Methods. The cross-sectional study of 202 engineers utilized questionnaires and electrophysiological nerve testing at the wrist. The definition for median or ulnar mononeuropathy required the combination of distal upper extremity discomfort and abnormal distal motor latency. The randomized controlled intervention trial followed 206 engineers for one year. Participants were randomized to receive a conventional mouse or an alternative mouse, and a forearm support board or no board. Outcome measures included weekly upper body discomfort scores and incident musculoskeletal disorders.