Perceived muscular tension, emotional stress, psychological demands and physical load during VDU work.
OBJECTIVE
The aim of this study was to investigate whether perceived muscular tension, psychological demands and emotional stress were associated with physical load or working technique during visual display unit (VDU) work.


METHODS
Subjects (28 women and 29 men) from two different organisations volunteered to participate in the study. The study design was cross-sectional, and the data were assessed when the subjects performed their usual work tasks at their usual work place. Multivariate linear and logistic regression models were used to investigate possible associations. The different outcome variables were: median muscle activity and muscular rest in the trapezius muscle bilaterally, wrist movements and working technique. The different explanatory variables were: perceived muscular tension (binary), emotional stress (binary), psychological demands (binary), organisation (binary) and gender (binary). Age (continuous) and present musculoskeletal pain (binary) were also controlled for in the multivariate models. Electromyography (EMG) and electrogoniometers were used to assess the physical load, and the data collection time was 15 min. An ergonomic checklist was used to assess working technique, i.e. work with lifted shoulders.


RESULTS
Subjects who perceived muscular tension at least a few times per week the month before the measurements were made worked with higher muscle activity [expressed as per cent of a reference voluntary electrical activity (% RVE)] in the trapezius muscle bilaterally (5% RVE, P=0.05). High emotional stress during the measurement was associated with higher muscle activity in the trapezius muscle on the side not operating the computer mouse (8% RVE, P=0.006). Subjects who reported high levels of emotional stress worked more often with lifted shoulders (odds ratio 6.0, 95% CI 1.2-28.9). However, when present musculoskeletal pain was included in the multivariate model the odds ratio for high emotional stress decreased to 4.5 (95% CI 0.9-23.2).


CONCLUSIONS
Perceived muscular tension and emotional stress were associated with physical load, in terms of muscle activity in the trapezius muscles, during VDU work in ordinary occupational settings.
Wahlström
Jens
J
Department of Occupational Medicine, Sahlgrenska University Hospital, S:t Sigfridsgatan 85, 412 66 Gothenburg, Sweden. jens.wahlstrom@ymk.gu.se
Lindegård
Agneta
A
Ahlborg
Gunnar
G
Ekman
Anna
A
Hagberg
Mats
M
D000328:Adult; D001696:Biomechanical Phenomena; D016288:Computer Terminals; D003430:Cross-Sectional Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018482:Muscle, Skeletal; D016272:Occupational Health; D010465:Perception; D012044:Regression Analysis; D013315:Stress, Psychological; D014584:User-Computer Interface; D016526:Workload