Are we there yet?
Should you run naked? Au naturale? Do barefoot runners get fewer injuries? Is heel-striking “eating you alive”?1 The first real science milestone in the story of natural running & running injury prevention (finally) arrived in 2016 … about 12 years since the fad began, when Lieberman and Bramble famously concluded that humans are “born to run” and (news flash!) did not evolve in running shoes. This gave some scientific justification for a popular new running style, and helped to inspire a new minimalist shoe industry with amazing profits — mostly based on a health claim.
So, does running barefoot, or in barely-there shoes, actually prevent injury? If you haven’t heard already, place your bets!
(And don’t misss the brilliant sequel, Shit Runners Say To Barefoot Runners 2:48)
Training quantity, not quality
There have been many faddish running styles and shoes that might, perhaps, maybe, help prevent or treat overuse injuries of the knee, legs, and feet — but no one really knows, and never has. The value of these things has always been based only on speculation.2 Basic questions, like whether running on pavement is actually a problem, remain unanswered.
I write a lot about repetitive strain injuries in runners — many articles, and four books, about iliotibial band syndrome, shin splints, plantar fasciitis, and patellofemoral syndrome — and for years I have mostly dismissed barefoot/ minimalist/natural running as a “fad,” the biggest one since the 70s. The nature of overuse injuries means that running biomechanics and technique can’t be anywhere near as important as the sheer amount of activity. Training volume and frequency probably move the needle more than any other factors by quite a bit. It’s unlikely that any running style or footwear can change the forces on your joints so much that it really matters very much one way or the other. If you’re doing so much running that you’re going to injure your legs or feet sooner or later, no biomechanical advantage is going to do any more than slightly delay your fate.
It might do that. It might matter, a little. Of course it might. And I realize that many badass distance runners are pushing the envelope and interested in the tiniest sliver of an edge, but there’s still a problem: tiny slivers of edges are super hard to prove. And even for regular folks, the benefit could be subtle. So I’ve been reserving judgement, saying wake me up when we’ve got some real data. For years, there was little else to say about barefoot running or any other running fad.
Things started to get interesting in 2012, but it wasn’t until 2016 we finally — more or less — got a clear answer about the effect of barefoot running on injury rates.
Dr. Lieberman’s 2012 paper: formal wishful thinking about barefoot running
Dr. Daniel Leiberman’s 2012 paper on injury rates, published in Medicine & Science in Sports & Exercise in 2012,3 reported “a 2.6-times greater chance of having a severe injury” from running in shoes than running barefoot or minimally shod. “It’s a huge difference,” he says. “As far as I know, it’s the biggest effect ever shown on running injury.”4
Large injury prevention effects in sports medicine are indeed virtually unheard of. If it is true, it’s a big deal, a huge deal. But is it true? Almost certainly not. The study had critical limitations. (Show of hands: who saw that coming? Everyone? Good.) By design, a study like this one cannot in principle actually demonstrate the cause of running injuries, let alone the “biggest effect ever.” Before I explain the problem, let’s review the story of barefoot running so far …
The Born To Run Timeline (with some key citations)
The first running fad was running itself: jogging boomed in the 1970s in the United States. About 25 million Americans started running regularly.
A new industry was born, and was soon pumping out “advanced” running shoes with many absurd features and claims, but above all the promise to protect runners from injuries. In spite of this, injury rates remained more or less stable,5 and there’s still no evidence that any popular running shoe design can prevent injury,6 and good reasons to suspect that they cannot — because there is no clear link in the first place between running injuries and the kinds of anatomical quirks (eg pronation) that these shoes supposedly control.7 The runners of the world (well, many of them) turned to the idea of getting rid of their shoes …
prehistory — Everyone was barefoot. For a long time.
1960 — Abebe Bikila ran barefoot to win the first of his several consecutive marathon gold medals.
1955–1967 — Bruce Tulloh broke European records, usually barefoot. Later, Tulloh ran 2,876 miles across America … but shod.
1999 — Invention of the first “barefoot” shoe. Designer Robert Fliri proposed minimalist shoes to Vibram CEO Tony Post, who became a true believer in “natural running,” convinced that it was a “solution to the knee pain and soreness he was experiencing when running.” Lieberman’s 2004 paper was important, but people were thinking about this before he was.
2004 — Bramble and Lieberman publish the paper in Nature that injected a huge dose of scientific credibility into natural running: “Endurance running and the evolution of Homo”.8 They famously concluded, “The fossil evidence of these features suggests that endurance running is a derived capability of the genus Homo, originating about 2 million years ago, and may have been instrumental in the evolution of the human body form.”
2005 — Vibram FiverFingers are unleashed on the world, soon after Bramble & Lieberman’s paper. Coincidental timing? Maybe. The product’s commercial success is notable and distinctly faddish — worth about a half million dollars back in 2006, and destined to get much higher still in the years after that.
2007 — Bramble and Lieberman elaborate on the “persistence hunting” idea in a follow-up paper for Sports Medicine, arguing that humans are not just good endurance runners, but fantastic ones, an unusual athletic superpower that evolved to “help meat-eating hominids compete with other carnivores.”9 Dr. Lieberman did a terrific interview about this for ABC Radio’s The Science Show.10
2009 — Christopher McDougall publishes a successful book, Born to Run.11 The book is an instant hit, the barefooting bible, but (naturally) it oversells the value of running naturally:12 there is still zero data on injury prevention.
2010 — Lieberman publishes again, but only to confirm that barefoot running involves less impact — no better than “circumstantial evidence” in a court room.13 It was probably quite misleading, as shown by studies many years later (see below). But it strongly fanned some flames of hope. At the time, it seemed like very promising corroboration of the basic idea — which was catnip for fans.
2011 — The natural running trend soars to new heights. FiveFingers sales hit about 200 million, and new products flood into a market now worth as much as $2 billion, “accounting for virtually all the growth in the $6 billion running market” (businessweek.com). With legions of true believers wearing silly shoes, mostly because of one book, parody is inevitable (e.g. Shit Barefoot Runners Say 2:17, or the tweet at the end of this section).
Spring 2012 — In a paper for Exercise & Sport Sciences Reviews, summarizing his ideas about barefoot running, Lieberman admirably and cleary concludes that “we simply do not yet know” if natural running prevents injuries. Nobody pays any attention to this.
Summer 2012 — Lieberman publishes the first almost kinda sorta direct evidence that natural running is more than just a beautiful idea: “habitually rearfoot strike have significantly higher rates of repetitive stress injury than those who mostly forefoot strike.” This is quoted everywhere, of course, and Lieberman himself (in Brains Plus Brawn for Edge.org) seems to have made up his own mind that barefoot running does indeed prevent injury, judging from how he ends that talk. But it’s not really the last word. It can’t be. It was the wrong kind of research — which I will explain below.
Spring 2014 — Vibram settles a class-action lawsuit, pays $3.75 million to customers, and removes all claims that their FiveFingers product “strengthens” or “reduces injury” until they can be proven. It’s good news, but companies will keep making premature health claims as long as the potential profits trump the risk of getting spanked for it (so, forever).
Spring 2014 — And then, finally, in early 2016, the British Journal of Sports Medicine published the first genuinely relevant evidence — the right kind of evidence — on injury rates.
So now what?
“Rough day. My cousin Tony was diagnosed with whatever the fuck it is that makes you wear those 5-toed rubber shoes.”
Rob Delaney, comedian
Perpertual controversy? (Or does it just feel endless?)
With the publication of Lieberman’s 2012 paper on injury rates, it seemed like natural running might be on the verge of an impressive vindication. Or maybe the data truly needed for vindication would fail to appear, in which case the fad deserves to fizzle? No, that won’t happen, because too many people have bought their minimalist shoes and “believe” in them. The topic is more likely to be stuck in the middle for a long time. In 2010, Alex Hutchinson of Sweat Science wrote:
I have a sinking feeling that this is just the beginning of the storm — we’re going to see a whole bunch of studies coming out, accompanied by press releases and news stories, that capitalize on this interest without really telling us what we want to know. Hopefully there are also people doing the long, painstaking, prospective research that would really shed new light on this question.
Was Lieberman’s 2012 paper “painstaking, prospective research”? No: it’s actually retrospective research, which has strictly limited power to answer the question. It is well-established that you can only learn so much in science by looking up bad things that have already happened and trying to match them up with characteristics in the present. There are just too many ways it can be misleading. Here’s a little research methods joke (there are so few!):
How many researchers does it take to change a light-bulb? None if it’s a retrospective study, because the light-bulb has already changed itself.
To nail a conclusion, you really have to do prospective research: you have to set up an experiment with conditions that are as ideal as possible, and ask very carefully designed questions about the results before you collect data. This is quite different than checking to see if the answer you want seems to exist in data previously collected for some other purpose. As a general rule, researchers can find almost anything they want to find in complex data, even when it’s not there at all, because it’s polluted with all kinds of confounding factors. This is the flaw baked into retrospective research that always limits its power, especially in smaller studies like this one, and especially when there’s a high risk of bias.
Randomized controlled trials, the gold standard of study design, are prospective studies. Only prospective RCTs can logically connect cause and effect. Was forefoot running really the cause of lower injury rates? Unknown! And indeed the abstract of the paper wisely declares that it “does not test the causal basis” for these results. Hurray for honest abstracts.
Common sense screams back: Of course it was the cause! What else? That big a difference? Come on! Gotta be! Emotionally, it’s an almost irresistible connection. And that is the connection Lieberman makes in “Brains Plus Brawn.”
Nevertheless, we should resist. But first, another digression.
What are elite runners doing?
Let’s take a break from the dry stuff and consider some pictures. Lots of pictures. What do scads of foot strike photos from 10k olympic trials say about barefoot running? This is smoking gun evidence … of exactly nothing. Briana Rognlin:14
The foot strikes, paired next to each athlete’s place and time in the trials, vary widely. But they all belong to elite athletes who, whether they made it to the Olympics or not, are amongst the world’s most talented runners. And yet, some clearly drive their heels into the ground, some land squarely on their forefoot, and others seem to practically land on their pinkie toes.
So that clears that up. Back to resisting the siren call of correlations.
2012-2016: Here be running science dragons
This period was one of those “moments” in science that separates the sober from the drunk-on-hope.
It is shockingly easy to be persuaded by the kind of graphs published by Lieberman in 2010, and then even more so by the appealing correlation he reported in 2012. Many alleged causal relationships in the history of science, just as “obvious” as this one or even more so, have turned out quite wrong. In fact, this is one of the most common ways in which science ends up looking indecisive to the public: because so much restrospective research misleads everyone (even scientists, sometimes especially scientists) to premature conclusions that have to be corrected. Awkward!
Retrospective research particularly suffers from “confounding factors” — unknown factors that may be the real explanation for the results. There are other possible reasons, quite a lot of them, why forefoot-striking Harvard runners might have lower injury rates. It is not necessarily running barefoot (or in barely-there running shoes) that did the trick. For instance:
Forefoot strikers may do other things differently as well. They may have adopted that running style out of an general zeal for injury prevention, and may therefore have other injury-reducing habits. Perhaps those runners are also twice as likely as their heel-striking peers to reduce loading when they detect early warning signs of injury — but the conditions of the experiment were not controlled, so we can’t know.
Almost nothing about this topic is as clear cut as anyone would hope.
The whole forefoot-versus-rearfoot thing is just astonishingly murky. For instance, rather incredibly, it’s not even safe to assume that higher impact is a risk factor for stress fractures.15 We literally cannot confirm that smashing the ground harder with your legs actually increases the risk of injuring them, and — this is really weird — it might even be exactly the other way around. It’s not clear.
Nor can you count on forefoot and rearoot striking to line up tidily with less and more impact — oddly enough, some runners manage to rearfoot strike rather lightly, and some forefoot strikers are surprisingly lead footed.16 And, from the same source, we learn that runners cannot even accurately report their own style: “lots of people are fooling themselves about how they’re running” (Hutchinson). (I find that last bit fascinating.)
Biomechanics expert Benno Nigg on forefoot running: “It increases some forces and decreases others, mainly shifting the load to different structures,” from his book Biomechanics of Sport Shoes, well-described by Amby Burfoot for RunnersWorld.com. (That’s a great little read, and an excellent companion to this rant.)
If you want to get picky and technical — and I really do — retrospective research is actually useless for doing anything except generating hypotheses.17
Short heels and big calves: another example of why “it depends”
Why does calf muscle size in humans vary so much? The bulkiness of the calf is an amplified sign of what kind of heel bone you have.
Anna Ahn, assistant professor of biology at Harvey Mudd College, showed that calf size is probably driven by how far the heel bone projects backwards.18 The calcaneus is the lever that the calf muscles pull on, via the Achilles tendon, to flex the ankle (point the toes). The shorter that bony lever, the more muscle is required to control it and the foot.
Elite sprinters, by the way, have heel lengths way higher than average for homo sapiens. A long foot lever is a speed booster!
Although Ahn’s paper didn’t get into this, I will: it’s reasonable to extrapolate from her results that these anatomical differences probably produce quite different injury risks, and mostly uncontrollable ones at that. That makes for a fine example of why it would be unwise to run around declaring that barefoot running is “better,” because it almost certainly depends on sneaky, idiosyncratic biomechanical variables like this.
Barefoot running is bouncier and probably relieves some impact stresses for some people, but it also relies much more heavily on the strength and elasticity of the calf and Achilles tendon. That might well work well — i.e. less risk of Achilles tendinitis,19 perhaps — for people with longer heels and better leverage on their feet. Or … perhaps it works better for the folks with the stronger calves that they’ve developed because of their short heels? Only more research is going to answer that one, I think.
Meanwhile, you can see the danger of making any assumptions one way or the other.
Born to run? More like born to believe
Through most of the story so far, obviously no one can possibly have any real clue if we’re better off running paleo-style. Which is completely unsurprising, really.20 Certainly the folks selling minimalist shoes don’t actually know.21 Without good evidence of injury prevention, natural running and minimalist shoes are not much more than a fashion statement and a gamble, but that clearly isn’t stopping many people from buying it, literally and figuratively. Although humans may be born to run, we sure as hell aren’t born to reserve judgement. We love wishful thinking and wishful believing. In fact, just like endurance running, we’re freakishly good at it. That’s why Lieberman’s caution in 2012 was so noteworthy and admirable:
Barefoot running raises more questions about injury than we have answers at the moment … We simply do not yet know if experienced barefoot runners have fewer injuries than habitually shod runners.
That was an important statement: the “father” of the natural running fad, making one of the only cautious expert declarations about this ever made. (It was echoed by Rixe et al, practically at the same time.22)
And yet it was met with a huge round of indifference. Everyone should have paid attention — remember, it was the conclusion to a major summary of the topic! — but almost literally no one did. If you Google the exact quote, my own citations dominate a single page of results. Amby Burfoot, who is awesome, also blogged it (Peak Performance, Runner’s World). There are no other prominent references to the quote whatsoever: just Amby and me. Meanwhile, articles about the potential of natural running have been in many mainstream publications, and of course Dr. Lieberman’s new study is being shouted from the roof tops.
Lieberman’s (retrospective!) 2012 results are interesting, and at the time I admitted that they could be promising. But kept on reserving judgement and refused to “recommend” natural running to injured runners until the power of natural running to stop (or treat, a different thing) repetitive strain injuries is confirmed by prospective research.
Without that, it’s obviously un-guessable. And yet that’s exactly what everyone seems to be happy to do: guess guess guess.
Given the shifting scientific analysis, runners are left with impassioned testimonials and heated debates.
from a nice little summary of this issue on Metafilter.com
There are probably dozens of well-known running techniques and hundreds or even thousands of groovy products that have never been properly tested and would quite likely fail if they were. Somewhere in there, there’s probably stuff that helps, at least a little bit, but it is literally impossible to know without testing.
So I don’t waste a heck of a lot of energy on trying to figure out if these things work when I know that the only way that it possibly can be figured out is not going to happen. To conclude, more from Benno Nigg:
Nigg has noted that running injuries have not changed over the years despite the massive development of the running-shoe industry. Unlike others, he hasn’t jumped to the conclusion that shoes are bad, or that barefoot or minimalist-running or forefoot-striking is the answer. Instead, looking at the same data, Nigg concludes: Okay, apparently shoes aren’t a big part of the equation.
So get over it.
Finally! in 2016, injury rates in barefoot runners were studied the right way: prospectively
In 2016, Allison Altman and Irene Davis published the first prospective comparison of injury rates in shod versus barefoot running, in British Journal of Sports Medicine.23 And “prospective” is what we needed the whole time: following a bunch of initially uninjured runners of both types to see what happens to them. Only this kind of study is qualified to answer the question. It wasn’t a perfect test, but it was a lot better than anything else so far.
For this test, 200 experienced runners were studied over the course of a year. The results are clear and unsurprising: there was no important difference in injury rates, just the types of injuries. Each was better in some ways, worse in others. Although the paper emphasizes “fewer overall injuries” for barefoot runners, injury rates are what matters — the number of injuries per 1,000 kilometres, say — and they were “not statistically different between groups due to significantly less mileage run in the barefoot group.”
But there’s an important caveat: The barefoot runners put in just 24km/week, while runners in shoes ran 41km/week without an increase in injury rate. As Alex Hutchinson put it for Runner’s World, “The only way the comparison has any relevance is if they’re arguing that barefoot running reduces injuries by preventing you from running as much as you’d like.”
Naturally, a larger, longer study may have different results. But this is an excellent start, and we can now say with high confidence that barefoot running is not a panacea for running injuries — and more and better data will probably, if anything, be even more embarrassing for the natural running fad’s claims of injury prevention.
More evidence since …A decade after the hype really got rolling, science is still catching up with clarifying evidence. Examples:
Fuller et al24 — A small (61 runners) randomized controlled trial comparing running pain and injury rates in regular running shoes versus minimalist shoes. Despite a nice gradual adaptation period of 26 weeks, these experienced runners developed more pain and injuries in the minimalist shoes: 16 of them got injured, compared to 11 runners in the regular shoe group. “Runners should limit weekly training distance in minimalist shoes to avoid running-related pain.” The study isn’t big enough for firm conclusions, but it adds to the mounting evidence that running in minimalist shoes may actually cause more injuries, rather than preventing them.
Udofa et al25 — Lieberman’s famous 2010 study of heel-strike reaction forces is strongly challenged by this new paper. Lieberman’s “force curves” showed a damning spike at heel strike, which seemed to disappear with barefoot/forefoot running. But Udofa et al. demonstrate that the heel-strike spike doesn’t really “disappear” with barefoot running after all, and it’s not caused by which part of the foot hits the ground first: the spike is always there, but whether it is separated from the main curve is mostly just a function of speed and an artifact of measurement methodology. The paper is complex and technical and does not obviously lead to this conclusion, so I will direct you to Alex Hutchinson’s excellent explanation.
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About Paul Ingraham
I am a science writer in Vancouver, Canada. I was a Registered Massage Therapist for a decade and the assistant editor of ScienceBasedMedicine.org for several years. I’ve had many injuries as a runner and ultimate player, and I’ve been a chronic pain patient myself since 2015. Full bio. See you on Facebook or Twitter., or subscribe:
- Massage Therapy for Your Quads — Perfect Spot No. 8, another one for runners, the distal vastus lateralis of the quadriceps group
- Does Hip Strengthening Work for IT Band Syndrome? — The popular “weak hips” theory is itself weak
- Is Running on Pavement Risky? — Hard-surface running might be a risk factor for running injuries like patellofemoral pain, IT band syndrome, shin splints, and plantar fasciitis
- Ian Griffiths debunks four rusty links in the chain of reasoning from “shoe choice” to “injury prevention.” Choosing Running Shoes: The Evidence Behind the Recommendations.
- A rather good-but-hard article about how bacon maybe causes cancer, or maybe not., except that it’s really an article about causality and how absolutely essential it is to really know what causes what before you start doling out advice, changing behaviour, or (!) public policy. “The only form of reliable evidence for causality comes from randomised controlled trials,” and the randomisation part is “not just pedantry. It is essential if you want to get the right answer.” Using the infamous example of hormone replacement therapy (HRT), the article explains how even prospective research (cohort studies) can and have very conspicuously failed to establish causation. So this all really strongly emphasizes how retrospective research about running styles is just hopelessly unable to answer the dang question. (Oh, and bacon probably does not cause cancer.)
What’s new in this article?
2020 — A couple science updates and a little editing. I haven’t dipped into this topic in quite a while!
2017 — Science update: upgraded a couple citations about the injury-preventing powers of shoes (or lack thereof).
2017 — Minor update: editing and clarification of the introduction; added a citation strengthening the case against barefoot running.
2011 — Publication.
Starrett (2014). Ready to Run: Unlocking Your Potential to Run Naturally. Victory Belt Publishing. p. 60.
Kelly “Supple Leopard” Starrett writes: “If you’re heel striking when you run, you have to stop. It’s eating you alive.” That’s hyperbolic fear-mongering about exercising “wrong” — Starrett’s speciality.
- Goss DL, Gross MT. A review of mechanics and injury trends among various running styles. U.S. Army Medical Department journal. 2012:62–71. PubMed 22815167 ❐
Can any running style or shoe type prevent running injuries? This is one of those reviews of a virtually non-existent literature. The authors speculate, as many others have, that styles and shoes probably involve risk trade-offs: less risk of one kind of injury, but more of another. But mostly the paper inevitably confirms that, as of 2012, there really is no hard data about this.
- Daoud AI, Geissler GJ, Wang F, et al. Foot strike and injury rates in endurance runners: a retrospective study. Med Sci Sports Exerc. 2012 Jul;44(7):1325–34. PubMed 22217561 ❐
- That comment is from an interesting one hour talk by Dr. Lieberman, which I recommend: he’s a good speaker with a lot of interesting knowledge.
- The significance of unchanging injury rates is often exaggerated to support barefoot running, to “prove” that running shoes must be useless. But there are a lot of other variables in this equation. For instance, consider how much more democratic the sport is today, with vast numbers of participants who are physically quite different people than the joggers of the 70s, who were mostly eccentric keeners. It just isn’t possible to judge whether running shoes have failed. For all we know, they keep injury rates from going through the roof! All we really do know is that runners do still get injured, and “advanced” running shoes chosen to match plantar shape are not more effective than any other cushy, shock-absorbing shoe. Despite near perfect lack of data, it’s more or less universally accepted in the natural running community that shoes are all washed up.
- Richards CE, Magin PJ, Callister R. Is your prescription of distance running shoes evidence-based? Br J Sports Med. 2009 Mar;43(3):159–62. PubMed 18424485 ❐
Are current prescriptions of distance running shoes featuring elevated cushioned heels and pronation control systems evidence-based? The authors did a thorough scientific literature search for relevant papers and found nothing whatsoever to review. Unlike so many reviews that come to tepid conclusions based on limited evidence, this one found literally no evidence at all. Thus, “The prescription of this shoe type to distance runners is not evidence-based.” (As of 2009. The situation is hardly any better in 2017.)
- Hespanhol Junior LC, De Carvalho ACA, Costa LOP, Lopes AD. Lower limb alignment characteristics are not associated with running injuries in runners: Prospective cohort study. Eur J Sport Sci. 2016 Jun:1–8. PubMed 27312709 ❐
Do runners with anatomical quirks get more injuries than symmetrical and aligned runners? This study was another attempt to settle an old question that just won’t die.
It was the right kind of study (prospective), but perhaps a bit underpowered with only 89 subjects and just 12 weeks of monitoring for new injuries. I wish I could see the same data for a couple hundred runners over six months. Subtle vulnerabilities might take quite a while to crop up, particularly in runners who have already gotten through at least six months without any injury. Still, 24 of these runners did get injured in those twelve weeks — which is a lot! — and “we did not find significant associations between lower limb length discrepancy, Q-angle, subtalar angle and plantar arch index and injury occurrence.”
Surprise surprise. And so, as we’ve known for years, either there’s no relationship between running injuries and anatomical imperfections at all … or it’s too subtle to detect easily, in which case who really cares? These things are mostly impossible to fix anyway.
- Bramble DM, Lieberman DE. Endurance running and the evolution of Homo. Nature. 2004 Nov;432(7015):345–52. PubMed 15549097 ❐
- Lieberman DE, Bramble DM. The evolution of marathon running: capabilities in humans. Sports Med. 2007;37(4-5):288–90. PubMed 17465590 ❐
- “Humans — built for long-distance running?” an audio recording from The Science Show (Australian Broadcasting Corporation).
Dan Lieberman gives a great interview. Audio no longer available, but the full transcript is.
- McDougall C. Born to run: a hidden tribe, superathletes, and the greatest race the world has never seen. 1st ed. Alfred A. Knopf; 2009.
- McDougall summarizes his big ideas in an entertaining TED talk. He’s a good speaker, but it doesn’t take him long to start making some pretty dizzying leaps of logic based on dubious premises that fit his story a little too nicely. By the end he sounds thoroughly convinced and convincing about what (still, years later) cannot possibly be more than an interesting hypothesis.
- Lieberman DE, Venkadesan M, Werbel WA, et al. Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature. 2010 Jan;463(7280):531–5. PubMed 20111000 ❐
This paper shows that “habitually barefoot endurance runners often land on the fore-foot before bringing down the heel” and “generate smaller collision forces than shod rear-foot strikers,” which “may protect the feet and lower limbs from some of the impact-related injuries now experienced by a high percentage of runners.”
Later work has challenged this conclusion; see Udofa et al.
Trying to infer injury prevention outcomes from these findings is pure guess work. It’s so, so, so easy to see the words “smaller collision forces” and assume that this is a good, injury-preventing thing, but that is really just not a safe assumption. For all we know, that smaller collision force (assuming it’s real) is coming at the expense of, say, much greater stresses on your calves and achilles to control the sproingier ankle action … which might protect against shin splints, but send achilles tendinitis rates through the roof. We don’t know that stuff, and we can’t know until thousands of runners have been carefully studied.
These findings have been challenged since, most notably by Udofa et al, which will be covered below.
- Source article no longer available. This definitely existed at some point! But there’s just no trace of it left on the web now, unfortunately.
- Zadpoor AA, Nikooyan AA. The relationship between lower-extremity stress fractures and the ground reaction force: a systematic review. Clin Biomech (Bristol, Avon). 2011 Jan;26(1):23–8. PubMed 20846765 ❐ This 2011 review was thoroughly inconclusive: “There is disagreement in the literature about whether the history of stress fractures is associated with ground reaction forces (either higher or lower than control), or with loading rates.”
- Goss DL, Lewek M, Yu B, et al. Lower Extremity Biomechanics and Self-Reported Foot-Strike Patterns Among Runners in Traditional and Minimalist Shoes. J Athl Train. 2015 Jun;50(6):603–11. PubMed 26098391 ❐ PainSci Bibliography 54223 ❐
- Ask any science philosopher, if you can find one. If this retrospective research was the first thing anyone had ever heard about natural running, we might look at it and think, “Hey, maybe natural running prevents running injuries,” and that would be reasonable. But we already had that idea. And this research can’t actually take us beyond the hypothesis.
- Ahn AN, Kang JK, Quitt MA, Davidson BC, Nguyen CT. Variability of neural activation during walking in humans: short heels and big calves. Biol Lett. 2011 Feb. PubMed 21288939 ❐ Ahn et al studied ten people of similar overall height and weight, lower limb length, and foot length and found that they were divided evenly: half were short-heeled with big-calves, and half had longer calcaneuses and more slender calves. They also looked at the neurology of the muscle recruitment. Folks with short heels and big calves were also using their medial gastrocnemius more than the lateral. So not only were their calves big, but they were pulling harder with the inside half of their gastrocs. By contrast, long-heeled humans appear to have more evenly distributed calf contractions.
“Tendinitis” versus “tendonitis”: Both spellings are acceptable these days, but the first is the more legitimate, while the second is just an old misspelling that has become acceptable only through popular use, which is a thing that happens in English. The word is based on the Latin “tendo” which has a genitive singular form of tendinis, and a combining form that is therefore tendin. (Source: Stedmans Electronic Medical Dictionary.)
“Tendinitis” vs “tendinopathy”: Both are acceptable labels for ticked off tendons. Tendinopathy (and tendinosis) are often used to avoid the implication of inflammation that is baked into the term tendinitis, because the condition involves no signs of gross, acute inflammation. However, recent research has shown that inflammation is actually there, it’s just not obvious. So tendinitis remains a fair label, and much more familiar to patients to boot.
- Don’t be surprised that there’s really no scientific solid ground for any running technique or shoe. For crap’s sake, the common cold still has dozens of popular but still-unproven remedies; the jury is still out on everything but decongestants (thumbs up—they do indeed unsnot ye) and vitamin C (thumbs down—just some weird thing Linus Pauling got obsessed with). We still don’t even know if cough suppresants work! (Smith)
- If Vibram had any research supporting the health/running benefits of their FiveFingers product, I’m pretty dang sure they’d be shouting it out—but they aren’t. Even their original, pre-lawsuit “health & wellness” page was barely longer than a haiku and offered only five incredibly broad bullet points of vague, meaningless, but nice-sounding things like “improve posture” and “move naturally” and (of course) “align the spine”—sure, it’s just like wearing a chiropractor on your foot! •eye-roll• Sometime in the middle of 2014, they changed the text to be even more vague:
The typical human foot is an anatomical marvel of evolution with 26 bones, 33 joints, 20 muscles and hundreds of sensory receptors, tendons and ligaments. Like the rest of the body, to keep our feet healthy, they need to be stimulated and exercised. Vibram FiveFingers® footwear is different than any other footwear on the planet. Not only does it bring you closer to your environment, it also delivers a number of positive health benefits—by leveraging all of the body’s natural biomechanics, so you can move as nature intended.
Uh huh. So basically the same stuff — but now too vague to get busted for.
- Rixe JA, Gallo RA, Silvis ML. The barefoot debate: can minimalist shoes reduce running-related injuries? Curr Sports Med Rep. 2012 May;11(3):160–5. PubMed 22580495 ❐
A summary of the state of barefoot-minimalist running science, much shorter than Lieberman’s early 2012 summary, with the same conclusion: on the one hand, “A growing body of biomechanics research has emerged to support the advantages of ‘barefoot’ running,” but unfortunately, “No clinical studies have been published to substantiate the claims of injury reduction using a ‘minimalist’ style.”
- Altman AR, Davis IS. Prospective comparison of running injuries between shod and barefoot runners. Br J Sports Med. 2016 Apr;50(8):476–80. PubMed 26130697 ❐
BACKGROUND: Advocates of barefoot running suggest that it is more natural and may be a way to minimise injury risk. In contrast, opponents believe shoes are needed to adequately cushion and support the foot. However, to date, there have been no prospective studies of injury patterns in barefoot and shod runners. The purpose of this study was to compare the incidence and rate of injuries between shod and barefoot runners.
METHODS: A prospective survey was conducted over the course of a year among 201 (107 barefoot and 94 shod) adult runners. Information regarding injuries and mileage was logged monthly using a custom, web-based database program. The number of injured runners, number of injuries per runner and injury rates were compared between habitual barefoot and habitual shod runners. Both musculoskeletal and plantar surface injuries were assessed.
RESULTS: Statistically fewer overall, diagnosed, musculoskeletal injuries/runner were noted in the barefoot group. However, injury rates were not statistically different between groups due to significantly less mileage run in the barefoot group. As expected, barefoot runners sustained a statistically greater number of injuries to the plantar surface of the foot. The descriptive analysis suggests a greater number of calf injuries, but lower number of knee and hip injuries in the barefoot group. Additionally barefoot runners reported less plantar fasciitis than the shod group.
CONCLUSIONS: Barefoot running is associated with fewer overall musculoskeletal injuries/runner, but similar injury rates. A larger scale cohort is needed to more accurately assess differences in individual injuries between these two groups.
- Fuller JT, Thewlis D, Buckley JD, et al. Body Mass and Weekly Training Distance Influence the Pain and Injuries Experienced by Runners Using Minimalist Shoes. Am J Sports Med. 2017 Jan:363546516682497. PubMed 28129518 ❐
- Udofa AB, Clark KP, Ryan LJ, Weyand PG. Running ground reaction forces across footwear conditions are predicted from the motion of two body mass components. J Appl Physiol (1985). 2019 May;126(5):1315–1325. PubMed 30763160 ❐