Effectiveness of ergonomic training to reduce physical demands and musculoskeletal symptoms - An overview of systematic reviews

Work-related musculoskeletal disorders are associated with awkward postures, excessive force, manual material handling and repetitive movements. This risk factors can be minimized through interventions such as ergonomic training. The literature covers several studies involving the use of this type of intervention, but there is no consensus about the effectiveness of ergonomic training. The aim of this study was to identify the available evidence about the effectiveness of ergonomic training to reduce physical work demand and musculoskeletal symptoms through an overview of systematic reviews. The searches were carried out in Pubmed/Medline, Web of Science, CINAHL, Embase and Cochrane Library. The START (State of the Art through Systematic Review, v.1.06.2) platform aided the selection and evaluation of studies. The studies were evaluated for methodological quality through the AMSTAR (Assessing the Methodological Quality of Systematic Reviews) criteria and the implications for practice. This overview identified a large number of studies with a low to moderate level of evidence, indicating the ineffectiveness of ergonomic training alone or associated with another type of intervention in reducing physical demand and musculoskeletal symptoms in workers. The findings may have occurred due to four main factors: superficial identification of the ergonomic risk factors; lack of scientific evidence about the appropriate configurations of the types of ergonomic training; ambiguous results in the application of ergonomic training; and the difficulty in the effectiveness of the intervention. The study identified an inconsistency in the level of evidence of ergonomic training to reduce physical demand and musculoskeletal symptoms among workers.     

Study protocol and baseline results for a quasi-randomized control trial: An investigation on the effects of ergonomic interventions on work-related musculoskeletal disorders,quality of work-life and productivity in knowledge-based companies

IntroductionWork-related musculoskeletal disorders (WMSDs) are the major causes of lost workdays, increased costs, and occupational diseases in all countries. The prevalence of WMSDs among the workers in small and medium-sized enterprises in Iran was reported as 73%. This paper aimed to describe the design of an interventional study to investigate the effects of ergonomic interventions on work-related musculoskeletal disorders, quality of work-life, and productivity among office workers of knowledge-based companies and introduce the results obtained from the baseline survey.Methods/designIt was a quasi-randomized control trial study on 313 participants with four parallel groups including ergonomic training intervention; management training and work changes intervention; ergonomic training, management training and work changes intervention; and non-interventional control group. The primary outcome was WMSDs, and the secondary outcomes were occupational stress factors, quality of work-life, and productivity. All primary and secondary outcomes were measured before the interventions, one, three, and six months after the interventions.ResultsAt this phase of study only baseline results were reported. 328 participants, with a mean age of 31.97 years (SD = 5.39), completed the baseline survey and entered the study. The highest prevalence of musculoskeletal disorders was found in neck (52.13%), right shoulder (41.16%) and right forearm (37.2%), respectively.ConclusionErgonomic interventions were conducted based on baseline data of the participants at individual and management levels. The focus of training program interventions was to reduce musculoskeletal disorders in upper limbs; in management training and work changes program, the focus was to increase social support.Trial registrationIRCT registration number: IRCT20181204041840N1 (date of registration: 2019-02-05).     

A new table for work with a microscope, a solution to ergonomic problems

Microscope workers are exposed to continuous static muscular work and an increased risk of musculoskeletal disorders in the neck, shoulder and upper extremities. In a Finnish research centre, microscope workers reported pain in the shoulder, neck, lower back and upper back. As a consequence, a programme to solve the ergonomic problems of microscope work was initiated and led to the construction of a new table for microscopes. Ten experienced male microscope workers were chosen as subjects to carry out an experimental study in which the new table and an old one, an ordinary non-adjustable laboratory table, were compared in a standardized microscope task. The dependent variable was the electromyographic activity measured from muscles in the neck–shoulder region. The new table allowed the microscope to be used with the head in an upright position, the forearms supported and with less flexion of the upper arm. Surface electromyographic measurements also confirmed that the changes were ergonomic improvements.     

The effects of an office ergonomics training and chair intervention on worker knowledge, behavior and musculoskeletal risk

A large-scale field intervention study was undertaken to examine the effects of office ergonomics training coupled with a highly adjustable chair on office workers’ knowledge and musculoskeletal risks. Office workers were assigned to one of three study groups: a group receiving the training and adjustable chair (n=96), a training-only group (n=63), and a control group (n=57). The office ergonomics training program was created using an instructional systems design model. A pre/post-training knowledge test was administered to all those who attended the training. Body postures and workstation set-ups were observed before and after the intervention. Perceived control over the physical work environment was higher for both intervention groups as compared to workers in the control group. A significant increase in overall ergonomic knowledge was observed for the intervention groups. Both intervention groups exhibited higher level behavioral translation and had lower musculoskeletal risk than the control group.     

The effectiveness of a training method using self-modeling webcam photos for reducing musculoskeletal risk among office workers using computers

An intervention study was conducted to examine the effectiveness of an innovative self-modeling photo-training method for reducing musculoskeletal risk among office workers using computers. Sixty workers were randomly assigned to either: 1) a control group; 2) an office training group that received personal, ergonomic training and workstation adjustments or 3) a photo-training group that received both office training and an automatic frequent-feedback system that displayed on the computer screen a photo of the worker's current sitting posture together with the correct posture photo taken earlier during office training. Musculoskeletal risk was evaluated using the Rapid Upper Limb Assessment (RULA) method before, during and after the six weeks intervention. Both training methods provided effective short-term posture improvement; however, sustained improvement was only attained with the photo-training method. Both interventions had a greater effect on older workers and on workers suffering more musculoskeletal pain. The photo-training method had a greater positive effect on women than on men.     

Flexible workspace design and ergonomics training: impacts on the psychosocial work environment, musculoskeletal health, and work effectiveness among knowledge workers

A macroergonomics intervention consisting of flexible workspace design and ergonomics training was conducted to examine the effects on psychosocial work environment, musculoskeletal health, and work effectiveness in a computer-based office setting. Knowledge workers were assigned to one of four conditions: flexible workspace (n=121), ergonomics training (n=92), flexible workspace+ergonomics training (n=31), and a no-intervention control (n=45). Outcome measures were collected 2 months prior to the intervention and 3 and 6 months post-intervention. Overall, the study results indicated positive, significant effects on the outcome variables for the two intervention groups compared to the control group, including work-related musculoskeletal discomfort, job control, environmental satisfaction, sense of community, ergonomic climate, communication and collaboration, and business process efficiency (time and costs). However, attrition of workers in the ergonomics training condition precluded an evaluation of the effects of this intervention. This study suggests that a macroergonomics intervention is effective among knowledge workers in office settings.     

An ergonomic expert system for risk assessment of work-related musculo-skeletal disorders

A computer-based expert system (SONEX) was developed to identify ergonomic risks for work-related musculoskeletal disorders (WRMSDs) in a wide variety of jobs and provide expert prevention advice. SONEX uses a rule base and 6 knowledge base modules: WRMSD risk factors are grouped into two main knowledge base modules (symptoms, engaged body part) with four supplementary knowledge base modules (work environment, work chair, work tools, organization factors). SONEX uses a menu-based interface and a series of simple questions that lead a user through each of the two main modules. Based on user responses it then recommends other knowledge base modules that are relevant for a detailed analysis of work risks. The SONEX rule base has over 140 questions, the knowledge base includes over 200 risk factors, and around 500 possible answers can be generated. SONEX relates ergonomic shortcomings in the job with worker's subjective symptoms; it predicts possible WRMSDs; and it offers preventive suggestions for ergonomic improvements to the job to prevent WRMSDs. It has been tested in a variety of work places with known ergonomic problems and with known employee WRMSDs by comparing its performance with conventional analytical methods and results show that it accurately predicts possible WRMSD risks and identifies ergonomic shortcomings. The advantages of SONEX are that it is much faster than other ergonomic analysis methods and it can be used by ergonomists and other professionals and also by workers themselves.     

Evaluation of musculoskeletal health outcomes in the context of job rotation and multifunctional jobs

Higher physical demands at work are associated with health outcomes such as discomfort, disorders and sick leave. Variations in work exposure patterns, introduced by multifunctional jobs and ergonomic interventions, bring confounders into the complex relation between occupational risks and musculoskeletal disorders. This study compared whole-body rating of perceived exertion (RPE), discomfort, ergonomic workplace analysis (EWA) and sick leave due to musculoskeletal disorders, among workers exposed to diversified work. The results showed that EWA performed by the observer differed from workers' ratings. There were no differences between groups of workers taking or not taking sick leave regarding RPE and discomfort at their current workstations. Workers significantly discriminated between progressive workload levels, and RPE scores for specific tasks were nonlinear during shifts. These differences might be associated with exposure variability. Thus, in the context of diversified work, the RPE scale seems more appropriate for evaluating acute effects of work variability.     

Reducing musculoskeletal disorders among computer operators: comparison between ergonomics interventions at the workplace

Typing is associated with musculoskeletal disorders (MSDs) caused by multiple risk factors. This control study aimed to evaluate the efficacy of a workplace intervention for reducing MSDs among computer workers. Sixty-six subjects with and without MSD were assigned consecutively to one of three groups: ergonomics intervention (work site and body posture adjustments, muscle activity training and exercises) accompanied with biofeedback training, the same ergonomics intervention without biofeedback and a control group. Evaluation of MSDs, body posture, psychosocial status, upper extremity (UE) kinematics and muscle surface electromyography were carried out before and after the intervention in the workplace and the motion lab. Our main hypothesis that significant differences in the reduction of MSDs will exist between subjects in the study groups and controls was confirmed (χ² = 13.3; p = 0.001). Significant changes were found in UE kinematics and posture as well. Both ergonomics interventions effectively reduced MSD and improved body posture.

Practitioner Summary: This study aimed to test the efficacy of an individual workplace intervention programme among computer workers by evaluating musculoskeletal disorders (MSDs), body posture, upper extremity kinematics, muscle activity and psychosocial factors were tested. The proposed ergonomics interventions effectively reduced MSDs and improved body posture.     

The impact of ergonomics intervention on psychosocial factors and musculoskeletal symptoms among office workers

Musculoskeletal disorders have a multi factorial etiology that includes not only physical risk factors but also psychosocial factors. This study aimed to investigate psychosocial risk factors and musculoskeletal symptoms among office workers of an Iranian oil refinery and also to examine the subsequent effects of ergonomics intervention on musculoskeletal discomfort and psychosocial risk factors.In this study, 73 office workers as a case group and 61 office workers as a control group from an Iranian oil refinery plant were randomly selected and examined. The Nordic Musculoskeletal Disorders Questionnaire and the Persian version of the Job Content Questionnaire (P-JCQ) were used as collecting data tools before and after the interventional program.Low back problem (28.8%) was found to be the most common problem among the office workers. Significant differences found between prevalence rates of reported musculoskeletal in upper back, lower back and feet/ankle regions before and after intervention. Our findings showed that psychosocial variables were not affected by the intervention. The only variables on the P-JCQ that were significantly different pre/post intervention are the physical variables: physical job demands, physical exertion and physical isometric load. None of the other psychosocial variables were found to be significant. With the top management support, improvements in all office workstation components were made successfully.

Relevance to industry

Recently, changes in the nature of work draw increased attention to the relation between psychosocial factors and musculoskeletal disorders. The results of the current study indicate that a well conducted implementation of an interventional program can lead to a decrease in musculoskeletal symptoms and to some extent in the psychosocial factors at work.     

Applying the K-nearest neighbor technique to the classification of workers according to their risk of suffering musculoskeletal disorders

The K-nearest neighbor (KNN) technique is a widely used classifier because of its simplicity and high efficiency. We adapted this technique and applied it with success to predict work-related musculoskeletal disorders. Among the general working population, the algorithm was able to identify workers that had reported work-related musculoskeletal complaints in the last twelve months. According to the model that was developed, poor lighting conditions, exposure to vibrations, an uncomfortable chair and a high mental demand are the factors that have the strongest influence on the development of this type of health problem.Relevance to industry:The approach described in this paper allows the KNN technique to be implemented for the prediction of musculoskeletal disorders among the general working population. The model is able to overcome the limitations of other traditional statistical learning techniques to predict this type of disorder with accuracy and effectiveness. The results may be used as a decision support tool for the prioritization of resources dedicated to ergonomic intervention programs.     

A multilayered ergonomic intervention program on reducing musculoskeletal disorders in an industrial complex: A dynamic participatory approach

Work-related musculoskeletal disorders (WMSDs) are closely identified with common complaints in different workplaces. This study aimed to implement an intervention program through which ergonomic measures were dynamically localized in industry. An interventional study, including three basic layers, namely, training workshops, participatory ergonomics (PE), and workstation redesign was fulfilled in an Iranian steel manufacturing complex from 2017 to 2020. A steering committee (SC) was formed following several meetings held for clarification of the project to the management team. The SC members then attended four organized workshops managed by an ergonomics specialist. Afterwards, the basics of ergonomics were transferred to action groups. After developing ergonomic assessment tools, the ergonomic problems were prioritized and numerous positive changes were made by the action groups. The findings of the tailored checklists revealed a load of WMSDs risk factors. All the three layers of the program were implemented as initiated. Ergonomics training workshops were then held and significant differences were observed between the participants' pre/posttest mean scores in all workshops (p < 0.001). Moreover, PE measures were exercised at all levels of the organization inducing enthusiastic motivation of the workforce to consider ergonomic requirements in the workplace. Consequently, the workers' innovative ideas and the managerial support yielded diverse workstation redesigns due to a growth in either the workers' ergonomics awareness or participatory culture grounding. A multilayered ergonomic intervention was implemented in this study. In conclusion, a multifaceted long-term follow-up intervention program could be applied to enhance workers’ health status and to raise system productivity.     

Effect of Physical Ergonomics on VDT Workers' Health: A Longitudinal Intervention Field Study in a Service Organization

This article examines the effect of physical ergonomic work conditions on occupational health in video display terminal (VDT)-intensive work settings. A longitudinal intervention field study was conducted in a catalog retail service organization in the Midwest to explore the impact of ergonomic interventions. There were 3 levels of ergonomic interventions, each adding incrementally to the previous one. The 1st level was ergonomic training for all VDT users accompanied by workstation ergonomic analysis leading to specific customized adjustments (Group C). The 2nd level added specific workstation accessories supplied by Details, Inc. if the analysis indicated a need for them (Group B). The 3rd level added a Steelcase Criterion(tm) 453 Series chair (Group A). Health data were gathered from 80 volunteer participants by administering a survey before (baseline), 6 months after, and 12 months after interventions were put in place. The findings show that neck, back, and shoulders as well as wrists stand out in terms of self-reported musculoskeletal pain in VDT-intensive work. Reductions in self-reported musculoskeletal discomfort were found for all 3 levels of incremental ergonomic interventions. The number of cases showing improvement in health over time was significant for intervention Groups A and B, but not C.     

A model for solving work related musculoskeletal problems in a profitable way

Interventions against occupational musculoskeletal disorders are usually performed by ergonomists. An overview of the literature shows that ergonomists often are unsuccessful; musculoskeletal disorders may be prevalent at workplaces where large ergonomic resources have been put in, thus illustrating the significance of other factors in addition to those against which the intervention is applied. It is claimed that some modern rationalization strategies may offer a potential for 'good' ergonomics. Thus, prevailing management approaches often now focus on team building, flat organizations, training of multiple skills and so on. The main scope of the present issue of Applied Ergonomics is to throw light on this possibility of 'achieving ergonomics impact through management intervention'. This present paper presents a historical overview of occupational physical work load as a function of ergonomics, as well as rationalizations and concludes with a more elaborate discussion of the present intervention concept for solving work related musculoskeletal problems in a profitable way. Rationalization and guidelines for physical work load are the basic parameters in the present intervention concept. Due to this the present special issue also presents historical overviews of the development of these parameters (Westgaard and Winkel; Bjorkman). 'Achieving ergonomics impact through management intervention' is illustrated through two case studies (Kadefors et al and Bao et al). They demonstrate an obvious ergonomic potential offered by the presented intervention concept. However, the two case studies also describe several practical obstacles which need to be further investigated in future intervention research.     

Corporate ergonomics programme at automobiles Peugeot-Sochaux

An ergonomic assessment tool for design procedures, exclusive to Peugeot-Citro?n, called ECM, was developed and applied at the design stage by method technicians in the 1990s. It generates data, which are followed up by the project leader of a new model and ergonomists until two years before each launch. During this time, vehicle design is subject to modification, to adapt to ergonomic demands. Simplified methods (DACORS and METEO) were also developed to assess workstations on the shop floor in trim and final plants. Assessments were used to grade the workstations into four profiles linked to physical and static requirements. Production technicians are responsible for the application of these local methods on the shop floor. The management of these centres aimed to reduce the risks of musculoskeletal disorders by reduced heavy profiles of these stations. New cases of musculoskeletal disorders, surveyed by the company doctor among workers on the assembly lines had decreased since 1996. In 1999, the incidence increased again, despite the pursuit of ergonomic methods. This increase in musculoskeletal disorders was above all linked to a major reorganisation of work conditions, including a reduction in the cycle time on the assembly line, and to a move into a new workshop.     

Occupational musculoskeletal disorders in the neck and upper limbs of forestry workers exposed to hand-arm vibration.

An epidemiologic and clinical study of neck and upper limb musculoskeletal disorders was carried out on 65 vibration-exposed forestry operators using chain-saws and 31 comparable control subjects (maintenance workers) performing manual activity and not exposed to vibration. Upper limb function was evaluated by measuring finger and wrist circumference size, maximal hand grip strength and range of motion manoeuvres in both the controls and the exposed workers. Vibration from two chain-saws was measured, and vibration exposure for each forestry worker was assessed in terms of 4 h energy-equivalent frequency-weighted acceleration according to ISO 5349. Job analysis indicated a slight excess risk of upper extremity cumulative trauma disorders (CTDs) in the forestry operators compared with the control workers. After adjustment for age and body constitution, significantly higher prevalence rates of persistent upper limb pain, muscle-tendon syndromes and carpal tunnel syndrome were observed among the forestry workers than among the controls. In the forestry operators, the occurrence of upper limb musculoskeletal disorders increased with increasing vibration exposure. Upper limb function was found to be impaired in the forestry workers compared with the controls. Vibration exposure was significantly related to increased finger circumference size, diminished muscle force and reduced joint function. Even though it is difficult to establish the relative importance of vibration and ergonomic factors in the aetiology of CTDs, nevertheless the results of this study indicate that musculoskeletal impairment to the upper limbs was more severe in the forestry operators than in the controls who did solely manual work. This finding and the observed dose-effect relationships suggest that vibration stress is an important contributor to the development of musculoskeletal disorders in workers using hand-held vibrating tools.     

An ergonomic evaluation of manual Cleco plier designs: effects of rubber grip, spring recoil, and worksurface angle

The present study evaluated two design modifications (rubber grip and torsion spring) to the conventional manual Cleco pliers by electromyography (EMG), hand discomfort, and design satisfaction. This study also surveyed workers' satisfaction with selected design features of the pliers for ergonomic improvement. A two-way (plier design x worksurface angle) within-subject (nested within gender and hand size) design was employed. Eleven workers simulated the plier task in an adjustable workstation for different plier designs and worksurface angles (0 degrees , 60 degrees , and 90 degrees ). Lower EMG values were obtained for the pliers with rubber grip and at 60 degrees of worksurface angle. EMG values varied significantly between the participants, but showed low correlations (Spearman's rank correlation = -0.27 approximately -0.58) with their work experience with the pliers. The hand discomfort and design satisfaction evaluations identified that the grip span (max = 14.0 cm) and grip force requirement (peak = 220.5 N) of the current pliers need ergonomic modification. The present study shows the needs of both the ergonomic design of a hand tool and the training of a proper work method to control work-related musculoskeletal disorders at the workplace.     

Musculoskeletal disorders among visual display terminal workers: individual,ergonomic, and work organizational factors

A number of individual, ergonomic, and organizational factors of presumed importance for the occurrence of musculoskeletal disorders were investigated in a group of 260 visual display terminal (VDT) workers. The cross-sectional study utilized medical and workplace investigations as well as questionnaires. The results were subjected to a multivariate analysis in order to find the major factors associated with various upper-body muscular problems. Several such factors were identified for each investigated type of musculoskeletal problem. Some were related to the individual: age, gender, woman with children at home, use of spectacles, smoking, stomach-related stress reactions, and negative affectivity. Organizational variables of importance were opportunities for flexible rest breaks, extreme peer contacts, task flexibility, and overtime. Identified ergonomic variables were static work posture, hand position, use of lower arm support, repeated work movements, and keyboard or VDT vertical position.     

A generic algorithm for computing optimal ergonomic postures during working in an industrial environment

The present study tries to decrease the risk of work-related musculoskeletal disorders for industry workers by proposing a generic algorithm that recommends an optimal ergonomic posture for accomplishing tasks in an industrial environment. In the case of a dangerous ergonomic pose, the optimization algorithm starts by heuristically changing it to a more ergonomic one. Each recommended posture's feasibility is tested with an inverse kinematic method that can predict the worker's behavior for accomplishing a task. This iterative optimization procedure continues until the optimal ergonomic pose for the worker is achieved. The algorithm's validity is tested in thirteen cases, people with different gender (50 percent male, 50 percent female) aged between 20 and 35, and different height and body morphologies. According to studies, there is a connection between musculoskeletal disorders and the wrong posture for accomplishing tasks in industries. We suggest an optimization algorithm that can indicate the worker the optimal ergonomic pose by considering task constraints in real-time.