This study was designed to identify the effects of a visual feedback device for hip adduction on trunk muscles and sitting posture when working at a visual display terminal. The forward head and trunk flexion angles of 20 workers were analyzed using a motion analysis system, and the activities of the lower trapezius, external abdominal oblique, internal abdominal oblique, and L5 paraspinal muscles were analyzed using a electromyography system. The statistical significance of differences between using and not using a visual feedback device was assessed by paired t tests. Using the visual feedback device during Visual Display Terminal work significantly decreased the forward head and trunk flexion angles, and significantly increased the activities of the external abdominal oblique, internal abdominal oblique, and L5 paraspinal muscles. The authors suggest that the visual feedback device for hip adduction promotes the adoption of standard spine and pelvic postures, which might be effective in preventing poor sitting postures.
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