Several distinct work-related psychosocial factors have been identified conceptually and can be measured reliably. They are associated with work-related low back pain and, less consistently, with work-related upper extremity disorders. The extent to which these variables interact with physical stressors remains to be determined. Also in terms of intervention, it is currently unclear what impact reducing physical stressors may have on psychological distress. The models of job stress presented in this chapter provide an important conceptual link between work-related psychosocial factors and work-related musculoskeletal disorders. They share many core features, providing additional (face) validity. These features include an association between stressful workplace conditions and a set of physiological responses, which, in turn, are associated with musculoskeletal disorders. These models need to be further validated.

While the precise biological mechanisms through which these physiological responses to stress lead to musculoskeletal disorders have not been fully elucidated, work to date suggests that musculoskeletal, neuroendocrine, and immunological pathways may be prominent. Further work in this area is needed to better define these biologic mechanisms. In addition, the knowledge currently available on psychosocial stress should be incorporated into interventions to ameliorate work-related musculoskeletal disorders.