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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 an increasing amount of attention in the last few years for many reasons: it can be utilized as a strength training tool for healthy subjects and athletes; it could be used as a rehabilitation and preventive tool for partially or totally immobilized patients; it could be utilized as a testing tool for evaluating the neural and/or muscular function in vivo; it could be used as a post-exercise recovery tool for athletes. The impulses are generated by a device and are delivered through electrodes on the skin near to the muscles being stimulated. The electrodes are generally pads that adhere to the skin. The impulses mimic the action potential that comes from the central nervous system, causing the muscles to contract. 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. In the United States, EMS devices are regulated by the U.S. Food and Drug Administration (FDA).

A number of reviews have looked at the devices.

Electrical muscle stimulation can be used as a training,therapeutic, or cosmetic tool.

In medicine, EMS is used for rehabilitation purposes, for instance in physical therapy in the prevention of disuse muscle atrophy which can occur for example after musculoskeletal injuries, such as damage to bones, joints, muscles, ligaments and tendons. This is distinct from transcutaneous electrical nerve stimulation (TENS), in which an electric current is used for pain therapy.

In EMS training few muscular groups are targeted at the same time, for specific training goals.

The FDA rejects certification of devices that claim weight reduction. EMS devices cause a calorie burning that is marginal at best: calories are burnt in significant amount only when most of the body is involved in physical exercise: several muscles, the heart and the respiratory system are all engaged at once. However, some authors imply that EMS can lead to exercise, since a person toning his/her muscles with electrical stimulation is more likely afterwards to participate in sporting activities as the body is ready, fit, willing and able to take on physical activity.

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