Relationships between job organisational factors, biomechanical and psychosocial exposures

Exploring the influence of individual factors on the perception of mental workload and body postures

Studies have revealed that physical and mental demands, psychosocial factors, and individual factors can contribute to the development of WMSDs. Yet, much is still unknown regarding the effects of individual characteristics on WMSDs susceptibility. Previous studies discovered people assumed more awkward body postures to perform an activity when the perception of mental workload is higher. This research study explored if individual characteristics such as age, sex, personality, and anxiety help explain changes or differences in the perception of mental workload and body postures assume when performing activities. The study provided evidence that these individual characteristics have a modifying role on perceived mental workload and body postures. The results suggest that perceived mental workload is influenced to a higher extent by individual characteristics such as anxiety, sex, and personality traits. Women have a higher (18.7%) mental workload perception than men. Likewise, NASA-TLX scores are 22% higher for feelers than thinkers. In general, higher perceptions of mental workload were observed in participants with higher anxiety levels. On the other hand, body postures seem to be influenced by different individual factors depending on the nature of the activity. RULA scores increased on average by 13.1% between baseline and time constraint conditions. Larger differences were observed in certain individuals (e.g. introverts (19.7%) and intuitors (13.8%)) across conditions.

Does the introduction of a cobot change the productivity and posture of the operators in a collaborative task?

Musculoskeletal disorders (MSDs) are the main occupational diseases and are pathologies of multifactorial origin, with posture being one of them. This creates new human-robot collaboration situations that can modify operator behaviors and performance in their task. These changes raise questions about human-robot team performance and operator health. This study aims to understand the consequences of introducing a cobot on work performance, operator posture, and the quality of interactions. It also aims to evaluate the impact of two levels of difficulty in a dual task on these measures. For this purpose, thirty-four participants performed an assembly task in collaboration with a co-worker, either a human or a cobot with two articulated arms. In addition to this motor task, the participants had to perform an auditory task with two levels of difficulty (dual task). They were equipped with seventeen motion capture sensors. The collaborative work was filmed with a camera, and the actions of the participants and co-worker were coded based on the dichotomy of idle and activity. Interactions were coded based on time out, cooperation, and collaboration. The results showed that performance (number of products manufactured) was lower when the participant collaborated with a cobot rather than a human, with also less collaboration and activity time. However, RULA scores were lower-indicating a reduced risk of musculoskeletal disorders-during collaboration with a cobot compared to a human. Despite a decrease in production and a loss of fluidity, likely due to the characteristics of the cobot, working in collaboration with a cobot makes the task safer in terms of the risk of musculoskeletal disorders.

Assessing the efficacy of a job rotation for improving occupational physical and psychosocial work environment, musculoskeletal health, social equality, production quality and resilience at a commercial laundromat: protocol for a longitudinal case study

INTRODUCTION

Job rotation is a work organisation strategy used to reduce work-related exposures and musculoskeletal complaints, yet evidence for the efficacy of the approach is weak. Mismatch between job rotation and company needs, lack of full implementation, lack of exposure variation in included tasks and failure to assess variation may underlie inconclusive research findings to date. The study aims to develop a job rotation with company stakeholders, perform a process evaluation of the implementation, and determine the extent to which the intervention improves the physical and psychosocial work environment, indicators of health, gender and social equality among workers and production quality and resilience.

METHODS AND ANALYSIS

Approximately 60 production workers at a Swedish commercial laundromat will be recruited. Physical and psychosocial work environment conditions, health, productivity and gender and social equality will be assessed pre and post intervention, using surveys, accelerometers, heart rate, electromyography and focus groups. A task-based exposure matrix will be constructed, and exposure variation estimated at the level of the individual worker pre and post intervention. An implementation process evaluation will be conducted. Job rotation efficacy will be assessed in terms of improvement in work environment conditions, health, gender and social inequality, and production quality and resilience. This study will provide novel information on the effects of the job rotation on physical and psychosocial work environment conditions, production quality and rate, health and gender and social inequality among blue-collar workers in a highly multicultural workplace.

ETHICS AND DISSEMINATION

The study received approval from the Swedish Ethical Review Authority (reference number 2019-00228). The results of the project will be shared directly with the employees, managers and union representatives from the participating company, other relevant labour market stakeholders and with researchers at national and international conferences and via scientific publication.

TRIAL REGISTRATION NUMBER

The study is preregistered with the Open Science Framework (https://osf.io/zmdc8/).

Low Back Pain and Upper-Extremity Musculoskeletal Disorders in French Postal Workers Driving Light-Duty Vehicles for Mail and Parcel Delivery

Occupational driving of light-duty vehicles (LDVs) became increasingly important in parcel delivery faced with the explosive growth of e-commerce. Since musculoskeletal disorders (MSDs) represent the most reported driving-related health problem, we aimed to analyze the risk of low back pain (LBP) and upper-extremity musculoskeletal disorders (UEMSDs) associated with driving LDVs for parcel delivery. In 306 postal workers exposed to driving and 100 unexposed workers, information on occupational driving, physical/psychosocial constraints, and work organization were collected via a questionnaire. MSDs were assessed using the Nordic Questionnaire, 14 additional questions regarding LBP, and a standardized clinical examination for UEMSDs. Statistical modeling consisted of multivariable logistic regression for UEMSDs and the item response theory approach for LBP. UEMSDs were associated with the distance of rural rounds and inversely associated with urban/mixed delivery rounds. Handling heavy loads was associated with LBP, and high physical demands during delivery rounds were related to MSDs. Karasek dimensions and mobbing actions were associated with MSDs. Work recognition, driving training, using an automatic gearbox, and the utilization of additional staff during peak periods were inversely associated with MSDs. Our results suggest that the distance driven in rural settings and high physical demands were associated with MSDs, while some organizational factors could protect from MSDs.

Profiles of women who have suffered occupational accidents in cleaning: perceived health, psychosocial risks, and personality variables

PURPOSE

The main goal was to identify the variables (sociodemographic, work, psychosocial, perceived health, and personality) associated with occupational accidents suffered in the past by women in the cleaning sector.

METHODS

A sample of 455 women was evaluated.

RESULTS

A total of 23.5% of the workers (n = 107) had suffered an occupational accident with medical leave. In general, women who had suffered some accident in their life had a worse situation in all areas evaluated. Two subsamples of women had a greater association with accidents. Specifically, the presence of work accidents was 15.9 times higher among those who presented a worse perception of their physical effort and a greater tendency towards risky behaviours and 13.5 times higher among those who had a moderate perception of physical exertion and a disability.

CONCLUSION

In general, the characteristics of female workers were found to be associated with different accident rates. Preventive actions should be designed individually.

Will the real relationship between lean and safety/ergonomics please stand up?

This paper provides a review of studies containing safety and ergonomic outcomes in lean manufacturing (LM) environments over the past 40 years. The aim is to identify effects from specific LM methods on specific safety/ergonomic outcomes, to understand the relationship in greater detail. One hundred and one studies containing one hundred and seventy outcomes were identified. Thirty-seven outcomes pertained to just-in-time (JIT) production, which contained twenty-three negative, eleven neutral, and three positive safety/ergonomic outcomes. Conversely, twenty-six outcomes pertained to 5S and consisted of twenty-four positive, two negative, and no neutral outcomes. The most common negative JIT outcome was stress and mental strain, while the most common positive 5S outcome was a tie between safety performance and hazard exposure. Studies containing other methods were fewer in number with more mixed outcomes. These findings suggest that individual LM methods, especially JIT and 5S, uniquely contribute to the safety/ergonomic outcomes attributed to LM.

Risk factors for shoulder disorders among French workers: prospective cohort study

Objectives

Shoulder disorders are common in the working population. This longitudinal study aimed to explore the relationships between personal factors and occupational organisational, psychosocial, and biomechanical factors and the incidence of shoulder disorders.

Methods

A total of 3710 workers in the Pays de la Loire region (Loire Valley area, France) were randomly included by their occupational physician in the Cosali cohort between 2002 and 2005. All workers completed a self-administered questionnaire about personal factors and work exposure, and using a standardised physical examination, occupational physicians diagnosed shoulder disorders. Between 2007 and 2010, 1611 workers were re-examined by their occupational physician. The 1,320 workers free of shoulder disorders at baseline were studied. A conceptual model was developed in which relationships between organisational, psychosocial, biomechanical, and personal factors at baseline and the incidence of shoulder disorders were assumed. Structural equation modelling was used to test the model.

Results

Shoulder disorders were directly associated with biomechanical factors and age but not with psychosocial factors. However, skill discretion and psychological demand influenced shoulder disorders indirectly through biomechanical factors. Exposure to a work pace dependent on an automatic rate and to a work pace dependent on customers’ demands were associated with biomechanical and psychosocial factors, but not directly to shoulder disorders.

Conclusions

This study identified the complex direct and indirect relationships between occupational factors and shoulder disorders. Our data confirmed our conceptual causation model: organisational and psychosocial factors were associated with biomechanical factors, while biomechanical factors were associated with the incidence of shoulder disorders.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00420-022-01853-9.

Redefining Safety in Light of Human-Robot Interaction: A Critical Review of Current Standards and Regulations

Policymakers need to consider the impacts that robots and artificial intelligence (AI) technologies have on humans beyond physical safety. Traditionally, the definition of safety has been interpreted to exclusively apply to risks that have a physical impact on persons’ safety, such as, among others, mechanical or chemical risks. However, the current understanding is that the integration of AI in cyber-physical systems such as robots, thus increasing interconnectivity with several devices and cloud services, and influencing the growing human-robot interaction challenges how safety is currently conceptualised rather narrowly. Thus, to address safety comprehensively, AI demands a broader understanding of safety, extending beyond physical interaction, but covering aspects such as cybersecurity, and mental health. Moreover, the expanding use of machine learning techniques will more frequently demand evolving safety mechanisms to safeguard the substantial modifications taking place over time as robots embed more AI features. In this sense, our contribution brings forward the different dimensions of the concept of safety, including interaction (physical and social), psychosocial, cybersecurity, temporal, and societal. These dimensions aim to help policy and standard makers redefine the concept of safety in light of robots and AI’s increasing capabilities, including human-robot interactions, cybersecurity, and machine learning.

Personal, biomechanical, psychosocial, and organizational risk factors for carpal tunnel syndrome: a structural equation modeling approach

This longitudinal study aimed at exploring the direct and indirect relationships between organizational, psychosocial, biomechanical, and personal factors and carpal tunnel syndrome (CTS) in French workers. Between 2002 and 2005, 3710 workers were included in the Cosali cohort. Between 2007 and 2010, 1611 workers were re-examined using the same standardized clinical protocol. Subjects free from CTS at baseline were studied (804 men and 563 women). We used structural equation models to examine the relationships between incident CTS cases and organizational (machine-paced work or work pace dependent on customers' demand), psychosocial (job strain model), biomechanical (Borg's rating perceived exertion, wrist bending, pinching, and hand-transmitted vibrations), and personal factors at baseline. Symptomatic CTS risk was directly increased by biomechanical factors (standardized coefficient = 0.19, P = 0.011), female gender (0.25, P < 0.001), and age (0.15, P = 0.042). No psychosocial factors had a direct impact on CTS, but decision authority and skill discretion had an indirect impact by influencing biomechanical exposure. Exposure to machine-paced work had an indirect impact on increasing CTS, either by raising biomechanical exposure (0.19, P < 0.001) or by lowering decision authority (-0.18, P < 0.001) and skill discretion (-0.20, P < 0.001), which in turn increased biomechanical exposure. Similar complex relationships were observed between risk factors and CTS defined by a more strict case definition. Biomechanical exposure had a direct impact on CTS, while organizational factors and psychosocial factors had an indirect impact on CTS. The findings support conceptual models linking work organization to CTS.

More Hype Than Substance? A Meta-Analysis on Job and Task Rotation

Although there exist numerous publications on job and task rotation from various disciplines, there is no consistent evidence of their effectiveness. Drawing on theories from industrial and organizational psychology, knowledge management, ergonomics, and management science, we meta-analytically investigated relationships between job/task rotation and employee attitudes, learning and development, psychological and physical health, and organizational performance. Due to a conceptual overlap and frequent confusion of terminology, we analyzed the design of the rotation (job rotation vs. task rotation) as a possible moderator. The three-level meta-analysis on 56 studies (N = 284,086) showed that rotation was significantly associated with job satisfaction (r = 0.27), organizational commitment (r = 0.16), career success (r = 0.31), labor flexibility (r = 0.32), general psychological health (r = 0.20), stress/burnout (r = -0.13), individual performance (r = 0.13), and productivity (r = 0.13). Positive relationships between rotation and physical health could only be found when rotation was compared to high-intensity work. Task rotation yielded stronger relationships with attitudinal outcomes, job rotation with learning and development, psychological health, and organizational performance outcomes. Further moderator analyses showed that individualism decreased relationships between task rotation and attitudes, and correlations with organizational performance and physical health were stronger for subjective measures. The findings indicate that many expectations toward job and task rotation are not fully supported.

Are Work-Related Musculoskeletal Disorders Claims Related to Risk Factors in Workplaces of the Manufacturing Industry?

OBJECTIVES

Varied work-related musculoskeletal disorders (WMSDs) claim rates were found between companies even when they were in the same sectors with similar sizes. This study aimed to (i) identify common risk factors for back, shoulder, hand/wrist, and knee WMSDs among manufacturing jobs, and (ii) characterize the biomechanical exposures in jobs and work organizational practices between high and low WMSD claim rate companies so that more focused, industry-specific intervention strategies may be developed.

METHODS

Using historical workers' compensation data, manufacturing companies were divided into two paired groups (low and high in the lower 25%ile and higher 75%ile, respectively). On-site job evaluations were conducted in 16 companies to determine job biomechanical risk levels. Management and workers' representatives in 32 paired companies were interviewed to identify possible differences between management strategies and management/worker relationships. A total of 39 injured workers were also interviewed to gather information of self-reported injury causes and suggested preventive measures.

RESULTS

Analyses of 432 job evaluations showed that more jobs had higher risk levels of prolonged standing and heavy lifting in the high back WMSD claim rate companies than the low claim rate ones. No high biomechanical risk factors were found to be associated with jobs in high shoulder claim rate companies. High repetition, pinch force, and Strain Index were associated with high hand/wrist WMSD claim rate companies. High work pace and job stress were common among high knee WMSD claim rate companies. There were no statistically significant differences for the organizational factors between high and low WMSD claim rate companies. Heavy lifting, fast work pace, high hand/wrist repetition, high hand force, and awkward shoulder postures were identified as major contributing factors by the injured workers.

CONCLUSIONS

High WMSD claim rate companies appeared to have more high biomechanical exposure jobs than low WMSD claim rate companies. Available job evaluation methods for the low back and hand/wrists are satisfactory in quantifying job risk levels in the manufacturing industry. Research into more sensitive job evaluation methods for the shoulder and knee are needed.

Psychosocial Factors and Tobacco Use Among Commercial Truck Drivers

OBJECTIVES

To explore the relationships between tobacco, social support, job satisfaction, and depression among truck drivers.

METHODS

Cross-sectional data were collected from 797 truck drivers in six US states. Data collected included self-reported medical history and biological samples. Modified Zung depression scale and Work Apgar scores were used to measure depression and social support. Adjusted logistic regression models were used to calculate odds ratios (OR).

RESULTS

24.0% of tobacco users were in the least depressed category and 18.2% were most depressed. 22.8% of the tobacco users had the most social support compared with 27.9% of the non-users. Drivers in the two most depressed categories were significantly less likely to use tobacco (OR = 0.62, 95% confidence interval [CI] = 0.39-0.96, and OR = 0.64, 95% CI = 0.41-0.99).

CONCLUSIONS

Drivers with low social support or low levels of depression are more likely to be tobacco users.

Shoulder pain among male industrial workers: Validation of a conceptual model in two independent French working populations

This study aims to validate a conceptual model for shoulder pain risk factors in two independent samples of male industrial workers: the Cosali cohort (n = 334) and one pharmaceutical company (n = 487). Direct and indirect relationships between work organization factors (automatic speed of a machine or movement of a product and work pace dependent on customers' demand), psychosocial factors (Job strain model), biomechanical factors (working with abducted arms, working with arms at or above shoulder level, and perceived physical exertion), perceived stress, and shoulder pain were explored using structural equation models. Shoulder pain was positively associated with biomechanical exposure in both samples, and with perceived stress only in the pharmaceutical preparation manufacturer, while factors related to work organization and psychosocial factors had indirect impacts on the risk of chronic shoulder pain in both samples. The results provide a deeper understanding of the complex relationships between workplace risk factors and shoulder pain.

ESTRESSE OCUPACIONAL NA MÍDIA IMPRESSA: UMA PERSPECTIVA DE CHRISTOPHE DEJOURS

Resumo O estresse no trabalho afeta os aspectos psicológicos, físicos e sociais do trabalhador, bem como a eficácia das organizações produtivas. O objetivo deste estudo foi compreender o estresse ocupacional na mídia jornalística sob a ótica da organização do trabalho. Trata-se de uma pesquisa qualitativa conduzida por análise de conteúdo de Bardin, com base nas categorias analíticas previamente definidas pela Organização Mundial da Saúde, no relatório “Work Organization & Stress”, sob a perspectiva do referencial teórico de Christophe Dejours. Foram classificadas 727 notícias que tinham como palavra-chave ‘estresse’, sendo 130 notícias específicas do tema estresse no trabalho. Dentre estas notícias, foram classificadas as categorias “Conteúdo dos Riscos do Estresse” (47) e “Contexto dos Riscos do Estresse” (59), ambas com suas subcategorias. Constatou-se que a mídia quase não tem funcionado como porta-voz dos trabalhadores a fim de cumprir seu papel social, sem estimulá-los como sujeitos sociais. Propõe-se que a mídia jornalística estimule ações que impulsionem o protagonismo dos trabalhadores, baseado na visibilidade das legislações vigentes, e aponte caminhos mais diretos para que os trabalhadores possam lutar pela garantia de direitos à saúde no combate ao estresse, com perspectiva crítica do entendimento sobre organização do trabalho e suas potencialidades na promoção da saúde.

Work-related upper limb disorders and risk assessment among automobile manufacturing workers: A retrospective cohort analysis

OBJECTIVE

To estimate the three-year cumulative risk of work-related upper limb disorders (WRULDs) in a cohort of automotive industry workers and to provide a first test of the ability of the European Assembly Worksheet (EAWS) methodology to predict WRULDs.

METHODS

292 workers were investigated by reviewing workers' medical records during the period from 2012-2015 to determine their exposure to biomechanical overload according to EAWS risk scores (0-25, low risk, Green zone; 26-50, medium risk, Yellow zone; >50, High risk; Red zone).

RESULTS

The risks were 0.83%, 5.71%, and 11.88% for the Control (unexposed), Green and Yellow Groups, respectively. Only the comparison between the Yellow/Control Groups was significant (p = 0.0014). In total, we observed 17 cases of musculoskeletal disorders (MSDs) (14 symptomatic and 3 cases detected by physical examination).

CONCLUSIONS

The EAWS is a useful tool for the preliminary risk assessments of biomechanical overload among automotive industry workers. The finding of mainly non-specific disorders highly suggests that health surveillance should aim to identify not only full-blown diseases but also symptomatic cases.

Prevalence of work-related musculoskeletal disorders in agriculture workers in Korea and preventative interventions

BACKGROUND

Work-related musculoskeletal disorders (WMSDs) are estimated to be the most common and frequent of all occupational diseases in agriculture in Korea, but the full extent of the problem has yet to be surveyed.

OBJECTIVE

This paper presents the results of a survey investigating the extent of WMSDs among self-employed farmers in Korea. It also describes ergonomics based preventive interventions initiated by the Korean government.

METHOD

The prevalence of WMSDs was surveyed among 358 farmers using a questionnaire adapted from the Nordic questionnaires, employing three case definitions.

RESULTS

The results showed that the overall prevalence rates of WMSDs by case definition 1 (any symptoms), 2 (symptoms with a pain intensity of moderate or greater), and 3 (symptoms with a pain intensity of high or greater) were 97.2%, 83.2%, and 39.7% respectively and that the shoulder, knee and lower back disorder rates were higher than those of other body parts. Compared to the prevalence rates of WMSDs for workers in other industries in Korea as well as USA farmers, the overall rates for farmers in Korea were much higher. The interventions, which adopted a participatory approach involving government, farmers, ergonomics, technical and industrial hygiene experts, showed benefits in terms of work efficiency, safety and farmer satisfaction.

CONCLUSIONS

The high WMSD symptom prevalence showed that agriculture is one of the most hazardous industries in Korea, and the Korean government's interventions were effective and successful.

A Pilot Study of Five Types of Maximum Hand Strength among Manufacturing Industry Workers in Taiwan

Background: The purpose of this study is to collect five types of maximum hand strength among workers in the manufacturing industry in Taiwan. Methods: This study is a cross sectional study with a stratified and convenient sample of workers on the production line in manufacturing industries in Central Taiwan. In total, we recruited 198 healthy subjects to participate in this study. Five types of hand strength were measured in both hands three times with 3 min rests between trials. Results: The strength of females for these five types of hand exertions were 52.0% to 67.6% of the strength of males (p < 0.001). For both genders, there was a main effect for the types of hand strength for the right hand (p < 0.001) and the left hand (p < 0.001). In general, the hand strength in U.S. and EU countries was 1.2 to 1.7 times greater than the strength among the three types of hand exertions in this study. Conclusion: These results can be used to evaluate the musculoskeletal burdens on the upper extremities in the manufacturing industry and could also be used for tool and job design and job modifications.

Association between Psychosocial Working Conditions and Perceived Physical Exertion among Eldercare Workers: A Cross-Sectional Multilevel Analysis of Nursing Homes, Wards and Workers

This cross-sectional multilevel study aims at investigating the associations between psychosocial working conditions of different workplace levels and perceived physical exertion among eldercare workers. Data were obtained from the 'Danish Observational Study of Eldercare work and musculoskeletal disorderS' (DOSES) study, including 536 eldercare workers, nested in 126 wards and 20 nursing homes. Psychosocial working conditions were measured by the Copenhagen Psychosocial Questionnaire (COPSOQ). The physical workload was measured with a self-administered scale (0-10) rating perceived physical exertion. Multilevel linear mixed models were used to determine associations of psychosocial conditions between nursing homes, wards, and workers with physical exertion. Most of the variance in the perceived physical exertion was explained by differences between workers (83%), but some variance was explained by wards (11%) and nursing homes (6%). Workers employed in nursing homes with low influence (p = 0.01) and poor leadership (p = 0.02), and in wards with high quantitative demands (p = 0.03), high work pace (p < 0.001), and low justice (p = 0.01) were at increased risk of reporting higher physical exertion. The strongest associations were found for low influence, low quality of leadership, and high work pace at nursing homes and ward levels. In conclusion, improving specific psychosocial working conditions at nursing home and ward levels may be of particular importance to reduce excessive physical workload in eldercare workers.

Task and sex differences in muscle oxygenation during handgrip fatigue development

The purpose of this study was to examine task and sex differences in forearm muscle oxygenation, measured using near infrared spectroscopy, during sustained submaximal handgrip exercises. Forty-eight adults (50% males) performed fatiguing handgrip exercises at 20, 40, 60 and 80% of their maximum handgrip strength. While males and females exhibited similar levels of relative fatigability, forearm oxygenation was found to be task (i.e. contraction intensity and phase of fatigue development) and sex dependent. Higher contraction intensities were associated with greater desaturation over time. Compared to females, males exhibited greater desaturation as fatigue progressed and this was augmented at higher contraction intensities. These may be likely affected by sex differences in muscle mass, morphology and strength differences during exercises at relative intensities. Future work that explores sex differences in muscle oxygenation during absolute force intensities are needed, which may have implications for muscle fatigue development and potential fatigue mitigation strategies. Practitioner Summary: Muscle oxygenation impacts fatigue development that can in turn affect worker health and productivity. Males exhibit greater forearm desaturation than females at higher relative work intensities, despite similar fatigue levels. Females may be predisposed to greater muscle delivery and oxygenation challenges that can increase their fatigability during work at absolute load levels.

Task rotation in an underground coal mine: A pilot study

BACKGROUND

Task rotation is used to decrease the risk of workplace injuries and improve work satisfaction.

OBJECTIVE

To investigate the feasibility, benefits and challenges of implementing a task rotation schedule within an underground coalmine in NSW, Australia.

METHODS

A mixed method case control pilot study with the development and implementation of a task rotation schedule for 6 months with two work crews. A questionnaire including The Nordic Musculoskeletal Questionnaire, The Need for Recovery after Work Scale, and The Australian WHOQOL- BREF Australian Edition was used to survey workers at baseline, 3 and 6 months. A focus group was completed with the intervention crew and management at the completion of the study.

RESULTS

In total, twenty-seven participants completed the survey. Significant improvements in the psychological and environmental domains of the WHOQOL-BREF questionnaire were found in the intervention crew. Musculoskeletal pain was highest in the elbow, lower back and knee, and fatigue scores improved, across both groups. The intervention crew felt 'mentally fresher', 'didn't do the same task twice in a row', and 'had more task variety which made the shift go quickly'.

CONCLUSION

Task rotation was positively regarded, with psychological benefits identified. Three rotations during a 9-hour shift were feasible and practical in this environment.

Risk Factors for Shoulder Pain in a Cohort of French Workers: A Structural Equation Model

Shoulder pain is common in the working population and causes loss of productivity, high economic costs, and long absences. Simultaneous evaluation of the complex relationships between work organization (e.g., work pace, application of quality standards), psychosocial and physical risk factors, stress, and shoulder pain is rare. The aim of this study was to explore the direct and indirect relationships between workplace risk factors, perceived stress, and occurrence of shoulder pain in workers of the Cohorte des Salariés Ligériens study. A total of 3,710 workers in a French region were randomly selected for inclusion between 2002 and 2005. They completed a self-administered questionnaire about musculoskeletal symptoms, individual factors, and exposure to work constraints. In 2007, they responded to a follow-up questionnaire. The study sample comprised 1,400 workers free of shoulder pain at baseline. Structural equation models were used. For both sexes, exposure to factors related to work organization had an effect on physical and psychosocial risk factors. Psychological demand was the only psychosocial constraint that increased perceived stress. Shoulder pain was influenced directly by physical risk factors for both sexes and by perceived stress for men. In view of their distal action, work organization is an important target for strategies to prevent shoulder pain in the working population.

An investigation into four different sit-stand workstation use schedules

Twelve office workers participated in a study investigating effects of four sit/stand schedules (90-min sit/30-min stand, 80/40, 105/15, and 60/60) via several objective and subjective measures (muscle fatigue, foot swelling, spinal shrinkage, and self-reported discomfort). Results showed that there were no significant differences in shoulder and low back static muscle activities between sitting and standing. Muscle fatigue was developed during workday under all schedules. The longest standing schedule seemed to have a tendency of reducing muscle fatigue. None of the schedules helped or worsened foot swelling and spinal shrinkage. More active break-time activities seemed reducing muscle fatigue and foot swelling. While the self-reported bodily discomfort levels were generally low, the preferred schedules among the participants were varied, although the least standing schedule was the least preferred. We may conclude that effects of using sit-stand workstation to improve musculoskeletal health may be limited but promoting more active break-time activities can help. Practitioner Summary: Sit-stand workstations are used to reduce work-related musculoskeletal disorders. This study shows that office workers prefer sit/stand durations in the range between 1:1 and 3:1. Longer standing may have the potential to reduce muscle fatigue. However, active break-time activities may be more effective in reducing muscle fatigue and foot swelling.

Risk assessments using the Strain Index and the TLV for HAL, Part II: Multi-task jobs and prevalence of CTS

The Strain Index (SI) and the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value for hand activity level (TLV for HAL) have been shown to be associated with prevalence of distal upper-limb musculoskeletal disorders such as carpal tunnel syndrome (CTS). The SI and TLV for HAL disagree on more than half of task exposure classifications. Similarly, time-weighted average (TWA), peak, and typical exposure techniques used to quantity physical exposure from multi-task jobs have shown between-technique agreement ranging from 61% to 93%, depending upon whether the SI or TLV for HAL model was used. This study compared exposure-response relationships between each model-technique combination and prevalence of CTS. Physical exposure data from 1,834 workers (710 with multi-task jobs) were analyzed using the SI and TLV for HAL and the TWA, typical, and peak multi-task job exposure techniques. Additionally, exposure classifications from the SI and TLV for HAL were combined into a single measure and evaluated. Prevalent CTS cases were identified using symptoms and nerve-conduction studies. Mixed effects logistic regression was used to quantify exposure-response relationships between categorized (i.e., low, medium, and high) physical exposure and CTS prevalence for all model-technique combinations, and for multi-task workers, mono-task workers, and all workers combined. Except for TWA TLV for HAL, all model-technique combinations showed monotonic increases in risk of CTS with increased physical exposure. The combined-models approach showed stronger association than the SI or TLV for HAL for multi-task workers. Despite differences in exposure classifications, nearly all model-technique combinations showed exposure-response relationships with prevalence of CTS for the combined sample of mono-task and multi-task workers. Both the TLV for HAL and the SI, with the TWA or typical techniques, appear useful for epidemiological studies and surveillance. However, the utility of TWA, typical, and peak techniques for job design and intervention is dubious.

Full-shift and task-specific upper extremity muscle activity among US large-herd dairy parlour workers

US large-herd dairy parlour workers experience a high prevalence of musculoskeletal symptoms in the upper extremity. The purpose of this study was to estimate and compare full-shift and task-specific muscle activity of the upper extremity among parlour workers. Surface electromyography data were recorded continuously throughout a full work shift for each participant (n = 60). For a subset of participants (n = 33), muscular effort was estimated for milking task cycles. Lower muscle activity levels and higher per cent muscular rest was observed among rotary parlour participants as compared to herringbone and parallel parlour participants for anterior deltoid, forearm flexor and forearm extensor muscles. These findings suggest rotary parlours may offer workstation designs or work organisational dynamics which may be more beneficial to the health and performance of the worker, as compared to parallel or herringbone parlours. Practitioner Summary: Study findings suggest milking parlour configurations present different biomechanical demands on workers which may influence worker health and performance. Our findings will enable more informed decisions regarding both engineering (e.g. parlour configuration or milking equipment) and administrative (e.g. work organisation) control strategies for large-herd milking parlours.

Impact of Work Organizational Factors on Carpal Tunnel Syndrome and Epicondylitis

OBJECTIVE

The aim of this study was to identify relationships between work organizational variables (job rotation, overtime work, having a second job, and work pacing) (These work organizational variables and their relationships with biomechanical and psychosocial exposures were studied previously and published in a separate paper.) and health outcome measures [carpal tunnel syndrome (CTS), lateral and medial epicondylitis (LEPI/MEPI)].

METHODS

Using a pooled baseline cohort of 1834 subjects, the relationships were studied using logistic regression models.

RESULTS

Varied degrees of associations between the work organizational and outcomes variables were found. Job rotation was significantly associated with being a CTS case [odds ratio (OR) = 1.23, 95% confidence interval (95% CI): 1.00 to 1.50]. Overtime work was significantly associated with lower LEPI prevalence (OR = 0.48, 95% CI: 0.28 to 0.84). No statistically significant associations were found between having a second job and different work pacing and any of the three health outcome measures.

CONCLUSIONS

Work organizational variables were only partially associated with the studied health outcomes.