http://www.eastcoastinternational.ie..._treatment.htm

[What is the most effective way to use TENS?

To achieve the best results of TENS therapy, it is important to remember that TENS merely activates the body's own pain-fighting mechanism. Placing electrodes directly over or around the painful area delivers pain-blocking current to the nerves leading to that area. Some healthcare professionals have found that placing the electrodes along acupuncture points is also effective. Also, it is good to vary the placement of the electrodes each treatment to avoid skin irritation.]
http://www.healco.com/news/tens.html