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The present aim was to measure and quantify upper-arm elevation and to find how changed work organization and work tasks influence arm movement during a working day. Sixteen female office workers participated in the study. Their main work was statistical data entry. Upper-arm elevation was measured on two occasions separated by 18 months, i.e., before and after a change of work organization. The measurements were performed during the whole of one ordinary working day. The differences between the two measurements were mostly non-significant. Arm elevation remained essentially below 30 degrees during the main time of the working day, and the subjects worked with limited arm movements. Despite new alternative office tasks, they did not achieve a change in their habitual arm postures, or in their neck-and-shoulder disorders.

This study investigated how ergonomic design influences neck-and-shoulder muscle strain, through keyboard assessment. Muscular activity was measured electromyographically (EMG) from six muscles in the forearm and shoulders of eight experienced typists using each of five different types of keyboard: one mechanical, one electromechanical, and one electronic typewriter; one personal computer/word processor (PC-XT) keyboard; and one angled at 20 degrees in the horizontal plane. The impact on muscular activity of using a palmrest was also studied. The mechanical typewriter induced a higher strain in the forearm and finger muscles than did the modern typewriters and keyboards. These induced no different strain on the neck-and-shoulder muscles, except for the right shoulder muscle, which was more active with the electronic typewriter than with the other machines. Using a palmrest did not decrease the strain on the muscles investigated. Use of the 'angled' PC-XT keyboard did not influence the measured muscular load on the forearm and finger muscles compared to typing on an ordinary PC-XT keyboard, but decreased the extensor muscular strain compared to the electronic typewriter.