Interferential therapy is a specialized form of transcutaneous electrical stimulation used to help provide relief of pain and to help promote soft tissue healing. Medium frequency electrical impulses are introduced into the tissues at the region of injury. Inferential therapy requires two separate electrical stimulation channels cycling at different patterns of repetition frequency. Typically, one channel has a frequency of 4000hz and the second channel has a frequency of 4100hz. The principle of interferential is based on the alternating carrier frequencies canceling out leaving the remaining 100 Hz therapeutic stimulation rate. The electrical waves intersect below the surface of skin at the lower base frequency, creating a centrally mediated pain blockade and the release pain relieving chemicals such as endorphins. Most individuals find interferential electrotherapy to be beneficial and describe the experience as a faint pins and needles sensation. Interferential therapy may also be used as an adjunctive part of a therapeutic pain management program.