Upper trapezius muscle: average rectified value (ARV). Slight shoulder elevation.

Upper trapezius muscle: average rectified value (ARV).

Map of the distribution of the differential longitudinal average rectified value on the surface of the upper trapezius. ARV calculation epoch = 0.5 s.

Grid of 5x13 electrodes with diameter of 3 mm spaced by 8 mm (32x96 mm).

Acquisition rate: 2 frames per second.

Reproduction rate: 2 frames per second with image interpolation.

Note the central innervation zone (blue band).