Are there differences in muscle activity, subjective discomfort, and typing performance between virtual and conventional keyboards? *

This study investigated whether muscle activity and fatigue differed between a touchscreen virtual keyboard and two conventional keyboards. Finger flexor, extensor, and shoulder muscle electromyography, subjective discomfort, and typing performance were measured while 19 subjects typed on a virtual keyboard and two conventional keyboards with differing tactile feedback. The results showed that the use of the virtual keyboard resulted in lower muscle activity on the extrinsic finger flexor and extensor muscles (p < 0.05), a trend toward higher shoulder muscle activity (p < 0.10), higher subjective discomfort (p < 0.0001), and lower typing performance (p < 0.0001), as compared to the conventional keyboards. The results indicate that the use of a virtual keyboard increases muscle loading and subjective discomfort; therefore, shorter periods of operation may be more appropriate when using a virtual keyboard.