Process by which the action potential trains of some active motor units are extracted from the EMG signal. Specialized algorithms can be used to identify motor unit action potential waveforms from the same motor unit contained within the EMG signal.

The factor of amplification (A_d) is given to the difference in voltage (V_d) between the two input terminals of a differential amplifier. The output voltage of the amplifier is Volt = A_d V_d (in an ideal differential amplifier, where the common-mode voltage gain is zero).

EMG is recorded from two electrodes aligned over the active muscle (typically with equidistant spacing). The signals are passed into one single differential amplifierto obtain the difference between the first and second signals. Performing the differential subtraction results in attenuation of signals originating from muscles.

A method of recording EMG using three electrodes and three differential amplifiers, which is used to reduce interference and crosstalk in the EMG signal.EMG is recorded from three electrodes aligned over the active muscle (typically with equidistant spacing). The signals are passed into two differential amplifiers (with one input common to both amplifiers) to obtain the difference between the first and second signals, and between the second and third signals. The output signals from the two differential amplifiers (i.e., bipolar or single differential EMG signals) are then used as an input to a third differential amplifier to obtain the double differential signal. Performing the differential subtraction twice results in a higher attenuation of signals originating from muscles that are further away (as these signals will appear similar, i.e., as common-mode signals, at all amplifier inputs).

Two successive action potentials of the same motor unit close together in time. Historically, the interspike interval for doublets has been defined as 2.5–20 ms, however, it may be more accurate to define a doublet as an interspike interval that is significantly shorter than the mean interspike interval for a given motoneuron. A doublet is also typically followed by a long interspike interval.

A technique widely used in electrocardiography, and occasionally in electromyography, whereby the common-mode voltage (primarily due to power line interference) on the body is negatively fed back (i.e., the phase is reversed) to a third electrode, through a feedback amplifier, driving the common mode voltage to a lower level and thereby reducing the power line interference. The additional ECG electrode is typically applied to the right leg (hence, the name).This technique is occasionally used in surface electromyography where the additional feedback electrode is not necessarily applied to the right leg.