Figure 1.

The experimental set up. The subject lies supine on a bed with the dominant arm horizontal and abducted to 90°. The forearm is 120° flexed (180° being full extension), with the hand supinated. The arm is placed in an isometric brace equipped with two torque transducers (one on each side of the arm) connected to a display that provides the subject with visual feedback of the torque level produced. The myoelectrical signals are picked up by a linear array of 16 electrodes placed on the skin overlying the biceps brachii muscle. The linear array can be identified as a white band on the biceps brachii.