The effect of degree of upper arm flexion on shoulder-neck discomfort at the VDT

Two experiments investigated the effect of upper extremity posture on reported discomfort in the shoulder-neck region. In Experiment 1, 12 participants worked in two postures that only differed in the position of the arms. The ''7 degrees posture'' required 7 degrees of upper arm flexion and a 90 degrees upper arm-forearm angle. The ''30 degrees posture'' required 30 degrees of upper arm flexion and a 90 degrees upper arm-forearm angle. Location and intensity of discomfort were reported every 5 min while participants performed a simple tracking task at the computer. Experiment 2 was identical to the first except participants worked in one of the postures for both work sessions. The 30 degrees posture generally resulted in more frequent and intense reports of shoulder-neck discomfort than the 7 degrees posture. However, the 7 degrees posture was not nearly as effective when it was assumed after the 30 degrees posture. The implications of such carry over effects for VDT work in a seated posture are discussed.