Laursen B., Jensen B.R., Ratkevicius A.*
Department of Physiology, National Institute of Occupational Health,
*NMR-center, Panum Institute, University of Copenhagen, Copenhagen,
The share of elderly employees is rising. Age-related changes in physical capacity ( Ilmarinen et al; 1991) and muscle function ( Kinoshita and Francis, 1996) may influence the workload when the work demands remain unchanged. This might increase the risk of developing work-related symptoms and pain in the musculoskeletal system. Some of the age-related physiological changes could be important in computer work, especially those concerning the ability to perform precision work. The aim of the present study was to test for age-related differences in working speed and muscle activation patterns when performing computer work.
Eight young (25 years, range 22-28 years) and nine elderly (63 years, range 5670 years) experienced female computer users participated in the study. The subjects performed computer work at a height-adjustable desk with forearms supported. During a 4-hour period, the subjects performed a computer mouse test, consisting of 11 tasks, five times. These tests were based on an ISO standard (ISO 9241, 1994). Six tasks consisted of clicking multidirectional targets of different width (8, 16, 32 pixels, corresponding to 2.5, 5, and 10 mim on the screen and approximately 0.3, 0.6, and 1.2 mim for the mouse) in a selfdetermined speed and a predefined speed (40 mim-1). A circle was traced in a predefined speed (1 rev / 8 s). The remaining tasks were horizontal and vertical (relative to the computer screen) clicking a 16-pixel wide target, double clicking (40 min-1), and dragging (20 mill-1). For each task, the error rate (failing/attempted operations) and working speed (successful operations · min-1)