A Forward Dynamics Simulation of Human Hopping: Modeling Afferent Feedback

INTRODUCTION Rhythmic, cyclic human movements may be generated without substantial control from supraspinal structures. There is some evidence that such movements may be largely controlled at the spinal cord level instead. Melvill Jones et al. (1973) described two neural pathways which play important roles during hopping, namely vestibular reflexes (VRs) and functional (long latency response) stretch reflexes (FSRs). They observed that, during hopping, activation as a result of VR arrives at the muscle just in time to help break the downward movement, while activation as the result of FSR arrives at the muscle just in time to help generate activity necessary for push off. The purpose of this study was twofold: (1) to investigate the potential role of VRs and FSRs in simulated human hopping movements, (2) to compare the performance of the model with experimental data on human hopping. The hypothesis of this study was that rhythmic, cyclic hopping movements can be generated with minimal control from supraspinal structures.