9/24/2019-  The aims of this study were to determine the effect of shoulder and elbow position on ulnar nerve conduction studies (NCS), and the length of reserve that asymptomatic individuals have in their ulnar nerves. Healthy subjects (n = 22) underwent ulnar NCS in 4 positions of shoulder abduction and elbow flexion. The mean increase in nerve conduction velocity (NCV) from the slack position of shoulder adducted and elbow extended to the stretch position of shoulder abducted and elbow flexed was 2.9 m/s (P < 0.01). Using this difference, the mean length of reserve in the ulnar nerve along the limb was found to be 28.3 (SD=13.8) mm. Shoulder abduction increased the mean NCV 0.8 m/s (P = 0.03) independent of elbow flexion. This study demonstrates an ulnar nerve reserve in healthy patients that is taken up with shoulder abduction and elbow flexion and suggests shoulder position should be standardized during ulnar NCS. Muscle Nerve, 2019.