Electromyography is an instrument that collects electrophysiological responses to muscle contractions to evaluate the nerve, neuromuscular junction, and muscle functional status, to diagnose the disease, and to evaluate the effectiveness of treatment afterwards. EMG is usually reported by a physician, and the diagnosis of the disease can be made based on the contents of the report. The principle of EMG is that the electrophysiological responses of muscles and nerves are different during different functions or states due to the presence of bioelectrical activity of muscles and nerves. By observing the electrophysiological waveforms in the resting state and in the loading state, it is possible to diagnose whether the disease is a neurological or a muscular disease, and where they appear accordingly. Electromyography involves the recording of many waveforms, and there is also waveform analysis by computer, and the report is usually a conclusive diagnosis given by the physician after a comprehensive judgment.