Left lumbar erector spinae during trunk flexion.

Map of the root mean square value (RMS) of the monopolar signal between T12 and L4 during trunk flexion at 80° , 60° , 45°. Grid of 64 electrodes (13x5-1): Ø=3mm, interelectrode distance = 8mm.

Maps are computed on epochs of 0.125s and interpolated.