Stretch reflex contribution to soleus activation during spastic gait

The authors studied the ankle extensor stretch reflex contribution to locomotor EMG for spastic gait by relating ankle angular velocity and soleus electromyography (EMG). The perturbations induced by the load variation during free gait were sufficient to characterize the stretch reflex contribution to soleus EMG during the beginning of the stance phase. Dorsiflexion peaks in the averaged ankle angular velocity were accompanied by peaks in the averaged rectified soleus EMG at a delay of approximately 50 ms. The coherence and transfer functions relating the raw angular velocity and EMG signals also indicated this stretch reflex contribution