The present review protocol is being reported in accordance with the reporting guidance the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) statement 43(see PRISMA-P checklist in Additional file 1). This review protocol was registered within the International Prospective Register of Systematic Reviews (PROSPERO) (registration number: CRD42019137211) This review will be reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement.
Criteria for considering studies for this review
Type of studies
Original quantitative research studies that assessed the effect of a warm-up intervention in a workplace setting aiming at preventing WMSDs or musculoskeletal pain or discomfort or fatigue in the worker will be included in the review.
As correctly argued, RCT are considered as the gold standard to assess the effectiveness of an intervention44. However, its implementation in occupational setting may not always be feasible and its implementation is called into question1,45–49. In that specific case, recent studies have suggested that non-RCT may maximize the body of evidence and have suggested including non-RCT in systematic-reviews50–52. For these reasons and as previously done in recent systematic reviews covering the scope of the present review8,47, both randomized and non-randomized controlled studies will be included. Therefore, quasi-RCTs (participants not randomly allocated), cluster randomized trials (i.e. randomization of a group of people for example randomization at a company level) will be included.
Period of studies publication was defined from inception onwards to July 2019. Finally, to be eligible for inclusion, studies had to be published in English in peer-reviewed scientific journals17,47. As only studies in English will be included and may lead to reporting bias, we will report potentially eligible studies in other languages.
The following types of studies will be ineligible: case reports, abstracts, editorials, conference abstracts, letters to the editor, reviews, and meta-analysis. Studies will be also excluded if the intervention was partially or totally implemented outside of the workplace, e.g. in a clinical setting and if the intervention was implemented in combination with another intervention, e.g. ergonomics. Therefore, studies will be excluded when differences can not only be attributed only to the warm-up intervention.
Types of participants
This review will include adult employees (18 years of age or older) and will exclude adults with specific comorbidities or diseases (such as diabetes, arthritis, cancer, stroke) and/or special populations (pregnant, severe or rare physical disability, or cognitive disability).
Types of intervention
This review will include studies which have implemented warm-up interventions in real workplaces. To facilitate the comprehension of a warm-up intervention, we will use the definition given by McCrary et al 35, i.e. “a warm-up is a protocol specifically undertaken to prepare the onset of subsequent physical activity”, in our case a working activity.
As recently used in a systematic review by Luger et al53, to describe work-break programs and a study by Slade and Keating54 about exercise prescription, we will characterize the warm-up intervention with the following four components:
(1) duration: warm-up may lasted 5 minutes as well as 1 hour ;
(2) frequency: warm-up may differ in number;
(3) type: warm-up may be stretching as well as cardio-training exercises or combination of strengthening exercises; and
(4) intensity: warm-up may be performed with/without load or performed at a low or high percentage of the maximum heart rate.
Studies will be excluded from this review if the warm-up intervention was partially or totally implemented outside of the workplace, e.g. in a clinical setting or under laboratory conditions and if the warm-up intervention was implemented in combination with another intervention, e.g. ergonomics.
Comparator
Inclusion criteria: We will consider studies that compared the warm-up intervention with a non-treatment control group (e.g. no intervention or usual activity or another type of workplace physical activity) or a non-active comparator (e.g. leaflets on benefits of physical activity)
Exclusion criteria: Studies with no comparison measures.
Types of outcome measures
Main outcomes
WMSDs are defined as a group of conditions or health problems affecting the locomotor apparatus. These conditions are characterized by pain, impaired function, overall fatigue and stress7,55. Therefore, among primary outcomes we will include all the outcomes associated with work related musculoskeletal issues, that are (1) participant musculoskeletal pain through the use of pain scales (e.g. numeric rating scale (NRS) or visual analog scale (VAS)) or questionnaire (e.g. McGill pain questionnaire)53 and (2) participant discomfort or fatigue8,53 through validated scales and (3) physical function as measured or estimated by questionnaires, performance and/or specific tests.
Secondary outcomes
For the prevention of the consequences of WMSDs we will include – if possible – and as secondary outcomes, all the outcomes associated with psychosocial function such as the measure of quality of life, job satisfaction, job control or motivation at work. In this review job control is considered as an indicator of psychosocial stress at work 56. This indicator is often measured with the job demand-control support model developed by Karasek 56.
Information sources and search strategy
Four electronic databases - Cochrane Central Register of Controlled Trials (CENTRAL), PubMed (Medline), Web of Science and Physiotherapy Evidence Database (PEDro) – will be searched systematically from inception onwards to identify studies satisfying the search criteria. Note that these databases have previously used in published reviews covering the scope of this review47,53,57,58. The proposed search strategy terms for Medline are listed in Table 1 and will be modified to fit the index system of other databases.
Table 1. Sample MEDLINE search strategy terms (ti: tittle ; ab: abstract)
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Keywords
|
|
Workplace terms
|
1
|
Work* ti,ab
|
2
|
Employ* ti,ab
|
3
|
Compan* ti,ab
|
4
|
1 OR 2 OR 3
|
|
|
|
Warm-up terms
|
5
|
Warm* ti,ab
|
6
|
Pre-exercise* ti,ab
|
7
|
Pre-activit* ti,ab
|
8
|
5 OR 6 OR 7
|
|
|
|
WMSDs, physical and psychosocial terms
|
9
|
Musculoskeletal disord* ti,ab
|
10
|
Musculoskeletal injur* ti,ab
|
11
|
Musculoskeletal pain ti,ab
|
12
|
Musculoskeletal complaint* ti,ab
|
13
|
Pain ti,ab
|
14
|
(endurance or strength or flexibility) ti,ab
|
15
|
(quality of life or job satisfaction or work ability or well-being or stress or disabilit* or health or discomfort or comfort or fatigue or injur*) ti,ab
|
16
|
9 OR 10 OR 11 OR 12 OR 13 OR 14 OR 15
|
|
|
|
Combining search terms
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17
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4 AND 8 AND 16
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Additional intended information sources
To be sure not to miss relevant studies for the review, the reference list of for all eligible articles will be checked. Then, a grey literature search will be performed on ClinicalTrials.gov. Finally, we will contacts experts in this domain to collect information on unknown or ongoing studies
Data collection
Study selection process
All studies that met inclusion criteria passed through a data extraction and quality assessment process performed by two independent reviewers. A third reviewer will be requested to resolve disagreement when consensus could not be reached. Reviewers will not be blinded to study author(s) or journal title. At stage 1, two independent reviewers will screen abstract and titles identified from the search strategy. At stage 2, the same two reviewers will screen the full-text articles for inclusion. At this stage, all reasons for exclusion of articles will be recorded and reported. Finally, the relevant studies, which respect eligibility criteria, will be screened by a senior review team member (NV) to be included in the systematic review.
Data extraction and management
First a data extraction form will be created and validated by the three team members. This data collection form will be fulfilled by one team member (NL) and corrected by another team member (RB). Any disagreement between the two reviewers will be resolved by consensus or discussion with the senior review team member (NV). This extraction form could be modified from the information collected in the eligible studies but should at least specify the following information57,59,60:
- General: authors, year of publication, journal’s name, source of funding (if any) and country of the study;
- Methods: study design, total duration of study, follow-up when data were collected, study setting and withdrawals;
- Participants: number, age, gender, inclusion/exclusion criteria, type of workplace or job task, health of the workers/health status, i.e. asymptomatic or symptomatic, year of work experience;
- Interventions: description of the type, duration, frequency, intensity, supervision of the warm-up program, description/content of the comparison/control group and number of participants allocated to each group;
- Data collection: primary and secondary outcomes, measurement tools, questionnaires, tests;
- Statistical tests;
- Main results
Risk of bias (quality) assessment
Two team members (NL and RB) will independently assess the risk of bias for each included study. Any disagreement between team members will be solved by consensus or discussion with the third team member. As both randomized and non-randomized controlled studies will be included in this review, two risk of bias tools will be used.
For RCT
The Cochrane tool for assessing risk of bias from the Cochrane Handbook for Systematic Reviews of Interventions will be used to assess potential biases of the included studies. This tool is a well-known and validated instrument to assess the risk of bias in RCTs 61. This tool has been revised in 2019 62 and has now 5 domains to assess bias arising from: (1) randomization process, (2) deviation from the intended intervention, (3) missing outcome data, (4) measurement of the outcome and (5) selection of the reported result. Each domain will be scored as follow (see Table 2): “high risk of bias”, “low risk of bias” and “some concerns”.
For non RCT
The Risk Of Bias In Non-randomized Studies - of Interventions (ROBINS-I) will be used to asses potential biases of the included non-RCT63. This tool has 7 domains to assess bias arising from (1) confounding, (2) selection of participants, (3) classification of the intervention, (4) deviations from the intended intervention, (5) missing data, (6) measurement of outcomes and (7) selection of the reported result.
Table 2. Risk of bias judgement for a specific domain (from Sterne et al. 2019).
Overall risk of bias judgement
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Criteria
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Low risk of bias
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The study is judged to be at low risk of bias for all domains for this result
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Some concerns
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The study is judged to be at high risk of bias in at least one domain for this result, but not to be at high risk of bias for any domain
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High risk of bias
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The study is judged to be at high risk of bias in at least one domain for this result
Or
The study is judged to have some concerns for multiple domains in a way that substantially lowers confidence in the result.
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Measures of treatment effect
For studies using continuous data, treatment effect will be reported as mean difference with 95% CI. In case the studies evaluate the same outcome with different scales, standardized mean difference (SMD) with 95% CI will be calculated. Regarding dichotomous/categorical variables, the treatment effect will be calculated using the relative risk (RR) with 95% CI64–67. Since the number of included studies is greater than 565 and when these studies are considered as sufficiently homogeneous, outcome data will be synthesized using a random effect meta-analysis53,66,68,69. If meta-analysis is not possible due to heterogeneity or if we are unable to pool the outcomes a narrative synthesis will be performed using text and table formats. Results will be also presented in forest plots.
Assessment of statistical heterogeneity
Statistical heterogeneity, defined as variability in the intervention effects will be estimated using the Chi² test, with Chi² p>0.10 provides significant evidence of heterogeneity. Chi² assesses whether heterogeneity is only due to chance. To ensure a right comprehension of heterogeneity, Chi² will be completed with I² statistics particularly relevant when studies have small sample size or are few in numbers. Heterogeneity will be categorized as follows69:
- 0-40%: not be important
- 30-60%: moderate heterogeneity
- 50-90% substantial heterogeneity
- 75-100%: considerable heterogeneity
Quality assessment and strategy for data synthesis
To assess quality of evidence of the included studies we will use the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach70. This approach grades studies as followed: very low, low, moderate and high. As suggested by Bordado et al 17, the quality assessment will be based on the findings in data extraction, and will follow the domains of quality evaluation in the GRADE approach: risk of bias, inconsistency, indirectness and imprecision.
Analysis of subgroups or subsets
In case a sufficient number of studies are included in the review, a subgroup analysis will be performed. The latter will be carried out for each outcome and for the following factors: (1) participants’ characteristics (e.g. sex, age. If possible we will compare participants aged 40 years and younger with participants aged 41 years and older), (2) WMSDs location (e.g. neck versus low back versus upper extremities), (3) occupational activity (e.g. active versus sedentary jobs), (4) length of intervention, (5) study design (e.g. RCT versus non-RCT) and (6) comparison group type (e.g. passive versus active control group)53,67.