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Keyword: ‘stretching’

Dynamic stretching doesn’t hurt (or help) running performance

January 24th, 2012

Back in 2010, researchers at Florida State published a study showing that trained distance runner became about 5% less efficient and covered 3% less distance in a time trial if they did static stretching before the run. This was significant because, after a long series of studies showing that stretching compromises strength and power, it was one of the first to look at endurance performance.

Now the same researchers have published another study, in the current issue of Journal of Strength & Conditioning Research, this time looking at “dynamic” stretching instead of static stretching. Other than the stretching routine, the protocol is exactly the same. The runners spend 15 minutes stretching (or sitting quietly, during the control condition), then run for 30 minutes at 65% VO2max for a running economy measurement, then run as far as they can in the next 30 minutes.

This time, stretching had no significant effect on the distance covered in the time trial: stretchers covered 6.1 +/- 1.3 km, non-stretchers covered 6.3 +/- 1.1 km. On the other hand, the dynamic stretching did increase range of motion in the sit-and-reach test just as much as static stretching (from 32.3 to 37.6 cm). So the basic conclusion: if you’re really into stretching before a run, dynamic stretching will allow you to work on your flexibility without hurting your running performance.

One subtlety, which you pick up if you look at the individual results:

The dynamic warm-up routine takes a fair amount of energy (more details on that below). So you might wonder: for the less fit runners in the group, is it possible that they’re just tired out? The researchers do allude to this possibility:

[I]t is interesting to note that our top 2 performance runners both increased their performance under the dynamic stretching condition with the top runner seeing the largest increase in distance covered in the dynamic stretching condition of 0.2 km. Furthermore, the 2 runners in our study who covered the shortest distance performed better during the nonstretching control condition with the worst performance runner seeing the largest decline in performance after the stretching condition (i.e., 0.6 km). It is possible that elite endurance runners need a warm-up protocol of greater intensity and duration than do recreationally trained runners.

Looking back at the data, it actually looks to me like the top runner was better in the non-stretching condition, but maybe that’s just an artifact of the line thickness they used in the graph. Either way, the differences are pretty small in all cases. To me, the moral of the story is: if you’re an endurance athlete, you may have many reasons for why and how you stretch, but “going faster” shouldn’t be one of them.

As an addendum, here’s the stretching routine the study used:

A total of 10 different movements were used and completed in 15 minutes by performing 2 sets of 4 repetitions of each movement. The dynamic stretching movements were performed in the following order:

(a) Toe and Heel Walks: In these exercises, the subjects walked on their toes for 4 steps followed by walking on their heels for 4 steps to stretch the entire calf complex.

(b) Hip Series: The subjects performed a dynamic stretch of the hip flexors and extensors by placing their hands on a wall with their arms fully extended so that their body was at a 45 angle. In this position, each subject lifted his leg off the ground while bringing the knee to the chest and stepping over a hurdle placed laterally before returning to the starting position.

(c) Hand Walks: The subjects stretched their calves and hamstrings by beginning in a pushup position and walking their feet as close to their hands while keeping their heels flat. As soon as the subjects’ heels came off the ground, they walked with their hands back to a pushup position.

After the hand walks, the subjects performed a series of walking lunges, including (d) rear lunges, (e) lateral lunges, (f ) forward lunges, (g) a knee pull to a lunge, and (h) an ankle pull to a lunge to focus on the quadriceps and gluteus maximus.

(i) Walking Groiners: The subjects began this movement in a pushup position and then brought 1 foot next to the same side hand as to perform a groiner. Instead of holding this position, the subjects walked their hands out to return to the starting position before performing the action on the opposite leg.

(j) Frankensteins: The subjects stood with their feet together and their arms extended straight out in front of them so that their arms were parallel to the ground. While walking, the subjects were instructed to kick 1 leg up to touch the opposite hand to focus on the hamstrings. Every time a step was taken, a kick was made.

 

Which “rules of running” should you break?

November 28th, 2011

Forgot to mention this earlier — I have an article in this month’s Runner’s World called “Breaking All the Rules,” which is now available online. Basically, I had a chance to chat with a bunch of veteran coaches — Jack Daniels, Frank “Gags” Gagliano, Roy Benson, Jeff Galloway, Hal Higdon and Pete Pfitzinger — and ask them which “rules of running” they’d recommend not following blindly. Here’s one example:

THE RULE: Do prerace strides
For generations, runners have followed the same rituals to warm up before races or workouts: Start with some jogging, move on to a little bit of stretching, then perform a series of “strides”—short sprints lasting about 10 seconds that get your heart pumping and kick-start the delivery of oxygen to your running muscles. But do these timeworn rituals really help us perform better? Jack Daniels, Ph.D., isn’t convinced. “What I most often see at races is a bunch of runners striding up and down at a speed that is clearly faster than the coming race pace,” he says. Since these strides are the last thing runners do before starting the event, that inappropriate pace is fresh in their minds. “And when the gun finally sounds, they ‘stride’ or sprint right out.” The result: a way-too-fast start followed by an inevitable crash.
HOW TO BREAK IT: For shorter events like 5-K and 10-K races, jogging just long enough to get a good sweat going is all you need to do, says Daniels. (For longer races, you can get away with even less: Run the first mile of a half or full marathon as your warmup.) To get the oxygen-boosting benefits of strides without skewing your pace judgment—and screwing up your race result—try a sustained two-to three-minute effort 10 minutes before starting the race or workout. Run it slightly faster than your half-marathon pace, or at a speed that feels moderately hard. You should not be sprinting.

Other topics covered include stretching, the length and pace of your long run, having a recurring weekly training structure, back-to-back hard days, cross-training during injuries, and so on. I should emphasize: none of the coaches are suggesting that existing rules-of-thumb are 100-percent bad. They’re just worth thinking about to make sure that they really do make sense for your personal situation and goals. For example, Higdon questions the wisdom of the 10-percent rule — he’s not saying that you should never increase your mileage by 10 percent; he’s just saying that sometimes it might make sense to increase it by more, sometimes by less, so you shouldn’t follow the rule blindly.

Sidney Crosby, chiropractic neurology, and the limits of evidence

November 23rd, 2011

The good news: Sidney Crosby is back from the concussions that kept him on the bench for more than 10 months, and he had two goals and two assists in his return against the Islanders last night. But one downside, a reader pointed out to me in an e-mail, is that Crosby’s return may give added credibility to “chiropractic neurology,” the alternative therapeutic approach that Crosby turned to during his rehab. What exactly is this? I don’t know — and I’m not alone:

It’s a field that’s unfamiliar to many traditional doctors, including Randall Benson, a neurologist at Wayne State in Detroit who has studied several ex-NFL players. Says Benson, “It’s very difficult to evaluate what kind of training, expertise or knowledge a chiropractic neurologist has since I have never heard of [the discipline].”

That’s a quote from David Epstein and Michael Farber’s excellent look at Crosby’s rehab from Sports Illustrated in October. A couple of other interesting quotes:

In 1998, at Parker University, a Dallas chiropractic college, Carrick [the chiropractic neurologist who Crosby worked with] worked on Lucinda Harman before 300 students. Two car accidents and a neurotoxic bite from a brown widow spider had left Harman, herself a Ph.D. in experimental psychology, wheelchair-bound and with headaches, during which she saw spots.”[Carrick] asked if they were red and yellow,” she says. “I said, ‘No, they’re green, blue and purple.’ ” Carrick informed the audience that this meant her brain was being drastically deprived of oxygen and that, without treatment, she had six months to live. Harman, now 59, says simply, “Miracle.” But Randall Benson says that “there’s nothing out in peer-reviewed literature supporting” an association between the color of spots a patient sees during a headache and the severity of the oxygen deprivation in the brain.

[...]

Carrick, who has had a handful of studies that have appeared in scientific journals, has never published data on vestibular concussions. “We don’t have enough time to publish studies,” he says, “but we’re doing a large one at Life [University] right now.”

It’s a great piece — fair but rigorous. In some ways, though, the most important quote may be the kicker:

“I don’t think this is a case of trying to do something wacky,” Crosby says. “When someone came along and invented the airplane, people must have thought they were out of their mind. Who thinks he can fly? I’m sure people thought that person might have been stretching it a bit… . At the end of the day, as long as the person getting the care is comfortable, I think that’s what’s important.

Much as my evidence-based personality protests, I do think there’s some truth to that. Especially in cases like this, where — as with so many health conditions — there isn’t a well-established “standard-of-care” treatment. It’s totally different from, say, Steve Jobs choosing “alternative” forms of cancer treatment instead of surgery. In that case, the potential benefits of the surgery are well-known and well-understood. But many people face health conditions where the verdict of the Cochrane review is basically “there is insufficient evidence to conclude that ANY interventions do any good.” In that case, it’s hard to argue against trying other, unproven approaches rather than simply doing nothing.

Of course, sports medicine is a little different — it’s not life-or-death. For pro athletes, the incentive to try anything and everything in order to return to play (and earn money during their brief career window) is enormous. If I were Tiger Woods or Terrell Owens, I would have tried platelet-rich plasma to speed tendon healing too, despite the lack of evidence that it actually works. The problem is that the use of these therapies by sports stars gives the general public the impression that they’re proven, established treatments — hence the huge surge in PRP over the last few years. Will the same thing happen with chiropractic neurology? I hope not. But on the other hand, if someone who’s been in two car accidents and been bitten by a neurotoxic spider is in pain and hasn’t been able to get relief from conventional treatment, I’d have a hard time criticizing them if they decided to give it a try.

After New York: how did marathoners get so fast?

November 7th, 2011

Another major marathon, another jaw-dropping course record — pretty much what we’ve come to expect in 2011. Geoffrey Mutai’s 2:05:06 at yesterday’s New York Marathon, a course record by 2:37, continues the string of unbelievable performances from Boston, London, Berlin, Frankfurt and so on that have redefined our (or at least my) perceptions about what’s humanly possible at this distance. For a great post-race look at what’s going with the marathon, check out David Epstein’s piece at Sports Illustrated (and for more background, read Ross Tucker’s Science of Sport piece from last week).

Epstein gives a nice overview of the various forces that are converging to give us all these 2:03 marathoners — most obviously money (more of it in marathons, less of it on the track), which is bringing talented runners to 42.2K earlier in their careers. But I just wanted to highlight two quotes from his piece. First:

“I think people are starting to figure out the training and physiology better,” said American Dathan Ritzenhein, who made his marathon debut in New York in 2006 at the age of 23 and finished ninth in the Olympic marathon in ’08.

And second (on the topic of whether all these runners moving to the marathon at a young age will end up having shorter careers than guys like Geb and Tergat, because of the inevitable physical toll of the distance):

Krista Austin, a physiologist who works with pro runners, thinks that this generation of young Kenyan marathoners will have a shot at long careers because “the Kenyans are just starting to do some of the basic [injury prevention] things, like stretching and massage and Pilates.”

The juxtaposition of these two quotes made me smile a bit. One on hand, Ritz saying that marathoners are getting faster in part because of greater understanding of physiology. On the other hand, Austin is correctly pointing out that the runners who are most obviously the fastest (the 20 fastest male marathoners of 2011 are ALL KENYAN) are barely taking advantage of even the most rudimentary suggestions of sports science. If we’re judging by results, we might want to think carefully about which approach we emulate!

Obviously it’s a very complex issue, and I won’t even get into the whole genes/environment question. But in addition to money, I think Epstein (citing Gabriele Nicola, the Italian coach of several of the top Kenyans) nails a vital point:

If one person can run fast, well, dammit, you can train or race with them, and you can, too. As much as we might say this is “in your head,” if it’s in your head, it’s in your body, at least within limits.

 

Yoga vs. stretching for lower back pain

October 31st, 2011

I tend to post a lot about studies that find no benefits from traditional static stretching. Does that mean stretching has no benefits? No — it just means that the benefits are hard to quantify. So to be fair and balanced, I figured I should mention this recent study from the Archives of Internal Medicine, which suggests that stretching may be helpful for lower back pain (press releases here and here).

The study was actually designed to test whether yoga helps back pain. They compared a 12-week yoga program to 12 weeks of stretching (chosen to have a similar level of physical exertion), or 12 weeks reading a self-care book. Both yoga and stretching were better than reading the book at improving pain and function; there were no differences between yoga and stretching.

Now, I can’t help pointing out that the study isn’t immune to placebo effects. The assessments of pain and function were done with telephone interviews, and relied on subjective reports from the patients. And let’s be honest: the suckers who were randomized into the “self-care book” group knew darn well that they got the short end of the stick! So I don’t view this as strong evidence of a mechanistic relationship between stretching and back pain (i.e. that the back pain is caused by tightness in some specific muscle, and stretching releases the pressure to eliminate the pain). But that’s kind of beside the point. The stretching made people feel better — and for a very simple, low-cost, low-risk, uninvasive intervention (unlike, say, surgery), that’s a good enough outcome.

Stretching doesn’t prevent or reduce muscle soreness

October 18th, 2011

[UPDATE: Welcome Reddit Running and Running Times folks! In answer to the question on the Running Times homepage, 11 of the 12 studies in this review used static stretching, while one used PNF stretching.]

The British Journal of Sports Medicine just published an analysis of the most recent Cochrane Review on stretching to prevent or reduce muscle soreness. The title says is all: “Stretching before or after exercise does not reduce delayed-onset muscle soreness.” This isn’t a surprise — while the exact mechanism that leads to DOMS is still up for debate, it’s pretty clear that it involves microscopic damage to muscle fibres and the subsequent repair process. Once those muscle fibres are damaged, no amount of post-exercise stretching can magically undamage them!

The analysis incorporated 12 studies, including one very large randomized trial with 2,377 participants. There was no difference between pre-exercise and post-exercise stretching in the effect on soreness. Of the 12 studies, 11 used static stretching and one used PNF stretching. Here’s a forest plot of some of the results, from the BJSM summary:

As the Cochrane Review notes, people generally stretch for one of three reasons:

  1. reduce the risk of injury;
  2. enhance athletic performance;
  3. reduce soreness after exercise.

There’s plenty of evidence that the second point is misguided: stretching actually seems to harm athletic performance in many contexts. Now this Cochrane Review reaffirms that the third point is misguided too — and the BJSM reviewers make it clear that, in their opinion, this isn’t one of those tentative findings that might be modified by future research:

The best available evidence indicates that stretching does not reduce muscle soreness. These findings were consistent across settings (laboratory vs field studies), types and intensity of stretching, populations (athletic or untrained adults of both genders) and study quality. As such, they are unlikely to be changed by further studies.

That leaves the first point — reducing injury. There’s still a little wiggle room here. Numerous studies have failed to find any reduction in injuries following stretching, but it’s certainly a complicated topic. In particular, I’m open to the possibility that individually tailored stretching targeted at specific areas of weakness, inflexibility or imbalance could help people avoid or treat certain injuries.

 

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.

Tendon length, joint flexibility and running economy

July 22nd, 2011

We already know that pre-exercise stretching makes you less efficient at running and cycling. But is it the stretching that’s bad (e.g. by temporarily interfering with the signals from your brain to your muscles), or is flexibility itself a potential problem? For running (though not cycling), your legs function like springs, storing energy with each stride then releasing it in the next stride. If you’re too flexible, the thinking goes, those floppy springs will be less efficient at storing energy.

A new study from the University of Alabama at Birmingham in next month’s issue of Medicine & Science in Sports & Exercise takes a look at this question. They took 21 male recreational runners and measured a bunch of physical traits, then measured their running economy to look for correlations. The key traits they measured were tendon length (Achilles, patellar and quadriceps) and joint flexibility (knee and ankle). They expected that longer tendons would be a good thing: they can store more elastic energy simply because they’re longer. On the other hand, they expected greater joint flexibility to be a bad thing (as far as running economy goes). And that’s exactly what they found:

In conclusion, lower limb tendon length, especially Achilles tendon length, is associated with improved running economy in male recreational distance runners. In addition, plantar flexion and knee extension flexibility are negatively related to running economy.

I don’t think the finding about longer tendons being more efficient means that we should aim to do lots of stretching (after workouts, perhaps) to lengthen tendons. Instead, I think that’s likely just something that’s genetic: some people (including a lot of Kenyans, it seems) have long, thin tendons, and they’re more likely to be efficient runners. But I’m not sure if that’s the correct conclusion. We don’t know whether a couple of years of dedicated stretching to lengthen tendons would have increased or decreased economy, and this study has nothing to say about the question. One problem is that stretching to lengthen tendons will also increased plantar flexion and knee extension, which hurt running economy — so it may be a case of one step forward, two steps back.

I’d also like to point out the contrast between these results and the cycling study I blogged about last month. The two studies seem to point to completely different mechanisms by which stretching could impact endurance performance. This study suggests that stiff musculo-tendon complexes are good for storing energy; the cycling study (which doesn’t involve this stored-energy effect) suggests that stretching does something to the muscle fibres or neuromuscular signalling. So it’s not a simple picture.

Finally, we should bear in mind that running (or cycling) economy isn’t the whole picture. Many athletes — particularly recreational ones — would happily accept a 0.5% decline in economy if it reduced their chances of injury by 50%. I personally don’t think that the evidence for stretching and injury prevention is convincing, but it’s important to remember that we’re balancing different desired outcomes in making training decisions.

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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Arthur Lydiard recording

May 20th, 2011

Bit of an obscure find for distance running fans out there: a three-hour recording of a speech by Arthur Lydiard in 1963 at San Jose State University, with Peter Snell and Murray Halberg throwing in their two cents and answering questions. This was three years after Snell, Halberg and marathoner Barry Magee took gold at the Rome Olympics, and the year before Snell took double gold in Tokyo. It’s on sale at BudWinter.com — Winter was the coach at San Jose State from 1941 to 1970, and he’s the one who hosted the talk and introduces Lydiard.

I’d never actually heard Lydiard speaking; it’s pretty funny in places. For example, Peter Snell’s first 22-mile run with the group:

[With 2.5 miles to go], he started crying like a kid, tears running down his face. And no one would help him. We said, ‘Look, you’ve only got a little way to go, just keep plodding’… He lay on the bed and he sobbed for half an hour like a kid. Now we’re not very sympathetic. We said, ‘Look, Snell, in two weeks’ time you’re going around there again.’

And his thoughts on stretching and other conditioning drills:

I don’t think Halberg or Snell or any of those guys could touch their toes. I honestly don’t. It’s not because I don’t believe in exercises, loosening and stretching. It’s solely because we haven’t got time to do it. And I don’t think it would make them run any faster anyway.

Anyway, a fun little piece of history for any Lydiard fans out there!