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

The number of workers suffering from work-related musculoskeletal disorders is estimated to account for 21% to 28% of all days of occupational sick leave in 2017/2018 in the UK, Germany and the Netherlands. These numbers indicate that work-related musculoskeletal disorders are a major problem for society as well as for employers. Interventions may counteract this problem, for example, by making changes to the workplace or work organisation. Many interventions have been investigated, such as training in ergonomics principles (work designs to increase productivity and comfort at the workplace), information and counselling, workstation adjustment, work-break schedule adjustment, and job rotation. The current review focused on the effect of different work-break schedules on outcomes related to work-related musculoskeletal symptoms, since a systematic overview on this particular intervention is currently lacking. Different work-break schedules may lead to an interruption or a decrease of long periods of repetitive or monotonous workloads. They may also lead to interruption of longer periods in which workers have to adopt static or awkward body postures, factors recognised as risk factors for developing work-related musculoskeletal disorders.

Aim

We wanted to find out whether different frequencies, durations and types of work breaks can prevent work-related musculoskeletal symptoms and disorders among healthy workers. We considered workers as healthy when they were free of musculoskeletal complaints at study enrolment.

Studies

We selected several primary outcome measures, including newly diagnosed musculoskeletal disorders, participant-reported musculoskeletal symptoms including pain, discomfort and fatigue, and productivity and work performance. The latter measure is not directly relevant to the worker but rather to the employer when it comes to maintaining business output. We selected changes in workload as a secondary outcome measure, which may include force output changes, electromyographic (recording of the electrical activity of muscles using electrodes) manifestations of muscle fatigue, or subjective change in workload (NASA-TLX). None of the included studies reported any newly diagnosed musculoskeletal disorders or workload changes.

We searched the literature until 2 May 2019 to find randomised controlled trials (RCTs), quasi-RCTs, cluster-RCTs and cross-over RCTs of work-break interventions aimed at preventing work-related musculoskeletal disorders at work. We analysed all relevant studies to answer the research question and found six studies involving 373 workers, the majority of whom were female (≥ 78%), with a follow-up period of two to 10 weeks.

Key results

Effect of different work-break frequencies

Five of the six studies evaluated different work-break frequencies. The implementation of additional work breaks (three studies) may not have an effect on musculoskeletal pain, discomfort or fatigue when compared to no additional work breaks or work breaks taken as needed. Additional work breaks (three studies) may have a positive effect on productivity and work performance when compared to a conventional work-break schedule. Additional higher frequency work breaks have been compared with additional lower frequency work breaks in one study, which resulted in no differences in participant-reported musculoskeletal pain, discomfort and fatigue, nor in productivity and work performance.

Effect of different work-break durations

None of the studies evaluated the effect of duration of work breaks.

Effect of different work-break types

Two of the six studies evaluated different work-break types. Active work breaks (one study) may not reduce nor increase the incidence of participant-reported musculoskeletal pain, discomfort and fatigue, or productivity and work performance. Similarly, different active work breaks have been compared with one another (one study), i.e. relaxation and physical active work breaks, which revealed no differences in participant-reported musculoskeletal pain, discomfort and fatigue, nor in productivity and work performance.

Conclusions

At present, we conclude that there is very low- to low-quality evidence that different work-break frequencies and types may not considerably reduce the incidence of musculoskeletal disorders. Although the results suggest that there may be a positive effect of different work-break frequencies on productivity and work performance, there is a need for high-quality studies with large enough sample sizes to assess the effectiveness of different work-break interventions. Furthermore, work-break interventions should be reconsidered, taking into account worker populations other than office workers and the possibility of combining work-break interventions with other interventions such as ergonomic training or counselling, which may possibly prevent musculoskeletal disorders.

Authors' conclusions: 

We found low-quality evidence that different work-break frequencies may have no effect on participant-reported musculoskeletal pain, discomfort and fatigue. For productivity and work performance, evidence was of very low-quality that different work-break frequencies may have a positive effect. For different types of break, there may be no effect on participant-reported musculoskeletal pain, discomfort and fatigue according to low-quality evidence. Further high-quality studies are needed to determine the effectiveness of frequency, duration and type of work-break interventions among workers, if possible, with much higher sample sizes than the studies included in the current review. Furthermore, work-break interventions should be reconsidered, taking into account worker populations other than office workers, and taking into account the possibility of combining work-break intervention with other interventions such as ergonomic training or counselling, which may may possibly have an effect on musculoskeletal outcomes and work performance.

Read the full abstract...
Background: 

Work-related musculoskeletal disorders are a group of musculoskeletal disorders that comprise one of the most common disorders related to occupational sick leave worldwide. Musculoskeletal disorders accounted for 21% to 28% of work absenteeism days in 2017/2018 in the Netherlands, Germany and the UK. There are several interventions that may be effective in tackling the high prevalence of work-related musculoskeletal disorders among workers, such as physical, cognitive and organisational interventions. In this review, we will focus on work breaks as a measure of primary prevention, which are a type of organisational intervention.

Objectives: 

To compare the effectiveness of different work-break schedules for preventing work-related musculoskeletal symptoms and disorders in healthy workers, when compared to conventional or alternate work-break schedules.

Search strategy: 

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, PsycINFO, SCOPUS, Web of Science, ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform, to April/May 2019. In addition, we searched references of the included studies and of relevant literature reviews.

Selection criteria: 

We included randomised controlled trials (RCTs) of work-break interventions for preventing work-related musculoskeletal symptoms and disorders among workers. The studies were eligible for inclusion when intervening on work-break frequency, duration and/or type, compared to conventional or an alternate work-break intervention. We included only those studies in which the investigated population included healthy, adult workers, who were free of musculoskeletal complaints during study enrolment, without restrictions to sex or occupation. The primary outcomes were newly diagnosed musculoskeletal disorders, self-reported musculoskeletal pain, discomfort or fatigue, and productivity or work performance. We considered workload changes as secondary outcomes.

Data collection and analysis: 

Two review authors independently screened titles, abstracts and full texts for study eligibility, extracted data and assessed risk of bias. We contacted authors for additional study data where required. We performed meta-analyses, where possible, and we assessed the overall quality of the evidence for each outcome of each comparison using the five GRADE considerations.

Main results: 

We included six studies (373 workers), four parallel RCTs, one cross-over RCT, and one combined parallel plus cross-over RCT. At least 295 of the employees were female and at least 39 male; for the remaining 39 employees, the sex was not specified in the study trial. The studies investigated different work-break frequencies (five studies) and different work-break types (two studies). None of the studies investigated different work-break durations. We judged all studies to have a high risk of bias. The quality of the evidence for the primary outcomes of self-reported musculoskeletal pain, discomfort and fatigue was low; the quality of the evidence for the primary outcomes of productivity and work performance was very low. The studies were executed in Europe or Northern America, with none from low- to middle-income countries. One study could not be included in the data analyses, because no detailed results have been reported.

Changes in the frequency of work breaks

There is low-quality evidence that additional work breaks may not have a considerable effect on musculoskeletal pain, discomfort or fatigue, when compared with no additional work breaks (standardised mean difference (SMD) -0.08; 95% CI -0.35 to 0.18; three studies; 225 participants). Additional breaks may not have a positive effect on productivity or work performance, when compared with no additional work breaks (SMD -0.07; 95% CI -0.33 to 0.19; three studies; 225 participants; very low-quality evidence).

We found low-quality evidence that additional work breaks may not have a considerable effect on participant-reported musculoskeletal pain, discomfort or fatigue (MD 1.80 on a 100-mm VAS scale; 95% CI -41.07 to 64.37; one study; 15 participants), when compared to work breaks as needed (i.e. microbreaks taken at own discretion). There is very low-quality evidence that additional work breaks may have a positive effect on productivity or work performance, when compared to work breaks as needed (MD 542.5 number of words typed per 3-hour recording session; 95% CI 177.22 to 907.78; one study; 15 participants).

Additional higher frequency work breaks may not have a considerable effect on participant-reported musculoskeletal pain, discomfort or fatigue (MD 11.65 on a 100-mm VAS scale; 95% CI -41.07 to 64.37; one study; 10 participants; low-quality evidence), when compared to additional lower frequency work breaks. We found very low-quality evidence that additional higher frequency work breaks may not have a considerable effect on productivity or work performance (MD -83.00 number of words typed per 3-hour recording session; 95% CI -305.27 to 139.27; one study; 10 participants), when compared to additional lower frequency work breaks.

Changes in the duration of work breaks

No trials were identified that assessed the effect of different durations of work breaks.

Changes in the type of work break

We found low-quality evidence that active breaks may not have a considerable positive effect on participant-reported musculoskeletal pain, discomfort and fatigue (MD -0.17 on a 1-7 NRS scale; 95% CI -0.71 to 0.37; one study; 153 participants), when compared to passive work breaks.

Relaxation work breaks may not have a considerable effect on participant-reported musculoskeletal pain, discomfort or fatigue, when compared to physical work breaks (MD 0.20 on a 1-7 NRS scale; 95% CI -0.43 to 0.82; one study; 97 participants; low-quality evidence).

Share/Save