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Posts Tagged ‘cycling’

Static stretching before cycling makes you less efficient

September 19th, 2011

I wrote a few months ago about an Italian study showing that static stretching hurts cycling performance — that was the first study I’d seen about stretching and cycling, joining a whole bunch of studies showing that stretching hurts speed, power and endurance in running. Now researchers at Cal State Fullerton have backed up that initial result with a slightly different study, published in the Journal of Strength & Conditioning Research, that reaches basically the same conclusion.

The study was very simple: 10 highly trained cyclists (5 men, 5 women) did two 30-minute rides at 65% VO2max pace, while the researchers measured economy (i.e. how much oxygen they needed to maintain the pace), perceived exertion, and heart rate. Before one of the rides, they did a standard 16-minute static stretching routine. Here are the results for oxygen use (squares indicate the non-stretching trial):

Pretty straightforward: after stretching, it took more oxygen to maintain the same pace. Note that the difference was statistically significant only at the five-minute mark, not for the rest of the data points, indicating that the effect gradually wears off. Perceived exertion was the same in both trials — so the volunteers felt the same, but their bodies were working less efficiently.

Why does this happen? The researchers write that the results “may be explained through either muscle mechanics or neural factors or a combination of the two.” Then they spend a few pages going through all the various muscle-related theories and the various brain/nerve-related theories. The short answer is that no one knows. One of the previous neural studies they mentioned was interesting, and I wasn’t familiar with it:

Cramer et al. (4) proposed neural factors, such as decreased muscle activation or altered reflex sensitivity, might be the primary mechanism underlying the stretching-induced decreases in force. After stretching only one leg, they reported the same pattern of stretch-induced decrease in both stretched and un-stretched limbs...

That’s pretty cool! It certainly suggests that, whatever is going on in the muscles, there’s also something going on in the nervous system. Bottom line is simple — and by now, should be no surprise: don’t static stretch before workouts or races. It hinders performance.

Time-trials, body weight and allometric scaling in cycling

August 5th, 2011

If you want to be a great sprint cyclist, you need to be able produce enormous bursts of power — so being big and muscular helps. If you want to be able cycle up mountains, on the other hand, you need great relative power — power divided by body weight — since every extra pound is deadweight that you have to haul upwards. But what about the middle ground? How does weight affect your performance in, say, a flat 40-km time trial?

Studies dating back to the 1980s have suggested that you need to use “allometric” scaling of weight to get the best prediction of performance in a 40-km time trial. Start by performing a graded peak power output (PPO) test, which is basically like a VO2max test, and PPO is the average power maintained for the last minute before you reach failure. Your PPO is a great way to predict how you’ll do in a 16-km time trial. Divide PPO by your body weight, and you have a great predictor of how you’ll do in a mountain race. And the interesting part: divide PPO by your weight to the power of 0.32 and you’ll have a great prediction of how you’ll do in a 40-km time trial.

This idea was first proposed by David Swain back in 1987, but hasn’t been tested much — which is why a new study just posted online at the British Journal of Sports Medicine, from Rob Lamberts and his colleagues at the University of Cape Town, put it to the test with 45 trained male cyclists. Here are some of the key results:

It’s pretty clear that the bottom graph (power divided by weight to the power of 0.32) provides a much better fit to the data than power (top) or power divided by weight (middle). So this is a useful piece of data for performance monitoring. But left unanswered is the question: why 0.32? Is this just an empirical number that happens to capture the tradeoffs between having more muscle and carrying more weight in exercise lasting about an hour? Or is there some physical or physiological explanation?

Static stretching lowers cycling effiency and time-to-exhaustion

June 22nd, 2011

What we know so far: static stretching seems to cause a decline in maximal power, strength and speed, as well as hurting running economy in endurance runners. What a new study in the Scandinavian Journal of Medicine & Science in Sports reveals: stretching is bad for cyclists too — possibly even worse than it is for runners.

The authors of the study, from the University of Milan, argue that the performance-damping effects of stretching may be more obvious in endurance cycling than in running. The reason is that type II muscle fibres (a.k.a. fast twitch) are affected more than type I muscle fibres (slow twitch) by stretching. When you’re running at below-threshold paces, your leg muscles are only applying about 20% of their maximal force, so they can rely mainly on type I fibres. Cycling, on the other hand, requires a greater proportion of maximal force: about 60% of max force at 85% VO2max, according to the paper. As a result, cyclists recruit a higher proportion of type II fibres, and are thus more vulnerable to stretching-induced weakness.

That’s all fine in theory — but what do the experiments say? The researchers did a series of tests of VO2max, mechanical efficiency, time to exhaustion (with the power set at 85% of power at VO2max, so that exhaustion took about 30 minutes), and so on. Here are the efficiency results, with open circles corresponding to no stretching and closed circles corresponding to 30-minute pre-exercise stretching routine:

On average, efficiency was about 4% lower after stretching. The time to exhaustion was decreased by 26% after stretching (22:57 vs. 31:12).

I’ve been explaining the reduction in running economy caused by stretching by talking about the legs as a set of springs that store energy (and do so less efficiently when they’ve been stretched). But these results suggest that the effects of stretching on the muscle fibres themselves (and perhaps on neuromuscular signalling pathways) are just as important, since cycling doesn’t rely on that springy-legs effect.

Anyway, this is, as always, just one study — but probably worth keeping in mind if you do a lot of static stretching before cycling.

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Extreme exercise: Tour de France cyclists live longer

June 21st, 2011

A little bit of exercise is good for you, but too much is bad for you. That seems to be a fairly widespread societal view — certainly anyone who trains seriously as a runner or cyclist or other endurance athlete is familiar with all the comments about how training so much can’t be good for you. And to be fair, there has been some recent research that raises questions about whether running multiple marathons over an extended period of time can damage your heart.

So I was very interested to see a study, forwarded by Brian Taylor (thanks!), that just appeared in the International Journal of Sports Medicine. Spanish researchers decided to study the records of cyclists who rode the Tour de France between 1930 and 1964 — an example of “extreme” exercise if ever there was one — and see how long they lived compared to the general population. They focused on riders from France, Italy and Belgium (who comprised 834 of the 1229 riders for whom birth records were available), and they compared the longevity of those riders to the general population from their home country in the year of their birth. Here are the aggregate results in graphical form:

The trend is pretty clear. The age by which 50% of the population died was 73.5 for the general cohort, and 81.5 for the Tour de France riders — who, according to the paper, ride about 30,000 to 35,000 km per year (though I’d be surprised in the riders competing in the 1930s were training as hard as modern riders).

So what does this tell us? Well, as in any case-control study, there are plenty of limitations on the conclusions we can draw. First of all, this doesn’t prove that “extreme” exercise is better than “moderate” exercise. It may be that riding 30,000 km/year is significantly better than doing no exercise at all (or than doing the relative pittance that the average modern person does), but is still worse for you than riding, say, 10,000 km/year. But it’s pretty clear that extreme levels of aerobic training don’t shorten your life. As the authors put it:

In our opinion, physicians, health professionals and general population should not hold the impression that strenuous exercise and/or high-level aerobic competitive sports have deleterious effects, are bad for one’s health, and shorten life.

It’s also worth mentioning some potential confounding factors. The paper notes that former athletes tend to smoke less, drink less alcohol and have a healthier diet than the general population. Fair enough: these factors almost certainly contribute to the increased longevity of the riders. Again, the conclusion we can draw isn’t that extreme riding makes you healthier; it’s that it doesn’t make you less healthy.

What about genetics and selection bias? Maybe the Tour de France riders tend to be the type of lucky person with a great metabolism who’s destined to be healthy for his entire life no matter what he does, and it’s those great genetics that predisposed him to become a competitive cyclist. Again, not an unreasonable point. In response, the authors point out a 2010 British Journal of Sports Medicine paper in which researchers in Sweden compared the genetic profiles of 100 world-class male endurance athletes (“Olympic finalists or Europe/World Champions and Tour de France finishers”) with 100 matched controls. They looked at 33 “risk-related mutations and polymorphisms” associated with cardiovascular disease, hypertension, insulin resistance, cancer, and other major causes of mortality — and found no difference:

[T]he overall picture suggests that there is no evidence that elite male world-class endurance athletes are genetically predisposed to have a lower disease risk than non-athletic controls. Thus, the previously documented association between strenuous aerobic exercise undertaken by elite athletes and increased life expectancy is likely not biased by genetic selection.

Bottom line: if the question is “How much exercise is too much?”, I still think the answer is “Way, way more than you think.”

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Cycling efficiency: strength training is key for masters

June 8th, 2011

The links between strength training and efficiency in sports like cycling and running have been studied for over a decade, but a study in the European Journal of Applied Physiology offers a new twist: the role of strength training becomes increasingly important as you get older.

Researchers in France studied nine masters cyclists (average age 51.5) and eight younger cyclists (average age 25.6), and measured their “delta efficiency” before and after a three-week strength training program focused on knee extensions. Each workout consisted of 10 sets of 10 bilateral knee extensions. While the younger cyclists improved their cycling efficiency by 4.1%, the older group improved by 13.8%.

Traditionally, researchers have figured that the big decline in endurance performance with age comes from lower maximal oxygen consumption, which seems to reduce performance by about 10% per decade. The new study suggests that the muscle loss that accompanies aging could also play a key role in endurance, perhaps because inefficient fast-twitch muscle fibres have to be recruited earlier in an exercise bout. That would explain why the older athletes saw a bigger jump in efficiency when they improved their strength, even after only three weeks.

You’d expect the same thing to apply in running. Bottom line: another reason that I need to get more consistent with strength training!

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Is less really more in warm-ups?

May 31st, 2011

A few people have e-mailed me about this University of Calgary study, (“Less is More: Standard Warm-up Causes Fatigue and Less Warm-up Permits Greater Cycling Power Output”) which has received a bunch of press. It seems to run counter to the message from this blog post a few weeks ago, which argued that a hard effort during your warm-up could enhance performance.

The new study had cyclists perform either a “standard” long warm-up (designed in consultation with elite track cyclists and coaches), or an experimental short warm-up. Then they tested performance, and the short warm-up group had a 6.2% advantage in peak power. Okay, cool. This is valuable information. But let me add two caveats:

  1. What was the “standard” warm-up? It was “about 50 minutes with a graduated intensity that ranged from 60 to 95 per cent of maximal heart rate before ending with several all-out sprints.” That’s one heck of a warm-up. In comparison, the experimental warm-up was “about 15 minutes, and was performed at a lower intensity, ending with just a single sprint.”
  2. What was the performance test? It was a 30-second Wingate test.

Now, bear in mind what athletes are hoping to achieve with a warm-up. According to the paper, it’s:

[I]ncreased muscle temperature, accelerated oxygen uptake kinetics, increased anaerobic metabolism and postactivation potentiation (PAP) of the muscles.

In the blog post a few weeks ago about the “priming” effect of a hard warm-up effort, the focus was on accelerated oxygen uptake kinetics. But in a 30-second sprint, oxygen kinetics have nothing to do with it. We’re talking about two different animals here.

Bottom line: if you’re a track sprinter who spends nearly an hour warming up at up to 95% of max heart rate, then this study tells you something very important. But if your event is longer than 30 seconds (so that oxygen kinetics matter), and your warm-up tends to be shorter and less intense, don’t assume that this study is telling you to shorten it even more!

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The priming effect: how a hard warm-up can help performance

May 9th, 2011

Most people who do hard interval sessions will have noticed this mystery: why does the second or third interval usually feel easier than the first one? I always figured it had to do with “getting into the rhythm” or something along those lines. Whatever the reason, Pete Sherry — my main training partner for 2002-2004 — and I eventually decided that we’d run 2x400m in ~72 sec a few minutes before every workout, in the hopes of making the first interval feel easier. Our impression was that it worked, and we started doing it before races too.

It turns out there’s plenty of physiology behind this. If you suddenly start running at a hard pace, with no warm-up, it takes a while before your body can adjust to start delivering oxygen to your muscles at its maximum possible rate. That’s one of the reasons VO2max tests take 10-12 minutes, rather than simply involving a short, all-out sprint. It takes time for the blood flow to your muscles to increase, and for the enzymes that extract oxygen from the blood and oxidize fuel to ramp up their activity levels. A good warm-up gets this ramp-up process over with, allowing your body up to deliver more oxygen to muscles right from the start of the workout or race, and reducing the temporary oxygen debt.

Still, most people warm up with gentle jogging, flexibility drills, and some short sprints. But how about including a six-minute “hard” effort (above lactate threshold but below VO2max pace), about ten minutes before the start of your race or workout? Would that “prime” your oxygen kinetics even more? The challenge is as follows: a sustained burst of hard exercise (above threshold) definitely improves how quickly your body can process oxygen once the actual race starts; this effect can last for a half-hour or more. If you exercise too hard, on the other hand, you deplete your anaerobic energy stores (phosphocreatine), and metabolites build up in your muscles that may slow you down. Numerous experiments over the past decade have found conflicting results: depending on the precise details of the duration, intensity and recovery time following the “priming” burst, performance either increases, decreases, or stays the same.

A new cycling study just posted online at Medicine & Science in Sports & Exercise, from Mark Burnley’s group at Aberystwyth, adds some more data on finding the right balance. They used a six-minute priming bout, 10 minutes before the “race” — a formula that other studies have found to be effective. For intensity, they compared “heavy” (about 25% of the way between threshold and VO2max power) and “severe” (about 63%) priming bouts. The findings: “heavy” priming boosted oxygen kinetics and significantly increased time-to-exhaustion in tests ranging from ~2-10 minutes. “Severe” priming also boosted oxygen kinetics, but didn’t increase time-to-exhaustion, suggesting that the downside of depleted anaerobic reserves outweighed the benefits of more aerobic energy available early in the test.

So what does this mean in practical terms? It’s hard to know how generalizable this protocol is, but I’d say it’s worth experimenting with some sort of extended surge ~10 minutes before the end of your warm-up. If you’re doing a six-minute effort, it looks like you should aim just above your threshold. I know quite a few runners who have incorporated similar but shorter surges of ~1-2 minutes into their warm-up routine. There may be a good argument for runners to stick to shorter surges, since the impact of leg-pounding is a bigger factor than it is in cycling. In that case, you may be able to get away with a higher intensity. But so far I don’t think the research has answered that question — for now, it’s trial and error.

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Cyclists: adjusting saddle height and maintaining bone density

March 2nd, 2011

Two studies in the March issue of  the Journal of Strength and Conditioning Research that may be of interest to cyclists:

First (and simplest), another study about cyclists and bone density. Lots of previous cross-sectional studies have found that cyclists seem to have lower bone density than non-athletes and people who do impact activities like running. This one, from UC San Diego, actually followed 19 male masters cyclists and 18 matched non-athletes for seven years. Sure enough, the cyclists started with lower bone density, and declined faster during the study. By the end of the study (when both groups had an average age of 57), 17 of the cyclists had osteopenia and six had more serious osteoporosis; in the control group, 11 had osteopenia and one had osteoporosis. The message: get some impact activity, do some strength training, and get your bone density checked periodically.

Second is a study about optimizing saddle height (using “saddle” rather than “seat” makes me snicker, but that’s what they use in the paper, so I’ll stick with it!) for both performance and injury prevention. Apparently there are two standard, well-studied approaches to setting saddle height. The Hamley method, based on research in the 1960s, recommends setting the distance between pedal and saddle as 109% of inseam, measured from ischium (hip bone) to floor. That’s based on optimizing performance. The Holmes method, on the other hand, suggests setting knee angle at the bottom of the stroke to between 25 and 35 degrees to avoid injury.

A useful aside in the paper, derived from the Holmes research: pain in the front of the knee usually means the saddle is too high low, pain in the back of the knee means it’s too low high. [Update March 6: Thanks to commenter Phil for catching the fact that the journal article had it backwards!]

Anyway, the problem is that these two methods don’t always coincide, mainly because people have very different ratios of upper leg to lower leg length. In this study, setting the seat at 109% of inseam led to knee angles ranging from 19 to 44 degrees, and only three of the 11 subjects (who were well-trained cyclists) fell into the 25-35 degree injury reduction zone. So which is best?

The researchers looked at anaerobic power (30 second sprints) and economy (15-minutes at 70% VO2max) for three different settings: 109% inseam, 25 degree knee angle, and 35 degree knee angle. Surprisingly, the 25 degree knee outperformed 35 degrees AND 109%, particularly for economy. These results in well-trained cyclists echoed earlier studies by the same group in casual cyclists. So they conclude that 25 degree knee angle is the best way to set saddle height, since it’s within the “minimize injury” range and also appears to optimize performance. Obviously if you’re a Tour de France racer, you’re going to optimize bike position in a much more sophisticated way, but this seems like a useful rule of thumb for the rest of us.

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Crowd support in Delhi

October 10th, 2010

There were some media stories early on about the lack of crowd support at the Commonwealth Games. I think that was a bit overblown — anyone who’s ever been to the weekday morning qualifying session of a major championship meet knows the crowds can be pretty sparse. I mean, people have jobs! Admittedly, the crowds for the cycling road races today (Sunday) were almost non-existent, because the security perimeter made it virtually impossible to get anywhere near the course! Even with accreditation, it took me ages to get anywhere the start-finish area.

For a true measure of Indian sports crowds, though, I went to the India-Pakistan field hockey match tonight. It was fantastic! Great energy, a friendly guy beside me explained some of the history behind the rivalry, and only a few giant bugs attacked me. Here’s some grainy cell-phone footage that gives some idea of the energy in the stadium:

“Light visors” to beat jet-lag

October 9th, 2010

Cyclist Tara Whitten has done a lot of travelling over the past few weeks — from the world road race championships in Australia directly to Delhi for the Commonwealth Games, 10 races in less than two weeks. I chatted with her yesterday after she picked up her third bronze medal of these Games, in the individual pursuit, about how she handled the travel.

light-visor

The cycling team — like many other Canadian national teams — has been working with Calgary sleep specialist Charles Samuels, the pre-eminent person in the field. He gave them lots of the standard advice about jet-lag, like getting as much rest as possible on the flight and then focusing on proper cycles of light and dark upon arrival.

She also used melatonin for a few days after arrival. As I mentioned a few weeks ago, I’m trying melatonin for the first time on this trip, which started in Canada, included four nights in London, two weeks in India, and then finishes in Australia. So far I’ve been very happy with it: while I’ve been tired after the flights, I haven’t had any trouble sleeping at night and staying awake during the day. That may simply be because my flights have all had morning arrivals, after which I’ve managed to stay up all day — a good way to reset your clock even without melatonin.

Anyway, the one thing Whitten mentioned that surprised me was that she (and other cyclists, I believe) are using light visors to make sure their bodies get the “daylight” signal loud and clear at the appropriate times of day (first thing in the morning if you’re flying east, late afternoon/early evening if you’re flying west). These things (which, from what I can tell, cost a couple hundred dollars) have been around for years, and are sometimes used for seasonal affective disorder, but it’s the first time I’ve heard an elite athlete mention them.

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