One side claims running shoes cause injury; the other side counters that barefoot running comes with its own risks. There are likely elements of truth on both sides. But when it comes to giving your patients advice about barefoot running, experts have more questions than answers.
by Cary Groner
For many people, barefoot running will forever be associated with the women’s 3000 meter race at the1984 Los Angeles Olympics. Coming around the backstretch, Zola Budd, the electrifying barefoot teenager from South Africa, got her legs tangled up with those of homegrown heroine Mary Decker. Decker tumbled to the infield grass, ending her career dream of an Olympic win; meanwhile Budd, mortified, faded back in the pack so she wouldn’t have to face a booing crowd from the winner’s podium.1 (Broadcast video of the race is on YouTube,2 for those who want a look.)
That unhappy race notwithstanding, Budd set world records in the 5K in 1984 and 1985, was the world cross-country champion in 1985 and 1986, and set the world indoor record in the 3K in 1986—all while running barefoot.
Does this mean your patients should run barefoot?
Well, are they Zola Budd?
For most folks, even weekend warriors, barefoot running has existed at the fringes, popping up occasionally in venues such as the Olympics but otherwise largely invisible in daily life. For others—think the Tarahumara people of Mexico, or Kenyan tribesmen—running long distances barefoot, or in minimal footwear, is an essential part of everyday existence.
This difference turns out to be a big one. Recently, a lively and occasionally acrimonious debate has erupted because some people believe that barefoot or “minimalist” running (e.g., in sandals, moccasins, or any of the new barefoot-style running shoes) offers a way to return to our evolutionary roots and escape injuries, whereas others see it as a falsely utopian disaster-in-waiting.
What is becoming increasingly apparent, however, is after the passing of the initial hype (and it is passing), the two sides are approaching a commonsense consensus. A lot of factors turn out to matter at least as much as shoes, including how a runner trains and what he or she got used to growing up.
In any case, it’s not an either/or situation. Zola Budd did everything barefoot as a child, as it turns out, but she did almost half her training in shoes. For that matter, in 1960, an Ethiopian named Abebe Bikila won the Olympic marathon in Rome running barefoot over all those cobblestones, but in 1964 he went to Tokyo and bested his world record—this time wearing shoes.
The ideal and the real
Last year, Christopher McDougall’s book Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World has Never Seen brought Mexico’s Tarahumara to the attention of mainstream readers.3 These are the Native American people who invented the ultramarathon, running two-day races through the mountains, sometimes while kicking a ball, and apparently grinning happily most of the way. McDougall made the case for minimalist running, noting that the Tarahumara run in lace-up sandals and report low injury rates. Some who read the book thought they’d like to be able to run like that, too, and sought to copy the style. Others thought those people were taking a simplistic view of a complex phenomenon and were basically nuts.
The discussion got amped up again earlier this year when Daniel Lieberman, PhD, a Harvard evolutionary biologist and running enthusiast, published a paper in Nature describing the high “impact transient” associated with running in the heel-strike pattern associated with modern, padded running shoes.4 In the paper, Lieberman and his coauthors pointed out that people have been running barefoot for millions of years, but that the modern running shoe wasn’t invented until the 1970s. The gist was that those running barefoot or in minimal footwear—and in particular those who had been habitual barefoot runners for their entire lives—were more likely to strike the ground with the forefoot or midfoot first, generating impact forces that were smaller and began later in the gait cycle than in shod rearfoot strikers.
This argument was quickly seized on as scientific justification by barefoot running enthusiasts—somewhat to the chagrin of Lieberman himself, who hastened to put a disclaimer on his website to the effect that he was just reporting his findings and was not in the advice business. The Nature paper does note that the modern running shoe has not been associated with any decrease in running injuries and lists several ways in which thick heeled, cushioned running shoes might actually contribute to injury. The paper concludes, however, that controlled prospective studies are needed before any conclusions about relative injury risks can be made.
Lieberman is not the least bit apologetic about his research or his views, however, and he doesn’t suffer skeptics gladly.
“It’s as if I’m suggesting something that’s not normal,” he told LER. “Until the mid-1970s nobody wore a shoe with a cushioned heel; what we think is normal is profoundly and unquestionably abnormal. People say, ‘Well, now we run on concrete,’ but I’ve run on almost every continent, and the entire world has been hard for a long time. The Serengeti where I run is hard.”
There’s a video on Lieberman’s website showing Kalahari “persistence hunters” running down a large antelope by sheer stamina and grit. A close look at the video reveals interesting details, however. First, the main runner—the guy who sticks it out to the end and spears the animal after it has collapsed from exhaustion—is, indeed, a forefoot striker. Second, however, he’s wearing shoes. Third, the ground is soft, loamy, and uneven. Fourth, all the hunters are supremely fit young men in their twenties.
So to what extent is it appropriate to extrapolate from this to the running community at large? Is there, perhaps, just a hint of Rousseauian idealism here?
Lieberman maintains that the world’s best natural runners are all forefoot strikers, in fact.
“There’s probably a reason for that, right? We’re not saying that everyone should run barefoot, but rather that barefoot style—which is primarily a forefoot or midfoot strike—is what the foot evolved to do,” he said.
The data famine
Part of the problem with having an informed discussion about the controversy is that to do so you need information, and there’s relatively little of it. For example, only one study has examined foot strike patterns in a large cohort. In 2007, Japanese researchers set up a high-speed camera at the midway point of a half-marathon for elite international competitors.5 They found that 75% of the runners were rearfoot strikers, 24% were midfoot strikers, and only 1.4% struck with their forefeet. If they’d all been running barefoot, the pattern would likely have been different, but they were wearing shoes (and even the most die-hard barefoot advocates agree this is a good idea when running in places prone to hazards such as broken glass and dog excrement, which are bad enough alone and downright lethal in combination).
Getting reliable information about injury rates is an iffy proposition, as well. The most oft-cited paper reported that the incidence of lower-extremity running injuries in the studies it surveyed ranged from roughly 20% to 80%, with the knee as the most common injury site, followed by the lower leg, the foot, and the upper leg.6
Even the lower end of that range, however, is eye-catching; in the best-case scenario, one in five runners was injured during or soon after a marathon, and most trainers say the real figure is much higher. But a central question remains: are injuries occurring because these athletes are wearing a certain kind of shoes, or because the shoes are allowing them to comfortably run greater distances than their bodies are prepared for? What’s the chicken and what’s the egg?
What We Know
In a 2009 paper in Footwear Science, Benno Nigg, PhD, of the University of Calgary, summarized the research regarding biomechanical differences between barefoot and shod running.7 These included, for barefoot versus shod: an increased external vertical loading rate, an earlier impact peak, greater tibial acceleration, flatter foot placement at initial contact, a larger minimal knee angle, higher ankle joint stiffness and lower knee joint stiffness, and earlier maximal electromyographic (EMG) activity in the tibialis anterior.
Nigg noted that oxygen consumption is typically 4% to 5% lower in barefoot running, which is attributed to factors including moving the shoes’ weight (energy demand increases about 1% for every 100g of additional mass on the foot), the bending resistance and friction of the sole, midsole energy absorption, and energy lost to metatarsophalangeal joint stiffness.
“Oxygen consumption may sometimes be higher when barefoot under certain conditions such running on a treadmill, however, for reasons not entirely clear.
Nigg also noted that there is little in the literature to support the claim that barefoot running is associated with lower injury rates, and that the few papers there are demand close scrutiny.8,9
Other articles have sought to clarify the biomechanical differences between minimalist and shod running, though it’s worth noting that subject populations varied in their experience with barefoot running, and such experience can affect outcomes because of the biomechanical learning curves involved.
For example, last year researchers reported that in treadmill running, barefoot athletes landed in more plantar flexion at the ankle, which reduced impact forces and led to shorter stride length and higher stride frequency.10
Scientists in France reported in 2005 that barefoot runners had lower contact and flight time, lower passive impact peak, higher braking and pushing impulses, and higher preactivation of the triceps surae.11 The same researchers reported in 2008 that stride frequency, anterior-posterior impulse, vertical stiffness, leg stiffness, and mechanical work were significantly higher in barefoot running.12
A 2009 article in Physical Medicine & Rehabilitation reported that shod running was associated with significantly increased joint torques at the hip, knee, and ankle, probably due to the shoes’ elevated heels and increased material under the medial aspect of the foot.13 Lead author Casey Kerrigan, MD, and her colleagues noted that such effects would potentially increase the work of the quadriceps, elevate strain through the patellar tendon, and raise pressure across the patellofemoral joint. The authors did not consider these findings prescriptive, however, and noted in the paper’s discussion that although medial posting and arch supports could inhibit the natural compliance of the foot in transitioning from supination to pronation near midstance and back to a supinated position near toe-off, the picture was more complicated. Recent research, they pointed out, had revealed that positive clinical outcomes accompanied the prescription of custom foot orthoses designed with medial posting.
“The individual needs of a runner should ultimately dictate footwear prescription,” they concluded, taking the safe route. (Kerrigan has since put her money where her mouth is: earlier this year she left academia to start her own running-shoe company.14)
“Not a single paper has ever shown that modern running shoes reduce injury rates,” said Lieberman. “On a heel strike, the impact transient is a classic saw-toothed profile. If you forefoot strike, there’s no collision, no spike. The hardness of the surface is irrelevant.”
When asked about the importance of a surface’s evenness, however—whether the problem might not lie entirely with the hardness of modern surfaces such as concrete but also their sameness—Lieberman paused.
“That’s a terrific question,” he said. “Any surface that’s completely even will lend itself to very stereotypical loading, and we know that repetitive stress injuries occur from doing things over and over again with unvarying motion.”
Nevertheless, he was quick to suggest that modern shoes might be contributing to the problem rather than alleviating it.
“Running shoes are designed to make every landing the same,” he said. “One advantage of minimal shoes or barefoot running is that they don’t have that flanged heel, so each landing is going to be slightly different. It’s good to vary it.”
Christopher MacLean, PhD, director of biomechanics at Paris Orthotics in Vancouver, BC, agreed that increased variability in movement patterns during running may be beneficial.
“In the biomechanics lab, we study variability,” he said. “For example, if your patella is tracking in the femoral groove, and if you’re running with less variability, it’s plausible that wear and tear could be localized to specific areas, causing repetitive stress injuries. Variability in the system may be healthier because stress is distributed rather than localized.”
MacLean and his colleagues suspect that running on treadmills and roads is probably less healthy than running on uneven surfaces such as trails, but he added that this is based on anecdotal evidence, not clinical data as yet.
“There may be certain style parameters that we can tweak in runners to enhance healthy technique,” he noted. “Barefoot runners take shorter and faster strides, which means less time weight bearing; these biomechanical variables can be adjusted whether you’re wearing shoes or not. Running posture may also be important in improving economy.”
Reed Ferber, PhD, director of the Running Injury Clinic at the University of Calgary, pointed out that shorter strides are unlikely to be a cure-all, however.
“When you shorten your stride you take more steps per kilometer,” he said. “But since your mass doesn’t change, that could be injury causative. My clinical opinion is that you’re probably just going to trade one injury for another.”
Ferber predicts that if minimalist running spreads, there will be an increase in Achilles tendinopathy and plantar fasciitis, but that the most prevalent problems will continue to be patellofemoral pain syndrome and iliotibial band syndrome.
He also agreed with Lieberman that the surface’s hardness may be overrated as a factor in injury risk—though he drew a different conclusion about what to do.
“In Calgary we have bike paths with grass beside them,” he said. “Our clinic collects data from every single person we see; some run on the path, some run in the grass, and it doesn’t affect injury rates. People get injured because they’re weak in one place, they’re inflexible in another, they’re in the wrong shoe, or they did too much that day. To avoid injury, people don’t need to run barefoot; they need to get stronger and more flexible.”
Acknowledging the trend, however, Ferber has instituted a barefoot running injury prevention program at his clinic that includes ankle-strengthening exercises.
“When people try to adopt a minimalist running style they seem to develop a lot of foot and shank problems,” he said. “We’ve found that there’s a strong correlation with weakness of the ankle stabilizer muscles. You have to get into this gradually to minimize injury risk—say, 10 percent gains on a weekly basis—and you have to have good ankle strength.”
Lieberman himself advocates moderation.
“If someone is wearing modern running shoes and not getting injured, why should they switch?” he asked. “Barefoot runners are going to get injured too. People learning to run in a more minimal style have to strengthen themselves and be careful. They should listen to their bodies, because there are costs and benefits to everything.”
Amid the general paucity of research about barefoot running and injuries, there’s a lot of speculation but little documentation. A 2009 study from the University of British Columbia, for example, reported that when patients with plantar fasciitis were given an exercise regimen, those who wore minimalist shoes reduced their pain earlier than those in standard running shoes.15 Mostly, though, people are still guessing.
Many in the field are more concerned about the downside, however. Chris MacLean predicted problems similar to those noted by Ferber.
“Without a proper transition, we’re going to see problems with Achilles tendinopathy due to the increased eccentric demands on the Achilles and the gastrocnemius-soleus complex,” MacLean said. “There will likely be increased soft-tissue injury to the forefoot, particularly the fourth and fifth metatarsal heads and in the digits, as well as increased bony injury to the fourth and fifth metatarsals.” (Runners’ websites and blogs are anecdotally bearing this out, incidentally, as they’re now replete with complaints about problems such as metatarsal stress fractures from runners wearing minimalist shoes.16)
According to Craig Payne, DipPod, MPH, a senior lecturer in podiatry at Latrobe University in Melbourne, Australia, runners have taken Lieberman’s research to mean more than it does.
“The thrust of that study is that barefoot running reduces heel strike and the impact associated with it, but there is not one piece of evidence that links high impacts to injury,” he said. “The most common running injuries—patellofemoral pain syndrome and fasciitis—have nothing to do with impact. Nor is there any evidence showing that running shoes weaken the muscles of the foot. For that matter, if barefoot running makes the muscles stronger, they must be working harder, which is the sign of an inefficient gait.”
Of course, coaches have had elite runners do some of their training barefoot for decades, under controlled conditions.17 It’s generally acknowledged to strengthen the feet and other muscles such as the biceps femoris and the gastrocs; the only question is how much is too much.
“We worry about athletes running barefoot on surfaces that have extreme contact forces and give repetitive stress to the tissues and joint capsules, particularly the metatarsal joints,” said Donna Robertson, ATC, CPed. Robertson, now a teaching consultant for Foot Solutions Corp., spent most of her career as a trainer of elite runners and worked with the foot and ankle medical team at the 2004 Olympics in Greece.
“This can lead to overuse syndromes, repetitive joint breakdown, and osteoarthritis,” she continued. “Then, when people develop symptoms, they compensate, which causes knee injuries, hip injuries, or lower back issues. So when we talk about barefoot running, I would say that there is an elite group that could do it with less injury, but that most people shouldn’t.”
A related issue is whether it’s actually helpful in competition. Earlier this year, Joseph Hamill, PhD, a professor and director of the biomechanics lab at the University of Massachusetts, Amherst, presented a study at the World Congress of Biomechanics in Singapore concluding that changing from a rearfoot striking pattern to a forefoot pattern offered no benefits aerobically or in terms of energy use.18
“We found, in fact, that it might be detrimental because you have a slight change in your lower extremity coordination,” Hamill said.
“The people I know who’ve made the transition to barefoot running most easily are those who grew up walking around barefoot,” said Kevin Kirby, DPM, assistant clinical professor at the California School of Podiatric Medicine in Oakland. “Other than that, the people I’d recommend it for would not be beginners, but rather those who are already running 60 or 70 miles a week and who want to vary it, give their legs a break, go on the golf course and do some intervals barefoot.”
Few runners are better known for growing up barefoot than Zola Budd Pieterse. The former Olympian still runs, but at age 44 she lives a much quieter life with her husband and children near Myrtle Beach, S.C., where she is a volunteer track coach at Coastal Carolina University.
“For me, growing up running barefoot was a lifestyle, not an option,” Budd Pieterse told LER. “All the kids in South Africa run barefoot, even today. It’s just something natural to do.”
Budd Pieterse always had a balance between her barefoot and her shod running, in any case. She estimates that when she was competing she did about 60% of her training barefoot, the other 40% in shoes.
“I used to do all my road running in shoes, and I still do,” she said. “My feet weren’t strong enough, and I was scared of the broken glass. Most of my training I did on the grass and on the track, and that I did barefoot.”
Not surprisingly, her students want to try barefoot running.
“My advice is to start out really slowly if you’re not used to it,” she said. “But I don’t know why people think it’s something new. It’s been around for eons. It always just felt so much easier running barefoot.”
Cary Groner is a freelance writer based in the San Francisco Bay Area.
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