Tag: stretching

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As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

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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.

 

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

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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.

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

***

Last year I blogged about some cool findings from the University of Cape Town on a gene called COL5A1, a certain variant of which seems to predispose people to be (a) inflexible and (b) efficient distance runners. That initial study looked at participants in the South African Ironman triathlon; the same research group now has a new study in press at the International Journal of Sports Physiology and Performance looking at 72 runners in the 56km Two Oceans ultra-marathon.

The results confirm the previous findings: runners with the “TT” variant of the COL5A1 genotype ran faster (5:41 versus 6:05 on average), and that group was also overrepresented in the “fast and inflexible” quadrant of subjects. The genotype accounted for about 7% of performance variance.

It’s worth emphasizing that the effect of this gene is still quite small overall — there are so many genes that affect performance that any one gene is unlikely to have a large effect. As the paper puts it:

[T]he magnitude of the effect of the COL5A1 gene on endurance running performance was calculated as being “moderate” in this study. Due to the polygenic nature of the endurance phenotype3, it is highly unlikely that a single gene would have any greater magnitude of effect.

There are plenty of other questions that remain to be answered — for instance, does this genotype allow you to directly run faster, or does it (for example) make you more injury resistant so that you can train more? This study apparently represents just one part of a larger cohort being studied, so perhaps there will be further insights before long.

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

***

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.