Thursday, December 26
Computer Monitor Height, Angle, and Distance - Ergonomics Guidelines Although most ergonomists agree that a low monitor is better for the visual system, the question has been "What happens to the neck and upper back?" Two recent studies have addressed that question. Turville and colleagues (1998) compared monitor locations with the center of the screen at 15? and 40? below horizontal. They compared the average (mean) muscle activity for 10 sets of neck and upper back muscles. The recommended limit for mean muscle activity is 10-14% maximum voluntary contraction (MVC) (Jonsson 1978). (MVC is the maximum muscle effort that can be voluntary exerted by the subject.) Although the 40? placement had higher readings than the 15? placement, all were much lower than the recommended limit. The highest was 6.8%. For the trapezius, the muscle most often associate with cumulative trauma disorders, the activity averaged an extremely low 2.2% MVC for the 15? and 2.0% MVC for the 40? conditions.
