ABSTRACT
Workers engaged in physical work are often exposed to psychological stresses that affect their physiological systems including their musculoskeletal, cardiovascular, and central and peripheral nervous systems. For example, helicopter pilots who experience seated whole-body vibration are also exposed to other ergonomic risk factors, such as awkward (and often prolonged) postures, the need for constant attention during driving/flying, and the operation of various controls and handheld levers. These activities combined with whole-body vibration can be both physically demanding and mentally challenging. Such combined exposures in these occupations have been implicated in low-back pain and other neuromuscular disorders (Maikala 2002). Similarly, with increases in job automation, data processing operators working with video display terminals, assembly line workers, and high-precision electronic workers experience more visual and cognitive demands than they do physical workloads. These less physically demanding jobs contribute to muscular activity that is nonpostural or nonvoluntary due to emphasis on mental workloads, and if such an increase in muscular activity is prolonged and repeated, Rissén et al. (2000) hypothesized that muscular tension resulting from this activity could be a causal link between psychological stress and various musculoskeletal disorders. However, establishment of a physiological pathway between mind and muscle during physical work is still in its infancy.
