An undisputed law of biology is that form both follows and determines function. The function of the foot is to provide an adaptable and stable base of support. A functional foot should therefore have dynamic flexibility i.e. be able to flex and extend (for smooth movement), and flatten under load (creating and wider base). A foot free from structural constraint would be expected to develop this function, following the biological law. A recent study supports this assertion.
Aibast et al. (2017) compared foot strength and arch function in habitually barefoot and habitually shod Kenyan adolescents, matched for age, weight and sex. Physical activity was also recorded.
Barefoot adolescents had more flexible arches and greater foot strength than their shoe-wearing counterparts. Despite higher physical activity in the barefoot children, there was no link with foot structure or function, suggesting footwear as the determinant of group differences.
The foot strength and flexibility developed by the habitually-barefoot adolescents are to be expected based on biological law. However, living and growing up barefoot is unrealistic in most western countries. Footwear that respects the structure and function of a barefoot is the only viable option to support the natural development of both.