Introduction: In Germany, approximately 35 % of the 36.6 million employees currently spend their normal working life in an office. The proportion of the working day spent sitting or in a static posture depends on the nature of the job and can be up to 80 % (sometimes even more). The lack of posture variation associated with office work is a known risk factor for the development of musculoskeletal disorders. Over sixty percent of office workers in Germany report musculoskeletal complaints. Aim: How are physical and psychological well-being and work performance affected if the time spent sitting is reduced by the introduction of dynamic sitting and standing for work at a VDU? Subjects and Methods: 60 male students of the University of Mainz were randomly assigned to either the intervention or control group. They carried out simulated office work, mainly data entry tasks. The intervention group worked partly standing (25 % of working time) and partly sitting (50 %) while the control group worked mainly sitting (75 % of working time). Both groups had a 10-minute long task with movement (i.e. photocopying, shredding, sending faxes) and a 5-minute break. The office work had to be carried out for 4 hours a day for 5 consecutive days. Group differences regarding psychic und physical well-being were tested with two questionnaires, the “Gießener Beschwerdebogen”, and the “Mehrdimensionaler Befindlichkeitsfragebogen”. Job performance was measured as the number of correctly typed characters per minute. In addition, heart rate (electrocardiogram), activity of the M. trapezius (electromyogram) and blinking frequency (electrooculogram) were recorded. Results: The physical well-being, represented by the Gießener Beschwerdebogen score, showed considerable group differences after one week of work. The summed score for limb pain revealed differences between intervention group and control group, 1.9 (1.0 ) ± 2.3 and 3.2 (2.5) ± 2.8 (mean (median) ± SD), respectively. Likewise the overall complaint score was different in the intervention group (5.0 (3.0) ± 5.1) and the control group (7.6 (6.0) ± 6.0). After one week of work, the intervention group’s performance was worse than that of the control group, with a slower learning curve (14.1 (14.5) ± 8.1 characters per minute) than the control group (18.6 (18.4) ±7.7 characters per minute; p = 0.046). During the work week, the muscular strain decreased in the intervention group from 60.2(43.0) ± 53.6 μV to 43.4 (27.4) ± 9.0 μV (p = 0.006). The control group did not show any changes in muscular strain. The blinking frequency and the heart rate also decreased after one week of experimental work, although there was no difference between the two groups. Conclusion: Introducing dynamic sitting and standing at work led to better physical wellbeing. This was seen in the summed score for limb pain and decreased muscular strain in the intervention group. The difference observed was not highly statistically significant, but considering the short duration of the work experience and the age of the subjects, it seems to be of biological importance. To improve primary prevention, it would therefore be useful to introduce dynamic sitting and standing workplaces for work with visual display units.
