Abstract

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 conventional 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

Author(s)

Tessy Luger, Stefan A Ferenchak, Monika A Rieger, Benjamin Steinhilber

Abstract

Plain language summary

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

Key messages

• We did not find enough good‐quality evidence to draw reliable conclusions about the benefits and risks of different work‐break interventions for preventing musculoskeletal symptoms and disorders (conditions that affect bones, joints, muscles, and connective tissues) in healthy workers.
• One study showed that additional work‐breaks may reduce the intensity of musculoskeletal back pain amongst office workers when compared to no additional work‐breaks, but the evidence is very uncertain.
• Larger studies are needed to provide better estimates of potential benefits and harms of different work‐break interventions for preventing musculoskeletal symptoms and disorders. Future studies should also consider people who are in jobs that are not office‐based.

What are work‐related musculoskeletal disorders?

Work‐related musculoskeletal disorders are a range of conditions that affect bones, joints, muscles, and connective tissues. They are a major problem for workers, employers, and society as a whole. The number of workers suffering from work‐related musculoskeletal disorders is high. 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.

How might work‐break interventions help prevent musculoskeletal disorders?

Sitting or standing in one position for a long time is a risk factor for developing work‐related musculoskeletal disorders. Different work‐break schedules are likely to interrupt or decrease long periods of repetitive or monotonous workloads during which workers may adopt static or awkward body postures. How long a work‐break is and whether it is active (e.g. doing a specific mental or physical activity) or passive may also be important factors. Several studies have been carried out to test if varying the work‐break schedule, or its length or content, can help reduce the risk of developing musculoskeletal disorders.

What did we want to find out?

We wanted to find out whether different frequencies, durations, and types of work‐breaks can prevent work‐related musculoskeletal symptoms and disorders amongst healthy workers compared to usual work‐break schedules. We considered workers as healthy when they were free of musculoskeletal complaints when they enroled in the study.

What did we do?

We searched medical databases until 31 May 2024 to find studies where participants were allocated randomly to different groups to investigate work‐break interventions that aimed to prevent work‐related musculoskeletal disorders. We used a system known as GRADE to judge the reliability of the evidence.

What did we find?

We found nine studies that involved 626 workers in total, almost all of whom were office workers (98%). Most of the workers were female (at least 75%). The length of the interventions varied between one day and six months.

Effect of different work‐break frequencies

Seven of the nine studies evaluated different work‐break frequencies. There may be little to no difference between additional work‐breaks and no additional work‐breaks in their effect on the new onset of musculoskeletal pain or the intensity of musculoskeletal discomfort, although the evidence is very uncertain. However, additional work‐breaks may reduce the intensity of musculoskeletal back pain compared to no additional work‐breaks, although the evidence for this is also very uncertain.

Whether additional work‐breaks are given more often (higher frequency) or less often (lower frequency) may have little to no effect on the intensity of musculoskeletal discomfort, but the evidence is very uncertain.

Effect of different work‐break types

Three of the nine studies evaluated different work‐break types. Active work‐breaks (e.g. a low‐intensity physical activity such as stretching) or cognitive work‐breaks (e.g. mental activity such as relaxation or mindfulness) may have little to no effect on the intensity of musculoskeletal fatigue compared to passive work‐breaks, but the evidence is very uncertain. Similarly, active work‐breaks may have little to no effect on the intensity of musculoskeletal fatigue compared to cognitive work‐breaks, but the evidence is uncertain.

What are the limitations of the evidence?

Our confidence in the evidence is very low. There were three main reasons for this: the studies were very small; the studies delivered work‐break content to workers in different ways; and the key outcomes were based on self‐reports by the study participants. Therefore, there is a need for high‐quality studies with larger sample sizes to assess the effects of different work‐break interventions at workplaces. Such studies could provide clearer insights into the potential benefits of varying the work‐break schedule, length, or content for jobs requiring repetitive motions, as well as any possible harm from the interventions. The studies we found focused on office workers; in future studies, work‐break interventions should take into account people who work in other types of jobs. Future studies could also investigate whether combining work‐breaks with other interventions, such as ergonomic (i.e. designing the work environment and tasks based on individual worker needs) training or counselling, may help prevent the development of work‐related musculoskeletal disorders.

How up to date is this evidence?

This review updates our previous review, which was published in 2019. The evidence is based on searches up to May 2024.

Author(s)

Tessy Luger, Stefan A Ferenchak, Monika A Rieger, Benjamin Steinhilber

Reviewer's Conclusions

Authors' conclusions 

Implications for practice

The evidence in the current review is very uncertain about the effect of additional work‐breaks on work‐related musculoskeletal back and neck pain and on productivity. Adverse effects were not measured in the studies in this review. Furthermore, the evidence is very uncertain about the effect of additional higher‐frequency work‐breaks and different types of work‐breaks on new musculoskeletal disorders or symptoms, and on productivity or work performance outcomes. We found no RCTs that investigated different durations of work‐breaks.

Due to the very low‐certainty of the evidence for all outcomes reported in this review update, it is likely that the true effect of different work‐break interventions compared to conventional work‐breaks on selected outcomes is different from that analysed and reported here. Several factors led to our judgement of 'very low certainty' in the evidence, specifically high risk of bias, small sample size, and low precision of the effect estimates [60].

Implications for research

This review demonstrates that we currently lack reliable evidence to judge whether additional work‐breaks or different types of work‐breaks prevent work‐related musculoskeletal symptoms or disorders in workers. There is very low‐certainty evidence that additional work‐breaks potentially increase productivity or work performance in office workers. The level of certainty in the evidence can be improved by including larger sample sizes (increasing precision of the results), publishing study protocols (minimising reporting bias), defining methods of random sequence generation and allocation concealment (minimising selection bias related to domain 1 of RoB 2), and adhering to blinding of participants and personnel (minimising performance and detection bias related to domain 2 of RoB 2).

Precision of the results may be increased by predetermining the relevant estimated effect of the intervention on the primary outcome based on previously published studies. With this information, a calculation for an appropriate sample size would indicate how many participants would be necessary to make a sound interpretation of the study’s outcomes [108, 109]. The estimated effect sizes and related sample size calculations were missing from the RCTs in this updated review other than for Kromberg 2020.

The risk of publication and reporting bias can be reduced by publishing study protocols, which is already widely recommended. Moreover, published study protocols inform the (scientific) community what studies will be or are being conducted, avoid duplication of studies [110], and may allow replication of the trial in cases where the intervention is not too complex [111]. The potential disadvantage of publishing study protocols is the impact on the blinding, but in many cases the advantages may outweigh the disadvantages. In the current review, only three studies published a study protocol prior to evaluating their work‐break intervention (De Bloom 2017; Díaz‐Silveira 2023; Waongenngarm 2021).

Only two of the studies that were included in the current review reported details about random sequence generation and allocation concealment (Kromberg 2020; Waongenngarm 2021). Future studies should include a clear description of both procedures in their methods to allow more transparent research and a more accurate assessment of the risk of selection bias (related to domain 2 of RoB 2).

In light of the nature of the interventions, performance bias was difficult to avoid because employees knew that they had undergone an intervention. Detection bias may be easier to tackle by deploying independent assessors who are blinded to the intervention. A disadvantage of applying and investigating interventions in RCTs at the workplace is that workers may become aware that colleagues are part of another intervention or control group. This may lead to unblinding and possible treatment group contamination. A cluster‐randomised design may be useful for avoiding treatment‐group contamination with employees from one department assigned to the control or intervention [112]. Such a cluster‐randomised design may furthermore enhance participant compliance because employees of the whole department are part of the control or intervention group, which may result in fewer dropouts and indirectly result in a higher sample size.

Eight of the trials were performed in high‐income countries (four in North America and four in Europe) and one in an upper‐middle income country (Thailand) [113]. We recommend conducting (more) studies in low and middle‐income countries, because there are differences in culture, politics, and economics, and therefore, also in work practices. Additionally, eight studies were with office workers; the effectiveness of work‐break interventions on workers other than office workers should be assessed. We recommend conducting studies with one heterogeneous sample across different occupational sectors or several homogeneous samples from different occupational sectors.

Finally, we could not perform any subgroup analyses due to the low number of studies and small sample sizes. More randomised controlled (cross‐over) trials and cluster‐randomised trials are needed, which may yield more evidence in general and more evidence about potential differences in the effects of work‐break interventions in men and women, different age groups, and different professions. In this respect, it is important to reconsider the work‐break intervention in view of the type of work, as two aspects can be of particular importance in designing the work‐break intervention: the physical load of the occupation and the typical work schedule.

Get full text at The Cochrane Library