A spring in your step

Humans have been running for as long as we’ve figured out how. We’ve gotten very good at it, too – we can run long distances (but don’t tell that to the poor guy who ran the first marathon and then some) and it’s been possible for people to run four-minute miles since 1954. Before we get on with the science, can we just agree that running on concrete is terrible? Yes, it’s a hard surface, and it well better be if we’re going to be running on it, but it doesn’t care how much impact you have on it. Your shoes won’t make a mark running in the concrete jungle (man, that was deep).

640px-dreidimensionales_modell_der_anatomie_eines_menschlichen_fusses_im_schuh
(credit: Wikimedia Commons, CC-BY-30, author/user: Mattes)

Our feet are really just sophisticated suspension springs like the ones in a car – they help your car bounce and absorb the bumps and jumps of your daily drive (and if you live in any of these places, you know it all too well). Your feet, particularly your arches, do one heck of a job absorbing the shock of walking and keeping your feet springy. All this harping on about arch support came about for a reason.Thanks to important developments in running shoe technology, we can run faster and longer without putting our knees and arches through too extreme a punishment, and some people can do stuff like this. However, there’s been a battle raging between adherents of running shoes and barefoot/minimalist shoes. Do shoes really mess around with our springs? That’s what this study was trying to address.

From what I can see, a lot of the debate between running with shoes and barefoot comes down to encouraging proper running form, the big one being heel-striking (land on your heel) vs. toe-striking (land on the balls of your feet). There’s a lot of advocacy that barefoot is better because it encourages proper form and that shoes impede your feet’s ability to act as springs, but there’s no hard evidence that it does. I think the barefoot argument may come mostly from psychology: shoes are meant to protect your feet from the nastiness that comes from running on hard surfaces. The trouble is that all that protection may make you more reckless, therefore causing more harm than good. That seems to be the logic behind the safety debate in American Football: you’re more protected, so you can hit harder or wade into hits instead of evading. The authors reason that the protection doesn’t give you a lot of feedback on how much discomfort you’re in, how jarring the impacts are, or really what the heck your feet are even doing.

So we’ve covered the brain angle. What about the feet?

They picked some volunteers with similar height and weight (good science is based on consistency) and they would run on a treadmill with and without shoes. They used motion-capture data to see if their running even looks different. At the same time, they also measured things like impact and muscle activation by using electrodes, some of which actually went in the muscles. And I complain when I get a rock in my shoe. I’m pretty sure the research is out there that keeps the pain at a minimum (who would volunteer for an insanely painful experiment?), but I’m not going to look that up. My lower legs are too busy cringing. Anyway, they also looked at their running styles; none of them seemed to be toe-strikers, so at least the volunteers were consistent.

So what happened? First of all, shoe runners tend to have significantly longer stride times and ground contact, but it’s only 0.03 seconds difference. I’ve already talked about how much weight we may need to put into how significant differences can be. Based on other findings (less loading, less pushing-off force), you get the feeling that the shoe runners may be taking it easy. They also tend to land differently: shoe wearers tend to bend their feet upwards (dorsiflexion) while the barefoot runners tend to bend their feet downwards (plantar flexion). It’s almost as if the shoe wearers had less problems with heel-striking, but we’re not mind-readers.

Dorsiplantar.jpg
(source: Wikimedia Commons, CC-BY-30, author: Connexions)

Some muscles (not going to go into which ones specifically) were activated when wearing shoes, but the soles of the feet went through less compression or recoil at the same time. Essentially, the shoes seem to add to the ‘springiness’ (I don’t seem to see a spell-check warning, so this is a word?) of the foot, mostly since it supports the arch, which does a lot of the springing. However, if anything, it’s messing around with the runners’ form.

So, shoes or no shoes? You really should ask a podiatrist and maybe a trainer about this – that’s beyond my scope. But, since according to the article’s sources injuries are still the same despite all the tech, in my opinion, maybe we need to just run better. We don’t need to run long distances to deliver news of our victories in battle (@KingOfAthens #winning), but quite a few people are running a lot, so it’s serious. If you’ve got bad form, even these won’t save you.

Featured article: Kelly LA, Lichtwark GA, Farris DJ, Cresswell A. (2016) Shoes alter the spring-like function of the human foot during running. J. Royal Soc. Interface 13. 10.1098/rsif.2016.0174

Featured image credit: Wikimedia Commons (CC-BY-40, author: Smcmurtrey)

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4 Comments

  1. I definitely run with shoes but wouldn’t you think that our muscles in our feet wouldn’t be used as much as if we are bare. Especially as we progress through life and our bodies adapting to our fast paced lifestyles. Food for thought.

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