FIG. 4.
Electromyographic (EMG) activity in response to a fast stretch. The activity in flexor digitorum superficialis (FDS), extensor digitorum communis (EDC), and flexor carpi ulnaris (FCU) during a fast stretch is shown for arm posture 1. Thin lines represent the raw EMG signal, thick lines represent the normalized signal EMGnormalized. The 1st and 2nd panels from the top show the profiles of rotation of and torque at the MCP joints during the stretch, respectively. The deflection in the torque profile at the onset of the stretch is an artifact arising from the inertial torque due to the initial acceleration of the structure coupling the subject's fingers to the servomotor and of the fingers themselves, which occurs over the 1st 10% of the range of the imposed MCP extension.