Effects of Key Travel Distances on Biomechanical Exposures and Typing Performance During UltraLow Key Travel Keyboards

This study investigated how differently ultra-low key travel (< 2.0 mm) keyboards affect typing force, muscle activity, and typing productivity as compared to a conventional keyboard. In a repeated-measures laboratory-based study with 20 subjects, we collected and compared typing forces, muscle activity in extrinsic finger muscles (flexor digitorum superficialis (FDS) and extensor digitorum communis(EDC)), and typing performance among five keyboards with different key travel distances (0.5, 0.7, 1.2, 1.6, and 2.0 mm). The results showed that there were differences between ultra-low key travel keyboards (0.5, 0.7, 1.2 and 1.6 mm) and a conventional keyboard (2.0 mm) in typing force (p < 0.001), muscle activity (p > 0.07) expect for FDS (p < 0.01), and typing speed (p < 0.001). However, in general, the differences appears to be practically small: muscle activity (less than 1.3%) and typing force (less than 0.5 newton). The study findings indicates that the ultra-low key travel keyboards may not increase or decrease physical risk factors and typing performances as compared to conventional keyboards.