The common electrical modalities used in the clinic are simply pieces of equipment that are designed to take ordinary current flowing from a wall outlet and convert it to produce specific physiologic effects on human tissue.
Clinically, following surgery or injury, physical therapists use electrical currents to create muscle contraction, to increase strength and prevent disuse atrophy, through nerve or muscle stimulation (electrical stimulator using high voltage, low voltage, or alternating current), stimulate sensory nerves to reduce pain (TENS), stimulate or alter the healing process of injured tissue, preventing scar tissue (interferential current, MENS, cold lasers), and drive ions beneficial to the healing process through the skin into the healing connective tissues (iontophoresis).
Electrical muscle stimulation (EMS), also known as neuromuscular electrical stimulation (NMES) or electromyostimulation, is the elicitation of muscle contraction using electric impulses. EMS has received increasing attention in the last few years, because it has the potential to serve as: a strength training tool for healthy subjects and athletes; a rehabilitation and preventive tool for partially or totally immobilized patients; a testing tool for evaluating the neural and/or muscular function in vivo; a post-exercise recovery tool for athletes. The impulses are generated by a device and delivered through electrodes on the skin in direct proximity to the muscles to be stimulated. The impulses mimic the action potential coming from the central nervous system, causing the muscles to contract. The electrodes are generally pads that adhere to the skin. The use of EMS has been cited by sports scientists as a complementary technique for sports training and published research is available on the results obtained.