Effect of Head Inclination on Neck Muscular Activity, Tracking Performance and Subjective Neck Strain: Visual and Biomechanical Conditions for Designing the Computer Workstation

At office computer work, musculoskeletal complaints can occur when workplace conditions are not designed according to physiological dispositions of the office worker. Regarding neck pain, the vertical position of the monitor should be adjusted in a way that the head adopts a comfortable posture. For investigating this physiological condition, this research compares several measures of performance and strain as a function of the inclination angle of the head. Head movement performance was measured when the head moves horizontally in a tracking task, while the myoelectrical activity of two types of neck muscles was recorded, i.e. of the sternocleidomastoid muscle and splenius capitis muscle. Additionally, the subjective rating of perceived musculoskeletal strain was assessed by questionnaires in the tracking task and in an office field study. All these measures represent ergonomic stress-strain functions that can be useful in physiologically based ergonomic research. Lowering the head inclination by a few degrees was able to reduce the subjectively rated musculoskeletal strain in field studies. The inclination of the head and vertical gaze direction to the monitor should agree with individual physiological dispositions.