Wrist support during typing--a controlled, electromyographic study

The effects of wrist support on the trapezius and brachial extensor muscle loads during touch-typing were investigated with 12 secretaries, who were suffering pain in one or more of these muscles. They typed for 15 min at each of four experimental situations. The load on the trapezius was significantly greater with wrist support than without, and more marked the higher the support was adjusted. The radial extensor muscle load did not vary significantly. In spite of the higher trapezius load, most of the secretaries preferred a wrist support. Typing performance and body movements, estimated from the movements transferred to a tiltable chair-seat, were both unaffected by wrist support. Whether or not a wrist support should be used for typing cannot be concluded from the present investigation. However, it can be concluded that for touch-typing the keys should be positioned low - probably as low above the thighs as possible.