Work-break interventions for preventing musculoskeletal symptoms and disorders in healthy workers.

RATIONALE: Work-related musculoskeletal disorders are amongst the leading causes of occupational sick leave worldwide and account for a high share of absenteeism. For example, in the UK in 2021 to 2022, musculoskeletal disorders were estimated to account for around 27% of all work-related illnesses and result in 6.6 million lost working days. Several workplace interventions are available for reducing the high prevalence of work-related musculoskeletal disorders. We focused on work-breaks as an organisational intervention for primary prevention. This is an update of a Cochrane review first published in 2019. OBJECTIVES: To assess the effects of different work-break interventions for preventing work-related musculoskeletal symptoms and disorders in healthy workers, when compared to conventional or alternative work-break interventions. SEARCH METHODS: We searched for randomised controlled trials in CENTRAL, MEDLINE, Embase, CINAHL, PsycINFO, SCOPUS, Web of Science, ClinicalTrials.gov, and the WHO ICTRP, up to 31 May 2024. ELIGIBILITY CRITERIA: We included randomised controlled trials (RCTs) of work-break interventions at workplaces for preventing work-related musculoskeletal symptoms and disorders amongst workers. The studies were eligible for inclusion if they intervened on work-break frequency, duration, or type, compared to conventional or alternative work-break interventions, and when the investigated population included healthy adult workers who were free of musculoskeletal complaints during study enrolment, without any restrictions on sex or occupation. OUTCOMES: Our critical outcomes were newly diagnosed musculoskeletal disorders or symptoms, and intensity of musculoskeletal symptoms (including pain, discomfort, or physiological fatigue). Our important outcomes were productivity or work performance, and workload as a measure of strain. RISK OF BIAS: We judged the risk of bias in the outcomes of the included studies using the Cochrane RoB 2 tool. SYNTHESIS METHODS: Two review authors independently screened search records or full texts for study eligibility, extracted data, and assessed risk of bias. We contacted authors for additional data where required. We used the random-effects model for meta-analyses, producing risk ratios (RR) for dichotomous outcomes and mean differences (MD) or standardised mean differences (SMD) for continuous outcomes. We rated the certainty of evidence using GRADE. INCLUDED STUDIES: We included nine RCTs (three of which were new in this update) with 626 workers (at least 75% of whom were female, and 98% of whom were office workers). The trials were conducted in high-income or higher-middle-income countries. Four of the RCTs used a parallel design; two used a cross-over design; one was a mixture of parallel and cross-over; and two were cluster-RCTs. Intervention periods ranged from one day to six months. Six studies investigated work-break frequencies, two investigated work-break types, and one investigated both. None of the studies investigated work-break durations. One study could not be included in the meta-analyses because no detailed results were reported or available. We judged all outcomes to have some bias concerns or to be at high risk of bias. SYNTHESIS OF RESULTS: We assessed the evidence available for all comparisons and outcomes as 'very low certainty'. Changes in frequency of work-breaks Compared to conventional work-breaks, additional work-breaks may make little to no difference to the new onset of musculoskeletal neck pain (RR 0.82, 95% CI 0.53 to 1.28; 1 study, 147 participants) or back pain (RR 0.58, 95% CI 0.30 to 1.11; 1 study, 147 participants), but the evidence is very uncertain. Likewise, additional work-breaks may make little to no difference to the intensity of musculoskeletal overall pain (MD -1.01, 95% CI -2.84 to 0.82; 1 study, 39 participants) or the intensity of musculoskeletal back discomfort (SMD -0.04, 95% CI -0.24 to 0.17; 5 studies, 372 participants), but the evidence is very uncertain. Additional work-breaks may reduce the intensity of musculoskeletal back pain (MD -0.91, 95% CI -1.45 to -0.38; 1 study, 147 participants), but the evidence is very uncertain. Intensity of overall physiological musculoskeletal fatigue and adverse effects were not measured in the studies investigating frequency of work-breaks. Additional higher-frequency work-breaks may make little to no difference to the intensity of musculoskeletal back discomfort, compared to additional lower-frequency work-breaks (MD 18.60, 95% CI -47.07 to 84.27, 1 study, 10 participants), but the evidence is very uncertain. Our other critical outcomes were not measured in this study. Changes in type of work-breaks The studies that evaluated different types of work-breaks assessed only one of our critical outcomes. Active work-breaks may make little to no difference to the intensity of physiological musculoskeletal fatigue compared to conventional work-breaks (SMD -0.23, 95% CI -0.55 to 0.10; 2 studies, 146 participants), but the evidence is very uncertain. Cognitive work-breaks may make little to no difference to the intensity of physiological musculoskeletal fatigue compared to conventional work-breaks (SMD -0.18, 95% CI -0.57 to 0.21; 2 studies, 141 participants), but the evidence is very uncertain. Active work-breaks may make little to no difference to the intensity of physiological musculoskeletal fatigue compared to cognitive work-breaks (SMD -0.03, 95% CI -0.37 to 0.30; 2 studies, 137 participants), but the evidence is very uncertain. AUTHORS' CONCLUSIONS: The evidence is very uncertain about the effect of additional work-breaks on the intensity of musculoskeletal back and neck pain and on productivity. The evidence is very uncertain about the effect of different work-break types on newly diagnosed musculoskeletal symptoms and on the intensity of musculoskeletal symptoms. Further high-quality studies are needed to determine the effectiveness of different frequencies, durations, and types of work-breaks amongst workers for preventing musculoskeletal disorders and symptoms, with much larger sample sizes than the studies included in this review. Furthermore, studies should consider worker populations other than office workers. FUNDING: This Cochrane review update was internally funded by institutional resources. REGISTRATION: Original review (2019): https://doi.org/10.1002/14651858.CD012886.pub2 Original protocol (2017): https://doi.org/10.1002/14651858.CD012886.