Psychosocial factors in sustained attention work and contribution to work related musculoskeletal disorders

The world has entered what has become known as the fourth industrial revolution. Technological advancements in ICT and automation including IoT, cloud computing and smart robotics have changed industrial manufacturing workplaces. The dull, dangerous and dirty work associated with manufacturing work has largely been replaced by supervisory monitoring work. Job demands in manufacturing are now more likely to be cognitive rather than physical demands. When job demands are too low or too high they are called psychosocial stressors. Prolonged monitoring work requires high levels of sustained attention for human operators which can pose high cognitive demands. Other psychosocial stressors that are prevalent in manufacturing environments include low autonomy, low skill discretion and social isolation. Psychosocial stressors can contribute to the development of musculoskeletal disorders. In modern manufacturing, where levels of physical work are low, psychosocial stressors and cognitive demand in particular are likely to be important contributors to musculoskeletal disorders. Several psychophysiological mechanisms are involved which range from activation of the sympathetic nervous system to changes in breathing and increases in muscular activity. Data from industrial survey based studies were analysed by structural equation modelling and used to investigate relationships between psychosocial stressors and musculoskeletal disorders. Three experimental studies were established to probe specific mediation and moderation mechanisms linking cognitive demands to increases in muscular activity, which is a pertinent risk factor in the development of musculoskeletal disorders. The industrial survey revealed that cognitive demand was significantly linked to shoulder and back complaints and social isolation to neck and lower back symptoms via distress as a mediating stress variable. Job control was linked to upper back complaints via worry as the mediating stress variable. Attention demand was found to predict an increase in musculoskeletal disorders, with task engagement as the mediating stress variable. The experimental studies proved that lowered end-tidal CO2 as a result of stress was found to strengthen the relationship between mental workload and mental stress due to attention work and muscle activity. This is advancement on the theory linking job stress and musculoskeletal disorders, which hypothesized that end-tidal CO2 acted as a mediator in this relationship. In addition to this, the parasympathetic nervous system was found to mediate the relationship between stress due to an attention task and muscle activity. An improved breathing technique was found to increase end-tidal CO2 levels and parasympathetic nervous system activity can be used to decrease muscle activity and consequently reduce musculoskeletal disorders. Hyperventilation, which can occur on exposure to stress strengthen the effect of the stressor on increased muscular activity. Exposure to chronic stress results in inhibition of the parasympathetic nervous system, which mediates the relationship between stress and muscular activity. Monitoring work can pose high cognitive demands and is consequently a psychosocial stressor which contributes to musculoskeletal disorders.