Does anyone have any firsthand experience using a Transcutaneous Electrical Nerve Stimulator (TENS)? I've read testimonies that it could be helpful for a number of sports related injuries like muscle strains, sciatica, mortons nueroma, heal spurs and achilles pain. I don't think its held in very high regard with massage therapists and conventional physical therapists. Is it a scam? Can it hurt you? There is so much information on the internet I dont know what to believe.