Jockology: running surfaces and injuries

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)

***

This week’s Jockology column tackles the longstanding question of how different running surfaces affect your risk of injury. The science here is a lot less clear than you might expect.

The question

Will running on hard surfaces like asphalt and concrete increase my risk of injury?

The answer

In a study to be published later this year, Brazilian researchers found that your feet feel about 12 per cent more pressure with each foot strike when running on asphalt compared to grass.
Thanks for that newsflash, Captain Obvious, you might say.
But the findings actually contradict several earlier studies, which – despite what our intuition tells us – have found that we seem to automatically adapt our running stride so that hard and soft surfaces administer roughly the same shock to the body.
In fact, it may be the smoothness of paved surfaces that makes them dangerous to runners, rather than their hardness. And softer, less even surfaces carry their own injury risks, so the best answer may lie somewhere in the middle. [read more…]

(And a random shout-out to Dan Peterson at the Sports Are 80 Percent Mental blog — I think he was the one who introduced me to the prodigious research output of Captain Obvious, though I can’t seem to find the post I’m thinking of anymore!)

Pay no attention to your form: how to improve running economy

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)

***

There’s a very interesting article in the current issue of the Journal of Sports Sciences about how your mental focus affects running economy (which is basically the amount of oxygen you use to run at given speed, something that we can’t control consciously). In brief, German researchers had a group of subjects run while focusing either on internal cues (their running form or their breathing) or external cues (a video clip of running through the streets). The running economy was significantly better when the subjects were focusing externally rather than internally, with breathing taking bottom spot.

This result fits in with a large body of research on motor control. The theory is that we have to pay careful attention when we’re learning complex tasks, but they eventually become part of the “procedural knowledge” that we execute automatically. Trying to pay specific attention to one part of a complex action disrupts this automated movement.

For example, Beilock et al. (2002) studied this effect on the motor skills of golf putting and dribbling with a soccer ball. In both sports, they found that for experienced players an internal focus of attention led to a deterioration of performance on behavioural measures (higher number of strokes per hole in golf and slower completion of a dribbling course in soccer).

There are other studies in sports ranging from hockey to dart-throwing. (In the latter case, in addition to differences in accuracy, “heart rate dropped just before the throw in the external condition, whereas it rose in the internal one.”) The basic gist is that thinking too hard about what you’re about to do messes things up.

In endurance running, though, it’s not obvious this would apply. In fact, there’s a fairly long literature arguing that “association” (paying attention to your body’s cues) leads to faster running than “dissociation” (thinking about the weather and last night’s episode of House). The authors of this paper cite a bunch of conflicting papers, making it clear that the topic is an open question right now. One of the tricky things about running studies is that measuring success by how far or fast the subjects run gets skewed by their motivation levels. That’s why they chose to use running economy as the outcome — it’s outside the conscious control of the runners.

For the record, the study used 24 trained runners with a mean 10K best of 36:27 and had them run at 75% of VO2max, a typical brisk training run. The external focus proved to be best in this case, but that may not apply, the authors point out, in racing a marathon or other contexts.

One final note: one of the pieces of advice beginning runners are often given is “pay attention to your breathing.” In this study, those who paid attention to their breathing for some reason slowed down their average breathing rate by almost 20 percent, taking deeper breaths and hurting their running economy.

The results for the breathing condition lead to the assumption that breathing, which is a highly automated process, will adjust most efficiently to the needs of the body when it is not subjected to conscious control.

In other words, you take care of the running, and your subconscious will make sure your muscles get enough oxygen.

The science of cool-downs after exercise

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)

***

The cool-down is another one of those well-established exercise habits, like stretching, that most people swear by without really wondering about the underlying science. And for good reason: it turns out there isn’t really much science there, according to a recent article by Gina Kolata in the New York Times.

Exercise researchers say there is only one agreed-on fact about the possible risk of suddenly stopping intense exercise. When you exercise hard, the blood vessels in your legs are expanded to send more blood to your legs and feet. And your heart is pumping fast. If you suddenly stop, your heart slows down, your blood is pooled in your legs and feet, and you can feel dizzy, even pass out.

So that suggests that, at the very least, you should keep moving, if only at a walk, for a few minutes after vigorous exercise. But there’s no evidence to support the idea that a cool-down will reduce stiffness or muscle soreness the next day, let alone “flush out lactic acid.”

Of course, this may simply be because scientists have yet to do rigorous research into the cool-down. (Kolata does mention a couple of studies that failed to find any benefits.) Based of their personal experiences, many people are firmly convinced that they feel better if they warm down, science or not. And, unlike stretching, there’s no significant evidence that cooling down actually hurts you, so you might as well stick with whatever makes you feel good!

Pump your arms to speed up your legs, thanks to “neural coupling”

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)

***

“Keep pumping your arms!” That’s one of those canonical pieces of advice that it seems every coach gives to his or her runners. The idea is that, late in a run or race when your legs are burning and you’re starting to slow down, if you keep moving arms briskly, your legs will follow. It’s a nice idea — it’s always good to have some concrete piece of advice that you can hang onto when it seems like the world is about to explode. But does it work?

Unfortunately, I don’t know. But in the course of researching a completely different topic today, I stumbled on an interesting piece of research by Daniel Ferris, a University of Michigan researcher who’s best known for his research into assisted movement using robotic exoskeletons. The paper, which appeared in the journal Exercise and Sport Science Reviews back in 2006, is called “Moving the arms to activate the legs.” The full text is available here.

Ferris’s main focus in the paper is on rehabilitation for patients with spinal cord injuries, helping them learn to walk again. The gist is as follows:

Humans have neural connections between their upper limbs and lower limbs that coordinate muscle activation patterns during locomotor tasks… Recent studies indicate that arm swing may also facilitate lower limb muscle activation via neural coupling. Clinical observations of individuals with spinal cord injury first suggested that rhythmic upper limb movement improved lower limb muscle recruitment during stepping. More recently, studies on neurologically intact subjects have demonstrated an increase in lower limb muscle activation that is proportional to upper limb muscle recruitment during seated recumbent stepping.

The “seated recumbent stepping” he mentions above is a neat set-up. Basically, you sit back in a contraption that you can power with either your arms, your legs, or both. With some careful experiments, Ferris and his colleagues were able to show that when the subjects moved their arms back and forth (opposite to leg motion, as in walking and running), they were able to achieve greater muscle recruitment in their legs. Now, you might assume this is just because it’s easier to get good leverage with your leg if your opposite arm is also moving, but they tried various set-ups with the torso partly or fully strapped to the seat (so you couldn’t twist the torso to get a better angle), and the same results were observed.

The link from this to “Pump your arms when you approach the finish, and your legs will move faster” is still pretty weak. But this idea of “neural coupling” is interesting — so I guess I’ll pump my arms with renewed vigour next time I’m starting to tie up.

Jockology: “active rehab” for pulls and sprains

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)

***

The latest Jockology column appears in today’s Globe, dealing with the question of when “RICE” (rest, ice, compression, elevation) should turn into “MICE” (movement, ice, compression, elevation). It’s a tricky one, because there’s such a wide range of possible muscle pulls, sprains and tears that it’s difficult to give general advice. But the overall theme is that if you keep protecting and favouring a weak point for too long, you can end up harming the healing process.

The question

Ouch, I think I sprained something. How long should I stay off it?

The answer

Canadian figure skater Anabelle Langlois returned to action last month, earning a bronze medal with partner Cody Hay at a tournament in Germany one year after fracturing her fibula in a training accident. With Olympic dreams on the line, Ms. Langlois’s doctors had pursued every possible avenue in her rehabilitation, including two operations.

One thing they didn’t recommend, though, was a long period of complete rest for the injured leg. [read on…]