A technique for recording the EMG of electrically stimulated skeletal muscle

A technique for recording the myoelectric activity of electrically stimulated muscle through its motor nerve without the interference of stimuli artifacts has been developed and tested. The technique consists of a wide band differential amplifier with fine intramuscular wire electrodes. The amplified signal is passed through a Chebyshev low pass filter with eight poles at a frequency of 550 Hz. A stimulus calibration study shows that low frequency stimuli had negligible effect on the EMG when set below three times suprathreshold. A test procedure shows artifact-free EMG during action potential rate stimulation as well as during superimposed high frequency recruitment stimulation.