This website deals with the evolutionary adaptation by humans to safe weight-bearing and locomotion when the bare foot is in direct contact with a support surface. All humans populations were essentially barefoot until the European Renaissance when people of all social classes began wearing shoes for the first time in human history. Interfaces placed between the foot and support surfces of all types interfere with protective mechanisms inherent to humans that make locomotion safe. As a consequence of footwear use Renaissance Europeans became the first group in human history to become sedentary - spending most wakeful hours sitting rather than weight-bearing, because footwear interfere with protective mechanisms that perserve the plantar skin. The profound health consequences of the change from weight-bearing to sedentary is an additional subject of this website. Background:
Circa 1980, I commenced research oriented at controlling the epidemic of “overuse” injuries associated with running. The modern running shoe was based on the biomechanists model of the human foot as inherently fragile thus needing protective packaging. I dismissed this analysis because it was inconsistent with the evolutionary necessity of a durable foot allowing safe mobility, and the observation that shoes based on the packaging solution failed to protect. I suspected that this injury susceptibility resulted from some aspect of modern life - perhaps shoes themselves. Fellow investigators allowed me 15 years to build, totally on my own, the foundation of our understanding of this issue, as reported in 19 scientific papers - each revealing a puzzle piece. There is now general acceptance of my analysis which has be aided by confirmatory reports from various disciplines. Yet those 19 papers are as fresh and current as the day they were written. |
How minimalist (“barefoot”) shoes cause so many injuries (April 2013)
A false sense of security resulting from deceptive advertizing of athletic shoes results in amplified impact, which explains the more than 100 percent greater injury frequency with wearers of expensive running shoes when compared to less expensive models.[1,2] Minimalist shoes are also called “barefoot shoes” (MBS) because they are sold based on deceptive advertizing suggesting protection through falsely suggesting that they elicit plantar sensory mediated mechanisms humans use to run safely barefoot. Since they resemble traditional running shoes regarding plantar sensory feedback that initiates human protective behavior, it was anticipated that the injury rate associated with their use would be similar to that found with expensive running shoes. The injury rate with minimalist shoes has exceeded these expectations. Specifically, forefoot injuries, such as metatarsal fractures, that have never been reported in exclusively barefoot runners, and occur only occasionally in runners wearing normal running shoes, is one of the common injuries with users of MBS.[3,4] A false sense of security from deceptive advertizing does not seem to fully explain this. An additional mechanism combined with excessive impact from a false sense of security is required to explain the danger of these products.
Minimalist shoes are not a clearly defined shoe category. For purposes of this discussion they are considered footwear without a heel counter, essentially no midsole material nor a cushioned sockliner. The fat pad of the human heel protects the calcaneus from damage from impact associated with activities such as running and jumping. The fat pad thins at the posterior calcaneus and disappears entirely as the posterior calcaneus thereby offering it no protection at all. [5] Absence of viscoelastic biologic sock absorbing material at the distal calcaneus results in a noticeable “thud” on even modest plantar surface–support surface impact in barefoot running when the bare foot is dorsiflexed. With full impact of running barefoot the result is pain and possible calcaneus damage. This serves as a negative reinforcer training the barefoot runner to make plantar surface contact with the support surface only when both are near parallel in the lateral plane.
Athletic shoes marketed for use when running typically possess a relatively thick layer of midsole material and also resilient material incorporated into the sockliner. These components protect the dorsiflexed calcaneus and allow painless surface contact when running with the dorsiflexed foot. Bereft of the feedback mechanism of barefoot runners that produce avoidance of posterior calcaneus, most runners using traditional running shoes make foot contact with the foot in significant dorsiflexion. Calcaneus loading is thereby greater and forefoot loading is moderated.[6-8] Also, knee extension increases thereby resulting in longer stride length is longer and vertical impact.[6-8]
The minimalist shoe offers relatively little posterior calcaneus protection. This results in foot position on impact that is only slightly more dorsiflexed than when barefoot, and stride length shorter than with typical athletic shoes – only slightly longer than when barefoot.[9] The consequence of less dorsiflexion with both barefoot runners and wearers of minimalist shoes is less loading of the calcaneus and greater loading of the forefoot compared to locomotion with traditional athletic shoes.[9] This similarity between locomotion with bare feet and with minimalist shoes resulted in an investigator to mistakingly conclude via inductive logic that running with MBS is the same as running barefoot in every aspect. This has encouraged some users to conclude that running with MBS is safe – furthering a false sense of security with these products.[9]
The barefoot runner is protected against damage to forefoot structures through a highly effective sensory feedback mechanism whereby the metatarsal-phalangeal joints have low pain threshold from combined vertical deformations and shear – an adequate stimulus for SA II mechanoreceptors.[10-11] This explains why metatarsal-phalangeal joints show minimal degeneration in barefoot populations when compared to an equivalent shod sample.[12] Although the sole of the minimalist shoe is thin, it party attenuates vertical deformations but horizontal (shear) considerably – both are needed as an adequate stimulus for SA II mechanreceptors. In this respect the minimalist shoe differs little from the traditional running shoe – both prevent the desire via sensory feedback to transfer load away from the delicate forefoot structures to the distal digits which are protected via fat pads. The wearer of traditional athletic shoes has little sensory feedback protecting forefoot structures but loads these structures less because of dorsiflexion on contact. Furthermore, users of traditional running shoes are protected modestly by the midsole and sockliner. The wearer of minimalist shoes is in the unfortunate position of greater forefoot loading compared to traditional athletic shoes yet no sensory feedback protection nor midsole protection of delicate forefoot structures. This, combination of elevated forefoot impact from the false sense of security caused by deceptive advertizing, greater forefoot loading with MBS and no protective forefoot load transfer to the distal digits results in a “perfect storm.” This explains why minimalist shoe use is associated with an alarming rate of forefoot injuries.
REFERENCES
[3] Ridge S, Johnson A, Mitchell, U et al. Foot bone marrow edema after 10 week transition to minimalist running shoes. Med Sci Sports Exerc 2013.
[4] Guiliani J, Masini B, Alitz C,Brett L, Owens D. Barefoot-simulating footwear associated with metatarsal stress injury in 2 runners. Orthopedics 2011 34:320-323.
[5] Logan B, Hutchings R. McMinns Color Atlas of Foot and Ankle Anatomy. Philadelphia: Saunders, 2011.
[6] Heiderscheit B, Chumanov E, Michalski M, et al. Effects of step rate manipulation on joint mechanics during running. Med Sci Sports Exerc 2011 43:296-302.
[7] Derrick T, Hamill J, Caldwell G. Energy absorption of impacts during running at various stride lengths. Med Sci Sports Exerc. 1998 30:128–135.
[8] Edwards W, Taylor T, Rudolphi J, et al. Effects of Stride Length and Running Mileage on a Probabilistic Stress Fracture Model. Med Sci Sports Exerc. 2009 41:2177–2184.
[9] Lieberman D, Venkadesan M, Werbel W, et al. Foot strike patterns and collision forces in habitually barefoot versus shot runners. Nature 2010 463:531-535.
]12] Zipfel B, Berger L. The emergence of forefoot pathology in modern humans? Foot 2007 17:205-213.August 2012
On March 29, 2012, the media became inundated with articles reporting a class action lawsuit that was filed against Vibram, manufacturer of Five Fingers shoes. This lawsuit resulted from a spectacular numbers of injuries reported with Vibram Five Fingers shoes compared to few reports indicating injury from true barefoot running which Vibram claimed their product emulated. This website has reported for two years about the danger of deceptive advertizing of products often referred to as “minimalist shoes” or “barefoot shoes,” and predicted that the additional false sense of security imparted via this advertizing would result in a many injuries.
This litigation against Vibram creates an opportunity to review the history of the marketing of the modern running shoe. Deceptive advertizing of athletic shoes did not begin with this new shoe category. It began when the modern running shoe was found to be associated with frequent injury decades ago.
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REVIEW OF PREVIOUSLY POSTED ENTRIES
Why humans continue to wear shoes - Posted May 2011
Many reports indicate that humans have used footwear for several thousand years. Few have dealt with the extent of their use within communities and their purpose, which is considered here. Outside of small groups living in extreme northern latitudes, footwear were used by small elite groups within many societies to indicate elevated status at the expense of health and functionality during locomotion. The first region in which the majority were shod was Renaissance Europe, where people of all classes donned footwear for the first time for reasons other than status. They were willing to pay a considerable price in terms of health and mobility through footwear use in an attempt to survive death from disease according to then current notions.
The recently shod from the developing world are under no such illusions about the benefits of footwear. They know that diseases acquired by being barefoot are rare and are not communicable. Whereas their feet feel fine when they are barefoot, they are painful when they wear shoes, and they remain so after they are removed. They find them unsafe because shoes cause them to trip and fall. They note that it is more tiring to walk and run wearing them. They may not know that the plantar surface has the highest density of sweat glands of any body part, but they notice foot stench for the first time in their lives when they remove their initial shoes, and wonder why people in the developed world tolerate this disgusting condition of keeping their feet perpetually bathed in sweat through footwear use. They avoid them when they are not required. They dismiss shoe wearing as a purely illogical price that must be paid for entry into the colonialist created educational system, administration and industry - simply another mandated change in a sensible traditional practice required to escape from poverty.
Ironically, most people living in developed countries are now historically so far removed from when their fore-bearers commenced footwear use that they have forgotten the actual reason why they were first worn and are presently in such widespread use. This has made them vulnerable to myths regarding the importance of footwear to good health fabricated mainly by self-serving pseudoscientists. What follows is an examination of the origins of footwear in terms of health and mobility, with emphasis on explaining their current prevalence. From this comes ideas about advancing public health.
Effect of footwear on mobility
Mobility with footwear in any era is considered here to be the ability to walk and run efficiently with footwear relative to the barefoot state on common pedestrian routes used by humans. Some of the earliest examples of footwear use in a society that are available from records and artifacts comes from ancient Greece and Egypt. The sandal was occasionally worn mainly by men in all but the poorest classes commencing perhaps 2000 BCE in ancient Egypt. Footwear use was not a social norm because men of even the highest classes were often visually portrayed barefoot. The shoe was made out of ornately decorated leather and papyrus reed for the higher and lower classes, respectively. It incorporated a thin, relatively delicate, flexible sole with a smooth external profile. The fixation system usually consisted of two thongs, which made them suitable for walking but not running. Almost all roads in Egypt were compacted naturally deposited ground, therefore shoes of this construction were insufficiently robust for continuous walking on this substrate. The smooth sole permitted only minimal traction on paths and roads compared to the bare foot which could accommodate to surface irregularities and grip with plantar flexion of the digits. This leads to the conclusion that footwear were mainly decorative and used within living quarters or briefly outdoors. Effective locomotion was performed with the bare foot.
Footwear design and construction techniques in Europe remained relatively unchanged until modern times. The first footwear which was allowed safe running appeared in Victorian England. It consisted of thin-soled leather shoes with protruding nails to aid traction, which closely resembles the modern running “spikes.” They were functional only on a limited array of natural surfaces such as “cinder” tracks or extremely uniform naturally deposited ground, but were hazardous on pavement which was by then the normal surface in urban areas. It can be said that under this limited array of conditions these footwear allowed efficient walking and running, perhaps equal or occasionally even superior to the bare foot. As for footwear in more general use by the public at this time, the limitations in mobility resembled those of earlier products.
Patellofemoral disorders are caused mainly by footwear use and are treated through bare foot weight bearing. These disorders are the result of repetitive "chipping" of the articular cartilage of the patella from chronic partial subluxation, followed by a snapping return to the patellar groove of the femur. This can occur when standing, but is more troublesome during locomotion, due to excessive stride length when wearing shoes compared to the bare foot condition. The mechanism is as follows. The barefoot lacks plantar fatpad protection of the posterior calcaneus, which forces, through sensory feedback, surface contact during locomotion with the plantar surface approximately parallel to the support surface. The protection of the porterior calcaneus offered by footwear encourages contact with the posterior aspect of the calcaneus with associated foot dorsi-flexion relative to the support surface. The related increased stride length is achieved through greater knee extension. This creates the condition for subluxation of the patella and patellofemoral disorders.
Falls risk is higher when wearing footwear compared to when barefoot. This is explained by balance mediated through precise sensory information from plantar tactile receptors when barefoot, verses less reliable muscle receptors when shod. This poor stability produces a behavioral response which amplifies impact. This phenomenon accounts for frequent chronic excessive impact related injuries particularly in runners wearing contemporary running shoes, which destabilize through oscillatory foot movements caused by thick, resilient layers underfoot.
Zipfel B, Berger LR, Shod versus unshod: the emergence of forefoot pathology in modern humans. The Foot 17, (2007)
Health benefit of footwear
Footwear clearly should be considered a net health benefit (health benefit in excess of health cost) when they are required for survival. The only available example of this is a specific example variably called the "mukluk" or "kamik" (depending on which native language used), which was worn by those peoples who have inhabited Arctic North America for perhaps 15,000 years, and up to 40,000 years (by some estimates) in Siberia. Although this footgear possess the same health and mobility limitations of most others, it uniquely protects against tissue damage from the extreme cold which kills. Insulation is attained through their loft (trapped air pockets), and their ability to retain insulating properties through dissipation of water vapor emanating from foot and leg transpiration and perspiration. Wearing these footwear, together with other specialized articles of clothing that insulate, was essential to migration to, and existence in the extreme North until modern times. When ancient mukluk artifacts are compared to more recent examples, there is an amazing similarity, perhaps with the exception of addition of mainly aesthetic elements in the form of bead decoration and fine sole stitching patterns, which became used to indicate tribal identification and class structure. North American native groups in moderate climatic regions continued the use of decorative tradition after they left the extreme North through use of the less insulated abbreviated mukluk, we now refer to as the “moccasin.”
Aside from the above cases, it is hard to think of other conditions where footwear health benefit rises above their health costs. This may come as some surprise to many because scientifically discredited notions regarding footwear health benefits have become contemporary collective folklore. For example, many imagine footwear prevent plantar penetrating wounds which would be prevalent without their use. This seems unlikely because barefoot runners report that this risk is actually extremely low, and this is confirmed by anecdotal report from parts of countries where barefoot activity is common. Also, there is no scientific evidence that footwear advance health through the ill defined concept of “support.” Support in shoes is sometimes used when discussing ankle sprain prevention. There is no evidence that footwear act as a effective brace against sprains, rather there is evidence that they are their main cause. Support is also used when considering maintaining height of the longitudinal foot arches. There is no scientific evidence that footwear function this way. What seems clear is that for the large majority of humans who currently wear shoes, health cost exceeds benefit.
Selected reference:
Betty Kobayashi Issenman, Sinews of Survival: Living Legacy of Inuit Clothing, UBC Presss, 1997
Footwear fashion and social norms
By the beginning of the Age of Discovery in Europe, footwear wearing had become an implicit social norm in all countries with the only limitation being their affordability. One feature that emerged during this era was the elevated heel, which remains intrinsic to most current footwear. In exploring the history of footwear, higher heels are occasionally though inconsistently found through the ages in many societies. However, following the ascent of Timur (usually now called Tamerlane) in the late fourteenth to early fifteenth centuries, elevated heels have been consistently present in footwear examples from many regions. The name “Tamerlane” is an altered contraction of “Timur the lame.” His lameness appears to have resulted from a calf injury sustained in battle which caused contracture of calf muscles on one side, thereby making his foot on his injured side permanently plantarflexed. Elevated heels allowed him to walk more normally and stand with square shoulders, presumably improving his otherwise disabled appearance. This may be an example of how influential figures exert influence on fashion in footwear. It also demonstrates who features of shoes may be best explained by fashion rather than function.
One might think that in the twentieth century people would have gradually commenced eschewing footwear outside of the home, considering the advancement of scientific notions indicating prevalent footwear created disorders, and the bare foot being essentially free from risk of disease acquisition. However, this natural course of health advancement has been delayed by the rise of foot pseudoscience. It is common to see men in white coats appearing to be true scientists or physicians, but are actually pseudoscientists in the form of podiatrists, chiropodists and the like, promoting scientifically discredited ideas strictly for personal gain.
Practitioners in field of podiatry and allied foot pseudosciences have made a good living largely dealing with footwear created problems ineffectively, much as the chiropractor profits from “subluxations.” They base their practices on the false notion that the foot is a delicate structure that requires specialized footwear and other devices, which they conveniently sell, to prevent and correct presumed “disorders.” They also claim falsely that there is an ideal foot geometry and alignment when bearing weight, that once attained, often with expensive “corrective devices,” which they again conveniently sell, health will be improved. The notion that footwear use is the cause of most painful feet, and barefoot activity may be the solution, is a threat to their existence, and they respond vigorously to this “preposterous” notion with feigned indignation. The fact that there is not a datum to support their ideas and a large body of scientific information discrediting them has perhaps only intensified their efforts to maintain their livelihood at the expense of their clients through treating fake disorders such as “fallen arches” or excessive pronation and supination.
What has made the maintenance of these self-serving notions of the foot pseudoscientists immeasurably easier has been the intellectual laziness of the medical profession. Legitimate medical practitioners are constantly faced with patients with painful, disabling feet. Rather than dealing scientifically with them, they refer to the pseudoscientists. By doing this, the medical profession has become complicit in maintaining this pseudoscience much as it maintains chiropractors.
Prevention - the sensible solution
Many health problem caused by footwear are caused by an accumulation of a multitude of sub-clinical injuries. This category has been given the inappropriate name of "overuse injuries."The term is improper because it gives the impression that these disorders are inherent to human weight-bearing in all its forms, rather than caused by an external device (footwear) which induce damage, and could have been avoided through more appropriate barefoot weight-bearing. The solution to footwear created disorders is best understood in terms of preventive medicine. It involves primary, secondary, tertiary and quaternary prevention. Primary prevention for many footwear created disorders would require barefoot weightbearing essentially from birth, therefore for most contemporary individuals who have worn footwear, primary prevention is not possible. Secondary prevention is the only possibility in an attempt to delay the expression of an already evolving condition. Once symptoms appear, management involves tertiary prevention in an attempt to avoid re-expression of an already advanced condition. Some others, have footwear created disorders so severe that they will never be symptom free. Quaternary prevention through barefoot activity may allow attenuating the symptoms and permit improved functionality. The details of prevntion of footwear created disorders varies in related to disease type, hence is complex. It will be the subject of the next series to appear on this website, commencing June, 2011.
Conclusion