Analysis of the human foot arch viscoelasticity using the simple model of the arch support elements

The viscoelasticities of arch support structures was recognized in this study, using the simple foot model with the torsional spring-damper model to apply the human foot arch complex. The arch is deformed during bipedal gait motion. Especially the maximum deformation was observed in midstance to push-off. Then the deformation is controlled by means of arch support elements. The recognizing method was based on the hypotheses that the experimented external arch moment was equal to theoretical internal arch moment. The stiffness of the arch was identified at 4 phases in a gait cycle, (I) heel contact phase, (II) the entire planter contact phase, (III) push off phase, and (IV) swing phase. This study shows three results. (1) The arch elasticity increases in the phase III (n =6, p<.01), since it's produced by functional changes based on Elftman, windlass mechanism based on Hicks, and muscle activities. (2) The arch viscosity increases in the phase II (n=6, p<.01), because of the shock absorption in some arch functions. (3) We recognized much more stiffness with the evening foot than the morning foot (n=6).