Table 1.

Glossary of terms used in this review.

Term	Definition	Effect on sEMG Signal
sEMG sensor 1 (often confused with the commercial term “electrode”)	System carrying and including the electrode(s) and their fixation system (e.g., adhesive rings)	Adhesive disks or straps might limit skin elasticity and create artifacts due to micromovements.
Electrode (or electrode sensitive area)	Conductive surface in contact with the skin (dry or wet, e.g., gel)	The voltage distribution on the skin under the electrode takes a single instantaneous value over the entire electrode (average in space). causing lowpass filtering.
sEMG sensor diameter or size	Diameter or size of the whole sensor applied over the skin	Large sEMG sensors require wide inter-electrode distance
Center to center inter-electrode distance (IED)	Distance between electrode centers	Larger IED results in larger detection volume and larger sEMG signal, which is often incorrectly considered a good thing, with the risk of crosstalk
Detection volume	Volume and shape of the region of 3D space containing motor units whose potential can be detected	Region containing motor units whose potentials are above the noise level.
Crosstalk	Signal detected on the target muscle but generated by the motor units of another muscle	When nearby muscles are active the muscle of interest seems to be active, leading to wrong conclusions/decisions.Crosstalk may critically affect clinical decision making
Innervation zone (IZ)	Physical region where the central (alpha-motor neuron terminations) and peripheral (muscle fibers) systems connect through special synapses [14]	During dynamic contractions, the relative movement of the muscle with respect to the skin (that is the electrode system) determines a strong alteration (e.g., reduction) of the signal amplitude when the IZ shifts under the electrode pair [14]

¹ As defined in the SENIAM recommendations.