Assessment of workload and arm position during different work sequences: astudy with portable devices on construction workers

It is recognised that work related shoulder pain is overrepresented among c onstruction workers compared to other occupations. Studies have shown that working with hands above shoulder level increases the shoulder load. Most s tudies have been confined to the laboratory. The present project was carrie d out to map the muscular engagement and postures of construction workers u ndertaking ceiling fitting, and to compare the results to those of the labo ratory studies. Two ambulatory devices were used, one allowing recording of electromyographic (EMG) signals bilaterally from the trapezius muscle, and the other to record the position of both arms and back by means of measuri ng the angles between the vertical line and the back and both upper arms. T hese recordings were performed during 1.5-2 h work sequences. The results s how that the work was mostly performed in an upright position, that both ar ms were used to a similar amount and that the workers for a large proportio n of their working time had their upper arms at levels that are considered harmful in view of shoulder load. The EMG data showed that nearly 50% of th e work was spent with trapezius activity that exceeded that of the referenc e contraction used (about 15% of maximal voluntary contraction) and that th e time spent in muscular relaxation was 10%. It was concluded that the expo sure of construction workers undertaking ceiling fitting meets the criteria formulated on the basis of laboratory experiments with respect to a high r isk of acquiring chronic shoulder pain, due to rotator cuff tendinitis. (C) 1999 Elsevier Science Ltd. All rights reserved.