A TENS machine and EMS machine are used primarily for pain relief (TENS) and muscle building (EMS). Electrotherapy in various modalities has been used for hundreds of years, TENS was developed after the findings of Professor Melzack and Wall ( The pain gate theory) and EMS after the scientific findings of Lugi Galvani. High frequency TENS (80 – 130 Hz) works by activation (excitation) of the A beta (Aβ) sensory fibres, and by doing so, reduces the transmission of the noxious stimulus from the ‘c’ fibres, through the spinal cord and hence on to the higher centres. Low frequency TENS (2 – 10 Hz) releases an endogenous opiate (encephalin) in the spinal cord which will reduce the activation of the noxious sensory pathways and thus reduce pain. EMS when used for strength training promotes neural and muscular adaptations that are complementary to the well-known effects of voluntary resistance training and can be used as a training, therapeutic, and cosmetic tool. In medicine, EMS is used for rehabilitation purposes, for instance in physical therapy in the prevention of disuse muscle atrophy