Electrical Muscle Stimulation, referred to as EMS, is an electronic device used to stimulate motor nerves by causing a muscle contraction. EMS is mostly used for preventing or reducing muscle atrophy. Atrophy is the weakening and loss of muscle tone, which is usually experienced after surgeries or injuries.
EMS has been perceived as a means of increasing blood flow to muscles, increasing range of motion, increase muscle strength, as well as enhance muscle endurance. EMS has pain management attributes in regards to muscle related pain, such as spastic muscle, sore muscles or tight muscles.
While using the EMS, the brain sends a nerve impulse to the "motor point" of your muscle. This signal is a message to the muscles to expand and contract. Electrodes are placed over the motor points of the muscle to be exercised. When the stimulation is applied through the pads, the signal finds its way to these motor points and causes the muscle to expand and contract. This makes it possible to duplicate a conventional exercise, similar to an isometric exercise.
During an exercise, our brain sends a message down the spinal cord through the nerves with all the muscles you're using that causes them to relax and contract. This is called voluntary muscle action. Your brain is controlling the muscle.