Hedge A, Powers J R
Department of Design and Environmental Analysis, Cornell University, Ithaca, NY 14853-4401.
Ergonomics. 1995 Mar;38(3):508-17. doi: 10.1080/00140139508925122.
Video-motion analysis was used to analyse hand/wrist posture for subjects typing at a 101-key QWERTY keyboard on a 68 cm high worksurface. Three conditions were tested: subjects typed at the keyboard without arm support, subjects typed with adjustable full motion forearm supports, and subjects typed with an adjustable negative slope keyboard support system. The average declination of the negative slope keyboard support chosen by subjects was 12 degrees below horizontal, which flattened the angle of the key tops. Ulnar deviation was comparable in all conditions and averaged 13 degrees for the right hand and 15 degrees for the left hand. Full motion forearm supports did not significantly affect any postural measures. Dorsal wrist extension averaged 13 degrees when typing with or without the full motion forearm supports, but this was reduced to an average -1 degree with the use of the negative slope keyboard support system. Subjects chose to sit at a distance of 79 cm from the computer screen when using the negative slope keyboard system compared with 69 cm without this.
视频动作分析用于分析在68厘米高的工作台上使用101键QWERTY键盘打字的受试者的手部/腕部姿势。测试了三种情况：受试者在无手臂支撑的情况下在键盘上打字、受试者使用可调节的全动式前臂支撑在键盘上打字、受试者使用可调节的负斜率键盘支撑系统在键盘上打字。受试者选择的负斜率键盘支撑的平均倾斜度比水平低12度，这使键帽的角度变平。在所有情况下尺骨偏斜情况相当，右手平均为13度，左手平均为15度。全动式前臂支撑对任何姿势测量均无显著影响。使用或不使用全动式前臂支撑打字时，腕背伸平均为13度，但使用负斜率键盘支撑系统时，这一角度降至平均-1度。与不使用负斜率键盘系统时的69厘米相比，使用该系统时受试者选择坐在距离电脑屏幕79厘米处。
