The Human foot is one or the most complicated structures in the conveyance of normal gait, with its 26 bones, 33 articulations, 19 individual intrinsic muscles and direct contribution from all of the lower leg musculature. It also contains a complexity of ligamentous structures that not only act as stabilizers, but also store and release energy in a spring like fashion (Ker 1987). This group of anatomical structures is modulated by a complex system of mechanoreceptors that allow for adaptation to a multitude of varying terrain, while maintaining stability and control. (Franklin 2018) Thus the investigators see the structural, spring and muscular systems all coordinating together to allow for bipedal gait through the natural world.~Multiple observational studies have found an exceptionally low prevalence of common foot pathologies in unshod populations that ambulate on variable terrain daily (Shulman, Choi). At the same time, these same pathologies have become increasingly common in western societies. These findings suggest that something about the western lifestyle is contributing to the development of common foot pathologies. Modern footwear has already been implicated as a contributor to foot pathology and changes in the biomechanics of gait. In a study by K. D'AoÛt et al. on an unshod vs shod Indian population, they found that barefoot walkers had a more equal distribution of peak pressures over the entire load carrying surface than in the habitually shod subjects. The shod subjects had regions of very high or very low peak pressures throughout the load carrying surface.~The increase prevalence of foot pain in the developed world has long been recognized as a significant risk factor for ambulatory disability, (Hill, C. 2008) with plantar fasciitis and hallux valgus being two of the most common causes of foot discomfort presenting in the clinical setting today. Plantar fasciitis accounts for approximately 13% of all foot symptoms requiring professional medical treatment and is believed to be the result of weakening of the intrinsic foot musculature and chronic overload to the plantar foot supportive structure. (Buchanan, B. 2020). Intrinsic foot muscle function seems to play and import role in the development of foot pathology, and is one of the key factors effecting foot health.~The lack of terrain variation found in urbanized western society may directly contribute to the development of foot pathologies. Terrain variation in a minimally shod foot should allow for more coordination and strengthening of the muscular and spring like systems within the foot, through the increase and variation of stimuli encountered by its mechanoreceptors. Lack of terrain variation most probably contributes to a decreased intrinsic foot muscle function and response. There have been many studies showing the correlation between improved intrinsic foot musculature strength and the reduction of foot pain and discomfort, but to date, there are no studies that examined the relationship between terrain variation and intrinsic foot muscle function and strength.
Modern footwear has been implicated as a contributor to foot pathology and changes in the biomechanics of gait. In addition to footwear, the investigators propose that the lack of terrain variation may directly contribute to the development of common foot pathologies, resulting from decreased intrinsic foot muscle function. This study will examine the current understanding of terrain variation on foot musculature strength and its possible correlation with structural and functional changes within the foot.