actively shortened muscle, increasing the risk of injury further. This theory is supported by reported findings from Divert et al. (2005), who reported greater pre-activation of triceps surae (calf) when running barefoot was compared to shod running. Combined with potentially greater eccentric loading requirements, it is not surprising to hear many anecdotal reports of calf muscle soreness from individuals attempting a transition from shod to barefoot running.

It must also be noted that typical running surfaces, especially in Western society, are different from those where habitually unshod people live and run, tending to be much harder. Harder surfaces yield higher peak impact forces and higher peak and average loading rates of vertical impact force during sports-specific movements compared to cushioned surfaces (40). Higher loading rates are associated with an increased risk of lower extremity stress fractures (41), and therefore transitioning to barefoot-style running on hard surfaces like pavement may predispose impact-associated injuries, (42). This may be particularly problematic if the individual transitions from shod to barefoot running without adequate gait retraining.

Although barefoot running may be the natural state from an entirely paleontological perspective, shoes have been commonplace in Western societies for millennia (43), becoming more supportive (some might argue constrictive) with time. Using traditional Chinese foot binding as an extreme example (44), it is clear that the foot is highly plastic, gradually adapting to the constraints placed on it. Prolonged shoe wearing has been shown to alter both the morphology and kinematics of the foot compared to those in habitually unshod populations (45). Constrictive footwear can act as a cast, gradually weakening intrinsic musculature the more we use it. To suddenly load muscles that have not had to work hard for many years may predispose to overload injuries. Although this could be said to be a strong argument for the barefoot state, it is important to be mindful that many Western sports people will likely not have completely ‘natural’ feet due to years of wearing shoes, and will be predisposed to these potential problems. Barefoot-style running may therefore not be beneficial or appropriate in all sports people.

At present, there is no definitive evidence that altering running gait to a barefoot-style reduces injuries. Given the potential problems and pitfalls of altering running form, especially in an environment not conducive to barefoot running and in populations who may already have foot deformities or adapted biomechanics, transitioning sports people to a barefoot-style must be gradual, structured and carefully monitored. Sudden or haphazard changes in biomechanics may increase the risk of injury.

Conclusion We have evolved to run. However, our modern practice of running in shoes may not prevent injury as first thought, but could, in fact, make us more susceptible. Studies of barefoot-style running and the potential for reduced incidence of overuse injuries are suggestive, but have a long way to go before becoming conclusive. The rationale for benefit and the potential risks are both clear, but, whereas the short- term ability to change one’s running style is evident, more robust evidence is required before recommendations for clinical practice can be made. Transition to a barefoot-style must be gradual and structured, otherwise we risk creating more problems than we solve. Yet, with the rapid growth of the ‘barefoot movement’ and interest from the general public, we may find that our clients are leading the way, and we are struggling (shod) to keep up.

References Due to the number of references in this article we have put these online. Please go to http://spxj.nl/REPsJournal

THE AUTHORS Paul Jones is a running enthusiast and medical student with a passion for all things barefoot, and has recently gained a first class bachelor’s degree in Sports and Exercise Medicine from Queen Mary, University of London (QMUL). Dr Christian Barton is an physiotherapist and post-doctoral researcher at QMUL with a passion for distance running – with shoes on. Dr Dylan Morrissey is a clinical academic at QMUL, and researches widely on the link between movement and pathology.

ANSWER THE FOLLOWING QUESTIONS ON-LINE TO EARN CPD POINTS Please log in to the members area of the REPs website to give your answers

Q1 Q2 Q3

18

In what year were the first cushioned heel shoes introduced by Onitsuka Tiger (now Asics)?: a) 1980 b) 1975 c) 1963

How many times does the average runner strike the ground per kilometre?: a) 450 b) 600 c) 825

Please devise CPD questions

When working with a client who wants to change to barefoot running shoes how should you advise them to make the transition?: a) Gradually over time b) Chop and change between a few different brands to see which they like best c) Simply change from your current shoe to your chosen barefoot style shoe and see how it goes

The REPs Journal 2013;27(May):16-18

This article has been adapted from an article published in sportEX dynamics. sportEX dynamics is published quarterly and aimed at people working in sports massage, therapy and fitness conditioning. Visit www.sportex.net

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