Electromyography

[Julian]

An EMG- [a procedure] to [assess] the health of muscles and the nerve cells that control them
Also known as the most painful procedure known to man, where student nurses stick you with [needles] then proceed to pulse electricity down through the needles to see how your muscles react to the stimulation. Often this causes extreme pain, as it aims to target nerves and the way they control the muscles.

[Justin Bieber]

The recording of the electrical activity of muscle tissue, or its representation as a visual display or audible signal, using electrodes attached to the skin or inserted into the muscle.