Background: Investigations of work-related low back (LB) and upper extremity (UE) disorders have increasingly utilized multivariable models that include biomechanical/physical and work organization factors. However, the nature of any interactive effects is not well understood.
Methods: Using questionnaires, high and low exposure groups for biomechanical/physical factors, cognitive demands, cognitive processing, interpersonal demands, participatory management, skill discretion, and time pressure for 289 individuals (U.S. Marines) were identified. Musculoskeletal symptom status was also determined by questionnaire. Individual and biomechanical-psychosocial combinations were examined in adjusted multivariable logistic regression analyses.
Results: Time pressure was associated with both LB and UE symptoms (odds ratio(s) (OR) range = 2.13-3.09), while higher biomechanical exposures were risk factors for LB symptoms (OR = 2.07; 95% confidence intervals (CI): 1.00-4.35) and concurrent LB and UE symptoms (OR = 2.80; CI: 1.35-5.83). Greater risks for concurrent LB and UE symptoms were indicated for combinations involving higher biomechanical exposure and: time pressure (OR = 2.21; CI: 1.19-4.10); cognitive demands (OR = 2.25; CI: 1.23-4.09); cognitive processing (OR = 2.08; CI: 1.16-3.75); interpersonal demands (OR = 2.44; CI: 1.35-4.41); participatory management (OR = 2.50; CI: 1.30-4.81). Results did not suggest any interaction between biomechanical and work organization factors.
Conclusions: While no synergism was indicated, the present findings emphasize the need to consider both biomechanical factors and specific work organization factors, particularly time pressure, in reducing musculoskeletal-related morbidity.