Modeling of heel strike transients during running

The goal of this study is to develop a mathematical model that can describe the dissipation and attenuation of the shock wave initiated during the impact of the foot striking the ground. A three-degree-of-freedom spring-damper-mass system was conceived as an equivalent model of the lower extremity. The mathematical model that was developed was used to investigate the shock absorption phenomena of the human body. The model and solution procedure were verified by a drop test. The instant of the impact of landing was assumed to be equivalent to foot strike transients. The results showed that the quasilinearization technique can identify the spring and damping constants of the system at the instant of impact fairly accurately. The acceleration pattern as predicted from the proposed model was very close to the measured one. The model was used to analyze the effect of the ground and footwear damping and spring constants on the dynamic loading on the human musculoskeletal system. It was shown that changes in the spring constant do not have a significant effect on the ground reaction forces, while increase of the damping constant resulted in decrease of this force. Thus, the damping constant is the dominant factor in controlling the impact on the human musculoskeletal system.