TENS, or transcutaneous electrical nerve stimulation, is a back pain treatment that uses low voltage electric current to relieve pain.

    TENS is typically done with a Tens Acupuncture Machine, a small battery-operated device. The device can be hooked to a belt and is connected to two electrodes. The electrodes carry an electric current from the TENS machine to the skin.

    There is little research to support how -- or even if -- TENS really works. Its use dates back to the 1960s with the introduction of the gate control theory of pain. According to the theory, stimulating nerves closes a "gate" mechanism in the spinal cord, and that can help eliminate the sensation of pain. During a TENS treatment for back pain, electrodes are placed on the skin over an area of pain in the back. This creates electrical impulses that travel along nerve fibers and create a tingling sensation.

    Some people feel less pain when the electrical impulses are delivered. This could be because stimulating the nerves blocks other pain signals. Another theory is that stimulating the nerves may help the body produce natural painkillers called endorphins.