Letter to the Editor to the article: The Effects of a Transition to Minimalist Shoe Running on Intrinsic Foot Muscle Size

The Effects of a Transition to Minimalist Shoe Running on Intrinsic Foot Muscle Size. A. W. Johnson, J. W. Myrer, U. H. Mitchell, I. Hunter, S. T. Ridge Int J Sports Med 2016 ; 37 : 154–158

The report by Johnson et al. [2] unintentionally examined the effect of deceptive athletic footwear advertising and deceptive informed consent on incidence of injury. For background, barefoot subjects are protected via plantar SA II mechanoreceptor discharge from vertical deformations and shear [1] [3] [9]. Loading is directed away from fragile foot structures (e. g., metatarsal-phalangeal joints) through avoidance of pain [1] [3] [8]. Aggregate vertical load is moderated through modest pain thresholds at preferred loading sites [1] [3] [8]. Shoe soles are known to attenuate shear thereby impair sensory feedback.[5] [7] [10] [11] [13] Overall this results in injury through overloading foot structures and amplified aggregate load following the neuropathic injury model [8] [10] [11].

When machine tested, impact absorption of all running shoes is similar, yet Marti reported that runners participating in an event wearing expensive shoes sustained 123% percent more injuries than wearers of cheaper ones [4]. This suggested that footwear which was deceptively advertised as offering better protection may have resulted in amplified impact. This hypothesis was tested with barefoot subjects landing from 4.5 cm above onto a bare force platform, or the same platform covered with identical sole material made to appear different and deceptively advertised as either originating from expensive or cheap shoes [12]. Impact was significantly different between conditions with it being lowest when there was no interface, highest with the “expensive shoe” interface, and intermediate with the “cheap shoe.” [12] Vigilance is considered here to be behavior that moderates impact that is elicited by fear of injury. A difference in vigilance is the only proven measure that accounts for injury differences between footwear, and deceptive advertising has significant effects on this measure [12].

Vibram FiveFingers ^TM shoes were introduced in 2005, and have been falsely promoted since their inception as protecting feet through enhanced sensory feedback. These shoes are expensive and are the most deceptively advertised footwear in history. However, injuries were frequent with their use due to sensory insulation and attenuated vigilance from the deceptive advertising [12]. A class action law suit was filed against Vibram in 2012 regarding deceptive advertising claims that led to injuries. It was settled in 2015, on behalf of the plaintiffs, and required user compensation and cessation of the deceptive advertising.

The report by Johnson, et al., tested FiveFingers ^TM shoes during the period of deceptive advertisement and following initiation of the class action suit [2]. 44% of subjects sustained foot injuries alone (bone marrow edema) while gradually transitioning to these shoes over a 10 week period, while transitioning to traditional shoes injured 5% of subjects [2]. 3 years earlier, (before the class action suit and with the deceptive advertising), many of the same authors found, following a similar protocol, that FiveFingers ^TM shoes resulted in 53% foot injuries compared to 5% transitioning with traditional shoes [6]. Presumably the 17% reduction in injuries between these 2 reports was due to greater subject vigilance with FiveFingers ^TM shoes because some were aware of the class action suit.

Johnson et al. never mentioned the role of vigilance in injury when wearing athletic footwear, nor the influence of deception on it [2]. Furthermore, it is certain that subjects in their experiment and likely also their university research ethics committee were not informed of the now known massive injury risk of this protocol. This condemned subjects to injury. If subjects had known this, only the foolhardy among them would have been willing to take part in this study, and those using FiveFingers ^TM shoes ironically would have been at low injury risk because of heightened vigilance. Moreover, an informed ethics committee probably would never not have approved this research protocol in the first place.

The World Medical Association Declaration of Helsinki, entitled Ethical Principles for Medical Research Involving Human Subjects [15], was a response to Nazi human experiments. The experiment performed by Johnson et al., [2] made numerous errors according to this declaration, particularly in relation to Articles 21, 26 and 31 that requires investigators to be aware of relevant scientific literature, that subjects be informed of risks and that there is an obligation to protect subject health [15].

Johnson et al. are not alone. A report in 2014 shoe novelty trumped design when transitioning to an expensive novel NIKE shoe caused injuries in 40% of subjects, while FiveFingers ^{TM i} injured 20% and traditional shoes 10% [14]. Biomechanists in their self imposed solitude search for their Holy Grail – footwear that can protect in the sensory feedback poor environment inherent to wearing shoes. This has become dangerous to their subjects and also users who are injured through a false sense of security resulting from their continued suggestion that running shoes are needed to protect. Footwear use for most has always been body art – an aesthetic tradition that has come with considerable health costs.

• References

• 1 Inglis JT, Kennedy PM, Wells C, Chua R. The role of cutaneous receptors in the foot. Adv Exp Med Bio 2002; 508: 111-117
• 2 Johnson AW, Myrer JW, Mitchell UH, Hunter I, Ridge ST. The effects of a transition to minimalist shoe running on intrinsic foot muscle size. Int J Sports Med 2016; 37: 154-158
• 3 Kennedy PM, Inglis JT. Distribution and behaviour of glabrous cutaneous receptors in the human foot sole. J Physiol 2002; 38: 995-1002
• 4 Marti B. Relationship between running injuries and running shoes – Results of a study of 5000 participants of a l0-km run – The May 1984 Berne “Grand Prix”. In: Segesser B, Pforringer W. (eds.) The shoe in sport. Chicago: Year Book Medical Publishers; 1989. 256-265
• 5 Pollard JP, Le Quesne LP, Tappin JW. Forces under the foot. J Biomed Eng 1983; 5: 37-40
• 6 Ridge ST, Johnson AW, Michell UH, Hunter I, Robinson E, Rich BS, Brown SD. Bone marrow edema after a 10 wk transition to minimalist running shoes. Med Sci Sports Exerc 2013; 45: 1363-1368
• 7 Robbins SE, Gouw GJ. Athletic footwear and chronic overloading: a brief review. Sports Med 1990; 9: 76-85
• 8 Robbins SE, Gouw GJ, Hanna AM. Running-related injury prevention through innate impact moderating behavior. Med Sci Sports Exerc 1989; 21: 130-139
• 9 Robbins SE, Hanna AM, Jones LA. Sensory attenuation induced by modern athletic footwear. J Test Eval 1988; 16: 412-416
• 10 Robbins SE, Hanna AM. Running related injury prevention through barefoot adaptations. Med Sci Sports Exerc 1987; 19: 148-156
• 11 Robbins SE, Hanna AM, Gouw GJ. Overlaod protection: avoidance response to heavy plantar surface loading. Med Sci Sports Exerc 1988; 20: 85-92
• 12 Robbins SE, Waked E. Hazard of deceptive advertising of athletic footwear. Br J Sports Med 1997; 31: 299-303
• 13 Robbins SE, Waked E, Krouglicof N. Improving balance. J Amer Geriatr Soc 1988; 46: 1363-1370
• 14 Ryan M, Elashi M, Newsham-West R, Taunton J. Examining injury risk and pain perception in runners using minimialist footwear. Br J Sports Med 2014; 48: 1257-6214
• 15 Special Communication| November 27, 2013 World Medical Association Declaration of Helsinki Ethical Principles for Medical Research Involving Human Subjects. JAMA 2013; 310: 2191-2194