Barefoot Running claims & controversies

ORIGINAL ARTICLES

Barefoot Running Claims and Controversies

A Review of the Literature

David W. Jenkins, DPM*David J. Cauthon, RPh*

Background: Barefoot running is slowly gaining a dedicated following. Proponents ofbarefoot running claim many benefits, such as improved performance and reducedinjuries, whereas detractors warn of the imminent risks involved.

Methods: Multiple publications were reviewed using key words.

Results: A review of the literature uncovered many studies that have looked at thebarefoot condition and found notable differences in gait and other parameters. Thesefindings, along with much anecdotal information, can lead one to extrapolate thatbarefoot runners should have fewer injuries, better performance, or both. Severalathletic shoe companies have designed running shoes that attempt to mimic the barefootcondition and, thus, garner the purported benefits of barefoot running.

Conclusions: Although there is no evidence that either confirms or refutes improvedperformance and reduced injuries in barefoot runners, many of the claimed disadvan-tages to barefoot running are not supported by the literature. Nonetheless, it seems thatbarefoot running may be an acceptable training method for athletes and coaches whounderstand and can minimize the risks. (J Am Podiatr Med Assoc 101(3): 231-246, 2011)

Barefoot running is slowly gaining a dedicated

following in developed countries around the world.

Evidence of this is seen in the popularity of barefoot

running Web sites and in the explosion of articles

written for the popular media. In the past several

years, articles have appeared in Runner’s World,

Men’s Health, Popular Mechanics, and The Wall

Street Journal, as well as on several Web sites.1-5

These articles provide vast quantities of informa-

tion, some based on clinical research, some based

on personal experiences, and some based on well-

intentioned but faulty logic. With the excitement

and promise of many benefits in performance and

reduced injuries, the hype is understandable.

Although barefoot running is, by definition, the

opposite of a ‘‘new’’ activity, the so-called barefoot

running movement is relatively new. Given the

significant role that many health providers play in

treating athletes, it is imperative that clinicians be

attuned to athletic trends (whether they be fads or

long-lasting movements) as our patient-athletes willcome to us for opinions and recommendations. Thisreview article examines the evolving barefootrunning movement and the professed benefits ofenhanced performance and injury reduction fromthe perspective of a thorough review of theliterature and the best available evidence. Nonethe-less, the clinician should be better equipped toanswer the many questions about barefoot runningthat are sure to come from their running patients.

History of Barefoot Running

The Genesis

Our ancestors walked with either no footwear at allor the simplest covering made of leather held on byrawhide strings (moccasins). What has changed isthe creation of modern surfaces that, according tosome, necessitate protective footwear. But did man-made surfaces drive this change? Was it thesurfaces that led to more modern shoes or was itstyle, vanity, and status that drove these changes, assome investigators believe?6 Nonetheless, earlydogma claimed that feet were evolutionarily unsuc-cessful,7 and it seemed that health-care providers

*Arizona School of Podiatric Medicine, College of Health

Sciences, Midwestern University, Glendale, AZ.Corresponding author: David W. Jenkins, DPM, Arizona

School of Podiatric Medicine, College of Health Sciences,

Midwestern University, 19555 N 59th Ave, Glendale, AZ

85308. (E-mail: [email protected])

Journal of the American Podiatric Medical Association � Vol 101 � No 3 � May/June 2011 231

and shoe companies considered feet inherentlyfragile and, thus, unable to hold up to the rigors of

running without protective cushioning, support, andmotion control. Now consider the barefoot running

proponents who claim that generations of moreconfining, motion-restricting, and increasingly sup-portive shoes has created an atrophy of the feet

through disuse, especially of those components thatwould be more greatly used if unshod, eg, the

plantar intrinsic musculature.8 For decades, therehave been strong advocates for going barefoot or

pointing out the liabilities of wearing shoes.9, 10

A major reason for the fresh interest in barefoot

running is the lack of improvement in running-related injuries despite advances in cushioning and

motion control in running shoes. In 1982, in one ofthe earliest studies on the incidence of injuries inrunners performed by Koplan et al,11 an incidence of

35% was found. In a study by Jacobs and Berson12 in1986, 47% of survey respondents claimed that they

had sustained an injury during the previous 2 years.Two large studies13, 14 in 1989 found a similar

incidence of approximately 50%. An excellentreview of the epidemiologic literature by Van

Mechelen15 in 1992 found an injury rate of 37% to56%. A 2004 prospective study16 found that 79% of

runners sustained a lower-extremity injury duringthe 6-month study, including injuries that caused a

reduction in mileage and a stoppage in running. In2006, McKean et al17 noted an injury rate of 46%.

Two of the most recent studies18, 19 found incidenc-es of 54.8% and 59%.

Despite the steady injury rates, clinicians contin-

ue to prescribe more cushioned and controllingshoes even though there is no evidence to support

the effectiveness of high-quality running shoes inpreventing injury. Indeed, these recommendations

may have the potential to cause harm.20 In fact,Clinghan et al21 concluded that expensive running

shoes were no better at reducing impact forces thanwere low-cost shoes.

Although they do not ascribe an overall incidence

of runners who become injured, James et al22 andBrubaker and James23 thoroughly reviewed the

prevalence of specific running-related injuries, theiretiology, and treatment. Interestingly, and quite

possibly paradoxically, James et al22 noted in1978, ‘‘It is our contention that if an adequately

designed shoe were available, many of the problemsattendant to long distance running, short of training

errors, could be prevented.’’22(p46)

Robbins,8 in his first of many publications on thebarefoot condition, notes significantly higher injury

rates in those wearing shoes in Haiti compared with

those not wearing shoes. Although there may beother reasons for this difference, such as access tomedical care, poor shoe quality, training habits, etc,

this finding provided a springboard for Robbins andHanna8 and others to scientifically explore whetherbarefoot running was less injurious or more

beneficial.

Although not a scientific investigator, a prominentand vocal proponent of the barefoot running

movement is Christopher McDougall. His pastwritings and recent book, Born to Run: A Hidden

Tribe, Superathletes, and the Greatest Race the

World Has Never Seen, discuss the TarahumaraIndians of Mexico, who routinely run ultramarathondistances without shoes or with simple coverings

and reportedly have none of the modern ‘‘runninginjuries’’ so commonplace in modern society. Heassociates the ills that runners experience to shoes,

and he claims that despite all of the technologicaladvances in the past 40 years, running-relatedinjuries have not been reduced and, indeed, are on

the rise.24

The thinking of Robbins and McDougall wascontrary to the idea that feet are fragile and need

protection. They believed that man is designed towalk barefoot and that biomechanical function ismost efficient when unshod. Coupling this with the

reported paucity of running-related injuries in theselegendary unshod runners, a variety of investigatorshave begun exploring the reasons for the lower

incidence of injuries and suspected benefits. It isthese claims of improved performance and reducedinjuries that, in part, motivate the modern barefoot

running movement. On the other hand, the numer-ous runners who decided to give barefoot running atry limping into the offices of foot specialists has

given rise to skepticism from many health-careproviders.

Time Frame and Participants

For a perspective on the age of the currentmovement, Ken Bob Saxton, the unofficial ‘‘godfa-

ther’’ of barefoot running, ran his first official bare-foot race in 1997.25 The Web site therunningbarefoot.com, which was founded by Saxton, has been

accessible since 1997.26

Although there is no reliable estimate of thenumber of barefoot runners, proponents of themovement claim that thousands of people are

running at least some of their weekly milesbarefoot. The Society for Barefoot Living (http://www.barefooters.org), which is not exclusive to

runners, has more than 1,200 members.27

232 May/June 2011 � Vol 101 � No 3 � Journal of the American Podiatric Medical Association

Although the current attention and excitement by

recreational runners is recent, barefoot running is

not new to elite runners, who many years earlier

saw significant world-class performances by bare-

foot runners. Although historically, barefoot run-

ners have had some success at the elite level, no

runner has won an Olympic medal or set a world

record barefoot in more than 2 decades. Some

examples of elite runners and performances include

the following:

1) Abebe Bikila became the first black African to

win an Olympic medal when he won gold in the

1960 Olympic Games Marathon. He ran the entire

race barefoot (the same way that he had trained),

but by the time he won Olympic gold in 1964

(Tokyo), he was running in Tiger shoes after

getting a sponsorship from Onitsuka, the precur-

sor to Asics.28

2) An 18-year-old Zola Budd set the world record

for 5,000 m on a track in 1984 while running

barefoot, but she finished seventh in the 1984 Los

Angeles Olympic Games in the 3,000 m after a

highly publicized collision with American Mary

Decker Slaney. Now 43 years old, Zola Budd

Pieterse has donned shoes while training on the

master’s circuit in the United States, and she

finished the 2008 New York Marathon in 2 hours

59 minutes.29

3) Herb Elliott is often mentioned as a barefoot

runner because twice he graced the cover of

Sports Illustrated running barefoot.30, 31 Howev-

er, he clearly is wearing shoes in the 1960

videotape of his world record–setting Olympic

1,500-m race. Elliott also served as president of

Puma America from 1995 to 1997 after serving as

CEO of Puma Australia from 1985 to 1995.32

4) Bruce Tulloh set United Kingdom records for 3

miles in 1960 and 1961 and for 2 miles in 1962 as

well as winning the 5,000 m at the European

Championships in 1962. Although most of his

races were run barefoot, he did resort to wearing

shoes if the surface required it.33

Before recreational running became mainstream,

it was not uncommon for coaches at various

competitive levels to incorporate some degree of

barefoot training in their workouts. Indeed, one of

us (D.W.J.) regularly participated in structured

barefoot workouts in high school track and cross-

country in the late 1960s. To gain an appreciation

for the modern barefoot running movement regard-

ing claims and philosophy, it is recommended that

Web sites such as runningbarefoot.org and Bare-

footTed’s Adventures (http://www.barefootted.com)be perused.

Despite the numerous players on the barefootrunning scene, it was a 1987 study,8 10 years beforeKen Bob Saxton’s therunningbarefoot.com, thatconcluded, ‘‘The solution to the problem of run-ning-related injuries could be as simple as promot-ing barefoot activity.’’8(p155) It was this assertionthat many proponents believe was the catalyst forthe scientific exploration that this article investi-gates.

Methods

The purpose of this review was to take an all-encompassing look at all aspects of this topic.Because most studies and reviews to date havefocused on one dimension of barefoot running, suchas biomechanical considerations, we have chosen toinvestigate even the most obscure claims orconcerns. We searched PubMed (MEDLINE), UpTo-Date, and Web publications using the key wordsbarefoot and running. Because results from studiesthat did not specifically look at barefoot runningmay be applicable, the words barefoot and walking

and finally just the word barefoot were also used.The reference sections of applicable researcharticles were also considered.

Results of the Review

Advantages of Barefoot Running

Numerous benefits of barefoot running are touted.Many of these will make sense logically, but anattempt to support or refute the claims is made bylooking at the current best evidence. As thepurported benefits are discussed, logic will alsoplay a supportive role and, in some cases, may bethe only source of ‘‘evidence.’’

Significant Alterations to Runner’s Gait. Al-though not necessarily an advantage, there aresignificant changes that are indisputable in acomparative observation of a barefoot runnerversus a shod runner. These modifications will, inpart, be responsible for many of the claimedadvantages described herein.

Several investigators have found consistentchanges when the runner is barefoot, includingdecreased stride length; increased stride rate;decreased range of motion at the ankle, knee, andhip; and a more plantarflexed ankle at contact. Theplantarflexed position at foot strike is the mostreadily observable distinction. The quicker and


shorter stride length leads to a lower contact andflight time.34-37

Another unique finding observed in the barefoot

runner was higher electromyographic activity inpreactivation of plantarflexory muscles (gastrocne-

mius lateralis, gastrocnemius medialis, and sole-us).34 The significance of this finding is addressed in

the ‘‘Reduction of Impact Forces’’ subsection.

Reduction of Impact Forces. Some investiga-tors believe that impact forces associated with

running are high and, along with overtraining, areresponsible for many of the running-related injuries

seen by clinicians.38, 39 This notion, however, isdisputed by Nigg40 not by study references but bythe lack of studies confirming it. Studies by Lieber-

man et al,37 Divert et al,34, 41 and Squadrone andGallozzi35 determined that impact forces were

reduced in those running barefoot.

Robbins found that through training, improvedsensory feedback resulted in gait alterations that

allowed for foot strike to be at the metatarsal headsinstead of the heel. In addition, there is adaptation

of the intrinsic musculature with resulting increasedstrength and, therefore, a medial longitudinal arch

that is higher and better able to deform with impactand provide improved shock attenuation.8 Nigg40

disputes this conclusion, noting a discrepancy

between peak impact force at 30 to 50 msec andmaximal arch deformation at 400 msec for this to be

valid.

Shakoor and Block42 hypothesized that the gaitchanges noted previously herein were responsible,

in part, for their finding that walking barefootresulted in decreased peak joint loads at the hips

and knees in 75 patients with osteoarthritis.

Kurz and Stergiou43 looked at how shoe hardnessand footwear in general affect ankle coordinative

strategies during the stance portion of running. Anankle coordinative strategy is an unconscious

modification of the subtalar joint to maximize gaitefficiency. Although they found no real differences

in the shoes evaluated, they found significantdifferences between shod and unshod feet. Similar

to the investigators discussed in the previoussections, they noted the more plantarflexed ankleposition and forefoot contact at foot strike in the

barefoot runner but also observed that the ankle(really the subtalar joint) is held in a more inverted

attitude as well.43

In another study by Kurz et al,44 the variability ofgait was increased in barefoot versus shod runners.

They concluded that the increased variations in thelower-extremity joints may be related to the ability

of the mechanoreceptors to adjust the joint pattern

and may be a mechanism for overcoming repetitiveimpact forces and, therefore, running injuries.

Nonetheless, how these improved coordinationstrategies come about when barefoot may be due

to improved overall proprioception seen in thebarefoot condition (see the ‘‘Increased Propriocep-tive Ability’’ subsection).

Divert et al,34 besides noting many of the typicalgait alterations seen in the barefoot runner, also

found higher braking and pushing impulses andhigher preactivation of the triceps surae. In essence,

the triceps will ready itself for the expected impactat contact. They concluded that these changes in

gait were largely designed to reduce the forces offoot strike.34 Indeed, Divert et al34 speculate that

some of the earlier studies that demonstratedincreased impact load in barefoot running werethe result of the test participants running barefoot

heel-toe because they had so little time to acclimateto the process.45

Robbins and others46-48 claim that modern run-ning shoes and manufacturers do such a good job

convincing wearers of the protection they give,through marketing and by perceived comfort, that

runners tended to be unaware of the forces theywere subjected to while running. Shod runnerswould, therefore, be unlikely to institute the

necessary shock-reducing behaviors and would bemore susceptible to injury.46-48

Increased Economy of Running. Early investi-gators49, 50 found that barefoot runners have re-

duced oxygen consumption and, thus, reducedenergy expenditure when running. One study found

4.7% higher oxygen consumption in those wearingshoes weighing 700 g versus the barefoot condi-

tion.51 By adding weight to individuals’ feet withoutadding a cushioned sole, Divert et al52 attributed theincreased energy utilization to shoe mass and not

gait changes. However, they also hypothesized thatshoe-related shock attenuation may concurrently

remove stored energy and add to the shod footinefficiency.52

Webb et al53 noted that a further inefficiency inthe use of energy while shod may occur when the

actual repetitive deformation of the shoe with eachstride requires energy that could be saved in thebarefoot state. A nonsignificant difference (P .

.05) in improved economy was noted by Squa-drone and Gallozzi,35 but they hypothesized that

barefoot running–experienced participants in theirstudy changed their running style, making even

their shod condition more economical becausethey ran with a barefoot running style even when

in shoes.


Increased Proprioceptive Ability. Althoughthere are no studies, to our knowledge, that

evaluate barefoot runners’ proprioceptive ability,several investigations have looked at proprioception

in the barefoot condition under static circumstanc-es. Robbins et al54 investigated the hypothesized

loss of plantar tactile sensibility in males bymeasuring the perception of the slope of variously

sloped platforms. They discovered that not only wasthere a demonstrated loss of proprioception with

aging but also with the wearing of shoes. It wassurmised that any barrier between the plantarmechanoreceptors and the supporting surface

would inhibit foot position awareness.54 In earlierstudies, Robbins et al found that thicker or softer

shoes decreased balance in the elderly55 and inyounger men.56

Reduction in Running-Related Injuries. Noevidence was found that demonstrates a reduced

prevalence of running injuries in barefoot runners;however, studies exist that demonstrate reduced

injury factors in laboratory situations.

Ankle injuries are the most common sports-related injury.57, 58 Ankle injuries account for 15%

to 30% of all injuries in sports with a highpercentage of sideward cutting movements such

as basketball, European handball, volleyball, soc-cer, and tennis.59 Similar values are seen with high

school athletics in the United States, with studiesciting that ankle injuries make up 12.3% of severe

injuries and 28.3% of recurrent injuries.60, 61

A variety of investigators claim that the improved

proprioceptive ability noted in the previous sectiondirectly leads to a reduction in foot position errors

and, thus, fewer lateral ankle sprains. Robbins etal62 found that taping the ankle improved proprio-

ceptive ability and, thus, foot position awareness,but compared with being barefoot, the taping group

had 58% less awareness. As a follow-up, Robbinsand Waked63 reiterate these findings, noting thatindividuals in countries where shoes are not worn

have significantly fewer ankle sprains, although noreference for this observation is given. It is

postulated by Robbins and Waked that ‘‘anklesprains are caused by impaired proprioception that

results in the inadequate use of anticipatorymuscular movements under dynamic conditions

when there is insufficient time to respond to theactual loading event.’’63(p65) Foot position, because

it is affected by plantar tactile receptors, is themeans for avoiding ankle sprains in the barefoot

condition.63 A study by Stacoff et al59 evaluated theability of sideward cutting movements in 12

individuals in five different shoes and barefoot and

found that those who were barefoot had significant-ly better lateral stability. Changes to shoes to

improve lateral stability, such as in hardness,reduced midsole thickness, torsional stiffness of

the sole, and using a high-cut upper, allowed somestability measurements to become more similar to

being barefoot, but none of the five shoes testedwere similar to being barefoot in all of the

parameters tested and it, thus, was concluded that‘‘the best lateral stability can be found in the

barefoot condition.’’59(p357) Waddington and Ad-ams64 reported similar findings when they foundthat elite barefoot soccer players were much better

able to discriminate ankle inversion movement thanwere shod individuals. The proprioceptive deficien-

cy resulting from being shod was, in part, reducedby replacing smooth insoles with textured insoles

that enhance direct plantar sensory stimulation.64

Unrelated to reduced proprioception but equally

contributory to ankle instability is the simple factthat a foot elevated by a shoe results in an

increased lever arm between the ground reactionforce and the axis of the subtalar joint, which may

then impart greater supinatory forces than a footunshod.59, 65, 66 An interesting application of the

reduced lever arm seen in barefoot individuals wasnoted when Kerr et al67 reported a significantly

greater muscle contraction of the peroneus longusin response to an unanticipated and sudden

inversion force when shod versus unshod and, thus,concluded that it is a compensatory mechanism to

oppose the increased moment created by theinverted foot/shoe condition.

Increased Strength of the Musculature. An

anthropometric study by Kadambande et al68

compared a group of 100 randomly selected

individuals from the United Kingdom who routinelywore shoes with 100 individuals from India who

never wore closed shoes. They found that thepliability of shod feet was significantly less than

that of bare feet, but they did not find a significantdifference in intrinsic foot muscle function. Rao and

Joseph69 evaluated 2,300 children for any effect offootwear on arch development and concluded that

wearing shoes (especially in early childhood) isdetrimental to the development of a normal medial

longitudinal arch and attributed this to stronger andmore developed plantar intrinsic musculature. As

discussed earlier, Robbins and Hanna8 claimed thatbarefoot runners develop, through training, in-

creased muscular strength adaptation of the intrin-sic musculature.

Nike claims a significant increase in intrinsic foot

muscle size and strength when their minimalist shoe


is used, which is elaborated on later herein. Themost discussed research regarding this claim was a

project funded by Nike whereby Bruggemann et al70

analyzed runners who wore the Nike Free minimal-

ist shoe (Nike, Beaverton, Oregon) during theirwarm-up regimen for 5 months, thus simulating

‘‘barefoot’’ running. He claimed an increase in thecross-sectional size and strength of selected intrin-

sic muscles. Specifics of how strength was mea-sured and what warm-ups entailed were not noted

in the study. More details from this study70 are inthe ‘‘Shoes that Mimic Barefoot Running (Minimal-ist Shoes)’’ section later herein.

Decreased Cost. If a runner changes shoes every500 miles and runs 40 miles a week, this equates to

four pairs of shoes a year. The average price ofathletic footwear in 2008 was $43.71 according to

the National Sporting Goods Association. Runningbarefoot could lead to an annual savings of

$175.00.71

Decreased Risk of Foot Deformities. Regard-ing children, Wolf et al72 states that ‘‘optimum foot

development can only occur in barefoot condi-tions.’’(p51) Likewise, Staheli73 claims that constric-

tive footwear can lead to deformity and stiffness.The American Academy of Pediatrics states that

children should not wear shoes until necessitatedby environment. The Academy74 claims that rigid

shoes prevent motion and development of theintrinsic musculature. Besides better arch develop-

ment (see previously herein), Rao and Joseph69

found that the incidence of flatfoot in children was

three times as high in those who wore shoes (8.6%)versus those who did not (2.8%). This held true even

after other factors, such as age, obesity, andligamentous laxity, were accounted for. In addition,

children who wore closed-toe shoes had evenhigher rates (13.2%), whereas those who wore

slippers and sandals were in between (8.2% and6.0%, respectively). They, thus, concluded that when

children begin to wear shoes at an early age, theyhave increased rates of flatfoot.69 In a follow-up

study of adults, Sachithanandam and Joseph75

found that the earlier a child began wearing shoes,

the higher the prevalence of flat feet. They alsonoted that wearing shoes longer than 8 hours per

day was associated with a higher rate of flat feet.

In multisegment foot model studies by Wolf etal72 and Morio et al,76 it was determined that

wearing shoes constrained the natural motions ofthe foot, especially regarding forefoot to rearfoot

motion. Last, Zipfel and Berger77 reviewed patho-logic changes to the metatarsals of rural and urban

populations compared with unshod prehistoric

populations. They found significantly more lesionsin the shod groups and concluded that shoes ormodern substrates may be responsible.

Disadvantages of Barefoot Running

Injury from Running Surface Debris and

General Hazards. Rocks, glass, and thorns are

just a few of the possible hazards that barefootrunners may encounter, but no study, to ourknowledge, has evaluated this risk. Nonetheless,

the advocates of barefoot running claim that thesolution to this problem is as simple as watchingwhere you place your feet.26 Although an unshod

foot is at greater risk for sharp object trauma, theplantar skin surface of the foot is uniquely designedto resist penetration and likewise requires 600%

greater abrading loads to reach the pain thresholdthan do other skin surfaces.78, 79

A bizarre example of a running surface hazard

that is probably unlikely in developed countries butis noted for completeness and curious interest ispodoconiosis (noninfectious, nonfilarial geochemi-

cal elephantiasis). It is an unusual manifestationdue to exposure of a barefoot individual to irritantalkalic clay soils in Africa, Central America, and

India. The silicate particles are absorbed and causeinflammation and blockage of lymphatic channels,which results in elephantiasis.80 Although concerns

such as stinging insects, blunt trauma, and even aspike injury in a competitive scenario may arise, nostudies regarding these risks to a barefoot runner

are found.

Thermal Injury from Extremes of Tempera-

ture on the Running Surface. No studies orsurveys demonstrate risk or document successful

running while barefoot on either hot or coldsurfaces; however, claims on barefoot runningWeb sites have shown that at least some runners

can adapt to these temperature extremes and notonly run in them but complete full marathons.26

Although not a running surface risk, the American

College of Foot and Ankle Surgeons warns of therisk of sunburn and skin cancer from goingbarefoot.81

Availabilty of Adequate Surfaces. Robbins and

Gouw47 claimed that the human foot does not needany external cushioning to deal with the impact ofrunning. No studies have yet determined the optimal

surface for barefoot running.

Exposure to Microorganisms/Infectious

Agents. Many health-care providers fear that an

unprotected foot, especially one that may experi-ence minor (or major) nicks and cuts, will be at risk


for inoculation by microorganisms. Preventivehealth experts warn of the hazards of being barefoot

in public showers and pools with respect to tineapedis and plantar verrucae.82 Similarly, plantar

verrucae may develop secondary to inoculationfrom a minor cut.83, 84

Several studies85-87 have demonstrated that being

barefoot is not a risk factor for plantar verrucae ortinea pedis and may, in fact, be therapeutic for

treating tinea pedis. More seriously, some individ-uals, many who are thought to be in excellent

health, such as athletes and military personnel, areat risk for community-associated MRSA that can

begin from the most minor cutaneous injury.88, 89

Although the unshod foot would be at greater risk

for a puncture wound and possible tetanus, the riskof an associated infection with pseudomonas isactually reduced.90, 91 One study92 found that

walking barefoot around pools is a predisposingfactor for onychomycosis in immunocompromised

individuals.

Although barefoot runners may be exposed to

infectious agents, such as leptospirosis, tungiasis,mycetoma, strongyloidiasis, and Mycobacterium

gordonae, most are found only in tropical countrieswith poor sanitation or are quite rare.93-96 However,the Centers for Disease Control and Prevention

warns that infection by hookworm larvae withresultant cutaneous larva migrans is a real possibil-

ity for anyone performing a barefoot activity in atropical area, including the southeastern United

States.97

Runners who Require Mechanical Control for

Existing Conditions. Although several stud-ies98-104 cite the success of orthotic devices in the

treatment of lower-extremity overuse–related inju-ries, scientific literature investigating the compara-tive treatment of conditions with barefoot running

and orthotic devices is nonexistent.

Loss of Protective Sensation. In comparing

groups of adults with puncture wounds, diabeticindividuals were more likely to be barefoot when

the injury occurred.105 In a study106 from rural SriLanka, walking barefoot was shown to be a risk

factor for diabetic foot disease. Individuals goingbarefoot had a higher rate of foot ulcers versusthose wearing some type of footwear. In addition, in

diabetic individuals who wore footwear, foot ulcersand web space and nail infections were increased in

those who wore footwear less than 10 hours per dayversus those who wore footwear longer than 10

hours per day.106 Another study107 comparedplantar pressures seen in shod and unshod individ-

uals while walking on a variety of surfaces and

found that shoes increased the contact area and,thus, reduced the peak pressures. Carl and Bar-rett108 similarly concluded that shoes and even flip-

flops were superior to the barefoot condition inmore evenly distributing forces and reducing peakplantar pressure.

Increased Shock at Impact. Komi et al45 foundincreased passive peak vertical forces in barefoot(2.65 body weight) versus shod (1.95 body weight)

conditions. This study used only four participants,measured forces on ten nonconsecutive impacts,and found no significant difference in stride rate and

stride length, which is contrary to multiple otherstudies.34-36 In a close look at methodology,however, the participants, while running barefoot,

landed heel first, which is not only going to increaseimpact forces but is an unnatural barefoot gait.45

The results of this study have been refuted multiple

times.34, 37, 39

A study by De Clercq et al109 demonstrated thatbarefoot runners will, at heel strike, undergo a 61%deformation of their heel pad versus a 36%

deformation when the foot is shod. They concludedthat the heel pad was maximally deformed during

barefoot running to the point that the heel pad wasno longer a shock absorber but a protectivestructure with a much greater risk of potential

injury. However, this study,109 similar to that byKomi et al,45 required the runner to strike with theheel, which is contrary to the barefoot running gait

pattern.

Increased Shock Transmission to Back Mus-

cles. A study by Ogon et al110 found an increasedrate of shock transmission to erector spinae back

muscles in barefoot conditions versus shod condi-tions and a delayed muscle response to theacceleration of the L3 vertebrae in the barefoot

group. However, this study forced the test partici-pants to standardize their gait to strike with their

heel during all of the running conditions. Gaitadaptations (which include a shift away from aheel landing) have been proved multiple times to be

one of the characteristics of running barefoot.8, 34-37

Implementing Barefoot Running

Although significant and detailed information re-

garding implementation can be found on barefootrunning Web sites,26, 111 no studies, to our knowl-edge, demonstrate the safest or most efficacious

method for instituting a barefoot running program.Robbins and Gouw47 estimated that shod individu-als would require 6 weeks of adaptation for plantar

skin and musculature and daily barefoot running to


maintain adaptation. In a later article, Robbins etal78 noted unsubstantiated and anecdotal reportsthat claim that 3 to 4 weeks of barefoot running at

30 minutes daily is sufficient for plantar surfaceadaptation.

Shoes that Mimic Barefoot Running (MinimalistShoes)

Vibram FiveFingers (Vibram, Concord, Massachu-

setts) were introduced in 2006 and were quicklynamed one of Time Magazine’s Inventions of theYear in 2007. Vibram FiveFingers have been shown

to be similar to barefoot running in reducing theamplitude of the impact peak vertical force andencouraging a more forwardly placed point of foot

strike in a study involving eight experiencedbarefoot runners. Also, foot angle and ankle angle

15 msec before touchdown were similar to thebarefoot condition and significantly decreased thefoot angle and increased the ankle angle versus the

shod condition.35

Nike introduced the Nike Free 5.0 in 2004 toprovide 50% of the support and stability of a normalrunning shoe. They followed this up with introduc-

tion of the Nike Free 7.0 and the Nike Free 3.0 to bemore stable and less stable than the 5.0, respective-

ly. In addition to their design research, Nike fundedresearch at the University of Cologne that waspresented at the International Society of Biome-

chanics’ Symposium in July 2005. In that study, 50participants were divided into two groups. Group 1performed a warm-up routine in Nike Frees, then a

workout routine in traditional training shoes threeto four times a week for 5 months. Group 2performed both routines in traditional training

shoes. The researchers found significant increasesin the anatomical cross-sectional area of the flexor

hallucis brevis, flexor digitorum brevis, abductorhallucis, and quadrates plantae muscles in the NikeFree group but no change in the anatomical cross-

sectional area of the leg muscles above the ankle.The control group showed no significant increasesin the anatomical cross-sectional area of any

muscles. Likewise, the strength of the flexorhallucis longus and flexor digitorum longus musclesincreased in the Nike Free group but not in the

control group.70

Nigg40 evaluated multiple minimalist shoes andconcluded that the term barefoot shoes is a

misnomer. Although different shoes may incorpo-rate specific aspects of the barefoot condition intotheir shoe, a ‘‘shoe condition is not a barefoot

condition.’’40(p78)

Discussion

Despite numerous upgrades and research-driven

changes in running shoes, the number of running-related injuries has not improved, and some would

say it is higher than ever. This has led manyclinicians and researchers as well as coaches and

runners to conclude that shoes themselves not only

do not reduce injuries but may cause or aggravaterunning-related abnormalities. Barefoot running

advocates claim numerous benefits, including stron-

ger muscles of the foot, better proprioception,reduced ankle sprains, less impact at foot strike,

increased economy of running, and the preventionof running-related injuries.

Advantages

Significant Alterations to Runner’s Gait.

There is little argument that running barefootprofoundly changes many aspects of gait compared

with wearing shoes. A clinical observer could make

logical assumptions of how these changes mightcreate advantages over shod running. Two such

advantages, well supported by the evidence but withqualification, would be reduced impact at contact

and improved proprioception.

Reduction of Impact Forces. The barefootrunner’s quicker, shorter strides and forefoot

landings are quite different from those of the shodrunner, who strikes at the heel. These changes are

said to reduce the shock at impact and, therefore,

reduce the incidence of numerous ailments associ-ated with the shock of running impact.

Barefoot running kinematics results in a forefoot/midfoot landing. The reduced ground reaction force

at foot strike is due to ankle joint plantarflexor

musculature impact attenuation (the reduced im-pact could also be due to a shortened stride length).

This does not necessarily mean that loading to the

lower extremity at large is reduced. More recently,some investigators have questioned the concept of

reduced impact in the barefoot runner. In fact,

incorporating the ankle plantarflexors (gastrocne-mius and soleus) during the impact phase of

running, as forefoot striking encourages, will reduceimpact ground reaction forces, but the additional

muscle forces may increase joint and skeletal

loading forces. In other words, a more activemusculature will pull osseous segments together,

increasing the load on the bones themselves and on

the interposed joints (ankle, knee, and possiblyeven hip). Although the barefoot running gait has

shorter strides and this would result in reduced


impact, the frequency of strides is increased, so theoverall total impact over a training run may not be

altered (Tim Derrick, PhD, written communication,November 2009). Indeed, a study by Edwards etal112 suggested that shorter strides probably reduce

the potential for stress fracture injuries, and runnerswishing to reduce their likelihood of stress fractures

should shorten their stride by 10%.

How these kinematic changes come about may be

through increased sensory feedback, creating gaitchanges in the barefoot runner known as anklecoordinative strategies. These result in the more

plantarflexed ankle position with forefoot contact atfoot strike and the subtalar joint held in a more

inverted attitude. The rationale for this is that therunner will modify ankle position (the so-called

coordination strategy) during running to maximizeperformance or because impact feedback to the

limb is unacceptable and must be altered. Thepositional modification of the subtalar joint during

barefoot running is said to come about from thebody’s reduced need for shock attenuation viasubtalar pronation because it can obtain it from

the musculature (largely the gastrocnemius). In-deed, reduced subtalar motion takes place in

barefoot runners. In other words, the shod runnerreceives feedback from the ankle ‘‘requesting’’ more

shock absorption because of how the foot landsand, thus, will land more pronated.

An increased variability of gait found in barefoot

versus shod runners and higher braking and pushingimpulses and higher preactivation of the triceps

surae are findings that suggest that improvedsensory feedback in barefoot runners is, at least in

part, responsible for the reduced impact forces.Conversely, sensory feedback is believed to be

diminished by wearing running shoes.

Last, stronger intrinsic musculature that raisesthe long arch, resulting in a more efficient shock

absorber, is another proposed mechanism forreduced impact in the barefoot condition; however,

maximal arch deformation and peak impact do notcorrelate chronologically.

Increased Economy of Running. Another sup-

posed benefit to running barefoot is increasedeconomy of running, and although it is clear that

elimination of the weight of the shoe will reduceenergy utilization, there is evidence that after

correcting for the weight of shoes, barefoot runningmay still be more efficient.

The initial assumption was that the reduced

energy expenditure was the result of the shoe’sadded mass and the expended effort in accelerating

and decelerating that mass multiple times during a

run. However, could the previously noted gaitchanges also be playing a role in reduced energy

expenditure? In other words, gait alterations seen inbarefoot runners may be more efficient. Divert et

al52 concluded that early studies correctly attributedthe increased energy utilization to shoe mass and

not gait changes. Some of the same gait alterationsthat reduced impact forces, such as shortened

contact time, forefoot landing, and triceps suraepreactivation, may also enhance the storage and

restitution of elastic energy.52 Studies35, 53 alsosuggested that the loss of stored energy duringshoe-related shock attenuation and the energy

required for repetitive shoe deformation add to theshod foot inefficiency.

Increased Proprioceptive Ability. With thefoot unshod, there is an intimate relationship with

the supporting surface. Given that numerous stud-ies113-119 have noted the significant role that plantar

mechanoreceptors play in postural control duringlocomotion, it is easy to see why barefoot running

advocates believe that the significant increase insensory input will substantially increase the pro-

prioceptive function of the foot while running. Thismore direct coupling of the runner to the ground

would result in a finer kinesthetic tuning (positionsense) to the running surface and, theoretically,

fewer injuries through adjustments to impact. Inaddition, besides disconnecting the supporting

surface from plantar sensory input, shoes, byelevating the foot from the ground, increase the

distance of the foot from the supporting surfaceand, thus, lessen the runner’s ‘‘feel’’ for the ground.

When one is barefoot, there is improved aware-

ness of foot position and, therefore, decreased footposition error. It was this greatly enhanced proprio-

ception seen in the barefoot condition that Robbinsand others8, 47 believed led to such better sensory

feedback that it would then create gait alterationsthat would ultimately lead to reduced impact and,

thus, reduced injury to striking structures, as wasoutlined in the previous subsection.

Note that the previously mentioned studies were

performed on individuals who were static and notwalking let alone running. In addition, many

studies120-122 assessed the plantar mechanorecep-tors that respond to pressure and vibration, and

some investigators have concluded that lower-limbmotor activity and postural control was more

affected by muscle spindle proprioceptive afferentsand Golgi tendon organs than by plantar cutaneous

afferents and, thus, may play a much greater role inbalance and proprioception. Nonetheless, most

investigators116, 117, 122 claim that they are just not


certain as to the hierarchy of importance when

considering plantar mechanoreceptors, Golgi ten-

don organs, muscle spindle afferents, and visual

clues. There is even the consideration that in an

unshod condition, proprioceptive elements (plantar

mechanoreceptors) may be dampened through

chronic impact loading.123

Last, Robbins and Gouw46 claimed that shoes

gave the runner a false sense of security and that

those runners, therefore, would not incorporate the

necessary gait changes to reduce impact. Their

study claimed that this could be much improved by

introducing simple surface irregularities to the

insoles, which would impart improved sensory

feedback that could assist in reducing impact.46

Reduction in Running-Related Injuries. Most

of the claims regarding the reduction of running-

related injuries in barefoot runners are made on the

basis of logical assumptions, such as running

barefoot results in stronger plantar intrinsic mus-

culature; therefore, this may be responsible for the

low incidence of plantar fasciitis seen in barefoot

runners.8 Or, barefoot runners have less impact and

because many running injuries are due to repetitive

high impact, barefoot runners may have fewer

injuries.39 However, no studies or even surveys

have substantiated these claims.40, 124 Although

there are numerous studies that demonstrate the

reduced lateral ankle instability in the barefoot

condition, they do not look at barefoot runners.

In their overview of ankle injuries, Robbins and

Waked63 make the point that although reduced

position sense while shod is a major factor in ankle

sprains, unanticipated foot placement (eg, on

another player’s foot) is frequently a factor as well.

Many runners have sprained an ankle on a trail

when a foot was placed on an unanticipated sloped

surface. It would stand to reason that an unexpect-

ed benefit of barefoot running is that in an effort to

avoid surface hazards through increased visual

surveillance, the barefoot runner would be much

less likely to have a misstep as the cause of an ankle

sprain.

Increased Strength of the Musculature. Bare-

foot running enthusiasts tout that by eliminating

confining and restrictive shoes, the foot will more

fully use the intrinsic musculature and, therefore,

develop greater strength and function. Improvement

in performance and reduction in injuries would then

result. Evidence is conflicting on the actual

strengthening potential of the barefoot condition,

and even if the barefoot condition led to increased

muscular strength, the claim that this results in

reduced injuries or improved performance has notbeen proved scientifically.

Decreased Risk of Foot Deformities. State-ments from professional organizations and studies

referencing the impact of shoes on foot develop-ment in children support the notion that shoes wornby children may inhibit normal development and,

hence, may increase the likelihood of deformitieslater in life. Although not directly related to barefootrunning, these findings were included because so

many barefoot running advocates extrapolate thefindings to the barefoot runner as a means toexplain some of the benefits.

Note that those studies on children do not suggestthat those running barefoot would necessarilydevelop fewer deformities but that an unshod foot

may be less confined and, thus, function morenaturally. The foot would, therefore, be less subjectto deformities and would more fully develop the

intrinsic musculature. The study by Morio et al76

looked at adults and came to a similar conclusionthat shoes inhibit the natural motions of the feet and

that this ‘‘could play a role in possible injurymechanisms.’’

Disadvantages

Although most layperson perspectives on barefootrunning revolve around the advantages, there arealso several possible drawbacks. Likewise, although

most scientific studies on barefoot running weredesigned to evaluate the advantages, there are alsoa variety of possible shortcomings. Many of the

downsides are readily obvious to those consideringbarefoot running and to the professionals who carefor feet. Following is a summary of some of these

concerns.

Injury from Running Surface. There are nopublished accounts of the risk of surface debris ortemperature extremes to the barefoot runner. Harsh

climates can significantly impact those wanting torun barefoot. Burns and frostbite are very realdangers in these types of conditions. Solutions for

reducing this risk range from wearing minimalistshoes that offer some protection to watching whereyou place your feet. This may be easier said than

done on surfaces such as grass, which wouldotherwise be one of the better surfaces for barefootrunning. Surveys of barefoot runners regarding their

experiences could verify its significance.

Availability of Adequate Surfaces. Although itmay seem logical that a more cushioned surface,

such as grass or a rubber track, would bepreferential for barefoot running, this need for


cushioning seems negated by the improved shockabsorption while running barefoot. One of us

(D.J.C.), who runs barefoot 50% of a 40-mile-per-week training program, has found that concrete or a

desert surface is a much kinder surface than isasphalt or grass (Fig. 1). A hard surface, such asconcrete, gives stability and instant feedback. He

reports that light-colored concrete also allowsforeign objects, such as rocks and glass, to be

visualized well. Concerns regarding climate-relatedsurface temperature extremes may be overcome

with indoor tracks or treadmills. The complete lackof evidence on the best surface for barefoot running

would bode well for the development of a surveytool that asks barefoot runners what surface they

prefer and why.

Exposure to Microorganisms/Infectious

Agents. Although inoculation with microorganisms

is a definite risk and in some instances isdocumented in the literature, it seems that the fears

of most people, including health-care practitioners,are exaggerated. The risk of exposure becomes

critical when a person is immunosuppressed or hasperipheral neuropathy. In these individuals, a minor

abrasion may lead to a debilitating infection.

Runners Who Require Mechanical Control

for Existing Conditions. Conceivably, foot spe-

cialists would worry that barefoot runners genuine-ly in need of customized support or motion control

shoes to alleviate existing conditions may becomeinjured if running barefoot. Proponents of barefoot

running claim that many of these runners wouldadjust and ultimately have fewer injuries if they

would go unshod. Runners who have been success-fully treated with orthotic devices for a running-

related injury may be reluctant to discontinueorthosis use and risk a return of their injury. Well-

designed controlled clinical trials need to beperformed to determine who needs specific shoes

or orthotic devices and who would be better offadding some barefoot activity. Surveys that query

barefoot runners on the outcomes of giving up theirorthoses would be beneficial.

Loss of Protective Sensation. Those with a

lack of protective sensation are advised to neverwalk without shoes, even in their own home, owing

to the increased risk of ulcers and even amputa-tion.105, 106, 125, 126 Given this potential, it would

seem quite inappropriate for this individual to berunning barefoot.

Increased Shock at Impact. This reported

finding, in conflict with multiple other studies,seems to be attributable to individuals running heel

first, contrary to barefoot running kinematics. Also

in conflict with the barefoot runner’s advantage of

reduced impact is a study110 that found an increased

rate of shock transmission to erector spinae back

muscles in barefoot conditions versus shod condi-

tions. This study required participants to begin the

contact phase with a heel strike. When given no

direction regarding gait changes, barefoot individu-

als naturally begin running with a midfoot strike.

We believe that any study of the barefoot condition

that requires its participants to adopt an unnatural

gait (encouraging a heel strike) will not achieve

valid results because it is not truly evaluating

barefoot function.

General Hazards. Blunt trauma, such as stub-

bing a toe, and encounters with insects, such as

scorpions, spiders, bees, and wasps, are a real

concern. Less likely would be a spike injury to the

barefoot runner in a competitive situation. On the

other hand, if the runner is barefoot, he or she is

unlikely to spike himself or herself.

Implementing Barefoot Running

Many barefoot runners do not recommend a rigid

schedule for implementing barefoot running. Most

barefoot runners who write about their experience

emphasize listening to your body and paying

attention to your interactions with your surround-

ings. If a barefoot runner chooses to use a

minimalist shoe as part of the adaptation process,

they may experience additional problems (see the

following subsection).

Figure 1. Running barefoot on desert terrain.


It is recommended that those considering bare-

foot running very gradually increase their barefoot

running activity because successful barefoot run-

ning seems highly dependent on proper implemen-

tation. There seems to be a consensus that with any

new activity, a gradual buildup be taken to allow for

musculoskeletal and cutaneous adaptation.

Shoes that Mimic Barefoot Running (Mini-

malist Shoes). Thus far, limited studies on two

minimalist shoes (Vibram FiveFingers and Nike

Free) indicate that kinematic changes similar to

barefoot running, as well as plantar intrinsic

strengthening potential, are occurring. Many coach-

es reported that several years ago when the Nike

Free became available, large numbers of high

school and college-level runners enthused with the

touted claims and benefits of barefoot running and

jumped into training at such a rate that many

became injured (Bill Strachan, MS, verbal commu-

nication, July 2009). Part of the reason may be that

the minimalist shoe gives a false sense of security

and the runner will train on a surface, at a pace, or

at a distance that the natural feedback, if totally

barefoot, would not allow. Put another way, a foot

with no covering will naturally disallow the ‘‘too

much, too soon, too fast’’ pitfalls when barefoot

running is initially undertaken. Nigg,40 in his review

of minimalist shoes, concluded that all of the shoes,

with their unique characteristics, may be beneficial

to the runner but that the label ‘‘barefoot shoe’’ is

more marketing than substance.

Research Needed and Unanswered Questions

Many of the questions that arise from reviewing the

topic of barefoot running may be answered with

future research efforts. We believe that the follow-

ing are just a few of the investigations that could

better inform runners, coaches, and health-care

providers on the merits and hazards of barefoot

running:

1) Survey of why people do or do not run barefoot.

2) Effects of barefoot running on competitive

performance.

3) Running-related injuries improved or eliminated

by barefoot running?

4) Barefoot running mechanics and the effect on

specific running-related conditions, such as

plantar fasciosis, medial tibial stress syndrome,

Achilles tendon disorders, and iliotibial band

friction syndrome.

5) Can using barefoot running mechanics while

running in shoes (eg, ChiRunning [http://www.

chirunning.com/]) reduce injuries?

6) Could the suggested greater requirement for

pronation when shod be the cause of so many

running-related injuries?

7) Can miles of unshod running dampen plantar

mechanoreceptors, making them less able to

function proprioceptively?

8) Could a forefoot/midfoot strike produce or

aggravate Achilles tendon abnormalities?

Conclusions

Multiple studies demonstrate profound gait differ-

ences in those running barefoot compared with

shod individuals.

Although numerous studies support the claimed

advantages of the barefoot condition, such as

reduced ground reaction force at impact and

improved sensory feedback and proprioception,

there is no evidence that these changes result in

reduced injuries or improved performance in

barefoot runners. It seems that these claims are

extrapolated or speculative.

Some other touted benefits of the barefoot

condition, such as increased strength of the plantar

intrinsic musculature and a more efficient utiliza-

tion of energy, have some supporting evidence, but,

again, there is no evidence to show that these

changes result in fewer injuries or improved

performance.

Evidence is strong that walking barefoot with a

lack of protective sensation is very risky and should

be avoided.

Many runners may benefit from the incorporation

of barefoot running into their regimen, and utiliza-

tion of highly controlling shoes or orthotic devices

may be detrimental for some.

Anyone implementing a barefoot training regimen

should begin with a minimal amount of activity and

should progress gradually to allow the plantar

surface of the feet, the intrinsic musculature, and

the osseous structures to adapt and avoid injury.

Those with conditions necessitating biomechan-

ical intervention, such as motion control shoes or

orthotic devices, should proceed with caution and

only if professionally supervised.

Evidence that barefoot running directly prevents

or improves running-related injuries is nonexistent.

More specifically, there are no studies to confirm

that barefoot runners have fewer lateral ankle

sprains, as the proponents claim. There is strong


laboratory evidence that those who are barefoothave such an improved position sense that theyhave much less lateral ankle instability or risk ofsprains.

Regarding the disadvantages involving hygiene,surface risk, and general hazards, the evidencesupports the notion that many of the purported risksare overblown.

We contend that many of the purported claimsmay have merit, but much more research onbarefoot running is needed, especially regardingcomparative biomechanics and injury rates as wellas surveys of runners’ opinions about barefootrunning.

In closing, professional organizations and manyclinicians with a keen interest in foot health andpodiatric sports medicine are becoming more awareof the purported claims and risks but are going to bereluctant to support or oppose barefoot runninguntil more definitive research and evidence areavailable.127 We believe that well-conducted studieswill demonstrate that barefoot running will, indeed,provide many of the touted advantages and at thevery least be a valuable adjunct to conventionaltraining methods.

Nonetheless, our opinion is that in addition to asports medicine foot specialist, those who are in thebest position to judge the appropriateness andusefulness of barefoot running are the coachesand runners themselves. Indeed, many coaches atmost competitive levels incorporate barefoot run-ning as part of the overall training regimen but notexclusively (Bill Strachan, MS, verbal communica-tion, July 2009).

Acknowledgment: Julie Jenkins for her assistancein providing photographs and proofing the manu-script and Bill Strachan for his invaluable inputfrom the coach’s perspective.Financial Disclosure: None reported.Conflict of Interest: None reported.

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Barefoot Running claims & controversies