It won't work for body building as it only stimulates nerves. They are used to shortcircuit the pain response system. It causes the nerve to "fire" and that blocks it's ability to fire for a few hours providing relief from specific types of pain. It may or may not work for people. When used sexually it causes the prostate peripheral nerves to fire causing uncontrollable or just really intense orgasm. When used on the breasts it causes a sensation that is very similar to a baby suckling, pleasurable for some annoying to others. When it fires the nerves in the breasts it can cause a release of oxytonin which causes the uterus to mildly contract which is again pleasurable to some and painful to others. It can also help with menstrual cramps but evening out the muscle contractions and causing them to "soften".

We learned all this from our family doctor after Sigel read about how TENS units were being used. He said unless you have a heart condition the electrical stimilus won't be enough to interrupt heart rythm and then showed Sigel how to position the pads for maximum effectiveness and to prevent injury. I use it on my neck and upper back as well as nipples. When I was nursing it helped to stimulate milk production (I have low thyroid function which makes it very hard for me to establish and maintain a good milk supply) and ease the lochia cramps.

I would suggest, if you have a good relationship with your Dr. asking him about where to place the pads for best effect. If not then there are loads of sites that can help.