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Transitioning to Minimalist Shoes Gradually Avoids Injury

Inspired by barefoot running, many runners are switching to minimalist shoes, which help alter a runner’s style into a more forefoot striking or ‘natural running’ gait. This running style has been associated with a reduced likelihood of injury and increased speed and efficiency.

What many runners fail to realise however, is that a rapid change to minimalist footwear often causes injury. In answer, inov-8™ have launched a unique range of shoes that can help provide an injury free transition into minimalist shoes by offering gradually reducing cushioning, support and differential.

Download a Training Program for making the transition to natural running here.

In this review of the evidence we find that a possible solution to the high incidence of running injuries has been inspired by barefoot running and lies in the gradual transition into minimalist shoes.

The great dichotomy between the grass routes driven interest in barefoot running and rush into minimalist footwear is that they can cause as many injuries as they prevent.

Changing from cushioned shoes to minimalist shoes is likely to change your running style. It’s the same experience you will have if you try barefoot running, which for most runners instantly transforms them from heel strikers to midfoot/forefoot strikers with an increased cadence. Indeed, in 2011 Hamilla et al found that runners in their study* “appeared to alter their footfall pattern from a rearfoot to a midfoot pattern when changing from running shod to barefoot”. It is this rapid change in style that puts new stresses and strains on the body and may lead to injury if not gradually introduced.

inov-8™ are unique amongst the running brands in offering a range of shoes that are neutral and have reducing levels of cushioning and differential (heel to toe drop). This enables runners to make a controlled and gradual transition into more minimalist shoes, significantly reducing the likelihood of injury but without loosing the long-term benefits of adopting a more natural running style.

Apart from a hearty band of barefoot purists, no one is claiming that the evidence for minimalist running is conclusive. However, it is compelling, logical and overwhelming.

Richards et al published a study* in 2008 seeking to answer the question “Is your prescription of distance running shoes evidence-based?” He concluded that “The prescription of this shoe type to distance runners is not evidence-based”. Famously, Richards then issued an open challenge to the established running shoe brands to provide any evidence that their shoes reduced injuries and or improved performance. Years later he is still waiting for any reply.

Many runners will be familiar with the average running store experience. Typically, the store will offer video gait analysis, identify a biomechanical fault and then offer a motion controlling or stability shoe to solve the problem. Apart from asking who trained the Saturday help, it would be fair to assume that this process is based on proven scientific evidence. It is not.

A recent 2010 study* by Knapik et al demonstrated that prescribing motion control shoes or neutral shoes randomly had “little influence on injuries”. Furthermore a 2009 study* by Ryan et al (co authored by Gordon Valiant, Head of Nike’s Biomechanical Research) found that “prescribing in-shoe pronation control systems on the basis of foot type is overly simplistic and potentially injurious” and their research concluded that, "This study is unable to provide support for the convention that highly pronated runners should wear motion control shoes."

Many research papers* in the 1980s made the link between running shoes and injuries. Burkett et al demonstrated in 1985 that “displacement of the knee during barefoot running was significantly less than shoe and shoe-plus-orthotic conditions” and that “… the aerobic cost of running increased as the amount of mass added to the foot increased. In absolute terms, running in shoes plus orthotics was significantly more costly than running barefoot.”

A seminal study* of the 1984 Bern Grand Prix by Marti et al showed that, as competitors trained prior to the race, injuries soared; “Of 4,358 male joggers, 45.8% had sustained jogging injuries during the 1 year study period”.

Back in the running store, it’s the footwear brands that provide the technical training to the retail staff, who then advise you. If you were an over-pronator, you almost certainly would have been recommended motion-controlling shoes. It would seem that the advice many runners receive has little basis in fact, and it remains obvious to anyone involved with running that injury rates are unacceptably high.

A significant body of research* indicates that running barefoot enables runners to increases their speed and efficiency whilst also reducing the likelihood of injury. In a watershed moment, Lieberman et al took the arguments for barefoot running mainstream with their 2010 paper* published in Nature stating that “habitually barefoot endurance runners often land on the fore-foot (fore-foot strike)” and that “Fore-foot- and mid-foot-strike gaits were probably more common when humans ran barefoot or in minimal shoes, and may protect the feet and lower limbs from some of the impact-related injuries now experienced by a high percentage of runners”

Binning your favourite running shoes is both impractical and fortunately unnecessary for most runners, especially those that run in rough terrain or high mileage. The logical solution points to adopting a natural running style through the use of minimalist footwear.

Natural running describes a forefoot-striking gait, where your centre of gravity is forward and your cadence is faster than if you were heel striking. Barefoot runners naturally adopt this style of running and minimalist shoes encourage runners to do the same.

Minimalist shoes are neutral, have minimal (or even no) cushioning, offer no support or motion control and crucially have minimal differential between heel and forefoot height (imagine your barefoot on the ground, it is flat and the heel isn’t raised, this means that your natural biomechanics are unaltered).

Hamill et al* made the link between shoe cushioning, support and injury in 1988 “since foot control seems to improve as cushioning is lost and foot control accounts for at least half of running shoe related injuries”. By shielding the foot from the ground with excessive cushioning, you limit proprioception (ground feel) and how the body reacts to the terrain through fine adjustments in balance and body position. Research* back in 1987 by Robbins et al indicated that “The sensory insulation inherent in the modern running shoe appears responsible for the high injury frequency associated with running”.

inov-8™ believe that by getting the foot closer to the ground (by minimising midsole cushioning) you increase proprioception and reduce the chance of injury. Combined with a forefoot ‘natural running’ style ever runner can limit the likelihood of injury further still.

inov-8™ are leading the running shoe industry by taking a responsible approach to the introduction of minimalist footwear and have launched a range of shoes that have decreasing levels of heel to toe drop (differential), cushioning and support so that runners can make a safe and injury free transition to minimalist shoes. The heel of each inov-8™ shoe has arrows on it, indicating the amount of cushioning, differential and support with a 4 Arrow Shoc-Zone shoe offering the most and Zero Shoc-Zone™ offering the least.

Returning to Richards et al.’s famous challenge from 2008. The mainstream running industry has failed to provide any evidence to support the use of cushioned and supportive running shoes. It is hoped that many runners will read this, view the research at www.inov-8.com/research and follow the links below before making up their own mind.

The Research

In an ideal world inov-8™ would commission and fund its own scientific research to support its claim that after making a gradual transition to minimalist running shoes and switching to a ‘natural’ forefoot striking running style, runners can expect to have fewer injuries and run with improved speed and efficiency. Unfortunately research of that nature is technical challenging and beyond the resources of a company the size of inov-8™

However, there is a wealth of independent, peer reviewed, scientific research stretching back to 1983 that broadly supports the inov-8™ philosophy. Whilst we are not claiming that this research is conclusive we do say that it is compelling.

Famously, Dr Craig Richards published a study in 2008 seeking to answer the question “Is your prescription of distance running shoes evidence-based?” He concluded that it was not and issued an open challenge to the established mainstream running brands to provide any evidence that their shoes reduced injuries or improved performance… he is still waiting for a reply.

Footwear Science – The Official Journal of the Footwear Biomechanics Group

Volume 3, Issue 1, 01 Mar 2011

Impact characteristics in shod and barefoot running

Joseph Hamilla, Elizabeth M. Russella, Allison H. Grubera, Ross Millera

http://www.informaworld.com/smpp/content~db=all~content=a933410094~frm=abslink

Increased impact characteristics are often cited as a cause of running injuries. One method that has been used to reduce impact characteristics is to increase the thickness of the midsole of running footwear with the intention of attenuating greater shock from the foot-ground collision. A second method that has been suggested is to run barefoot. The purpose of this study was to compare the impact characteristics of running footwear of different midsole thickness to a barefoot condition. Three-dimensional kinematic and kinetic data were collected as participants ran at their preferred running speed and at a fixed speed. Impact characteristics (impact peak, time to impact peak and vertical loading rate) were derived from the vertical ground reaction force component. Ankle and knee joint stiffness during the loading phase of support were derived from the change in moment divided by the change in angle. The impact parameters were statistically analyzed using a two-way, repeated measures ANOVA. There were no significant speed by footwear condition interactions. For impact peak, ankle stiffness and knee stiffness, there was no difference among the shod conditions but there were significant differences between the shod and barefoot conditions. Based on their strike index, participants in this study appeared to alter their footfall pattern from a rearfoot to a midfoot pattern when changing from running shod to barefoot. It may be concluded that the change in the impact characteristics is a result of changing footfall pattern rather than midsole thickness.

The American Journal of Sports Medicine

September 2010 vol. 38 no. 9 1759-1767

Injury Reduction Effectiveness of Assigning Running Shoes Based on Plantar Shape in Marine Corps Basic Training

Joseph J. Knapik, Daniel W. Trone, David I. Swedler, Adriana Villasenor, Steve H. Bullock, Emily Schmied, Timothy Bockelman, Peggy Han, and Bruce H. Jones

http://ajs.sagepub.com/content/38/9/1759.abstract?sid=bf81eb89-4315-4663-b722-cc61c39bb04b

Background: Shoe manufacturers market motion control, stability, and cushioned shoes for plantar shapes defined as low, normal, and high, respectively. This assignment procedure is presumed to reduce injuries by compensating for differences in running mechanics. Conclusion: This prospective study demonstrated that assigning shoes based on the shape of the plantar foot surface had little influence on injuries even after considering other injury risk factors.

Nature – International Weekly Journal of Science

Nature 463, 531-535 (28 January 2010)

Foot strike patterns and collision forces in habitually barefoot versus shod runners

Daniel E. Lieberman, Madhusudhan Venkadesan, William A. Werbel, Adam I. Daoud, Susan D’Andrea, Irene S. Davis, Robert Ojiambo Mang’Eni & Yannis Pitsiladis

http://www.nature.com/nature/journal/v463/n7280/full/nature08723.html

Humans have engaged in endurance running for millions of years1, but the modern running shoe was not invented until the 1970s. For most of human evolutionary history, runners were either barefoot or wore minimal footwear such as sandals or moccasins with smaller heels and little cushioning relative to modern running shoes. We wondered how runners coped with the impact caused by the foot colliding with the ground before the invention of the modern shoe. Here we show that habitually barefoot endurance runners often land on the fore-foot (fore-foot strike) before bringing down the heel, but they sometimes land with a flat foot (mid-foot strike) or, less often, on the heel (rear-foot strike). In contrast, habitually shod runners mostly rear-foot strike, facilitated by the elevated and cushioned heel of the modern running shoe. Kinematic and kinetic analyses show that even on hard surfaces, barefoot runners who fore-foot strike generate smaller collision forces than shod rear-foot strikers. This difference results primarily from a more plantarflexed foot at landing and more ankle compliance during impact, decreasing the effective mass of the body that collides with the ground. Fore-foot- and mid-foot-strike gaits were probably more common when humans ran barefoot or in minimal shoes, and may protect the feet and lower limbs from some of the impact-related injuries now experienced by a high percentage of runners.

Nature – International Weekly Journal of Science

Nature 463, 433-434 (28 January 2010)

Biomechanics: Barefoot running strikes back

William L. Jungers

http://www.nature.com/nature/journal/v463/n7280/full/463433a.html

Detailed analyses of foot kinematics and kinetics in barefoot and shod runners offer a refined understanding of bipedalism in human evolution. This research will also prompt fresh studies of running injuries.

The American Academy of Physical Medicine and Rehabilitation

Volume 1, Issue 12, Pages 1058-1063, December 2009

The Effect of Running Shoes on Lower Extremity Joint Torques

D Cassey Kerrigan, Jason R. Franz, Geoffrey S. Keenan, Jay Dicharry, Ugo Della Croce, Robert P. Wilder

http://www.pmrjournal.org/article/S1934-1482(09)01367-7/abstract

Increased joint torques at the hip, knee, and ankle were observed with running shoes compared with running barefoot. Disproportionately large increases were observed in the hip internal rotation torque and in the knee flexion and knee varus torques. An average 54% increase in the hip internal rotation torque, a 36% increase in knee flexion torque, and a 38% increase in knee varus torque were measured when running in running shoes compared with barefoot.

British Journal of Sports Medicine

doi:10.1136/bjsm.2009.069849

The effect of three different levels of footwear stability on pain outcomes in women runners: a randomised control trial

Michael B Ryan, Gordon A Valiant, Kymberly McDonald, Jack E Taunton

http://bjsm.bmj.com/content/early/2010/06/26/bjsm.2009.069849.abstract

Background The present study examines the injury status in women runners who are randomised to receive a neutral, stability or motion control running shoe. Conclusion The findings of this study suggest that our current approach of prescribing in-shoe pronation control systems on the basis of foot type is overly simplistic and potentially injurious

The American Journal of Sports Medicine

December 4, 2009, doi: 10.1177/0363546509347985

Predictors of Running-Related Injuries in Novice Runners Enrolled in a Systematic Training Program

Ida Buist, Steef W. Bredeweg, Koen A. P. M. Lemmink, Willem van Mechelen, FACSM, and Ron L. Diercks.

http://ajs.sagepub.com/content/early/2009/11/25/0363546509347985.abstract

Background The popularity of running is still growing. As participation increases, running-related injuries also increase. Until now, little is known about the predictors for injuries in novice runners. Methods Participants were 532 novice runners (226 men, 306 women) preparing for a recreational 4-mile (6.7-km) running event. After completing a baseline questionnaire and undergoing an orthopaedic examination, they were followed during the training period of 13 weeks. An RRI was defined as any self-reported running-related musculoskeletal pain of the lower extremity or back causing a restriction of running for at least 1 week. Results Twenty-one percent of the novice runners had at least one RRI during follow-up. The multivariate adjusted Cox regression model for male participants showed that body mass index (BMI) (hazard ratio [HR], 1.15; 95% confidence interval [CI], 1.05–1.26), previous injury in the past year (HR, 2.7; 95% CI, 1.36–5.55), and previous participation in sports without axial load (HR, 2.05; 95% CI, 1.03–4.11) were associated with RRI. In female participants, only navicular drop (HR, 0.85; 95% CI, 0.75–0.97) remained a significant predictor for RRI in the multivariate Cox regression modeling. Type A behavior and range of motion (ROM) of the hip and ankle did not affect risk. Conclusion Male and female novice runners have different risk profiles. Higher BMI, previous injury, and previous sports participation without axial loading are important predictors for RRI in male participants. Further research is needed to detect more predictors for female novice runners.

American College of Sports Medicine

September/October 2009 - Volume 8 - Issue 5

Foot and Ankle Injuries in the Barefoot Sports

Vormittag, Kara; Calonje, Ronald; Briner, William W.

http://journals.lww.com/acsm-csmr/Abstract/2009/09000/Foot_and_Ankle_Injuries_in_the_Barefoot_Sports.12.aspx

Playing sports barefoot has been contested since the very beginnings of athletic competition. Even today, some data suggest that shoes may limit the adaptive pronation that occurs after footstrike during running gait. This pronation likely protects runners from injury. Boardsport participants who perform their sports barefoot on the water seem to be at risk for foot and ankle injuries. The high-impact forces in gymnastics place participants at risk for foot and ankle injuries, as well. Swimming and diving have a low rate of foot and ankle injuries. The risk of ankle sprain in beach volleyball, which is played barefoot, seems to be lower than that for indoor volleyball, played wearing shoes. Martial arts place competitors at risk for injuries to the foot and ankle from torsional and impact mechanisms. Athletes who hope to return to barefoot competition after injury should perform their rehabilitation in their bare feet.

Journal of Sports Medicine and Physical Fitness

2009 Mar;49(1):6-13.

Biomechanical and physiological comparison of barefoot and two shod conditions in experienced barefoot runners.

Squadrone R, Gallozzi C.

http://www.ncbi.nlm.nih.gov/pubmed/19188889

The first aim of this study was to assess how changes in the mechanical characteristics of the foot/shoe-ground interface affect spatio-temporal variables, ground pressure distribution, sagittal plane kinematics, and running economy in 8 experienced barefoot runners. The second aim was to assess if a special lightweight shoe was effective in mimic the experience of barefoot running. RESULTS: Compared to the standard shod condition when running barefoot the athletes landed in more plantarflexion at the ankle. This caused reduced impact forces and changes in stride kinematics. In particular, significantly shorter stride length and contact times and higher stride frequency were observed. CONCLUSIONS: The data of this study support the assumption that changes in the foot-ground interface led to changes in running pattern in a group of experienced barefoot runners.

British Journal of Sports Medicine

43:745-749 doi:10.1136/bjsm.2008.047761

Running in new and worn shoes: a comparison of three types of cushioning footwear

P W Kong, N G Candelaria, D R Smith

http://bjsm.bmj.com/content/43/10/745.abstract?sid=34372667-14e7-46c3-8894-28f0e853ab5e

Objectives: In this study, the effect of shoe degradation on running biomechanics by comparing the kinetics and kinematics of running in new and worn shoes was investigated. Three types of footwear using different cushioning technologies were compared. Conclusions: As shoe cushioning capability decreases, runners modify their patterns to maintain constant external loads. The adaptation strategies to shoe degradation were unaffected by different cushioning technologies, suggesting runners should choose shoes for reasons other than cushioning technology.

The Journal of Physical Education, Recreation and Dance

April 2008

Preventing running injuries through barefoot activity: sometimes "dressing out" means not putting on your shoes.

Hart, Priscilla M.; Smith, Darla R.

http://www.highbeam.com/doc/1G1-178448803.html

The purpose of this article is to describe for coaches and runners the theory behind the use of barefoot activity as a method of reducing running injuries. It will also provide practical advice for implementing barefoot activity in a training regimen.

British Journal of Sports Medicine

43:159-162 doi:10.1136/bjsm.2008.046680

Is your prescription of distance running shoes evidence-based?

C E Richards, P J Magin, R Callister

http://bjsm.bmj.com/content/43/3/159.short

Objectives: To determine whether the current practice of prescribing distance running shoes featuring elevated cushioned heels and pronation control systems tailored to the individual’s foot type is evidence-based. Conclusion: The prescription of this shoe type to distance runners is not evidence-based.

International Journal of Sports Medicine

2008 Jun;29(6):512-8.

Barefoot-shod running differences: shoe or mass effect?

Divert C, Mornieux G, Freychat P, Baly L, Mayer F, Belli A.

http://www.ncbi.nlm.nih.gov/pubmed/18027308

The higher oxygen consumption reported when shod running is compared to barefoot running has been attributed to the additional mass of the shoe. However, it has been reported that wearing shoes also modified the running pattern. The aim of this study was to distinguish the mass and shoe effects on the mechanics and energetics when shod running. Twelve trained subjects ran on a 3-D treadmill ergometer at 3.61 m . s (-1) in six conditions: barefoot, using ultra thin diving socks unloaded, loaded with 150 g, loaded with 350 g, and two shoe conditions, one weighing 150 g and another 350 g. The results show that there was a significant mass effect but no shoe effect for oxygen consumption. Stride frequency, anterior-posterior impulse, vertical stiffness, leg stiffness, and mechanical work were significantly higher in barefoot condition compared to shod. Net efficiency, which has metabolic and mechanical components, decreased in the shod condition. The mechanical modifications of running showed that the main role of the shoe was to attenuate the foot-ground impact by adding damping material. However, these changes may lead to a decrease of the storage and restitution of elastic energy capacity which could explain the lower net efficiency reported in shod running.

Journal of the New Zealand Medical Association

18-April-2008, Vol 121 No 1272

Barefoot running and walking: the pros and cons based on current evidence

Keith Rome, Dene Hancock, Daniel Poratt

http://nzmj.com/journal/121-1272/3024/

In response to the recent debate on barefoot running and walking of children published in the New Zealand Herald1 we have put together an argument relating to the pros and cons based on current evidence. There is very limited evidence specifically relating to barefoot running and walking in children. One study from Germany reported that the increased prevalence of flatfoot and hallux valgus (bunions) in modern societies may be the consequence of inadequate footwear in childhood.2 The German study postulated that barefoot walking represents the best condition for the development of a healthy foot…

Medicine and Science in Sports and Exercise - The Official Journal of the American College of Sports Medicine

February 2007 - Volume 39 - Issue 2

Gait-Related Risk Factors for Exercise-Related Lower-Leg Pain during Shod Running

Willems, Tine Marieke; Witvrouw, Erik; De Cock, Anneleen; De Clercq, Dirk

http://journals.lww.com/acsm-msse/Abstract/2007/02000/Gait_Related_Risk_Factors_for_Exercise_Related.16.aspx

Purpose: Exercise-related lower-leg pain (ERLLP) is a common chronic sports injury. In clinical practice, deviant gait biomechanics are frequently considered to play a role in the development of ERLLP, although there is scarce scientific evidence that gait-related variables predispose athletes to this injury. The purpose of this study was to examine prospectively the gait-related risk factors for ERLLP during shod running in a young, physically active population. Conclusion: The findings of this study suggest that altered gait biomechanics during shod running play a role in the genesis of ERLLP and, thus, should be considered in prevention and rehabilitation of this pathology.

British Journal of Sports Medicine

42:189-193 doi:10.1136/bjsm.2007.038844

Do you get value for money when you buy an expensive pair of running shoes?

R Clinghan, G P Arnold, T S Drew, L A Cochrane, R J Abboud

http://bjsm.bmj.com/content/42/3/189.abstract?sid=7cda87c0-b007-4479-99f2-c4fa8b51b6c8

Objective: This investigation aims to determine if more expensive running shoes provide better cushioning of plantar pressure and are more comfortable than low-cost alternatives from the same brand. Conclusions: Low- and medium-cost running shoes in each of the three brands tested provided the same (if not better) cushioning of plantar pressure as high-cost running shoes. Cushioning was comparable when walking and running on a treadmill. Comfort is a subjective sensation based on individual preferences and was not related to either the distribution of plantar pressure or cost.

British Journal of Sports Medicine

44:598-604 doi:10.1136/bjsm.2007.044677

Incidence and risk factors of running-related injuries during preparation for a 4-mile recreational running event

I Buist, S W Bredeweg, B Bessem, W van Mechelen, K A P M Lemmink, R L Diercks

http://bjsm.bmj.com/content/44/8/598.abstract

Objective In this study, the incidence and the sex-specific predictors of running-related injury (RRI) among a group of recreational runners training for a 4-mile running event were determined and identified, respectively. Conclusions The incidence of running-related injuries in recreational runners preparing for a 4-mile running event is substantially high (at least one RRI reported by 25.9% of the runners during the 8-week observation period. The incidence of RRI was 30.1 (95% CI 25.4 to 34.7) per 1000 h of running exposure). Male and female participants have different risk profiles. Furthermore, the findings suggest that novice runners may benefit the most out of preventive interventions for RRI.

British Journal of Sports Medicine

38:576-580 doi:10.1136/bjsm.2003.005488

Relation between running injury and static lower limb alignment in recreational runners

V Lun, W H Meeuwisse, P Stergiou, D Stefanyshyn

http://bjsm.bmj.com/content/38/5/576.abstract

Objectives: To determine if measurements of static lower limb alignment are related to lower limb injury in recreational runners. Results: At least one lower limb injury was suffered by 79% of the runners during the six months observation period. Conclusions: In recreational runners, there is no evidence that static biomechanical alignment measurements of the lower limbs are related to lower limb injury except patellofemoral pain syndrome. However, the effect of static lower limb alignment may be injury specific.

Sport Science

Sportscience 5(3), sportsci.org/jour/0103/mw.htm, 2001

Barefoot Running

Michael Warburton

http://www.sportsci.org/jour/0103/mw.htm

Running barefoot is associated with a substantially lower prevalence of acute injuries of the ankle and chronic injuries of the lower leg in developing countries, but well-designed studies of the effects of barefoot and shod running on injury are lacking. Laboratory studies show that the energy cost of running is reduced by about 4% when the feet are not shod. In spite of these apparent benefits, barefoot running is rare in competition, and there are no published controlled trials of the effects of running barefoot on simulated or real competitive performance.

British Journal of Sports Medicine

1997;31:299-303 doi:10.1136/bjsm.31.4.299

Hazard of deceptive advertising of athletic footwear.

S Robbins, E Waked

http://bjsm.bmj.com/content/31/4/299.abstract?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=& fulltext=barefoot+running&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetype=HWCIT

OBJECTIVES: Athletic footwear are associated with frequent injury that are thought to result from repetitive impact. No scientific data suggest they protect well. Expensive athletic shoes are deceptively advertised to safeguard well through "cushioning impact", yet account for 123% greater injury frequency than the cheapest ones. This study tested the hypothesis that deceptive advertising creates a false sense of security with users of expensive athletic shoes, inducing attenuation of impact moderating behaviour, increased impact, and injury. CONCLUSIONS: These data provide a plausible mechanism explaining higher injury frequency in users of expensive athletic shoes. This is the first report to suggest: (1) deceptive advertising of protective devices may represent a public health hazard and may have to be eliminated presumably through regulation; (2) a tendency in humans to be less cautious when using new devices of unknown benefit because of overly positive attitudes associated with new technology and novel devices.

Journal of Biomechanics

Volume 28, Issue 7 , Pages 817-827, July 1995

Influence of shoes and heel strike on the loading of the hip joint

G. Bergmann, H. Kniggendorf, F. Graichen, A. Rohlmann

http://www.jbiomech.com/article/0021-9290(94)00129-R/abstract

The forces and moments acting at the hip joint influence the long-term stability of the fixation of endoprostheses and the course of coxarthrosis. These loads may depend on the kind of footwear and the walking or running style. These factors were investigated in a patient with instrumented hip implants. He wore different sports shoes, normal leather shoes, hiking boots and clogs and walked barefoot with soft, normal and hard heel strikes. The loads were lowest while walking and jogging without shoes. All shoes increased the joint force and the bending moment at the implant slightly, but the torsional moment rose by up to 50%. No relation was found between the different type of shoes and the load increase, only shoes with very hard soles were clearly disadvantageous. Soft heels, soles or insoles did not offer advantages. Gait stability seems to play the most important role in increasing the joint loading and should be the criterion for the choice of footwear. Smooth gait patterns with soft heel strikes are the only means to reduce joint loading during slow jogging.

Kasturba, Medical College, Manipal, India

VOL. 74-B. No. 4, JULY 1992

The Influence of Footwear on the Prevalence of Flat Foot

Udaya Bhaskara, Rao Benjamin Joseph

http://web.jbjs.org.uk/cgi/reprint/74-B/4/525.pdf

We analysed static footprints of 2300 children between the ages of four and 13 years to establish the influence of footwear on the prevalence of flat foot. The incidence among children who used footwear was 8.6% compared with 2.8% in those who did not (p < 0.001). Significant differences between the predominance in shod and unshed children were noted in all age groups, most marked in those with generalised ligament laxity. Flat foot was most common in children who wore closed-toe shoes, less common in those who wore sandals or slippers, and least in the unshod. Our findings suggest that shoe-wearing in early childhood is detrimental to the development of a normal longitudinal arch.

Medicine and Science in Sport and Exercise

Vol. 21, No. 2, pp. 130-139, 1989.

Running-related injury prevention through innate impact-moderating behavior

Robbins, S. E., G. J. Gouw, A. M. Hanna.

http://journals.lww.com/acsm-msse/Abstract/1989/04000/Running_related_injury_prevention_through_innate.4.aspx

The purpose of these experiments was to test the Robbins and Hanna hypothesis, which relates differences in discomfort from localized deformation at certain positions on the plantar surface to protective behavior (intrinsic foot shock absorption). A penetrometer was used to quantify the relations between localized load and pain and between load and depth of deformation. The magnitude of load required to elicit pain varied significantly (P < 0.005) in relation to position on the plantar surface. With a load of 9 kg and a 10 mm spherical end on the penetrometer, 6% of the sample reported pain at the heelpad, 32% at the distal first digit, and 66% at the first metatarsal-phalangeal joint. This pattern was predicted by the Robbins and Hanna thesis. Two deformation patterns were observed which were best explained by deformation constraint by tight trabecular tethering of the epithelial membrane at the heelpad and distal first digit and unrestricted deformation due to loose trabecular tethering of the epithelial membrane at the first metatarsal-phalangeal joint. These data provide insight into how, when barefoot, the plantar surface resists perforation yet provides protection to local bony structures. These data further support the notion that plantar sensory feedback plays a central role in safe and effective locomotion.

The American Journal of Sports Medicine

June 1988 vol. 16 no. 3 285-294

On the epidemiology of running injuries The 1984 Bern Grand-Prix study

Bernard Marti, John Paul Vader, Christoph E. Minder, Theodor Abelin

http://ajs.sagepub.com/content/16/3/285.abstract

Using a survey questionnaire design, we investigated the incidence, site, and nature of jogging injuries among all participants of a popular 16 km race. The response rate was 83.6%. Of 4,358 male joggers, 45.8% had sustained jogging injuries during the 1 year study period, 14.2% had required medical care, and 2.3% had missed work because of jogging injuries. Occurrence of jogging injuries was independently associated with higher weekly mileage history of previous running injuries and competitive training motivation. Higher mileage was also associated with more frequent medical consultations due entirely to jogging-related injuries.

Medicine and Science in Sport and Exercise

1988 Feb;20(1):85-92.

Overload protection: avoidance response to heavy plantar surface loading.

Robbins SE, Hanna AM, Gouw GJ.

http://www.ncbi.nlm.nih.gov/pubmed/2893969

Current footwear which are designed for use in running are examples of intentional biomechanical model integration into device design. The inadequacy of this footwear in protecting against injury is postulated to be due to fixation on inadequate models of locomotory biomechanics that do not provide for feedback control; in particular, an hypothesized plantar surface sensory-mediated feedback control system, which imparts overload protection during locomotion. A heuristic approach was used to identify the hypothesized system. A random series of loads (0 to 164 kg) was applied to the knee flexed at 90 degrees. In this testing system, plantar surface avoidance behavior was the difference between the sum of the leg weight and the load applied to the knee, and the load measured at the plantar surface; this was produced by activation of hip flexors. Significant avoidance behavior was found in all of the subjects (P less than 0.001). On all surfaces tested, including modern athletic footwear (P less than 0.001), its magnitude increased directly in relation to the load applied to the knee (P less than 0.001). There were significant differences in avoidance behavior in relation to the weight-bearing surfaces tested (P less than 0.05). With the identification of a feedback control system which would serve to moderate loading during locomotion, an explanation is provided as to why current athletic footwear do not protect and may be injurious; thus allowing the design of footwear which may be truly protective.

The Journal of Orthopedic and Sports Physical Therapy

1988;10(2):47-53.

A kinetic evaluation of the effects of in vivo loading on running shoes.

Hamill J, Bates BT.

http://www.ncbi.nlm.nih.gov/pubmed/18796978

The purpose of the study was to assess the effects of repeated in vivo loading on shock attenuation and mediolateral stability of running shoes using ground reaction force data. Six healthy subjects were each given a new pair of running shoes and asked to run 140 km between each of four experimental sessions. Ground reaction force data were collected for 10 successful trials/session using an A.M.T.I. force platform system. The mean values for selected ground reaction force parameters were evaluated using a single subject repeated measures design based on a 95% confidence interval. Mean parameter group data were also evaluated. The results support previous findings that material properties of the systems evaluated deteriorated resulting in a loss of shock absorbing capabilities (7.3%) but the magnitudes of the losses were far less than previously reported results (23-40%). The reason for this discrepancy is presumed to be the result of the different loading and evaluation methods used in the present study. The results also suggest that these changes are not totally deleterious since foot control seems to improve as cushioning is lost and foot control accounts for at least half of running shoe related injuries. A further implication of these results is that the initial "feel" or performance characteristics of a shoe may be misleading since reasonable functional changes appear to occur during the initial 300-400 km of wear.J Orthop Sports Phys Ther 1988;10(2):47-53.

Medicine and Science in Sport and Exercise

1987 Apr;19(2):148-56.

Running-related injury prevention through barefoot adaptations.

Robbins SE, Hanna AM.

http://www.ncbi.nlm.nih.gov/pubmed/2883551

A number of reports indicate an extremely low running-related injury frequency in barefoot populations in contrast to reports about shod populations. It is hypothesized that the adaptations which produce shock absorption, an inherent consequence of barefoot activity and a mechanism responsible for the low injury frequency in unshod populations, are related to deflection of the medial longitudinal arch of the foot on loading. It is also hypothesized that the known inability of this arch of the shod foot to deflect without failure (foot rigidity) is responsible for the high injury frequency in shod populations. To evaluate these hypotheses, 17 recreational runners were analyzed to study the adaptive pattern of the medial longitudinal arch of the foot due to increased barefoot weight-bearing activity. Changes occurred in the medial longitudinal arch which allowed deflection of this arch on loading which substantiated the hypotheses. Other evidence suggests that sensory feedback largely from the glabrous epithelium of the foot is the element of barefoot activity which induced these adaptations. The sensory insulation inherent in the modern running shoe appears responsible for the high injury frequency associated with running. The injuries are considered "pseudo-neuropathic" in nature.

Journal of Sports Science

1986 Winter;4(3):169-84.

Kinematically mediated effects of sport shoe design: a review.

Frederick EC.

http://www.ncbi.nlm.nih.gov/pubmed/3586110

One prominent pattern emerging from a review of the literature on sport shoes and biomechanics is the observation that many effects are the indirect result of shoe-induced adjustments in movement, i.e. a particular shoe characteristic elicits a kinematic adaptation which in turn has secondary consequences on kinetics and on injury and performance. For example, in addition to its variable effects on peak forces, cushioning system design has been shown to alter electromyographic patterns and to affect knee flexion during foot strike and affect indirectly the economy of running. Mediolateral stability as measured by rearfoot kinematics is strongly influenced by shoe design features such as heel lift, and sole hardness and geometry. The frictional properties of the shoe and surface interface have also been shown to affect kinematics in a way that in turn affects the recorded frictional forces themselves. Such kinematically mediated responses are the most provocative result of studies of the biomechanical effects of footwear. It is becoming apparent that the shoe can be a powerful tool for manipulating human movement. The abundance of shoe design possibilities coupled with the body's tendency to adjust in predictable ways to shoe mechanical characteristics have given us a new way to manipulate human kinematics and kinetics, as well as a convenient model for studying biomechanical adaptation.

Medicine and Science in Sport and Exercise

1985 Feb;17(1):158-63.

Effects of shoes and foot orthotics on VO2 and selected frontal plane knee kinematics

Burkett LN, Kohrt WM, Buchbinder R.

http://www.ncbi.nlm.nih.gov/pubmed/3982270

The objective of this study was to investigate the effects of shoes and foot orthotics on running economy and selected frontal plane knee kinematics during the support phase of running. Twenty-one male runners who had been fitted with orthotics served as subjects. Subjects participated in three submaximal runs on a treadmill under the following conditions: barefoot, shoes, and shoes plus orthotics. A run consisted of 1 min at 161 m . min-1, 2 min at 180 m . min-1, and 4 min at 201 m . min-1. VO2 was calculated for the last 3 min of each test. Frontal plane motion was filmed during the sixth min of each submaximal run, and linear and angular displacement of the knee were then calculated from film data. Results from the mechanical aspect of this study indicate that there were no significant differences among the means for linear displacement of the knee. Angular displacement of the knee during barefoot running was significantly (P less than 0.05) less than shoe and shoe-plus-orthotic conditions. There was no difference, however, between shoes and shoes plus orthotics. The economy results revealed that the aerobic cost of running increased as the amount of mass added to the foot increased. In absolute terms (1 . min-1), running in shoes plus orthotics was significantly (P less than 0.05) more costly than running barefoot. It appears that if orthotics do, in fact, improve running economy by improving running mechanics, the amount of improvement is negated by the additional cost of running associated with the mass of the orthotics.

International Journal of Sports Medicine

1983 Nov;4(4):247-51.

Effects of shoe cushioning upon ground reaction forces in running.

Clarke TE, Frederick EC, Cooper LB.

http://www.ncbi.nlm.nih.gov/pubmed/6654550

To determine the effects of widely varying amounts of cushioning upon vertical force (VF) parameters, ten male subjects, (mean weight = 68.0 kg) ran at a speed of 4.5 m . s-1 (6 min/mile pace) and contacted a Kistler force platform. Two shoes were tested: a hard one and a softer shoe that had 50% more cushioning as measured by an instrumented impact tester. Five right footfalls were collected for each shoe on each subject during which the ground reaction forces were sampled at 500 HZ using a PDP 11/34 minicomputer. Eight parameters from the VF data obtained for each trial were selected for analysis and compared statistically using a paired difference t test. It was found [force magnitudes expressed in multiples of body weight (BW)] that the time to the vertical force impact peak (VFIP) was significantly longer (hard = 22.5 ms, soft = 26.6 ms) in the soft shoe; however, no differences were seen in the magnitudes (hard = 2.30 BW, soft = 2.34 BW). The minimum after the VFIP was also significantly delayed in the soft shoe (hard = 33.8 ms, soft = 37.9 ms) and was significantly greater in the soft shoe (hard = 1.46 BW, soft = 1.90 BW). The peak VF propulsive force occurred statistically at the same time in both shoes (hard = 85.7 ms, soft = 84.0 ms), but was significantly greater in the soft shoe (hard = 2.73 BW, soft = 2.83 BW). (ABSTRACT TRUNCATED AT 250 WORDS)

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Transitioning to Minimalist Shoes Gradually Avoids Injury

The Research

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