Postural responses to platform perturbation: kinematics and electromyography

Dynamic postural control may be studied using feedback paradigms which disturb standing balance. In this study the kinematics and electromyography of the reaction to an unexpected slip were examined simultaneously in 16 young, healthy volunteers to characterize the response to postural perturbation in the context of the perturbation characteristics. Kinematically, results showed ankle plantarflexion, knee flexion, hip extension, and shoulder flexion. Electromyographically, sequences of activation of the postural muscles of the leg were primarily anterior distal. Data is presented that supports a new model of the reaction to perturbation which incorporates the timing and type of muscular activity, the type of motion (active or passive), and the perturbation characteristics.