The interaction effect of posture and psychological stress on neck-shoulder muscle activity in typing: A pilot study

Work-related musculoskeletal disorders are common among computer users, especially involving the neck and shoulder region. Previous studies showed subjects with neck pain had altered muscle recruitment patterns that persisted throughout the sustained computing task. Moreover, some studies reported that working posture and psychological stress also influence muscle recruitment. Therefore the aim of this study was to investigate the interaction effect of working posture and psychological stress on muscle activity. Fourteen subjects (7 neck pain subjects and 7 healthy subjects) were recruited in this study. This study designated two working postures (upright sitting posture/ backward sitting posture) and two levels of psychological stress (standard typing task/ stressful typing task), and used surface EMG to collect the muscle activity of the upper trapezius and cervical erector spinae during a10-min typing process. Results showed psychological stress trends to increase the muscle activity, while a backward sitting posture trends to decrease muscle activity. Considering the busy and stressful life in modern lifestyle, this study suggests subjects with neck pain should maintain a backward sitting posture during computer use. © 2011 Springer-Verlag Berlin Heidelberg