Conventional techniques for measurement of the activity of motor units are invasive, therefore painful and not suitable for long term examinations. On the other hand the resolution of noninvasive techniques is not high enough to visualize the activity of single motor units.
The method of High-Spatial-Resolution EMG (HSR-EMG), developed at the Helmholtz-Institute, allows the non-invasive acquisition of the activity of these units.
The High-Spatial-Resolution electromyography consists of a two-dimensional array of electrodes. By the minimum distance between the electrodes the signal of the activity of more distant motor units is filtered. The resulting measured signal contains mainly information about the electrical activity of skin-deep motor units.