Effects of physical and mental task demands on cervical and upper limb muscle activity and physiological responses during computer tasks and recovery periods

Abstract

The present study examined the effects of physical and mental workload during computer tasks on muscle activity and physiological measures. Activity in cervical postural muscles and distal forearm muscles, heart rate and blood pressure were compared among three tasks and rest periods of 15 min each in an experimental study design. Fourteen healthy pain-free adults participated (7 males, mean age = 23.2 ± 3.0 years) and the tasks were: (1) copy-typing ("typing"), (2) typing at progressively faster speed ("pacing"), (3) mental arithmetic plus fast typing ("subtraction"). Typing task was performed first, followed by the other two tasks in a random order. Median muscle activity (50th percentile) was examined in 5-min intervals during each task and each rest period, and statistically significant differences in the "time" factor (within task) and time × task factors was found in bilateral cervical erector spinae and upper trapezius muscles. In contrast, distal forearm muscle activity did not show any significant differences among three tasks. All muscles showed reduced activity to about the baseline level within first 5 min of the rest periods. Heart rate and blood pressure showed significant differences during tasks compared to baseline, and diastolic pressure was significantly higher in the subtraction than pacing task. The results suggest that cervical postural muscles had higher reactivity than forearm muscles to high mental workload tasks, and cervical muscles were also more reactive to tasks with high physical demand compared to high mental workload. Heart rate and blood pressure seemed to respond similarly to high physical and mental workloads.

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

“…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]. 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].…”

“…Many previous studies used plain copying as a baseline for muscle activity [1,14,20,27,28]. The participants need to copy some text at their own comfortable pace and condition.…”

“…Many previous studies show that there is another factor that might play a role in the MSD symptom which is called psychosocial stress [12][13][14][15]. The definition of psychosocial stress was given as a stress that associated with a non-physical factor.…”

“…Different tasks may produce different levels of stress, hence lead to different effects on the muscle activity. Based on our literature review, stress induced by a stressful environment (including noise, verbal provocation, calling out any mistakes and evaluation by a supervisor) has the largest effect on trapezius muscle activity (but not on other muscle activity) followed by skill and intelligence tasks, time pressure tasks, arithmetic task and color-word tasks [1,8,12,14,18,19,28,30]. Therefore, we believed that psychosocial stress would increase trapezius muscle activity (First Hypothesis).…”

The position of a standard optical computer mouse affects cardiorespiratory responses during the operation of a computer under time constraints

“…Additionally, mental stress levels are known to increase with the duration of computer-related tasks. Mental stress affects autonomic nerve activity [13][14][15][16] in CRDs caused by tasks that are performed under time constraints (for example, to meet deadlines) [17][18][19] or require speedy performance [16]. Although computers are operated using keyboards, touchpads, and mouse devices, CRDs and computer arm syndrome can even be associated with tasks involving IJOMEH 2014;27(4)…”