TENS units????

just wondering if anyone uses, or has used a TENS unit (transcutaneous electrical nerve stimulation)...i have chronic back pain, and have seen about 3 docs, and always tell me the same shit...most say not to lift heavy, especially above my head...but as i stated to them, i would rather live with the pain and lift heavy, then lift like a puss for a little relief....the TENS units are supposed to facilitate the release of natural endorphins/enkephalins, that block the neural transmission of pain...they can be relatively inexpensive ($100), up to $400+...i have used one in the past, but it was purely experimental in school......anyone?????

bumpin....