An EMG is an electrodiagnostic study that amplifies general and skeletal muscle electrical activity and allows a physician to analyze the function of the nerve roots exiting the spine. Your doctor may order an electromyogram if you have certain types of unexplained numbness, tingling, pain, weakness, and/or muscle cramping. During an EMG, muscle activity is measured and recorded (1) at rest, (2) during voluntary movement, and (3) with electrical stimulation by inserting small electrodes into the muscle. By looking for abnormal electrical signals in the muscle, the EMG can determine if the nerve that supplies that muscle is being irritated or pinched as it leaves the spine. Your active participation is necessary to a successful test, and you may experience some discomfort. Before the EMG Tell the doctor if you are taking aspirin, blood thinners like Coumadin, have a pacemaker, or have hemophilia. Take a bath in order to remove oil on your skin. Do not use body lotion on the day of the test. If you have Myasthenia Gravis, ask your doctor if you should take any medications before the test.