Foot pronation during walking is associated to the mechanical resistance of the midfoot joint complex

Background: The demonstration of the relationship between midfoot passive mechanical resistance and foot pronation during gait may guide the development of assessment and intervention methods to modify foot motion during gait and to alter midfoot passive mechanical resistance. Research question: Is foot pronation during the stance phase of gait related to the midfoot passive mechanical resistance to inversion? Methods: The resistance torque and stiffness provided by midfoot soft tissues of 33 participants (21 females and 12 males) with average of 26.21 years were measured. In addition, the participants' forefoot and rearfoot kinematic data during the stance phase of gait were collected with the Qualisys System (Oqus 7 + ). Correlation Coefficients were calculated to test the association between kinematic variables representing pronation (fore-foot-rearfoot inversion, forefoot-rearfoot dorsiflexion and rearfoot-shank eversion) and maximum resistance torque and maximum stiffness of the midfoot with alpha = 0.05. Results: Reduced maximum midfoot resistance torque was moderately associated with increased forefoot-rearfoot inversion peak (p = 0.029; r = 0.38), with forefoot-rear-foot dorsiflexion peak (p = 0.048; r = -0.35) and with rearfoot-shank eversion peak (p = 0.008; r = - 0.45). Maximum midfoot stiffness was not associated to foot pronation. Significance: The smaller the midfoot resistance torque, the greater the forefoot-rearfoot inversion and dorsiflexion peaks and the rearfoot-shank eversion peak during gait. The findings suggest the existence of a relationship between foot pronation and midfoot passive mechanical resistance. Thus, changes in midfoot passive mechanical resistance may affect foot pronation during gait.