Steven E. Robbins and Adel M. Hanna. "Running-related injury prevention through barefoot adaptations," Medicine and Science in Sports and Exercise, 19(2), 1987, pp. 148-156.

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 loaw 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 know inability of this arch of the shod foot to defelct without failure (foot rigidity) is responsible for the high injury frequence 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 weightbearing 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.

Excerpts

A number of reports indicate an extremely low running-related injury frequency in barefoot populations in contrast to reports about shod populations.

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Despite the modern engineered running shoe, a sports medicine clinic reported a large series of running-related injury referrals with an average weekly mileage at the time of injury of 19 miles for women and 27 miles for men. Practitioners of sports medicine have observed injuries in runners using every shoe model available. The above reports can hardly be considered an endorsement of the modern running shoe as a protective device.

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The opinion that the lower extremities are inherently fragile goes against the authors' understanding of the concept of natural selection.

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The reports that the authors have received indicate a low frequency of plantar fasciitis in barefoot populations.

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A paradox in presented of lower extremity fragility associated with the wearing of protective footwear and relative resistance to injury in the barefoot or unprotected state. To explain this paradox, the authors hypothesized that there exist adaptations associated with barefoot activity that provide impact absorption and protection against running-related injuries. An adaptation involving foot arch deflection on loading is hypothesized to be an important adaptation providing impact absorption. In contrast, it is hypothesized that the known rigidity of the shod foot may explain the reported high injury frequency in North American runners.

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The modern running shoe and footwear in general have successfully diminished sensory feedback without diminishing the injury inducing impact, a dangerous situation.

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The arch support, which is present in all running footwear, would interfere with the downward deflection of the medial arch on loading. Furthermore, the use of orthodics, or other structures that are fitted to the mold of the soft tissues of the foot, could cause similar difficulty. Such designs occur when an engineer looks at the foot as an inflexible lever which is delicate and thus requires packaging. Various myths persist about foot behavior due to poor understanding of its biology.

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The solution to the problem of running-related injuries could be as simple as promoting barefoot activity . . .