Intensive Computer Mouse Work
-- Relation to Age.
Jensen B.R., Laursen, B. and Ratkevicius, A.* Department of Physiology, National Institute of Occupational Health, Copenhagen, Denmark. * NMR-Center, Panum Institute, University of Copenhagen, Denmark
Muscles undergo a whole variety of morphological and neurological changes with age. A reduction in muscle cross-sectional area, a decrease in total number of motor units, an increase in average motor unit size and a general slowing of skeletal muscles have been reported in aging humans (e.g. Grimby and Saltin 1983; Davis, Thomas and White 1986). The precision of force exertions also appears to decrease with age (e.g. Cole 1991; Galganski, Fuglevand and Enoka 1993). However, it remains unclear if these age-related changes in neuromuscular function affect the performance of computer work. Reports on age related changes in muscle fatigue resistance are contradictory (e.g. Davis, Thomas and White 1986; Klein, Cunningham Paterson and Taylor 1988). Thus, it is even less clear if aging contributes to muscle fatigue during intensive computer mouse work performed for prolonged periods of time.
The aim was to investigate to which extent 4 hours of intensive computer mouse work elicited electromyographical signs of muscle fatigue in young and elderly subjects. Furthermore, to study if development of muscle fatigue is related to work intensity in terms of number of mouse clicks per unit of time.
Eight young (25 years, range 22-28 years) and nine elderly (63 years, range 5670 years) experienced female computer users participated in the study. They performed four 50-min sessions of intensive computer mouse work. The sessions were separated by 10-min breaks. The subjects performed a combination of computer mouse tests and electronic painting. The computer mouse test was performed in the beginning of the first session and at the end of