Abstract
The purpose of this study is to investigate the influence of the heel-gradient, which is the heel-toe drop in shoe-sole, on the dynamic characteristics of the support leg muscles in a constant pace running motion. Two types of indices; such as, muscle contributions to the whole-body CG acceleration, and dynamic conversion ratios of individual muscle to the generation of the whole-body inertial force, are calculated from a dynamics analysis utilizing the equation of the whole-body motion. The results obtained from seven heel strikers' running motion at the speed of 3.3 m/s indicate that (1) increase in rearfoot midsole thickness relative to forefoot one provided i) increase in the contribution of vasti to support caused by the increase of the magnitude of muscle force, ii) increase in the contribution of vasti to braking caused by increase of the dynamic conversion ratio, iii) decreases of muscle force and relative load of gastrocnemius, and iv) decrease in the contribution of gastrocnemius to propulsion, and (2) decrease in the contribution of soleus to support was affected by decrease of magnitude of muscle force, and increase in the contribution of soleus to propulsion was affected by increase of the dynamic conversion ratio.
