The effectiveness of a chair intervention in the workplace to reduce musculoskeletal symptoms. A systematic review

BACKGROUND Prolonged sitting has been associated with musculoskeletal dysfunction. For desk workers, workstation modifications frequently address the work surface and chair. Chairs which can prevent abnormal strain of the neuromuscular system may aid in preventing musculo-skeletal pain and discomfort. Anecdotally, adjustability of the seat height and the seat pan depth to match the anthropometrics of the user is the most commonly recommended intervention. Within the constraints of the current economic climate, employers demand evidence for the benefits attributed to an investment in altering workstations, however this evidence-base is currently unclear both in terms of the strength of the evidence and the nature of the chair features. The purpose of this study was to evaluate the evidence for the effectiveness of chair interventions in reducing workplace musculoskeletal symptoms. METHODS Pubmed, Cinahl, Pedro, ProQuest, SCOPUS and PhysioFocus were searched. 'Ergonomic intervention', 'chair', 'musculoskeletal symptoms', 'ergonomics', 'seated work' were used in all the databases. Articles were included if they investigated the influence of chair modifications as an intervention; participants were in predominantly seated occupations; employed a pre/post design (with or without control or randomising) and if the outcome measure included neuro-musculoskeletal comfort and/or postural alignment. The risk of bias was assessed using a tool based on The Cochrane Handbook. RESULTS Five studies were included in the review. The number of participants varied from 4 to 293 participants. Three of the five studies were Randomised Controlled Trials, one pre and post-test study was conducted and one single case, multiple baselines (ABAB) study was done. Three studies were conducted in a garment factory, one in an office environment and one with university students. All five studies found a reduction in self-reported musculoskeletal pain immediately after the intervention. Bias was introduced due to poor randomization procedures and lack of concealed allocation. Meta-analysis was not possible due to the heterogeneity of the data (differing population, intervention and outcomes across studies). CONCLUSION The findings of this review indicate a consistent trend that supports the role of a chair intervention to reduce musculoskeletal symptoms among workers who are required to sit for prolonged periods. However the amount, level and quality of the evidence are only moderate therefore we cannot make strong recommendations until further trials are conducted. The review also highlights gaps: for example in showing whether the effectiveness of a chair intervention has long-term impact, particularly with respect to musculoskeletal symptoms, as well as the recurrence of symptoms and the consequent cost of care.