Computer key switch force-displacement characteristics and short-term effects on localized fatigue

Area of Science:

• Ergonomics and Human Factors
• Biomedical Engineering
• Occupational Health

Background:

• Repetitive keyboard use can lead to localized muscle fatigue in the forearm and hand.
• Key switch design parameters, such as make force and over travel, are potential factors influencing user comfort and fatigue.

Purpose of the Study:

• To investigate the effects of key switch make force and over travel on short-term localized muscle fatigue.
• To compare subjective and objective measures of fatigue under different key switch conditions.

Main Methods:

• An experimental apparatus simulated key switch forces and travel distances.
• Nine subjects performed repetitive key tapping tasks under varying conditions.
• Localized muscle fatigue was assessed using visual analogue scales and surface electromyography (EMG).

Main Results:

• Lower make force resulted in reduced subjective reports of fatigue.
• No significant differences in objective EMG-based fatigue measures were found between key switch parameters.
• Increased over travel reduced key strike force but did not decrease subjective fatigue, potentially due to increased finger movement.

Conclusions:

• Key switch make force appears to influence subjective fatigue perception.
• Objective measures of localized muscle fatigue were not significantly affected by the tested key switch parameters in the short term.
• Further research is needed to explore potential long-term health benefits of reduced key strike force.