Joint associations of occupational standing and occupational exertion with musculoskeletal symptoms in a US national sample.

OBJECTIVE: Observational studies have linked occupational standing or walking to musculoskeletal pain. These prior studies, however, are flawed as few accounted for physical exertion; a potential confounder that accompanies many standing-based occupations. The purpose of this study was to examine the individual and joint associations of occupational standing/walking and exertion with musculoskeletal symptoms.
METHODS: Data for this analysis come from the 2015 National Health Interview Survey, a US nationally representative survey. Occupational standing/walking and exertion were assessed by self-report on a 5-point Likert scale. The presence of musculoskeletal symptoms (pain, aching and stiffness) for upper extremities (neck, shoulders, elbows, wrists and fingers), lower extremities (hips, knees, ankles and toes) and lower back was also assessed.
RESULTS: Occupational standing/walking was associated with a greater likelihood of upper extremity, lower extremity and lower back musculoskeletal symptoms; however, associations were attenuated and no longer significant with adjustment for exertion. When stratified by levels of occupational exertion, occupational standing/walking was associated with musculoskeletal symptoms only among the group with high exertion (eg, OR=1.69 (95% CI: 1.48 to 1.94) for lower back symptoms comparing high/high for standing or walking/exertion vs low/low). Among groups with low exertion, occupational standing/walking was not associated with musculoskeletal symptoms (eg, OR=1.00 (95% CI: 0.85 to 1.16) for lower back symptoms comparing high/low for standing or walking/exertion vs low/low).
CONCLUSION: Results from this US representative survey suggest that the association between occupational standing/walking and musculoskeletal symptoms is largely driven by the co-occurrence of occupational exertion and does not provide evidence that standing or walking incurs adverse musculoskeletal symptoms. © Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.