Effects of different sorting table heights on low back and shoulders biomechanical loads during dungeness crab sorting

Abstract

West Coast Dungeness crab fishers suffer a high prevalence of musculoskeletal injuries, especially low back pain. Substantial trunk flexion and associated low back loads during crab sorting tasks have been attributed to awkward sorting table heights. This study examined how varying table heights affect biomechanical loads on the low back and shoulders. Twenty-five participants performed crab sorting tasks at three table heights while trunk and shoulder joint angles, moments, muscle activity, perceived exertion, and discomfort were measured. Increasing table height reduced trunk flexion and lumbosacral (L5/S1) joint moments but increased shoulder flexion moments and upper trapezius muscle activity. Table height did not affect perceived exertion or discomfort. These findings indicate that increasing sorting table height can reduce biomechanical load on the low back but results in increased shoulder strain. This trade-off underscores the importance of adopting ergonomic designs balancing low back and shoulder biomechanics to determine appropriate sorting table height.