Kotz current is used for strengthening normally innervated muscles and allows maximum muscle recruitment with the least painful sensation. The excitomotor effect of this current is realized in deep muscles; in fact, it has been shown that the skin decreases its electrical impedance with increasing frequency.

Moreover, this increase creates a dissociation between the threshold of muscle contraction and that of painful sensation. At these frequencies, electrical impulses stimulate motor nerve fibers and not those of pain sensation and, therefore, cause essentially painless muscle contractions.

In using this technique, however, care must be taken to ensure that the electrodes are placed in a targeted manner at the ends of the muscle belly, according to the bipolar technique, and to set the equipment so that 10 seconds of stimulation and 50 seconds of pause are performed. Indeed, it has been shown that the maximum contraction force is reduced after 12.5 seconds of stimulation and after short pauses of less than 20 seconds due to the phenomenon of accommodation. The current should be dosed slowly until a valid muscle contraction is induced.

The main indications of this current are:

Muscle strengthening of athletes

The use of this current in sports began with the 1976 Montreal Olympics, with the aim of strengthening muscles and improving one’s performance.

Idiopathic scoliosis

The technique of treating scoliosis with Kotz current is called SPES (Superficial Electric Paravertebral Stimulation) and was developed by the Milan school. It consists of cycles of outpatient electrostimulation; each cycle consists of 15 sessions lasting 20 minutes and is repeated every 3 months. Electrodes should be placed at the paravertebral site, on the side where less electrical activity was found during electromyographic evaluation. Current is delivered for 10 seconds, followed by a 50-second pause.