Muscle activity and blood flux during standardized data-terminal work

Abstract
To determine the effects of computer work on muscle microcirculation, blood flux was recorded by laser-Doppler from the upper trapezius muscle, during and after standardised data-terminal work with variable time- and precision demands. Fourteen subjects, mean age 39 years (range 22–66 years), performed nine trials of tracking with three levels of time pressure and three widths of the tracks, and a complex reaction-time task. Mean arterial pressure, heart rate and electromyography from the forearm and shoulder muscles were measured.
Blood fluxes increased during the tracking. In spite of the very low muscle activity required to perform the tracking, a marked hyperemia was observed after cessation of tracking. This response may be a mechanism for pain during and after computer work. There were, however, large inter-individual variations in the blood-flux responses to tracking, and laser-Doppler measurements need to be compared with other methods in humans.
Relevance to industry
The present study shows that it is possible to measure microcirculation in the upper trapezius during tasks that model computer work. The increased blood flow observed after computer work of short duration with very low muscle activity may be of importance for pain during this type of work.