Summary of main results

This systematic review evaluated the effectiveness of different work‐break interventions for preventing work‐related musculoskeletal symptoms and disorders in healthy workers, when compared to conventional or alternate work‐break schedules. We included six randomised controlled trials and 373 participants, of which four used a parallel RCT (De Bloom 2017; Henning 1997; Irmak 2012; McLean 2001) and two a cross‐over RCT design (Galinsky 2000; Galinsky 2007). The studies were all performed in real work places but addressed office workers only. All studies were at overall high risk of bias. We included three types of interventions: work‐break frequency, work‐break duration and work‐break type. From the included studies, we deduced five comparisons of which three belonged to work‐break frequency (summary of findings Table for the main comparison; summary of findings Table 2; summary of findings Table 3), none to work‐break duration, and two to work‐break type (summary of findings Table 4; summary of findings Table 5).

For the interventions related to frequency of work breaks, three comparisons were included: (1) additional work breaks versus no additional work breaks; (2) additional work breaks versus work breaks as needed (i.e. microbreaks taken at own discretion); (3) additional higher frequency work breaks versus additional lower frequency work breaks. For the first comparison, there was low to very low‐quality evidence, based on three studies, that additional work breaks have no considerable effect on self‐reported musculoskeletal pain, discomfort or fatigue or on productivity or work performance compared to no additional work breaks (summary of findings Table for the main comparison). For the second comparison, there was low‐quality evidence, based on one study, that additional work breaks have no beneficial effect on self‐reported musculoskeletal pain, discomfort or fatigue and very low‐quality evidence that additional work breaks may have a positive effect on productivity or work performance compared to work breaks as needed (summary of findings Table 2). For the third comparison, there was very low‐quality evidence, based on one study, that additional higher frequency work breaks have no beneficial effect on self‐reported musculoskeletal pain, discomfort or fatigue or on productivity or work performance compared to additional lower frequency work breaks (summary of findings Table 3). For all three comparisons, musculoskeletal outcomes were pooled and productivity and work performance outcomes were pooled. The sensitivity analyses showed that the pooling did not influence the results of the meta‐analyses.

For the interventions related to type of work breaks, two comparisons were included: (4) active work breaks versus passive work breaks; (5) relaxation work breaks versus physical work breaks. For the fourth comparison, there was low‐quality evidence, based on one study, that active work breaks have no considerable effect on self‐reported musculoskeletal pain, discomfort or fatigue compared to no passive work breaks (summary of findings Table 4). For the fifth comparison, there was low‐quality evidence, based on one study, that relaxation work breaks have no considerable effect on self‐reported musculoskeletal pain, discomfort or fatigue compared to no physical work breaks (summary of findings Table 5).

Taken together, the five studies that were included in the comparisons did not show a considerable effect of different frequencies and types of work‐break schedules on our primary outcomes, i.e. self‐reported musculoskeletal pain, discomfort or fatigue and productivity or work performance. None of the included studies reported newly diagnosed musculoskeletal disorders, secondary outcome measures or any adverse events resulting from the added or alternate work breaks.

Overall completeness and applicability of evidence

The aim of this review was to compare the effectiveness of different work‐break schedules for preventing work‐related musculoskeletal symptoms and disorders in healthy workers. The review included a broad search strategy that aimed to find all RCTs including healthy workers in real work places. The large number of potentially relevant references resulting from the search (i.e. 9,675; see: Figure 1) was checked by two reviewers. Only six studies were eligible for inclusion, of which one study could not be used due to poor data reporting and studies could be pooled only for the main comparison (total of three studies). Of the three categories of work‐break interventions, only two could be addressed, i.e. frequency and type of work breaks, meaning that duration of work breaks has not been investigated in randomised controlled studies so far.

The evidence resulting from the five comparisons dealing with different work‐break frequencies and types, was of low to very low‐quality. Furthermore, none of the comparisons yielded a statistically significant beneficial or detrimental effect of the intervention (corresponding risk) compared to the control (assumed risk). In addition, the studies included office workers only, which could be due to the locations where the studies took place, which were in high‐income countries (Europe and Northern America). Thus, office work was not being characterised by strict, predetermined work‐break schedules, as can be found in the production industry, but was rather characterised by low physical demands. The small, statistically non‐significant findings that were reported by the included studies may be the result of the marginal effect the different work‐break interventions have among office workers on the selected outcomes. Work breaks may be more effective in occupations requiring higher physical load, such as in assembly work or in nursing. Consequently, work‐break interventions should be reconsidered, by including an examination whether the work‐break intervention is sufficient to improve musculoskeletal outcomes and might be more effective when combined with another type of intervention, such as targeting worker's fitness so that employees are better able to tolerate the workload or providing ergonomic counselling so that employees are better informed about the risks of their work.

The population of 373 workers included in this review included mainly women (at least 295; i.e. ≥79%) and relatively few men (at least 39; i.e. ≥11%). This ratio may not be representative of the population of office workers.

The outcomes included in the studies all belonged to our predefined primary outcomes: self‐reported musculoskeletal pain, discomfort or fatigue, and work productivity or performance. None of the studies reported newly diagnosed musculoskeletal disorders or workload changes. We did not consider this as a disadvantage, because the primary outcomes are much more relevant than the secondary outcomes for evaluating work‐break interventions. The primary outcomes should give insight into the potential of the intervention regarding improvements of the musculoskeletal system and stability of productivity and performance.

Quality of the evidence

For each outcome of the five comparisons, we assessed the quality of the evidence using the GRADE profiler software (GRADEpro GDT) based on the five considerations, i.e. study limitations, consistency of effect, imprecision, indirectness and publication bias. Downgrading for potential study limitations was done using the outcomes of the 'Risk of bias' assessment. Since all studies had an overall high potential risk of bias, the certainty of the evidence of all outcomes was downgraded one level. The main reasons for the high risk of overall bias were high risk of performance, detection, attrition and reporting bias (see: Figure 2; Figure 3). Consistency of the effect was judged based on the heterogeneity or I² statistic provided in Data and analyses. None of the outcomes was downgraded, because consistency of the effect was considered not serious because none of the outcomes had an I² statistic over 75%. Indirectness of the results was judged as serious for the primary outcome productivity and work performance, because this outcome was not directly important for workers. All objective outcomes were therefore downgraded one level for certainty of the evidence. The certainty of the evidence of the subjective outcomes was not downgraded for indirectness, because the subjective outcomes were considered directly relevant for the worker. Imprecision of the results may influence the certainty of the evidence when sample sizes are very small (rule of thumb is > 400 subjects) and when the precision of the effect estimate is low, i.e. when the standardised mean difference (SMD) crosses 0.5 in the 95% confidence interval (CI). In case of either low sample size or low precision of the effect estimate, we downgraded the certainty of evidence for the outcome one level. In cases of both low sample size and low precision of the effect estimate, we downgraded the certainty of evidence for the outcome two levels. We were not able to judge whether there was publication bias and judged this GRADE consideration as undetected.

All in all, the overall quality of the body of evidence was assessed based on the judgements of the five considerations (see Chapter 12 of the Cochrane Handbook for Systematic Reviews of Interventions; Schünemann 2011). Consequently, the evidence of all subjective outcomes under each comparison was judged to be of low quality, meaning that our confidence in the effect estimate is limited, and the true effect may be substantially different from the estimate of effect. Furthermore, the evidence of all objective outcomes under each comparison was judged to be of very low quality, meaning that we have very little confidence in the effect estimate and the true effect is likely to be substantially different from the estimate of effect. The consequence of this very low‐ to low‐quality evidence makes further research highly necessary for developing recommendations about the effect of work‐break interventions based on the reported outcomes in this review.

Potential biases in the review process

We conducted a comprehensive and transparent review process, where two review authors independently performed the selection of studies, data extraction, and 'Risk of bias' assessment. We attempted to minimise selection bias in the search by not restricting by date of publication or language. We furthermore screened the reference lists of included studies and selected literature reviews (Hoe 2018; Shrestha 2018; Stock 2018), after which we added another two references for potential inclusion. During the full‐text assessment, both potential references had to be excluded due to wrong outcomes (Evans 2012; Gilson 2009). Disagreements in the selection process were resolved through consensus, meaning that a third assessor was not necessary. Due to the very small number of studies included in the current review, we were not able to create funnel plots and assess publication bias. In case more studies can be included in an update of this review, we aim to assess publication bias.

We avoided duplicate publication bias by using study data only once. This strategy was applied only in the case of De Bloom 2017, where we selected both the registered trial and article publication for potential inclusion. We contacted authors in case data reporting in the identified study was marginal or in case other relevant information was unclear or missing, which was the case for all six included studies. When contacting the authors, all of them replied. The authors of the study of Henning 1997 informed us that they did not have the data any more because the study was performed too long ago. The authors of the study of Irmak 2012 shared their detailed results with us and answered additional questions about the study protocol and population. The authors of the studies of De Bloom 2017, Galinsky 2000, Galinsky 2007 and McLean 2001 shared additional information about their study protocol and population.

Three randomised controlled trials that incorporated a work‐break intervention had to be excluded because the intervention was part of a bigger program and could not be assessed separately (Oude Hengel 2013), because the study population contained symptomatic workers (Faucett 2007) and because the outcomes did not fit with our primary outcome measures (Brown 2014). The authors of two studies (Faucett 2007; Oude Hengel 2013) were contacted to gather this information and make the decision for exclusion.

We performed the data analyses, during which we decided to pool the primary outcomes musculoskeletal pain, discomfort and fatigue. This applied to the data analyses as part of three comparisons (Analysis 1.1; Analysis 1.2; Analysis 2.1; Analysis 3.1). To make sure that these pooled analyses were representative of each single data analysis, we performed sensitivity analyses to compare the pooled analyses with each single analysis (Analysis 6.1; Analysis 6.2; Analysis 7.1; Analysis 8.1). We concluded that the pooled analyses were representative, since their results (Analysis 1.1; Analysis 1.2; Analysis 2.1; Analysis 3.1) did not differ that much from the single analyses (Analysis 6.1; Analysis 6.2; Analysis 7.1; Analysis 8.1). Because the pooled musculoskeletal and productivity/work performance outcomes were both assessed on different scales, we had to report the standardised mean differences (SMD) for the pooled analyses.

In this review, we did not incorporate adverse events as a potential secondary outcome. However, adverse events resulting from additional or alternate work breaks could lead to an increase of harmful effects to be prevented, in this case more instead of less musculoskeletal pain, discomfort or fatigue as a surrogate for disorders. We have screened post hoc the included studies and can report that, of the six trials included in the current review, no trials noted that they measured adverse events and no trials reported adverse event rates in both the control and experimental groups. Additionally, this review primarily focussed on musculoskeletal outcomes, which means that we could not make any conclusions about the effectiveness of work breaks on other health aspects, such as cardiovascular health and mental well‐being.

Agreements and disagreements with other studies or reviews

Several literature reviews have been published that focussed on work breaks or on workplace interventions in general to prevent or decrease musculoskeletal‐related outcomes. When comparing our results with the other literature reviews, most of the findings were not comparable for different reasons. Our review focussed on RCTs within which participants had to be symptom‐free during study enrolment. Some other reviews had no restrictions on whether the study population was symptomatic or non‐symptomatic and included other designs than RCTs as well, such as non‐RCTs (Boocock 2007; Hoe 2018; Kennedy 2010; Van Eerd 2016; Verbeek 2019; Waongenngarm 2018). Due to these criteria, the one review that focussed on work breaks only included 11 studies (Waongenngarm 2018). Four other reviews focussed on workplace or occupational health and safety interventions in general, of which one review included 31 studies (Boocock 2007), one included 36 studies (Kennedy 2010), one included 61 studies (Van Eerd 2016), and one included 28 studies Verbeek 2019. Another review that was somewhat comparable to the current review, included workplace interventions in general among office workers only, and included 15 studies (Hoe 2018).

The review of Waongenngarm 2018 aimed to evaluate the effect of breaks on low back pain, discomfort and work productivity in office workers. The study included studies that were published in English, investigated office workers only, and did not set strict restrictions on the study design resulting in included studies being both RCTs and non‐RCTs. Since they used relatively few key words to search through the databases, they may have failed to include studies that we included in the current review. The authors concluded that there was low‐quality evidence supporting the effectiveness of breaks on discomfort prevention and moderate‐quality evidence that breaks had no adverse effect on work productivity. The four studies that were included in the current review under different work‐break frequencies, were also among the eleven studies included in the review of Waongenngarm 2018. However, due to the additional seven studies, which were mainly laboratory studies or field RCTs also including symptomatic workers, the results of their meta‐analyses, that there was low‐quality evidence that breaks were effective in preventing discomfort, were different from those of the current review.

In Boocock 2007, the aim was to evaluate the effect of primary, secondary and tertiary interventions on upper extremity musculoskeletal disorders. Studies were included when they were published in English, were published between 1999 and 2004 and included follow‐up periods of two months or longer. The latter criterion is the main reason that Boocock 2007 included a completely different pool of RCTs and non‐RCTs. Therefore, it is difficult to compare the conclusions of Boocock 2007 with the current review, since they did not include a category of work breaks based on their 31 included studies.

In the review of Kennedy 2010, the primary aim was to evaluate whether occupational health and safety interventions had an effect on upper extremity musculoskeletal symptoms, signs, disorders, injuries, claims and lost time. Their secondary aim was to evaluate which types of occupational health and safety interventions were effective. The authors used a broad search strategy, as was used in the current review. One of the intervention categories evaluated in the review of Kennedy 2010 was 'rest breaks', which included four studies. Three of the studies were similar to the ones we included (Galinsky 2000; Galinsky 2007; McLean 2001). However, the fourth RCT that was included by Kennedy 2010 was excluded by us during our full‐text screening phase, because the investigated study population contained symptomatic workers, which we used as an exclusion criterion (Van den Heuvel 2003). The conclusion of the review of Kennedy 2010 was that limited evidence supported a positive effect of work breaks on upper extremity musculoskeletal outcomes. They furthermore concluded that there was insufficient evidence to support the possibility that active breaks may have a positive effect on upper extremity outcomes. Although they restricted their intervention effect to the upper extremity instead of the whole body, the conclusions are comparable and support the need for high‐quality studies about work‐break interventions for preventing musculoskeletal symptoms and disorders. In line with our review, the work populations studied in the included RCTs and non‐RCTs of Kennedy 2010 consisted mainly of office workers. Given this limitation, we propose that the effectiveness of different work‐break interventions in other work settings be investigated as well, possibly as a combined intervention to increase its effectiveness.

The aim of the review of Verbeek 2019 was to provide an overview of a wide range of interventions for improving recovery from cognitive and physical work, for which the authors used an exhaustive study inclusion process. Seven categories of interventions were formed and grouped into person‐directed and work‐directed interventions. Work breaks were considered a work‐directed intervention, to which four of the 28 included studies were assigned. None of these four studies were included in the current review, because they either used a study design other than an RCT (Beynon 2000; Mathiassen 1996), included the wrong outcomes (Oude Hengel 2012) or the wrong patient population (Lim 2016). From the four work‐break studies, the review authors reported that longer breaks are suggested as being beneficial for increasing work recovery based on the work physiology theory. Although this scoping review could not comment on the effectiveness of workplace interventions, it provides a nice overview of different types of interventions aimed at increasing recovery from work and it provides encouragement for future studies that are suggested to focus on the development and improvement of the different types of interventions, including work breaks. Due to the different approach used in the scoping review of Verbeek 2019, their conclusions cannot be compared with the interpretations coming from the current review.

The review of Van Eerd 2016 aimed to evaluate the effect of workplace interventions to prevent upper extremity musculoskeletal disorders. They searched for studies eligible for inclusion and set restrictions on the outcome measures, which had to be related to the upper extremity and to the publication language, which had to be English. Both RCT and non‐RCT designs were allowed. The one intervention category evaluated in the review of Van Eerd 2016 that may be comparable to the current review, is the stretching exercise program, within which six studies were included. One of those six studies was also included in the current review (Galinsky 2000); the other five studies reported effects of interventions other than break interventions, were non‐RCTs, or included symptomatic workers. The different included studies have resulted in the different conclusion developed by Van Eerd 2016, that there is moderate‐quality evidence for stretching exercise programmes having a positive effect on preventing upper extremity musculoskeletal disorders.

In Hoe 2018, the goal was to evaluate the effect of interventions on preventing work‐related musculoskeletal disorders in office workers. The databases searched were similar to those searched in the current review; however, the search string used by Hoe 2018 was rather narrow compared to the current review. During their study selection process, Hoe 2018 included studies that used a randomised controlled design, assessed office workers only, evaluated interventions performed in the workplace examining a physical, organisational or cognitive ergonomic intervention, and measured outcomes related to the neck and upper extremity or work‐related function and productivity. Hoe 2018 included four studies in the category organisational ergonomic interventions, three of which were included also in the current review. The fourth included study evaluated a biofeedback intervention which interrupted the work flow at the computer but did not provide a work break as based on our criteria, including a moment of non‐work (King 2013). The conclusion of Hoe 2018 with respect to organisational ergonomic interventions was that they found low‐quality evidence that supplementary breaks may reduce self‐reported discomfort. This trend is similar to our review, but the confidence intervals of the single outcomes per study did not show statistical significance, which may have resulted in the different final conclusion.