Fig. 1.

The experimental setup consisted of two devices, one for each arm, to constrain the position of the forearm and hand. The upward force exerted at the wrist by the elbow flexors of each arm was measured with a force transducer attached underneath the forearm-hand orthosis. Electromyographic (EMG) signals were recorded from the left biceps brachii muscle with a subcutaneous, fine-wire electrode (red wire) and a pair of surface electrodes (blue wires). Surface EMG recordings were also obtained for brachioradialis (green wires). Neuromuscular electrical stimulation (NMES) currents were delivered to the right elbow flexors via a pair of conductive fabric electrodes (yellow pads) and a braided ground cable (blue wire) was wrapped around the proximal upper arm.