Exploring the relationships between terrain, structural foot morphology, and adaptive foot morphology

The arch of the foot is considered a principal element of the structure and function of the foot, and its claimed causative relationship with injuries has been commonly researched. The impact of terrain (Natural and Developed) on the development of the arch has not yet been clearly researched and could be a critical part in the structure-function-injury discussion. Collecting postcodes and Foot Flexibilities (FF) from a range of participants and data gathered using smart insoles allowed for relationships between terrain, foot structure, dynamic response, and the biophysics of the foot to be examined.

Young participants growing up on a Natural terrain were found to have a more flexible arch; however, the same was not observed in an adult population. High FF feet and low FF feet did not yield significantly different values for walking characteristics, nor did they show a difference in adaptability to walking on varying terrains. Moreover, no correlations could be found between FF and walking characteristics. It was found, however, that the dynamic response of the foot differs between varying terrains. Few correlations were observed between terrains per walking characteristic, and the characteristics themselves did not appear interrelated either. Lastly, it was shown that a more deforming arch stores more energy than a rigid arch.

Terrain has been shown to influence the foot structure of a developing foot, but a standardised protocol to classify terrains is required to observe this trend consistently. Pronation was often found to be the outlier in general trends, facilitating development of the theory that pronation is inherent to the foot, undecided by environmental factors or correlated to certain intrinsic classifications. The vertical displacement of the arch was found to be the main cause of higher energy storage in flexible arches, although calculations leading to this observation were based on simplifications of the mechanisms.