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

October 19th, 2009

“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.

  1. October 19th, 2009 at 16:26 | #1

    Continue to love all your research discoveries Alex. I assume these tidbits that apply to running apply to walking..but maybe there is research out there that proves otherwise.

  2. alex
    October 19th, 2009 at 19:45 | #2

    Thanks for the comment, Lee. In this case, the study definitely applies to walking as much as running — in fact, the original paper was more focused on walking (and helping people recover the ability to walk) than running. I’ll try to remember to include both walking and running in the future!

  3. selam
    October 30th, 2009 at 03:34 | #3

    I know that I recently learned in my Motor Systems Control class that the Singulate Motor Area is involved in bilateral coordination of the limbs. This is the area that helps you to link the motion of your arms and legs. There is definitely a link between using the arms and legs. But these areas are all programming areas, they themselves don’t actually drive the action themself. The central pattern generators are actually in the Lumbar part of the spinal cord (the things that actually drive walking & running). But tt’s the Mesenphalic Locomotor Region in the midbrain that governs activation (and the speed of locomotion), so the more the MLR is activated the faster the gait.

    The question is does the MLR activate both concurrently, do the legs drive it and can the arms affect this activation… I know I what I think, but I’ll ask the prof what he thinks.

    (I think yes, but that’s more from experience than any hard evidence).

  4. alex
    October 30th, 2009 at 04:20 | #4

    Cool! Let us know what your prof thinks. Because you’re right — for now, we’re just speculating!

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