Fig. 4

Representative kinematic, electromyography (EMG) and kinetic responses from participant A96 to back trunk perturbations delivered at Low (12%Bodyweight, BW), Mid (16%BW) and High (20%BW) magnitude. Vertical grey dotted lines depict perturbation onset. Pert: perturbation magnitudes; Trunk: trunk displacement toward the back (B); L: left; TA: tibialis anterior; MG: medial gastrocnemius; hGRF: resultant horizontal ground reaction force. Note the different trends of EMG amplitude modulation for TA (i.e., increased EMG amplitude at High) and MG (i.e., longer inhibition) with increasing perturbation magnitude.