A running human body has been modelled with assumptions that the knee stiffness is changed according to the knee angle and shoe sole is deformed continuously.
An optimization technique was used to find the material properties of the shoe sole which minimize energy consumption or ground reaction forces.
The results of the motion analysis and optimal design from this model were compared with the one from the model with constnt knee stiffness and with shoe sole of three discrete springs and dampers.
The ground reaction forces were measured by a force plate for a subject running with three different kinds of shoes (three jogging shoes, two tennis shoes and three basketball shoes). The force plate data were transformed by means of FFT (Fast Fourier Transform) to compare and analyze frequency components. Jogging shoes were best suited for long distance running from the view point of low impact load and frequency components.