Effect of the difficulty level of a biofeedback device for postural correction on the orbicularis oculi and upper trapezius muscle activity and trunk flexion angle during computer work

[Purpose] The purpose of this study was to investigate the effect of the difficulty level of a biofeedback device for postural correction on the orbicularis oculi and upper trapezius muscle activity and trunk flexion angle during computer work. [Subjects] Ten computer workers were included in this study. [Methods] The biofeedback tool used in this study provided visual and auditory feedback with regard to changes in trunk flexion angle under two different conditions during computer work: The first condition was when there was an increase of more than 10 degrees in a standard sitting posture. The second condition was when there was an increase of more than 20 degrees in the same posture. [Results] The trunk flexion angle showed no significant difference between conditions. The muscle activities of the orbicularis oculi and upper trapezius under condition 1 (high difficulty level) was significantly increased compared with those under condition 2 (low difficulty level). [Conclusion] This result showed that frequent feedback with greater sensitivity can trigger stress and lead to the outbreak of other illnesses.