Any form of current that is applied through the surface electrodes to deliver the current through the skin to the underlying tissues is know as TENS or Trancutaneous electrical nerve stimulation. Interferential current is the transcutaneous application of alternating medium frequency currents, amplitude modulated at low frequency for therapeutic purposes.

Indication for use of Interferential are as under:

1- Pian relief
2-Tissue healing
3-Muscle stimulation
4-Circulatory

The mechanisn of pain relief with interferential is comparable to a TENS unit. Sensory level, motor level and noxiuos level mode of electrical stimulation may be used to get the desired pain relief.

Because of its low frequency component interferential current is claimed to offer similar therapeutic benefits to the healing process as the low frequency electrical stimulation.

The muscle stimulation produced by the interferential is more comfortable as compared to the low frequency currents. As skin resistance becomes lower with IF so it has the added benefit of stimulating the deep muscles like pelvic floor muscle re education.

Interferential is claimed to cause the depolarization of the autonomic nerves so causes the vasodilatation of the blood vessels. Hence it increases the blood flow with out warming the muscles.

For optimal muscle contraction use the beat frequency of 0-10 beats per second.

Amplitude modulation or sweep frequency can itself be modulated by frequency. The AMF can be made to alternate over a set range by manipulation of the sweep frequency control-the original AMF becomes the base frequency, e.g. 100Hz. Applying a sweep frequency of 10Hz will result in a AMF varying between 100Hz and 10 Hz. The medium frequency will vary correspondingly between 4050 and 4055 Hz. Also use patient comfort and tolerance as a guide to the frequency mode chosen.