The association between trunk flexion and low back pain in blue-collar workers: A systematic review

BackgroundTrunk flexion has been considered as an important risk factor for low back pain (LBP) in blue-collar workers. There is controversy about this claim, and prior reviews mainly included studies assessing trunk flexion with questionnaires and/or outside of the work setting.ObjectiveIn this systematic review, we aimed to investigate the association between objectively measured trunk flexion at work and LBP in blue-collar workers from epidemiological studies.MethodsLiterature searches were performed in PubMed, Embase and Web of Science until June 2024. Cross-sectional and longitudinal cohort studies were included if they objectively measured trunk flexion (amplitude and duration) under normal working conditions in blue collar workers. Two reviewers independently performed study selection, data extraction and risk of bias assessment, and studies were described narratively.ResultsFrom 800 references, four studies with 2013 participants in total were included. There was no evidence for an association between trunk flexion amplitude/duration and increased LBP prevalence, incidence and/or intensity. One study showed an association between higher duration of trunk flexion above 30° and reduced risk of LBP (hazard ratio 0.87, 95%CI: 0.78-0.97).ConclusionsThese results suggest that trunk flexion is not associated with LBP development or aggravation in blue-collar workers. However, based on the limited number of studies and lack of geographical diversity, the certainty of evidence is low and more evidence is needed from studies with objective measures of trunk flexion at work.