An electromyogram (EMG) measures the electrical activity of muscles at rest and during contraction. Nerve conduction velocity (NCV) measure how well and how fast the nerves can send electrical signals.

Nerves control the muscles in the body with electrical signals called impulses. These impulses make the muscles react in specific ways. Nerve and muscle problems cause the muscles to react in abnormal ways.

If you have leg pain or numbness, you may have these tests to find out how much your nerves are being affected. These tests check how well your spinal nerves and the nerves in your arms and legs are working.

A nerve conduction velocity (NCV) test determines how quickly electrical signals move through a particular peripheral nerve. It is also sometimes known as a nerve conduction study and is used in the diagnosis of nerve damage or nerve dysfunction


Flat, patch-style electrodes are placed on the skin at intervals over the nerve that is being examined. These electrodes give off low-intensity electrical impulses, which stimulate the nerve. This stimulation may feel like a slight electric shock, though it is not particularly painful.

The impulses produced by this electrical current are viewed on an oscilloscope or computer screen. This monitoring system allows the physician to determine how fast the impulses are traveling through the nerves.