Effects of typing positions on the upper trapezius and neck extensor muscles electromyography in office employees: A single-blind cross-sectional study

Abstract

BACKGROUND: Holding incorrect postures over a long period could lead to chronic nonspecific neck pain (CNNP) in office employees. OBJECTIVE: The present study aimed to evaluate the effects of different typing positions on the activity of the neck extensor and upper trapezius (UT) muscles of office employees diagnosed with CNNP. METHODS: This assessor-blinded cross-sectional study was performed on 22 female subjects with the mean age of 39.95±5.30 years. The neck extensors and UT muscle activities of the participants were assessed in the upright, forward, and slouching postures by electromyography (EMG). In addition, neck proprioception and the performance of the cervical stabilizer muscles were evaluated using an inclinometer and biofeedback pressure unit, respectively. RESULTS: A significant difference was observed between the cervical erector spine (CES) and UT muscle activities in the upright, forward, and slouching typing positions (P < 0.05). In addition, a difference was observed between the upright and slouching postures in these muscles. A positive correlation was denoted between CES muscle activity in the slouching and forward postures and the activation index of neck muscles (P < 0.05). Furthermore, a significant, negative correlation was observed between the UT muscle activity in the slouching posture and neck proprioception (P < 0.05). A positive correlation was also noted between the pain index and repositioning error rates (P < 0.05). CONCLUSION: CES muscle activity increased in a forward head posture, which could damage neck proprioception through causing early fatigue and stimulating a cumulative damage cycle.