Work-related neck and upper limb disorders

Úrdráttur úr Masters ritgerð frá the University of Birmingham.

Work-related neck and upper limb disorders (WRUNLD) are a negative factor of increased computer use.  Neck pain has been associated with neck and head posture but according to the literature the outcome is conflicting.  The purpose of this study was to investigate the muscular activity in the sternocleidomastoid (SCM) muscles during sitting in two different cranio-cervical postures (CCP’s) in a standard computer environment using electromyography (EMG). 

The muscular activity was measured during 5 minutes period, twice with the head held in a resting posture (RHP) and ones after being placed, by the author, in a neutral head posture (NHP) as defined by Kendall et al. (2005).  Linear excursion measurement device (LEMD) was used to determine the differences between the resting and neutral head postures.  Twenty-four students from University of Birmingham (aged 19-31) responded to e-mail request for volunteers and fulfilled the inclusion criteria.  The study was single-blinded, one-tailed, using the same subject design with A-A-B repeated measurements where A- represents the resting and B- the neutral head posture. The participants attended laboratory room for measurements where the total procedure time was approximately 30 minutes.  Root-mean-square (RMS) values over one minute of the sEMG signals were calculated for data analysis.  The paired t-test was used for statistical analysis using SPSS (version 15).  The results showed no significant difference (P=0.08) in muscular activity in the sternocleidomastoid muscles when sitting with the head in resting or neutral head postures.  The LEMD outcome showed that the participants’ resting head postures deviated significantly (P<0.001) from the neutral head posture. The findings suggest increased activity in the SCM muscles in the neutral head posture compared with the resting one. It also shows that neutral head posture is unfamiliar among young individuals working on computers.