Barefoot vs shoes, a running commentary

Barefoot running has many passionate adherents, but there is very little in the way of experimental evidence to show whether it’s good or bad. Most of the reasoning seems to be theoretical or laboratory-based, with the predicted benefits perhaps having more to do with how you run than what you wear or don’t wear on your feet.

Despite millenia of bipedalism, running really only took off as a major human pastime in the 1970s. But as forms of exercise go, it’s pretty appealing: it doesn’t require much in the way of fancy equipment or facilities to get started, there are plenty of events like fun runs for training motivation, and it feels natural, due to the aforementioned bipedalism.

But of course, once people started running a lot, they started getting running injuries. The most likely explanation for this was the stress of the foot striking the pavement, so shoe manufacturers started adding cushioning, mostly beneath the heel. This led to an arms race of fat-sole technology, perhaps reaching its peak with the very 90s, air-filled Reebok Pumps.

Paradoxically, this same goal of reducing impact stress is the reason some runners have turned to wearing thinner, minimalist soles, with next to no cushioning, or even running completely barefoot. You can even buy special-purpose, oxymoronic ‘barefoot running shoes’ – even though that sounds the same as selling pants to nudists.

Biomechanical studies, where they look at how people’s bones and muscles move, show that the biggest impact is when the heel strikes the ground. But when people run with bare feet, they tend hit the ground more with the front of the foot, so the impact is much more spread out, and so you shouldn’t actually need the cushioning (see Lieberman DE, Venkadesan M, Werbel WA, Daoud AI, D’Andrea S, Davis IS, Mang’eni RO & Pitsiladis Y 2010, “Foot strike patterns and collision forces in habitually barefoot versus shod runners”, Nature 463, pp. 531-5, doi:10.1038/nature08723 [PDF 346 KB]).

Graph of reaction forces from running under three different conditions: barefoot, running heel-to-toe; wearing shoes, running heel-to-toe; and barefoot, running toe-heel-toe. Both barefoot and shod, there is a sharper peak when the heel strikes the ground first (click to embiggen)
Comparison of reaction forces for the same runner under three different conditions: (a) barefoot, running heel-to-toe, (b) wearing shoes, running heel-to-toe, and (c) barefoot, running toe-heel-toe. Both barefoot and shod, there is a sharper peak when the heel strikes the ground first (image by Liebermann et al.)

This all sounds logical, and there are a lot of laboratory studies comparing the way people run shod and un-shod – even testing the energy efficiency – but there haven’t been any clinical trials to compare actual injury rates. As the article cited above states, “If impact transient forces contribute to some forms of injury, then this style of running (shod or barefoot) might have some benefits, but that hypothesis remains to be tested” (emphasis mine).

This uncertainty of course means that critics can respond and say no, it’s not a good idea. After all, for decades people have been trying to make shoes with bigger and better cushioning to reduce the danger, so there’s a lot invested in it; even if it’s been shown to be possible to sell shoes to barefoot runners, the notion that older shoes might have actually contributed to injury is still a worry.

But there have also been anecdotal claims and published case studies of barefoot running being associated with stress and possibly fractures of the metatarsals. These are 5 long bones in the middle of the foot that lead to the toes, and which bear most of the strain in barefoot running (see Giuliani J, Masini B, Alitz C & Owens BD 2011, “Barefoot-simulating footwear associated with metatarsal stress injury in 2 runners”, Orthopedics, vol. 34, no. 7, e320-e323, DOI: 10.3928/01477447-20110526-25).

Again though, metatarsal fractures afflict runners with shoes as well, and no one has shown that the injury rates are higher for bare feet. In fact, there isn’t good clinical evidence that wearing running shoes helps at all.

Turning, as usual, to the good old Cochrane Library, there’s only one relevant review which concludes that “running shoes prescribed to suit individual foot shape are better than standard running shoes for preventing injuries” (Yeung SS, Yeung EW & Gillespie LD, “Interventions for preventing lower limb soft-tissue running injuries” Cochrane Database of Systematic Reviews 2011, Issue 7. Art. No.: CD001256. DOI: 10.1002/14651858.CD001256.pub2).

Considering that customising shoe selection is a common selling point at sporting goods stores, the evidence base for this practice is pretty thin. But that’s as far as the research goes, with no relevant studies on the rate of injuries for shoes versus no shoes.

Until there is such research, what can a runner do in the meantime? Well, you could just do what you want. If you like your old running shoes, there’s no hard proof that wearing them causes injuries.

Or, if the barefoot running theory appeals, then there’s no reason not to try it, apart from the postulated risk of metatarsal injuries. The most popular recommendation for minimising that concern is to ease into barefoot running, based largely around Wolff’s Law, which states that bones gradually adapt to increased load (although the Cochrane review cited above showed it makes no difference to soft-tissue injuries).

But perhaps the last word should go to Giuliani et al. from the Keller Army Hospital at West Point NY, who published the case studies of metatarsal injuries. They proposed that “the alteration from a cushioned-heel shoe to barefoot-simulating footwear without specific gait training may have contributed to their injuries”. After all, it’s the change to your gait that is the main rationale for the barefoot approach, but that front-foot step is achievable in normal, cushioned running shoes too.

So possibly, it’s more about how you run than what you wear or don’t wear on your feet.

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