Effects of precision demands and mental pressure on muscle activation and hand forces in computer mouse tasks

Abstract

The objective of the present study was to gain insight into the effects of precision demands and mental pressure on the load of the upper extremity. Two computer mouse tasks were used: an aiming and a tracking task. Upper extremity loading was operationalized as the myo-electric activity of the wrist flexor and extensor and of the trapezius descendens muscles and the applied grip-and click-forces on the computer mouse. Performance measures, reflecting the accuracy in both tasks and the clicking rate in the aiming task, indicated that the levels of the independent variables resulted in distinguishable levels of accuracy and work pace. Precision demands had a small effect on upper extremity loading with a significant increase in the EMG-amplitudes (21%) of the wrist flexors during the aiming tasks. Precision had large effects on performance. Mental pressure had substantial effects on EMG-amplitudes with an increase of 22% in the trapezius when tracking and increases of 41% in the trapezius and 45% and 140% in the wrist extensors and flexors, respectively, when aiming. During aiming, grip-and click-forces increased by 51% and 40% respectively. Mental pressure had small effects on accuracy but large effects on tempo during aiming. Precision demands and mental pressure in aiming and tracking tasks with a computer mouse were found to coincide with increased muscle activity in some upper extremity muscles and increased force exertion on the computer mouse. Mental pressure caused significant effects on these parameters more often than precision demands. Precision and mental pressure were found to have effects on performance, with precision effects being significant for all performance measures studied and mental pressure effects for some of them. The results of this study suggest that precision demands and mental pressure increase upper extremity load, with mental pressure effects being larger than precision effects. The possible role of precision demands as an indirect mental stressor in working conditions is discussed.

The effect of psychosocial stress on muscle activity during computer work: Comparative study between desktop computer and mobile computing products

“…On the other hand, another group of researchers found that the existence of a certain psychosocial stress did not have any significant effect on trapezius muscle activity [9,14,18,19,23,24,27,28]. Meanwhile, there are several studies that can be categorized in a third group where this group obtained a combination of the two aforementioned results [1,25,26,29].…”

“…Even for the most common muscle studied which is the trapezius muscle, the effect of stress on muscle activity can be divided into two main groups. One group found that when a certain psychosocial stress exists, the trapezius muscle will become affected and the muscle activity will be increased significantly [8,12,18,21,[29][30][31]35]. On the other hand, another group of researchers found that the existence of a certain psychosocial stress did not have any significant effect on trapezius muscle activity [9,14,18,19,23,24,27,28].…”

“…In addition, the force they need to press a touch screen button is lower than the actual keyboard. Finally, in a study to determine the effect of precision demand and mental pressure on the load of the upper extremity, the authors found that unlike mental pressure, the precision had a small effect on trapezius muscle activity [29]. However, they also argued that in a case where the performance is essential, precision might has a hidden effect.…”

Concordance between VDU-users’ ratings of comfort and perceived exertion with experts’ observations of workplace layout and working postures

“…The results of similar studies, in which mental stress was induced amongst computer users in a laboratory setting, support these findings (Lundberg et al, 2001). A recent study investigating the possible effects of mental pressure and demands for precision on upper extremities found a considerable increase in the load as a result of mental pressure (Visser et al 2004). Another study, which investigated the effects of time pressure and precision demands on the oxygen of two muscles, m. trapezius and m. extensor carpi radialis, found reductions in oxygenation of the latter during a mouse-operated computer task carried out und time pressure and high precision demands (Heiden et al, 2005).…”

“…3-4 hours) can result in fatigue of the forearm muscles (Johnson, 1998 (Wahlstrom et al, 2002). It w further supported by the results of another study, which explored effects of mental pressure on precision and on the force applied when working with the computer mouse (Visser et al, 2004). P S and neck/upper extremity symptoms during computer work (Bergqvist et al, 1995;Faucett and Rempel, 1994;Karlqvist et al, 2002;Punnett and Bergqvist, 1997;Tittiranonda et al, 1999).…”