Discomfort in the upper limb is commonly aggravated by prolonged use of a mouse. This has led to a proliferation of mouse designs that each has various “ergonomic” features. Contoured designs, vertical mice, track balls, touch pads and other such designs may be able to correct poor upper limb postures for certain individuals and are therefore useful on a case-by-case basis. However, in some instances, changes to posture associated with a move to a different mouse design have not resulted in decreases in symptoms. Other strategies for reducing discomfort, while maintaining productivity are required.
It may be a case where changes to another posture still results in fatigue and passive strain of tissues. Still, each posture and mouse design may demand a unique muscle recruitment strategy and change force distribution on various tissues and joints. Prolonged exposure to only 1 mouse type results in the same muscle use and force distribution, and ultimately can lead to discomfort. However, if an individual were to rotate between two mouse types on a frequent basis it may prevent fatigue of the same muscle fibers and change force distributions before the onset of strains that lead to discomfort.
In recent months, this strategy was investigated with a client of EWI Works. The individual had been experiencing wrist and hand discomfort that was affecting her work and ability to complete tasks outside of work. The client had trialed switching to use the non-dominant hand for mousing, but this led to discomfort in that wrist and hand as well. The client also trialed 4 different mouse types, but prolonged use of each type throughout the day would lead to discomfort. During an ergonomic assessment, the concept of varying mouse exposures was discussed and the client agreed to trial a rotation between a touch pad mouse and a contoured design mouse. The client would use each mouse type for a maximum of 40 minutes before rotating. After 3 weeks, the client reported that wrist and hand discomfort had dissipated.
This suggests that rotation of mouse type can be an effective intervention strategy. Investigations of which mouse types provide the most benefit for rotation are required. The impact of rotation on fatigue, discomfort and muscle use should also be investigated with a larger group of people.
