To use a TENS unit, you place sticky electrodes on the skin around a painful area, such as on the small of your back. When the TENS unit is turned on it delivers a small current through the electrodes to the skin and tissues just beneath it.
You are likely to feel a bit of pins-and-needles tingling at the usual settings. But the intensity can be set high enough to make a muscle twitch.
How TENS really work?
It work by sending electronic stimulating pulses across the surface of the skin and along the nerve strands. The stimulating pulses help prevent pain signals from reaching the brain. Tens devices also help stimulate your body to produce higher levels of its own natural painkillers, called "Endorphins".
TENS work on two main theories:
One of these theories is called The Gate Control Theory and is the most advanced explanation. The gate-control theory suggests that there’s a neural mechanism in spinal cord that acts as a kind of gate, shutting down or opening up the flow of signals from the periphery to the brain. Whether the gate is open, closed or partially closed depends on what sort of signal it receives from the brain to change the perception of pain in the user’s body. These frequencies interfere with the transmission of pain messages at the so spinal cord level, and help block their transmission to the brain.
Another theory is called The Endorphin Release, which suggests that electrical impulses stimulate the production of endorphins and encephalin in the body. These natural morphine-like substances block pain messages from reaching the brain, in a similar fashion to conventional drug therapy, but without the danger of dependence of other side effects.
TENS units are used by hundreds of thousands of people all over the world for the relief of physical pain. This is why hundreds of doctors, nurses, and patient technicians often recommend that their patients uses T.E.N.S. unit for minor and major pain relief.