コンベア流れ作業者の腰部を中心とした筋骨格系障害の予防に関する人間工学的研究

Abstract

The incidence of musculoskeletal disorders of the lower back is high in female assembly line workers. This has posed serious problems in health management at workplaces. We have already pointed out that such health related problems are closely related to working conditions and have advocated the need for ergonomy-based improvement of working conditions for the prevention of occupational diseases. This study was designed to ergonomically determine the optimum working height and the optimum period of work for the relief of muscle stress associated with working postures. A field experiment was undertaken. In the experiment, the body length distribution of workers was taken into consideration. 1. Many of the workers felt that the low working height, high speed of the conveyor-belts and long period of work were the sources of stress. The complaint that the working height was too low was more frequent in tall workers. 2. To determine the optimum working height, conveyor-belts of four different heights, 73, 78, 83 and 88 cm, were prepared and tested. The conveyor-belt of 78 cm in height was best suited por 90% of the workers, regardless of their statures. When the angle of stooping action and the smooth movement of arms are taken into consideration, a 5-10 cm increase from the current height (73 cm) seemed to be the optimum working height. 3. Shortening the current period of 60 minutes to 20 minutes was found to be desirable. The above results suggest that introduction of working time management and ergonomically-derived measures in addition to the already advocated health-management plans would be effective for the relief of musculoskeletal disorders.