Archive

Archive for May, 2010

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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A few thoughts about training zones

May 23rd, 2010

Last week’s Jockology column about pacing and deliberate practice contained a “training zone” pyramid to illustrate roughly how you might divide your training time:

training-zones

One of the comments on the Globe site disagreed with this information:

I question the chart they put in this article. For a 40 minute 10 km, they say spend 20% of your training time at threshold, and threshold is 4:00 to 4:21 min / km, but to run a 40 minute 40 k your pace must be 4:00 for the race. I doubt you’d get there if you’re only running 4:10/km in training 20% of your time, and the rest at 4:45 – 5:25 as they’ve shown. Seems insufficient.

I was surprised to see this comment, because to be honest, I was worried it skewed too much in other direction — i.e. that the training it recommended was too hard! Some background: this idea of a 70:20:10 split between “aerobic,” “threshold” and “maximum” training zones (the names vary depending on who you talk to, but the ideas are fairly consistent) came from talking to Carl Foster, a professor at the University of Wisconsin – La Crosse and past president of the American College of Sports Medicine. It’s by no means an iron-clad rule, as there are obviously many different ways to train successfully. But Foster said it was a common pattern that had emerged from studies across a variety of endurance sports like running and cross-country skiing. In my opinion, the key message here (and the reason I use this pyramid) is that the majority of your runs should actually be quite easy — something I think many beginners don’t realize. I know that when I started running, I was going as hard as I could every time I stepped out the door, and I think that’s a common experience.

When I check it against my own past training, I find that it gets me into the right ballpark — though I tend to do LESS training in the threshold zone than he recommends. To illustrate, here are a couple of sample weeks that I would alternate in a 14-day cycle when I was in my best shape (in kilometres):

Workout “aerobic” “threshold” “maximum”
Mon 8k easy 8
Tue am 8k easy 8
Tue pm 5x(800/300) 8 6
Wed 13k easy 13
Thu am 16k progression 11 5
Thu pm 12x60s hills 6 3
Fri 13k easy 13
Sat 1600/8k tempo/5×300 8 8 3
Sun 20k easy 20
TOTAL 120 95 13 12
Percent 100 79.16667 10.8333333 10
Mon off 0
Tue am 8k easy 8
Tue pm 6×1600 8 10
Wed 13k easy 13
Thu am 8k tempo 4 8
Thu pm 8×300 8 3
Fri 13k easy 13
Sat 26k progression 13 13 0
Sun 16k easy 16
TOTAL 117 83 21 13
Percent 100 70.94017 17.9487179 11.1111111
14-day average percentages: 75.10549 14.3459916 10.5485232

So I was generally right around 10% for the hardest zone, a little lower than recommended for the middle zone, and and little higher for the easiest zone.

Note that the McMillan pace calculator has quite a big gap between what I’m calling the “aerobic” and “threshold” zones. (Other coaches like Jack Daniels also agree with this approach, suggesting that this “dead zone” is fatiguing without offering any major training benefits.) For the 40-minute 10K runner above, there’s no training recommended between 4:21 and 4:46 per kilometres. For a 30-minute 10K runner, that dead zone is between 3:16 and 3:40 per kilometre. Because I did many progression runs (and even my “tempo” runs were generally run getting progressively faster), I actually spent quite a bit of training time in the dead zone. In the chart above, I’ve included those kilometres as “threshold,” so if anything I’m overestimating my time in that zone.

Of course, I didn’t always train like that. Those sample weeks were from 2003; in 2007-2008, I started doing a long tempo run on Saturdays, and often doing one other long fartlek that primarily stayed in the threshold zone, so I probably did more than 20% threshold (but less than 10% maximum).

Anyway, just thought I’d throw that out there and see what people think about the right balance. Do I need to stop using that pyramid?

Caloric restriction extends your life, but may make you stupider

May 23rd, 2010

Okay, that’s not really a fair headline or a good summary of the research I’m describing (which is a neat study by researchers at Princeton, explained in an excellent and detailed press release). But I have to admit, I’m not always perfectly neutral — like everyone, I prefer to see some results more than others. And research into caloric restriction is a good example: there’s been plenty of evidence over the past few years of the age-defying benefits of starving yourself:

To date, caloric restriction has been observed to extend lifespan in every organism tested, including worms, mice and monkeys, [Princeton prof Coleen] Murphy said. While the reasons for this are still under investigation, scientists generally believe that the benefits of caloric restriction go well beyond preventing diseases associated with obesity, such as heart disease and diabetes, Murphy added. It appears that limiting food intake actually slows the aging process.

In general, I’m used to leafing through studies and press releases that give me a nice pat on the back. Aerobic exercise is good? Super, I do tons of it! Eating lots of fruits and vegetables is good? Fantastic, I do pretty well on that front. But caloric restriction? That’s the antithesis of everything I stand for, which is doing ridiculous amounts of exercise and consequently being able to eat more or less until I get bored with no ill effects — or at least, no ill effects that I knew of until the emergence of this idea that eating less slows down aging.

So you should read the press release for yourself, and judge its merits in an unbiased manner… but here’s what I took from it:

Young worms whose calories were restricted had normal short-term memories, but their long-term memories were severely impaired; the memories faded within 24 hours, as opposed to 40 hours in normal worms.

(40 hours in worm time corresponds to about 15 people years.)

Now, the study has a lot more to say. While caloric restriction impaired long-term memory, the (impaired) memory abilities didn’t decline as much with old age as they normally do. The study also investigates how insulin-signalling pathways affect longevity and cognitive function (this appears to operate independently of the calorie-restriction effects). So there’s a lot of on-the-one-hand-this, on-the-other-hand-that going on. But it’s the first sign I’ve seen that caloric restriction, even if it extends life, may have some significant downsides:

“The assumption in the field of longevity research has been that organisms able to live longer will function longer as well,” said [Murphy]. “It seems we need to revisit that.”

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Distance running trains the heart, intervals train the muscles

May 22nd, 2010

“High-intensity interval training” (HIIT) has been receiving lots of research attention recently as a time-efficient way to get in shape. An interesting pre-print has just appeared in Medicine & Science in Sports & Exercise (thanks to Amby Burfoot for noticing it) that adds a couple of interesting wrinkles.

First of all, the study used running rather than the usual stationary biking — so it provides some evidence that the same kinds of protocols that have been extensively studied in cycling also apply to running. Researchers at the University of Western Ontario had 20 (untrained) volunteers perform six weeks of training, three times a week. One group ran steadily at 65% VO2max, starting with 30-minute runs and building up to 60 minutes; the other group did 30-second sprints with four-minute recovery, starting with four repetitions and building up to six.

As expected, the sprinters improved almost exactly as much in a variety of outcomes as the subjects doing long, sustained runs. They both increased VO2max by about 12%; they both increased 2,000-metre time trial performance by about 5%; they both lost fat (the sprinters lost 1.7 kg while the long-runners lost 0.8 kg). So yes, the HIIT paradigm is applicable to running.

But the study offers one more twist. They measured maximal cardiac output (Qmax), which is the biggest volume of blood your heart can pump in a given amount of time. In this case, the long-runners increased Qmax by 9.5%, while the sprinters didn’t improve at all.

To understand what this means, consider that VO2max (the maximal amount of oxygen you can deliver to your muscles in a given amount of time) is the product of two quantities: Qmax (how much blood your heart can send to the muscles) and “maximal arterial-mixed venous oxygen difference” (how much of the oxygen sent to your muscles is actually extracted from the blood and used by the muscles before the blood heads back to your heart). This latter quantity (the researchers write) depends on “O2 delivery to active muscle fibres (blood flow distribution, capillary density, and arterial O2 content), local enzymatic adaptations, and mitochondrial density/volume.”

So what the study tells us is that short sprints and long, steady runs both increase endurance, but they do it in different ways. Sprints act peripherally (i.e. the muscles), while long runs act centrally (i.e. the heart).

Of course, nothing is quite so black-and-white in real life, and many types of training session will stimulate both types of adaptation. Still, it’s a good reminder that the best training programs will balance different types of stimulus — which is, of course, what every elite runner already does. But those looking to HIIT as a way of getting fit should ideally try to also make time for at least one more sustained session each week.

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The science of proper warm-up

May 19th, 2010

Gina Kolata has an article in the New York Times on whether warming up improves performance that’s worth a read. Overall, her message seems to be that there’s very little evidence about whether warming up helps or hurts performance, or does nothing. To reach this conclusion, she relies largely on a recent review by Andrea Franklin at Bloomberg University of Pennsylvania, which begins with this statement:

The value of warming-up is a worthy research problem because it is not known whether warming-up benefits, harms, or has no effect on individuals.

I agree that there’s lots of research that needs to be done — for example, there have been several interesting recent studies looking at the effects of dynamic warm-up activities as opposed to traditional static stretches, but more is needed to identify what works best for different activities and what the mechanisms are. But I think it’s a little melodramatic to claim that we have no idea whether warming up helps. Even Franklin describes her analysis of 32 “high-quality” studies as follows:

Warm-up was shown to improve performance in 79% of the criterions [sic] examined. This analysis has shown that performance improvements can be demonstrated after completion of adequate warm-up activities, and there is little evidence to suggest that warming-up is detrimental to sports participants.

That seems to be quite a bit more positive than the opening sentence, to say the least. There’s still lots to learn about warm-ups, but let’s not exaggerate our ignorance.

Running a marathon halts cell death

May 17th, 2010

[18/5 NOTE: I don't really understand this study. See the comments below -- and help out if you can!]

Researchers from the University of Rome just published a study in the journal BMC Physiology in which they analyzed blood samples from 10 recreational runners before and after completing a marathon (press release here). The chief finding:

Apoptosis, the natural ‘programmed’ death of cells, is arrested in the aftermath of strenuous exercise. Researchers… studied peripheral blood mononuclear cells (PBMCs), isolated from whole blood samples taken from people after finishing a marathon, finding that the balance between expression of pro- and anti-apoptotic genes is shifted after the race.

The idea that exercise helps your cells live longer has been in the news recently (see, for example, Gretchen Reynolds’ piece on telomere length in the New York Times a few months ago). This appears to be another piece of the puzzle — though a marathon is a pretty intense bout of exercise, so you have to wonder whether you’d get similar benefits from a shorter workout.

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Sports genetics: Kenyans, Ethiopians… and Tibetans

May 16th, 2010

A must-read article for anyone interested in the interplay of sports and genetics (and for anyone who’s adamantly convinced that Kenyans and Ethiopians dominate distance running because they’re born to run), by Sports Illustrated’s David Epstein. The article is too good and too packed with info to summarize with a few pithy quotes — the fact is, it’s a very complicated area. But the overall message plays down the roles of genes:

Pitsiladis selected 24 gene variants most often associated with sprinting or endurance prowess and looked for them in the genomes of four men who have held the world record in the 100-meter dash and five who have held the world record in the marathon. What he saw was that based on those genes, the world-beaters are not genetic outliers at all. Pitsiladis analyzed the DNA of some of his graduate students for comparison and found that “a student of mine has a better rating for sprinting than the likes of an Asafa Powell or Usain Bolt.”

And:

A decade ago, when Pitsiladis began to study elite athletes, his medical students would ask why East Africans dominate distance running, to which he would reflexively respond that their secret is in their genes. “But after 10 years of work,” he says, “I have to say that this is a socioeconomic phenomenon we’re looking at.”

Having read Epstein’s article, I was interested then notice this press release from the University of Utah this morning:

Researchers have long wondered why the people of the Tibetan Highlands can live at elevations that cause some humans to become life-threateningly ill – and a new study answers that mystery, in part, by showing that through thousands of years of natural selection, those hardy inhabitants of south-central Asia evolved 10 unique oxygen-processing genes that help them live in higher climes.

Of course, the Tibetans live at much higher elevation than Kenyans and Ethiopians do (and they don’t seem to be particularly good at running). Still, the study seems to suggest that many generations of living at altitude does produce changes that show up in your DNA. It would be interesting to find out whether East African populations living at altitude show any particular patterns for these 10 genes related to oxygen processing.

Scott Jurek, the vegan ultrarunner

May 14th, 2010

Interesting article in the New York Times about ultramarathoner extraordinaire Scott Jurek, who relies on a vegan diet to get the 5,000 to 8,000 calories per day that he needs. NYT food writer Mark Bittman (a.k.a. The Minimalist) invited Jurek over to cook a (delicious sounding) meal. My favourite paragraph from the piece:

He said he spent a great deal of time shopping, preparing and cooking food — and chewing. He is among the slowest and most deliberate eaters I know, and there is something about his determination at the table that is reminiscent of his determination on the road: he just doesn’t stop.

The article also notes Jurek’s quest to set an American record at the 24-Hour Run world championships in France, which are taking place as I type. According to Jurek’s Twitter account, he seems to have just taken the lead for the first time shortly after the 14-hour mark, from Japan’s Shingo Inoue (who had been on world-record pace through halfway, 5K ahead of Jurek).

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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Age-related slowdown: run vs. bike vs. swim

May 13th, 2010

A paper in last month’s International Journal of Sports Medicine takes a look at how much you slow down as you age, comparing the three triathlon disciplines. Researchers in France crunched data from the top ten finishers in each age group at the 2006 and 2007 world championships, for both Olympic-distance and Ironman triathlons. Since a picture is worth 1,000 words:

untitled

The top graph is for Olympic-distance, while the bottom graph is for Ironman. What sticks out is that cycling declines more slowly than running and swimming, and the researchers suggest a bunch of different explanations for this. One is that running and swimming rely more on fast-twitch muscle fibres, which atrophy more quickly than slow-twitch fibres. Another is simply that running is harder on the body, so older athletes have to spend less time running to avoid injuries, while cyclists are able to maintain higher training volumes as they age. There are also more subtle possibilities, such as the idea that identical declines in your power output would affect running more than cycling (since running speed is directly proportional to mechanical power, but cycling speed only proportional to the cube root of mechanical power).

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