Alternative computer mouse design and testing to reduce finger extensor muscle activity during mouse use.
OBJECTIVE
The purpose of this study was to design and test alternative computer mouse designs that attempted to reduce extensor muscle loading of the index and middle fingers by altering the orientation of the button switch direction and the force of the switch.


BACKGROUND
Computer users of two-button mouse designs exhibit sustained lifted finger behaviors above the buttons, which may contribute to hand and forearm musculoskeletal pain associated with intensive mouse use.


METHODS
In a repeated-measures laboratory experiment, 20 participants completed point-and-click, steering, and drag tasks with four alternative mouse designs and a reference mouse. Intramuscular and surface electromyography (EMG) measured muscle loading, and movement times recorded by software provided a measure of performance.


RESULTS
Changing the direction of the switch from a conventional downward to a forward design reduced (up to 2.5% maximum voluntary contraction [MVC]) sustained muscle activity (10th percentile EMG amplitude distribution) in the finger extensors but increased (up to 0.6% MVC) flexor EMG and increased movement times (up to 31%) compared with the reference mouse (p < .001). Implementing a high switch force design also increased flexor EMG but did not differ in movement times compared with the reference mouse (p < .001).


CONCLUSIONS
The alternative mouse designs with altered switch direction reduced sustained extensor muscle loading; however, trade-offs with higher flexor muscle loading and lower performance existed.


CONCLUSIONS
Potential applications of this study include ergonomic and human computer interface design strategies in reducing the exposure to risk factors that may lead to upper extremity musculoskeletal disorders.
Lee
David L
DL
Harvard School of Public Health, Boston, Massachusetts 02115, USA.
Fleisher
Jacob
J
McLoone
Hugh E
HE
Kotani
Kentaro
K
Dennerlein
Jack T
JT
D000328:Adult; D016287:Computer Peripherals; D004867:Equipment Design; D005260:Female; D005383:Finger Injuries / Q000517:prevention & control*; D006801:Humans; D008297:Male; D014584:User-Computer Interface