An electromyogram (EMG) measures the electrical activity of the muscle when it is at rest and again during a contraction. A nerve conduction velocity (NCV) test, measures how fast the individual nerve tested sends electrical signals down its course. Both tests are typically completed during the same office visit. The information gathered helps the provider find the cause of weakness, paralysis, radicular pain and paresthesia (numbness and tingling). Although needles are used for the muscle portion of the EMG, it is not particularly painful. You may experience some temporary discomfort similar to getting an injection.