Electrotherapy and Transcutaneous Electrical Nerve Stimulation (TENS), is the electrical stimulation of the body, to help relieve pain, without the use of potentially addictive medication.
Electrotherapy (EMS) use a low voltage electrical current to activate the muscles and nerves, which in turn improves the blood flow to the area. Once the blood flow has been increased, the muscles receive the oxygen carrying red blood cells which aid their recovery much quicker than usual. This increased blood flow can aid the removal of lactic acid. EMS can also be very effective to reduce muscle wastage post injury. If you injure your knee, you often find that through lack of exercise, the quadricep muscle in the thigh can diminish very quickly. Using EMS to stimulate the muscle, you can help reduce this wastage.
TENS machines, if used frequently for chronic pain symptoms or long term nerve damage, can confuse the brain signals causing the pain, by overstimulating the tissue. The brain then cannot correctly characterise the signals, giving almost instant pain relief.