EMG & Nerve Conduction ProcessNCS testing is done by placing small electrodes on your skin. The stimulator will then deliver small electrical currents to the nerves which will cause your nerves to react. These signals are shown on our specialized computers so that we can see if your nerves are reacting too quickly or too slowly. Our conclusion on how your nerves are functioning is based upon comparison to the average nerve reaction. EMG testing is done by placing small needles in the muscles of your legs, arms and/or back. The needles show electrical activity caused by muscle contractions on our specialized computers. This test determines whether or not your muscles are receiving signals from your nerves properly.