You do not need to fast to have an EMG; you should eat moderately and be prepared to have an EMG. You do not need to fast before having an EMG; there are no clear, specific things you need to do to prepare for an EMG, but you should eat moderately and not be overly full. You should try to make sure that the test site is clean before doing EMG to avoid infection; wear loose clothes in order to fully expose the test site such as upper and lower limbs; turn off your cell phone during the test to avoid interference, which may affect the test results. EMG is widely used in clinical practice, mainly for diagnosis and differential diagnosis of neurogenic damage and myogenic damage, to exclude diseases of neuromuscular junction. It helps to localize the lesions in the anterior horn cells of the spinal cord, nerve roots, nerve plexuses, peripheral nerves and neuromuscular junctions, and muscle fibers, and to guide the selection of injection sites for intramuscular drugs (e.g., botulinum toxin or other drugs).