Abstract
Work-related musculoskeletal disorders affect millions of workers and run up enormous costs by affecting both worker well-being and by production loss. Jobs that require static trunk flexion create biomechanical loads on the muscles and soft-tissue of the lower back, and may contribute to disability caused by low back pain. This paper presents the preliminary results from a laboratory study to identify personal and work factors that determine endurance limits for maintaining non-neutral trunk postures. Subjective and objective measures of performance were recorded using a visual analog scale for discomfort, time of distracting discomfort (TDD), total endurance time (TET) in each posture, and surface electromyography. Endurance time dropped significantly between 15 and 30° of flexion. Older subjects outperformed the younger subjects in TET. Perceived discomfort increased monotonically as a function of trunk flexion angle, with younger subjects perceiving greater discomfort than the older population.
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