Sinusoidal current is evenly alternating sine wave currents having a frequency of 50hZ. It gives 100 pulses or phases in
The main action of the sinusoidal current is to to produce the muscle contraction. If it is applied continuously, tetanic contraction will occur and there is stimulation of both sensory and motor nerves which will produce tingling and needle like sensation. This is the prime reason for which the surging of current has been carried out. Once the current is surged it will produce rhythmic muscle contractions. the pain relief occurs when sensory nerves are stimulated , by pain gait mechanism. Also when there is contraction of the muscles, this contraction has a massage like effect which not only improves the circulation of the blood butt also help in the reduction of edema  by improving the lymphatic drainage.
