Electrical stimulation appropriate in intensity and duration is capable of causing contraction of a muscle or a group of its fibers.

If the muscle is normoinnervated, the resulting muscle contraction is related to motor nerve excitation and not to direct stimulation on the muscle.In electrostimulation of normally innervated muscle, iterative currents of low frequency (faradic current) or medium frequency (interferential current and Kotz current) can be used.

Faradic current is characterized by a series of unidirectional, triangular but also rectangular pulses of short duration (0.1 to 1 msec) with frequency 50 Hz or 100 Hz, is delivered with stimulation time of two seconds and pauses of six seconds, but usually modulated an amplitude so that each pulse has a different intensity value from the previous one.

Faradic current finds application in the early stages of muscle reeducation (to be later replaced by active exercise) and in those patients who, for fear of awakening painful symptoms, are unable to increase muscle tonotrophy.

It is also indicated when it is desired to teach the patient to exercise conscious control of some particular muscle, such as the vastus medialis, or in muscle transplants in which the contraction produced by stimulation determines appropriate afferents to the new motor situation.