| Objective: To investigate muscle activations and the kinematics of the postural responses to external perturbations with forward and backward directions and provide theoretical guidance for the rehabilitation of patients with balance disorders. Method: Three-dimensional video graphic and surface electromyography (sEMG) data were collected from 13 male young people, who were disturbed by forward and backward platform movements. Horizontal CoM displacement, onset latency and magnitude of muscle activations, and angular change of three lower limb joints and trunk during postural control (from onset of perturbation to 200 ms after perturbation) were measured. Results: The results showed that when platform moved forward or backward, CoM moved in opposite directions. The ankle, hip and trunk showed opposite angular changes. The gastrocnemius muscle had greater activation magnitude when the platform moved backward, while rectus femoris, tibialis anterior and erector spinae showed greater activation magnitude when moved forward. Except rectus abdominis and erector spinae, there was no significant difference in onset latency of other muscles between forward and backward perturbations. Conclusion: According to different directions of surface external perturbations, the central nervous system will automatically adjust postural responses by changing the pattern of joint movement and muscle recruitment to maintain body stability. |
