Barefoot and minimalist running: what is left of the injury claims

0:03 · The promise of barefoot running

In two thousand and nine, a best-selling book set off a movement away from cushioned running shoes. Run the way the body was built, the promise went, and you will get hurt less. Trials have since tested that promise, and none found that runners in thin shoes got hurt less. But something did change, at least in the lab, and later in this video you will see where the load went. This is barefoot and minimalist running: what is left of the injury claims. We follow five questions, and the first is whether thin shoes protect you. Then what changes when your foot lands, what the switch itself does, and whether you get any faster. And last, where the load goes.

0:39 · Do they protect you?

First, what counts as a minimalist shoe at all? A panel of forty two experts named five features. Low weight, a thin sole, little or no drop from heel to toe, flexibility, and no motion control. Each counts for twenty per cent on a scale from zero to a hundred. But the panel could not say where on that scale a shoe becomes minimalist. Running barefoot is something else again, and that matters, because the trials tested shoes, not bare feet. So did thin shoes protect anyone in the trials? A Cochrane review brought together five randomised trials with seven hundred and sixty six runners. They were followed for three to six and a half months. With minimalist shoes, two hundred and seventy three in a thousand got injured. With ordinary cushioned shoes, two hundred and ten. That is about twenty seven against twenty one in every hundred. The review concludes that the type of shoe may change the injury count little or not at all. There is a catch in that total. Two thirds of its weight comes from one trial in which the minimalist shoes were ordinary cushioned shoes with a lower drop. That trial found no difference in injuries. The trials of truly minimalist shoes are smaller. Over twelve weeks, runners in a neutral shoe had four injuries, and in a part minimalist shoe twelve. In a full minimalist toe shoe it was seven, by our own subtraction from that trial's total. Over twenty six weeks, sixteen of thirty one men in minimalist shoes got injured, against eleven of thirty in ordinary shoes. A gap of that size could be chance. A trial from twenty twenty six, too recent for the review, saw a few fewer injuries in minimalist shoes, also within chance. No trial showed that thin shoes protect. So why do so many barefoot runners say they get hurt less? Because surveys count the runners who stayed. A Brazilian survey asked over a thousand runners who had tried minimalist shoes. Thirty one per cent had stopped, most of them because of pain or discomfort. Those who stopped had no fewer injuries than runners who had never tried the shoes. Only the twenty eight per cent who stuck with them did, and the authors name survival bias as one possible reason. A one year study adds a second twist. Barefoot runners had fewer injuries per runner, but they also ran about ten miles a week less. Per mile, there was no difference. So the first answer is this: in the trials, thin shoes did not protect. Now to what happens when the foot lands.

3:04 · How do you land?

A paper in Nature measured, in six runners per group, how fast the force rises in the first instant of contact. Runners who normally wear shoes, landing on their heel without them, reached four hundred and sixty three body weights per second. In their shoes it was seventy. Habitual barefoot runners landing on the forefoot reached sixty five. That is about as soft as a heel strike in a cushioned shoe, not softer. A later study had twenty two heel strikers try each condition for the first time. Landing on the heel, the rate was eighty three in a standard shoe and a hundred and forty three in a minimal shoe. Barefoot, it was two hundred and fourteen. Barefoot on the forefoot it was ninety six, still above the standard shoe. So a barefoot heel strike is the hardest landing of all. Whether that jolt causes injuries is a separate question, and still an open one. But it raises the next one: does a thin shoe change how you land? For most runners, not by itself. Most runners land on their heel, about four in five in a road race. A trial split a hundred and forty heel strikers into three groups. One got minimalist shoes, one got coaching on how to land, and one kept its own shoes and did a stretching routine. After a year, fewer than half of the minimalist group landed on the forefoot, against almost eighty per cent of the coached group. In the first six weeks of the twenty six week trial, only two runners in minimalist shoes switched to the forefoot. Shorter, quicker steps are part of the barefoot style too. In recreational runners on a treadmill, raising the step rate by five per cent took about a fifth off the energy the knee absorbed. The ankle did not get off any lighter. So much for what changes at the landing. Three questions are left: what the switch does, whether you get faster, and where the force goes. The last one holds the clearest picture in this video. Then to the switch itself, the months of changing shoes.

4:57 · The switch

Here the studies went very different ways. In one small study, twelve of fourteen runners reported an injury, mostly calf and Achilles pain, after five to six weeks on average. None of them had kept to all the switching advice. In another, ten of nineteen showed swelling in a foot bone on a scan after ten weeks. Of those who stayed in their usual shoes, it was one of seventeen. Yet in twenty runners on a six month plan with foot and calf exercises, nobody got injured by the switch. Those runners also grew larger muscles in the foot and lower leg, though whether that prevents injuries has not been measured. Single studies pointed to heavier runners and to women, but neither has been confirmed in a second study. So the switch went from twelve of fourteen runners hurt to none of twenty. And do thin shoes make you any faster?

5:45 · Are you faster?

A little more economical, and partly that is just a lighter shoe. Each hundred grams of shoe costs about one per cent more oxygen. Two reviews that combined the economy studies found a small gain for minimalist over conventional shoes. Many of the runners in those studies were already used to thin shoes or bare feet. In fifteen such runners, a minimal shoe was still two to three per cent more economical after correcting for weight. For a heel striker who changes how they land, a review found no support for a gain. And economy is not the same thing as speed. Only one trial here timed runners: the first six weeks of the twenty six week trial. There, the minimalist group improved its five kilometre time slightly more, a difference only just beyond chance. So thin shoes are slightly more economical, partly because they weigh less. Several studies in this video had ties to shoe makers, through funding or donated shoes. That does not make any finding wrong, but it is a reason to read each next to the others. Now to where the force goes when the landing changes.

6:49 · Where does the load go?

A twenty twenty five study had twenty young men, not regular runners, run barefoot with three landings in turn. We turned its results into percentages ourselves, with the heel strike as the starting point. Per step, landing on the forefoot put twenty three per cent less load on the kneecap joint than a heel strike. It put thirty two per cent more on the Achilles tendon. And forty five per cent more on the plantar fascia, the band under the sole. In the lab, then, the load does not vanish but moves down the leg. Taking the shoe off pointed the same way in thirty male runners, in percentages we worked out ourselves. The peak force on the kneecap was twenty two per cent lower, and on the Achilles tendon twenty one per cent higher. Not every study agrees on that peak: in the twenty two heel strikers, the highest Achilles force did not change. What does recur is the total load on the Achilles per step, which came out higher with a forefoot landing. So do the injuries follow the load? Partly, and less cleanly than the lab suggests. In a one year study, runners in shoes had twenty one hip and knee injuries, barefoot runners five. For the lower leg it was the other way round, twenty seven barefoot against twelve in shoes. The authors did not test those differences. Plantar fasciitis, an injury of the sole, went against the story: three barefoot against eleven in shoes. The twenty six week trial saw more lower leg and foot injuries in minimalist shoes, but also slightly more knee pain. In the twenty twenty six trial, the coached group had fewer hip injuries than the control group. In some of the analyses it also had more foot injuries. One review concludes from the lab studies that changing how you land may expose runners to different injury mechanisms, rather than making one landing safer. So the load moves down the leg in the lab, but in the injury counts the picture is less clean.

8:39 · What this leaves you with

So, taking the cushioning away has not made running safer in any trial. What it does, at least in the lab, is move the load from the knee to the calf, the Achilles tendon and the foot. Every source and figure is on the page at enduranceproof dot com. Still to come on this channel: running economy, the number behind that small saving.