The impact of drywall handling tools on the low back

Carpenters and other construction workers who install drywall have high rates of strains and sprains to the low back and shoulder. Drywall is heavy and awkward to handle resulting in increased risk of injury. The purpose of this study was to evaluate several low-cost coupling tools that have the potential to reduce awkward postures in drywall installers. Five coupling tools were evaluated using the Lumbar Motion Monitor that measures trunk kinematics and predicts probability of low back disorder group membership risk (LBD risk). Workers answered surveys about their comfort while using each tool. The results indicate that use of the 2-person manual lift and the J-handle provide the best reduction in awkward postures, motions, low back sagittal moment, and LBD risk. The two-person manual lift appears to be the safest method of lifting and moving drywall, though using the two-person J-handle also significantly reduces injury risk. Given that carpenters are skeptical about using equipment that can get in the way or get lost, a practical recommendation is promotion of two-person manual lifting. For single-person lifts, the Old Man tool is a viable option to decrease risk of MSDs.     

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.     

An ergonomic intervention to reduce back strain among apple harvest workers in New York State

The impact of modifications to the apple picking bucket on common picking postures, self-reported comfort, ease of use, and speed of harvest were measured. Fourteen apple pickers wore an intervention hip belt, were interviewed and measured using posture-activities-tools-handling methodology. The use of hip belt did not significantly alter time spent in various postures. 78.6% of interviewed workers preferred the modified bag, 71.4% noted a difference in the back, neck, or shoulder, while 64.3% said regular use of modified bag would slow their work. Major themes in worker comments are discussed. The hip belt modification to apple harvest bag seems generally acceptable to workers, but needs further development to overcome unintended effects. Although work sampling demonstrates that the bag does not affect work practices, workers appear somewhat concerned that productivity will be negatively impacted. Further training of workers in the use and potential benefits of bag are needed.     

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.     

Work-related musculoskeletal complaints: some ergonomics challenges upon the start of a new century

Three themes likely to be important within health-related ergonomics in the coming years are discussed. The first two themes concern methods for risk analysis of low-level biomechanical and psychosocial exposures. The third theme is approaches to successful implementation of ergonomics interventions. Evidence on the assessment of low-level biomechanical and psychosocial exposures by instrumented measurements is discussed. It is concluded that, despite recent advances in our understanding of exposure-effect associations under these exposure conditions, we must at present rely on more subjective methods, employed in a collaboration between expert and worker. This approach to risk analysis identifies in most cases critical exposures in a work situation. The focus should then be on the successful implementation of measures against those exposures, as identification alone does not solve problems. The aim of improved health for the workers further requires that the full complement of risk factors be considered, including work, leisure time and person-based risk factors. Finally, the need to put ergonomics intervention initiatives in an organisational context is emphasised, and examples of approaches used by Norwegian companies are presented.     

Exploring physical exposures and identifying high-risk work tasks within the floor layer trade

Introduction

Floor layers have high rates of musculoskeletal disorders yet few studies have examined their work exposures. This study used observational methods to describe physical exposures within floor laying tasks.

Methods

We analyzed 45 videos from 32 floor layers using Multimedia-Video Task Analysis software to determine the time in task, forces, postures, and repetitive hand movements for installation of four common flooring materials. We used the WISHA checklists to define exposure thresholds.

Results

Most workers (91%) met the caution threshold for one or more exposures. Workers showed high exposures in multiple body parts with variability in exposures across tasks and for different materials. Prolonged exposures were seen for kneeling, poor neck and low back postures, and intermittent but frequent hand grip forces.

Conclusions

Floor layers experience prolonged awkward postures and high force physical exposures in multiple body parts, which probably contribute to their high rates of musculoskeletal disorders.     

Ergonomic risk factors for the wrists of hairdressers

This study utilized a portable data logger to measure the wrist angles and forearm flexor and extensor electromyography (EMG) of 21 hairstylists. The hairstylists were divided into two groups, one with 11 barbers (9 males and 2 females) specializing in men's hairdressing, and one with 10 hairdressers (2 males and 8 females) specializing in women's hairdressing. The standard haircut task was divided into three subtasks: hair cutting, washing and blow-drying. The mechanical exposures of the overall task and subtasks were quantified to compare how subtasks, occupational groups, and gender groups differ. Experimental results show that the average time to finish a woman's haircut (51.4 min) is significantly longer than that for a man's haircut (35.6 min) (p < 0.005). Female hairstylists had significantly greater EMG activity than male hairstylists did (p < 0.001). The non-dominant hands of hairdressers have significantly higher overall wrist velocity than those of barbers (p < 0.005). Analytical results suggest that the relatively higher force exertion and wrist velocity of female hairstylists combined with prolonged exposure may account for the higher rate of hand/wrist pain in female hairdressers than in male barbers.     

The Suitability for the Work‐Related Musculoskeletal Disorders Checklist Assessment in the Semiconductor Industry: A Case Study

Musculoskeletal disorders and symptoms are common among workers in the semiconductor and related industries. Ergonomic‐related checklists are used to identify musculoskeletal disorder risk factors in the workplace. This study explores the suitability of the Occupational Safety and Health Administration (OSHA) musculoskeletal disorders (MSDs) checklist for use in the semiconductor manufacturing industry. Six companies were enrolled in the current study, and 122 subjects, ranging in age from 21 to 54 years old, were evaluated through a questionnaire survey and field observation using the OSHA MSDs checklist. The observers were administered an ergonomics‐based checklist training course with a duration of 36 hours. Experimental results demonstrated that nearly 50% of subjects reported physical discomfort, with shoulder symptoms (38.5%) being the most common complaint. In addition, the aggregated sensitivity, specificity, and positive predictive values for the MSDs checklist in the six companies were 47.3%, 62.4%, and 30.0%, respectively. This study concluded that the OSHA MSDs checklist appeared to contain better estimates for capturing musculoskeletal discomfort and found that the OSHA MSDs checklist provided an easily administered, proactive surveillance instrument to assist in early identification of musculoskeletal discomfort. © 2012 Wiley Periodicals, Inc.     

An improved physical demand analysis framework based on ergonomic risk assessment tools for the manufacturing industry

Most of the operational tasks in the manufacturing process entail numerous physical involvements, despite the introduction of automated equipment. Due to this high physical demand in manufacturing, the need for proactive risk assessment to decrease potential injury cannot be ignored. Physical Demand Analysis (PDA) is a widely used tool recommended to all manufactures by the Canadian Workers’ Compensation Board to document the physical, cognitive, and environmental demands of essential tasks. However, limitations exist in utilizing the content generated in current PDA practice to conduct risk identification and risk assessment, and it has limited functionality for providing modified work to proactively mitigate risk. This paper summarizes the input requirements of risk assessment tools and proposes an improved PDA form with an integrated framework to facilitate the comprehensive and intelligent use of PDA. This paper focuses on three aspects of PDA implementation—risk identification, risk evaluation, and risk mitigation—targeting the development of modified work for the manufacturing industry. The framework is implemented in a window and door manufacturing facility, and a case study of a window glazing station is described in this paper in order to assess awkward body postures. Four main ergonomic risk assessments and identifications are recommended.     

The Etienne Grandjean Memorial Lecture Situated cognition and action: implications for ergonomic work analysis and anthropotechnology

Abstract

After a short history of the study of work activities, the methodology of Ergonomic Work Analysis (EWA) is described and the diversity of practices is underlined. The methodology of analysis of activities involves exhaustive checks of the behaviour of operators in critical situations and confronts the operator with his own behaviour in order to obtain pertinent explanations and evoke the cognitive unconscious. Ethnological work may constitute a contribution as regards the choice of the operator(s) whose behaviour is the most significant for the problem posed. In the same way, ethnologists using recording tools that are similar to those of ergonomists offer interesting frameworks for discussion of the qualities of these tools and the posture and balance aspects of behaviour. Moreover, interpersonal communications lead to beneficial exchanges with the ethnographic experience. Although the American school of situated cognition (cognitive and psychological anthropology) is very useful to know for activity analysts, it should not be confused with EWA which, by definition, is directed towards an objective: knowing and transforming obstacles of all types that hinder and prevent satisfactory activities. First of all, EWA has to show, from the viewpoint of operators, how they build problems in order to be able to solve them. Ergonomists and ethnologists note how difficult this problem building may be in view of the variability of the technical system and of the state of operators' knowledge. The technology transfer situations studied by anthropotechnology need EWA even more in view of the frequent degradation of technical systems and the heterogeneous character of the two cultures present in the mind of the operator: his own culture and that which has inspired the imported technology. From this viewpoint, here and there the operator may be considered not as a performer but as the iterative creator of his task.     

The impact of ergonomic work environment exposures on the risk of disability pension: Prospective results from DWECS/DREAM

The objectives were to identify the impact of ergonomic work environment exposures on the risk of disability pension. A representative sample of 8475 employees of the total working population in Denmark were interviewed regarding work environment exposures and followed in a national register with data on granted disability pension. For women, approximately 34% of the disability pension cases were attributable to ergonomic work environment exposures. For men, 21% of the disability pension cases were attributable to ergonomic work environment. Ergonomic work environment, especially physically demanding work, working with hands lifted and repetitive work, are areas of intervention at the workplace that can facilitate and prolong labour market participation. The study provides estimates for the association between ergonomic exposures at work and administrative, cost-related measures of work disability in a large population-based longitudinal cohort study over 14 years. Approximately 21% for men and 34% for women of the disability pension cases were attributable to ergonomic work environment exposures.     

A checklist for evaluating ergonomic risk factors resulting from awkward postures of the legs, trunk and neck

A one-page checklist for determining the presence of ergonomic risk factors associateed with awkward postures of the lower extremities, trunk and neck was developed and evaluated as part of a joint labor-management ergonomics intervention program. This checklist was used by plant personnel at four work sites to assess the postural requirements on 335 cyclical (i.e., work-cycle duration less than five minutes) manufacturing and warehouse jobs. In addition, results generated by the checklist were compared to the results of ergonomic analyses performed by persons with advanced training in occupational ergonomics.

Workers were observed using awkward postures for most of the jobs in the survey. Awkward postures of the lower extrimities were relatively uncommon, occuring in 25 percent or less of the jobs. Awkward postures of the trunk and neck were common, occuring in more than 70 percent of the jobs. Results generated by the checklist were generally in agreement with results generated by the experienced ergonomists; however, the checklist was found to be more sensitive in identifying the presence of awkward postures.

The checklist was found to be an effective rapid-screening instrument for identifying cyclical jobs that expose workers to potentially harmful postures. However, the checklist methodology did not include sufficient documentation of work methods to identify the specific job attributes associated with these exposures. Furthermore, the checklist was not used to evaluate non-cyclical jobs (e.g., maintenance and skilled trades).     

Comparing the physiological and perceptual responses of construction workers (bar benders and bar fixers) in a hot environment

This study aimed to (1) quantify the respective physical workloads of bar bending and fixing; and (2) compare the physiological and perceptual responses between bar benders and bar fixers. Field studies were conducted during the summer in Hong Kong from July 2011 to August 2011 over six construction sites. Synchronized physiological, perceptual, and environmental parameters were measured from construction rebar workers. The average duration of the 39 field measurements was 151.1 ± 22.4 min under hot environment (WBGT = 31.4 ± 2.2 °C), during which physiological, perceptual and environmental parameters were synchronized. Energy expenditure of overall rebar work, bar bending, and bar fixing were 2.57, 2.26 and 2.67 Kcal/min (179, 158 and 186 W), respectively. Bar fixing induced significantly higher physiological responses in heart rate (113.6 vs. 102.3 beat/min, p < 0.05), oxygen consumption (9.53 vs. 7.14 ml/min/kg, p < 0.05), and energy expenditure (2.67 vs. 2.26 Kcal/min, p < 0.05) (186 vs. 158 W, p < 0.05) as compared to bar bending. Perceptual response was higher in bar fixing but such difference was not statistically significant. Findings of this study enable the calculation of daily energy expenditure of rebar work.     

Establishing a dynamic ergonomic evaluation index system for complex product designs based on the theory of product life cycle

Ergonomic design and evaluation for complex product (tractor as an example) in different lifecycle stages should be different and specific according to changing business strategies. Being key factors for multi-attribute evaluation, how to define indicators and assign weights to them for tractor's different lifecycle stages are discussed in this paper. Focus group has been used for brainstorming initial indicators as many as possible. Then, indicators and their relationship-structures for three lifecycle stages were assessed and optimized by two rounds of Delphi surveys involving 15 experts. After that, a synthetic indicator weight assignment method suitable for value evaluation and ranking evaluation was proposed. Indicators' weights for value evaluation was composed by experts' value judgment weight and experts' credibility weight, the former was assigned by Group Analytic Hierarchy Process method and the latter was assigned by calculating distances between individual weight and the average weight. To differentiate alternatives' ergonomic performances clearly, weight set of value evaluation has been modified by indicator's information entropy weight. The results show that there are some significant differences in three indicator systems (for three lifecycle stages) and weight sets developed by the proposed method, and this will have significant impacts on ergonomic evaluation results, which can provide useful feedback for tractor's design during its early design stage. The proposed method can be applied to ergonomic evaluation study of other complex products in their lifecycle.     

Assessing the influence of repeated exposures and mental stress on human wayfinding performance in indoor environments using virtual reality technology

This study aimed to examine the effect of repeated exposures to indoor environments on people’s indoor wayfinding performance, both under normal condition and during fire emergency which could induce significant mental stress. Indoor wayfinding experiments were conducted in an immersive virtual museum developed using virtual reality technologies. Participants of the experiments were divided into three groups, who participated in one, two and three trials, respectively. Those who participated in more than one trial were given an interval of two weeks between two consecutive trials. Each trial of the experiment included a treasure hunting task and an egress task. Participants were presented with a virtual fire emergency during the egress task of their last trial. Data of wayfinding performance measures of the participants, as well as their physiological and emotional responses, sense of direction, wayfinding anxiety and simulator sickness were collected and analyzed. The results revealed significant positive impact of repeated exposure on participants’ wayfinding performance, which resulted in a decrease in the time needed to complete the treasure hunting task. The results also revealed significant negative impact of mental stressed caused by the fire emergency on participants’ wayfinding performance, which led to increased travel time and distance during egress. Such negative impact of stress, however, could be noticeably diminished by the repeated exposures, showing significant interaction effect between these two factors.     

Stand up: comparison of two electrical screed levelling machines to reduce the work demands for the knees and low back among floor layers

Electrical screed levelling machines are developed to reduce kneeling and trunk flexion of sand–cement-bound screed floor layers. An observational intervention study among 10 floor layers was performed to assess the differences between a self-propelled and a manually moved machine. The outcome measures were work demands, production time, perceived load, discomfort and applicability. Compared to the self-propelled machine, the duration of kneeling (?13 min; p = 0.003) and trunk flexion (?12 min; p < 0.001) was shorter using the manually moved machine, and the duration of pushing and pulling increased (?39 min; p < 0.001). No significant or relevant differences were found for production time, perceived load and discomfort. Nine out of ten floor layers found the manually moved machine applicable and three out of ten found the self-propelled machine applicable. When compared with the traditional manner of floor laying, both electrical machines reduced the exposure towards kneeling and trunk flexion.

Practitioner Summary: Electrical machines may help to reduce high physical work demands on floor layers. A manually moved machine is better applicable for the installation of screed floors in residences with smaller floor areas. A self-propelled machine is better applicable on large floor areas with a minimum width of 4 m.     

Designing ergonomic interventions for EMS workers, Part I: transporting patients down the stairs

The objective of the current work was to test ergonomic interventions aimed at reducing the magnitude of trunk muscle exertions in firefighters/paramedics (FFPs) providing emergency medical services (EMS) when transporting patients down the stairs. The interventions, developed using focus groups, were a footstrap to prevent the patient from sliding down on the backboard, a change in the handle configuration on the stairchair, and 2 devices, the "backboard wheeler" and a tank tread-like device (descent control system, DCS) for a stretcher, that change the backboard and stretcher carrying tasks into rolling and sliding tasks. Eleven two-person teams transported a 75 kg dummy with each intervention and its corresponding control condition down a flight of steps. Surface electromyographic (EMG) data were collected from 8 trunk muscles from each participant. Results showed that the backboard footstrap reduced the erector spinae (ERS) activity for the FFP in the "leader" role by 15 percent, on average. The change in handle configuration on the stairchair had no effect on the variables measured. The backboard wheeler reduced the ERS activity bilaterally in the FFP in the leader role and unilaterally for the FFP in the "follower" role, by 28 and 24 percent, respectively. The DCS reduced the 90th percentile ERS activity for both FFPs from 26 to 16 percent MVC, but increased the latissimus dorsi activity in the follower from 11 to 15 percent MVC. The DCS was the only intervention tested that resulted in a reduced rating of perceived exertion relative to the corresponding control condition. In summary, the hypotheses that the proposed interventions could reduce trunk muscle loading were supported for 3 of the 4 transport interventions tested.     

Construction of an osteomuscular discomfort scale for the upper region of the body of footwear industry workers

The objective of this study was to build a scale of musculoskeletal discomfort for the upper body of footwear industry workers. The self-reported symptoms of 1821 workers were analyzed via exploratory factor analysis and item response theory. The anatomical regions located in the upper body showed ability to discriminate workers with different levels of musculoskeletal discomfort. A scale with six levels was built, ranging from minimal discomfort to maximum discomfort, with greater precision of discomfort scores between 0 and 3. The region of least discomfort on the scale only indicates rare symptoms in the left shoulder. In the region of maximum discomfort, workers experience symptoms in all regions analyzed on a daily basis, with emphasis on the elbows, neck, trapezius, and middle and upper back. The scale has satisfactory psychometric properties to assess musculoskeletal symptoms in footwear industry workers and can be useful in ergonomic studies.     

DASH questionnaire for the analysis of musculoskeletal symptoms in industry workers: a validity and reliability study

Purpose

The disabilities of the arm, shoulder and hand (DASH) questionnaire is a self-administered region-specific outcome instrument developed as a measure of self-rated upper-extremity disability and symptoms. The aim of this study was to evaluate the reliability and the construct validity of the DASH questionnaire by establishing its correlation to the Medical Outcomes Study Short Form-36 (SF-36) in industry workers. Also we aimed to investigate whether the DASH can be used as a standardized questionnaire to evaluate the work-related musculoskeletal disorders (WMSDs) in upper extremity in industrial settings and epidemiological studies.

Material and methods

The Turkish version's reliability and construct validity were evaluated in 240 industry workers with upper-extremity musculoskeletal complaints. Workers were asked to complete a packet that included the DASH and the SF-36. Test-retest reliability was assessed in all workers who filled in the DASH questionnaire 15 days later. Construct validity was evaluated by comparing the overall and work component DASH scores with SF-36 summary and subscales.

Results

The mean DASH score for the textile workers whose duties were confection, dyeing, sewing, quality control and packaging was calculated as 65, 55, 68, 54 and 67, respectively. As a result of this study, pain intensity in shoulder, wrist and hand was significantly associated with the DASH score (p<0.05). Internal consistency of the DASH was high (Cronbach alpha 0.91). Test-retest reliability was excellent for the overall DASH (intraclass correlation coefficient (ICC) 0.92). Moderate correlations (p<0.05) were found between the overall and work component DASH and the SF-36 summary scales. Pearson correlation coefficients of the overall and work component DASH to the SF-36 subscales ranged from −0.33 to −0.82.

Conclusion

These results support that DASH is a reliable and valid instrument to measure functional disability and investigate the ergonomic risk factors in textile workers with upper-extremity musculoskeletal complaints.     

Assessing attitudes, beliefs and readiness for musculoskeletal injury prevention in the construction industry

The objectives are to determine attitudes and beliefs among construction workers and supervisors related to taking action to reduce musculoskeletal injuries (MSIs). “Action” stage of change was confirmed if workers in the last 6 months are continuing to take steps to reduce MSIs. Surveys (520 workers; 35% and 171 supervisors; 67%) revealed that more workers are concerned about MSIs (p < 0.05) and are taking action to reduce MSIs (p < 0.05) than supervisors. Workers taking action tended to be younger and less experienced than other workers (p = 0.00). The final multivariate model showed those workers taking action were more likely to be mechanics and general laborers, to have experienced pain within the last week, to be involved in health and safety, to feel that changes aimed at reducing MSIs would be effective, and that injuries are due to adverse work conditions rather than with characteristics of individual workers. This information can be used to target ergonomics interventions in this industry.