Towards a better understanding of human sprinting motions with and without prostheses

Amputee sprinting motions are of high interest due to the remarkable performances of individual athletes and the resulting question what the share of their running-specific prostheses is. The goal of our study was to compare twelve ablebodied and amputee sprinting motions which were synthesized by combinations of ten optimality criteria. We created rigid multi-body system models with 13 degrees of freedom in the sagittal plane for both an able-bodied and an amputee sprinter. The joints are powered by torque actuators, except for the prosthetic joint which is equipped with a passive linear springdamper system. The sprinting motions are the solutions of an optimal control problem with periodicity constraints and objective functions which combine different optimality criteria. For both athletes, we found realistic human-like sprinting motions. The analysis of the motions suggested that the amputee athlete applies less active joint torque in the hip and knee of his affected leg compared to the able-bodied athlete.