A nerve conduction study another part of EMG. An Electromyogram (EMG) is a test that is used to record the electrical activities of muscles. The activity is displayed visually on computer and may also be detected audibly with a speaker. EMGs can be used to detect abnormal electrical activity of muscles that can occur in many diseases and conditions, including muscles weakness, muscle pain or cramping, certain types of limb pain, muscular dystrophy, inflammation of muscles, pinches nerves and peripheral nerve damage, myasthenia gravis.