and 89.5% of them meet the criteria for osteopenia or osteoporosis. In comparison, only 61.1% of a group of matched controls meet the same criteria.

It’s still not entirely clear why cyclists seem to have poor bone density. Obviously cycling is a non-weight-bearing, non-impact activity, so they’re not getting any bone benefits from their time in the saddle. But it appears that their cycle training makes them less likely to do any weight-bearing activity even compared to non-athletic controls who don’t do any training at all. Another possibility is that they’re sweating out too much calcium, hindering bone formation and repair. This study doesn’t do much to clear up the mystery, but it does show that this is a real effect, not just an artifact of the general skinniness of cyclists — otherwise the equally skinny control group would show the same effects.

One important note: four of the 19 cyclists in the group started weight training during the seven-year interval, and they were able to slow their rate of bone loss. It’s another reminder to everyone whose main sports is something like cycling or swimming: you need to do something that stresses your bones, either through sharp impacts or the torque applied by strength training.

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“Heart rate recovery” and acute vs. chronic training fatigue

June 6th, 2010

I had a chance to see an interesting study in progress a few days ago, during my visit to Cape Town, which prompted me to look up a paper that appeared earlier this year in the European Journal of Applied Physiology. It’s a case study of an elite Dutch cyclist being monitored with something called the Lamberts and Lambert Submaximal Cycle Test (LSCT), which was first described last year in a British Journal of Sports Medicine paper.

The gist is as follows: to warm up before a hard workout, you do a specific 15-minute protocol (6min at 60% of max heart rate, 6min at 80%, and 3min at 90%). You measure your power output and perceived exertion during these three stages, and then you measure how much your heart rate decreases during the 90 seconds after the test. Doing the test frequently (it’s not too strenuous, so you can do it as a warm-up before pretty much every workout) gives you objective data that tells you whether you’re fresh or tired, and whether your training is making you faster or slower.

Just as a sample, here’s a snippet of data, showing the power (at a fixed heart rate) for the first stage of the test, compared to the weekly training load. Pretty clear correlation:

lsctYou can see a gradual increase in power as the training cycle progresses, indicating that the cyclist is getting fitter. But you can also see big spikes in power during the heavy training weeks — that’s not because he was “fitter,” but because the acute training-induced fatigue meant he had to work harder (and thus produce more power) in order to get his heart rate up to 60% max. The mechanism has to do with decreased sympathetic nerve activity and increased parasympathetic nerve activity — and what’s most interesting to me is that the exact opposite happens in the case of chronic training-induced fatigue.

The same pattern can be seen in the heart rate recovery data:

lsct2During the heavy training weeks, the athlete’s heart dropped more quickly than during the other weeks. So he was tired from the dramatic increase in training load — but the test suggests that he was what the researchers call “functionally overreached” as opposed to “non-functionally overreached.” Had he persisted with the extreme training load for too long, his heart-rate recovery would have started to dip down instead of up, indicating overtraining. In other words, the researchers conclude:

This suggests that training-induced acute and chronic fatigue are reflected differently in the LSCT, which has important practical applications for monitoring.

Obviously this test is best suited to cycling, since you can precisely measure your power output. But I wonder whether a simplified version of the test, where you just exercise (run, row, whatever) at a set submaximal heart rate and then measure your heart rate recovery, would provide any meaningful information.

Oh yeah, the study I saw in progress: two groups of cyclists, each doing two (I think) hard workouts a week. One group does them on set days, come hell or high water; the other group does the LSCT three times a week, and determines whether or not to work out that day depending on the results. The hypothesis is that working out when your body is ready to go, and resting when it’s not, will lead to greater gains in fitness and performance. It’ll be interesting to see the results.

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Biking biomechanics, pedalling muscles, cadence, etc.

May 31st, 2010

I’m back online after an unplanned hiatus — I’m currently on a reporting trip in South Africa, and had some trouble (now sorted out) updating the blog. As a result, I didn’t get a chance to point out this Jockology column that appeared last week: it’s an infographic with a somewhat random assortment of neat tips and factoids about cycling. I particularly like the illustration of which muscles you use at various points of the pedal stroke.

Yesterday, I had the opportunity to watch the Comrades Marathon, an 89-km race that had somewhere around 23,000 entrants. It was a pretty amazing sight. Here’s a picture of the literally thousands of runners streaming towards the finish line in the last five minutes before the 12-hour cut-off (at which point the race director fires a gun indicating the course closing, and volunteers rush across the finish line and link hands to prevent anyone else from crossing and getting an undeserved finishing medal!):

comrades-finish

And here’s another shot showing something that I suspect we’ll be seeing a lot of in the coming month: those colourful horns are called “vuvuzelas,” and they make an incredible racket. Anyone with ticket to a South Africa game during the World Cup had better bring earplugs…

vuvuzela

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Pacing, “deliberate practice,” and Jerry Schumacher

May 13th, 2010

In a post last month, I mentioned having a chance to chat with Simon Whitfield about his recent training camp in Portland with the Nike running groups coached by Alberto Salazar and Jerry Schumacher. This week’s Jockology column in the Globe and Mail explores some of the ideas Whitfield talked about — in particular the fact that the Portland groups are very precise in monitoring their training paces, and how that relates concepts in sports psychology like “deliberate practice”:

… The group Mr. Whitfield trained with in Portland included Simon Bairu of Regina, who earlier this month smashed the Canadian record for 10,000 metres by 13 seconds at a race in Palo Alto, Calif., running 27:23.63. Chris Solinsky, another member of the group, broke the U.S. record in the same race, and a third member of the Portland group also dipped below the old U.S. record.

“They’re so precise about their pacing,” Mr. Whitfield says. “We came home with the message that when a tempo run is supposed to be, let’s say, 3:05 [per kilometre] pace, then 3:03 pace is not a success. That’s a fail.”

Such precision may be daunting, but it’s a hallmark of “deliberate practice,” a concept advanced by Florida State University cognitive psychologist Anders Ericsson and popularized in recent books like Malcolm Gladwell’s Outliers: The Story of Success. The best way to master an activity is not simply to repeat it mindlessly over and over again, Dr. Ericsson argues, but to set specific goals and monitor how well you meet them.[READ THE FULL ARTICLE]

I also chatted to Lex Mauger, the lead author of a recent study on pacing in a 4-km cycling time-trial. The study showed that getting accurate pace feedback during a hard effort really does lead to better performances — something many athletes would have told you intuitively, but which had never been shown. In particular, pace feedback seems to be crucial in the early stages of a race, before you’ve settled into a rhythm.

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Staying fuelled while cycling helps bone density

May 9th, 2010
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I’m not sure if my headline is misleading. There’s a new press release from the University of Missouri titled “Maintaining Energy Balance During Stage Races May Protect Cyclists’ Bones, MU Researcher Says,” but the description of the research is a little confusing (and the journal paper in Applied Physiology, Nutrition and Metabolism has yet to appear).

The new study is by Pam Hinton, who I interviewed last year for a piece on exercise and bone density. That previous study compared running, cycling and weightlifting, and concluded that running was good because of the jarring impacts, weightlifting was good because the added muscle puts stress on bones, but cycling had neither of those benefits.

The new study monitored cyclists during the Tour of Sutherland, a six-day, 10-stage race:

Hinton found significant increases in markers of bone formation and bone breakdown among the athletes whose energy intake matched their energy expenditure throughout the race.

Fortunately, bone formation increased more than bone breakdown, which suggests that everything is fine for those who take in enough calories.

“The findings suggest that participation in stage races might not have negative effects on bone turnover if energy intake matches the energy cost of high-intensity racing over several days,” said Pam Hinton, associate professor in the Department of Nutrition and Exercise Physiology. “The results are consistent with the practical recommendation that elite cyclists should match their energy intake to the high energy demands of stage racing.”

What’s unclear from the press release is whether she actually observed enhanced rates of breakdown in cyclists who weren’t getting enough calories during the race. If so, you’d think they’d mention it. If not, then I’m not sure how the study proves anything about adequate energy intake (though it’s obviously a good idea with or without this study!). I’ll follow up on this when I see the full study.

Anyway, uncertainty aside, the message seems to be: hauling ass during a brutal multi-day stage race won’t have any negative effect on your bones, assuming you’re taking in enough calories.

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Tylenol’s pain-blocking boosts endurance performance

January 26th, 2010

To the scientist in me, this is a really interesting study. But to the athlete and fan in me, it seems like bad news. British researchers fed highly trained cyclists acetominophen (Tylenol, as it’s known around here) before a 10-mile time trial. It was a double-blind, placebo-controlled trial. The riders who were fed Tylenol cycled about 2% faster, and had higher heart rate and lactate production (i.e. they were working harder) — but their perceived exertion was identical to the placebo group’s.

To read more about the study and its implications, read this entry in Amby Burfoot’s Peak Performance blog, which includes a Q&A with one of the researchers. The basic interpretation is simple: Tylenol blocks pain, and pain is what makes us slow down during long races. This is an important scientific result, because it sheds light on a red-hot debate about the nature and origins of fatigue. The authors of the study view their results as supporting the “central governor” theory, which argues that our brain subconsciously makes sure that we never let our body get too close to its absolute limits.

This, of course, is not the main message that many athletes will take from the study. A 2% performance boost is nothing to sneeze at for the well-trained athlete, so I expect that many athletes will start experimenting with Tylenol in training and racing. Is this dangerous? I don’t really know. (Gretchen Reynolds wrote an interesting article last summer about the risks athletes incur by overuse of NSAIDs like ibuprofen; Tylenol is a different class of drug.) But I have to admit: whenever I see a study of a potentially performance-enhancing pill, I cheer when the results come up negative, because (in my view) it keeps the sport a little simpler.

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“Heart rate recovery” to monitor overtraining

October 3rd, 2009

Back in the late 1990s, I was training under the guidance of Harry Wilson, the coach who steered Steve Ovett to Olympic gold and world records at 1,500m and the mile. Harry was an interesting mix of old-school traditionalist and cutting-edge training buff. Instead of prescribing a set amount of rest between hard intervals (like two minutes, say), he liked to wait until the athlete’s heart rate had returned to given value (generally 120bpm for me). Being a young technophile, I would wear my heart-rate monitor for these workouts in order to have instant feedback. But Harry never really trusted this newfangled technology, so I would stand there between each interval while Harry jammed his fingers into my jugular, listening to my pulse himself until it had slowed to his satisfaction. [EDIT: An astute reader points out to me that you take your pulse from the carotid artery, not the jugular vein. My apologies for any misunderstanding!]

I bring this up because, while I was browsing through the pre-prints of the Scandinavian Journal of Medicine & Science in Sports yesterday, I noticed an article by researchers at South Africa’s University of Cape Town, including Tim Noakes, on “heart rate recovery” to monitor training fatigue. The gist is as follows: 14 cyclists took part in a four-week high-intensity training program that included two interval sessions (eight repetitions of four minutes hard, with 90 seconds recovery) each week. Immediately after the final hard interval of each session, the researchers recorded how much the athlete’s heart rate decreased in the next 60 seconds.

After the four-week training period was finished, the researchers divided the subjects into two groups: those whose heart rates had recovered more and more quickly throughout the study, and those whose heart rates had recovered more and more slowly. The hypothesis was that getting better at recovery indicated the subjects were adapting to the training, while getting worse would be a sensitive indicator that they were overtraining. To test this, the subjects rode a 40-km time trial, and compared the results to a similar time trial they had ridden at the start of the study. Sure enough, the group that was recovering better rode faster, and increased power by 8.0%, compared to the slower-recovering group, which only improved power by 3.8%.

This study is part of a larger project investigating the role of heart rate recovery, so it will be interesting to see the remainder of the results when they appear. Monitoring overtraining — the failure to recover from a heavy training load, essentially — is much more of an art than a science, so having some objective tools to use would be really helpful to endurance athletes. (And I’m sure it’ll work better with heart-rate monitors than using a finger to the jugular.) Read more…

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