| 1. |
- Arvidsson, Inger, et al.
(author)
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Changes in physical workload with implementation of mouse-based information technology in air traffic control
- 2006
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In: International Journal of Industrial Ergonomics. - : Elsevier BV. - 0169-8141 .- 1872-8219. ; 36:7, s. 613-622
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Journal article (peer-reviewed)abstract
- Effects on physical workload were quantified when introducing new information technology in air traffic control. Seven female and 7 male air traffic controllers were studied in an old control system, and during simulated-but similar-work in a new, mouse-based system. Postures, movements and muscular load were recorded (inclinometry for head, neck, back and upper arms; goniometry for wrists; elect romyography for the trapezius and forearm extensor muscles). The new system was associated with lower movement velocities than the old one (examples: [50th percentiles] head flexion: 2 vs. 5 degrees/s, P < 0.01; right arm elevation: 3 vs. 6 degrees/s; P < 0.01; [90th percentile] wrist flexion: 19 vs. 50 degrees/s, P < 0.01), less varying postures (head: 95th-5th percentile range 17 degrees vs. 34 degrees; P < 0.01), and less muscular rest in the right forearm extensors (3.5% vs. 9% of time; P < 0.05). The old/new system differences were amplified at high work intensities. The new air traffic control system caused a major change of physical exposures, probably associated with an increased risk of musculoskeletal disorders in arms and hands. Relevance to industry While this study concerned the specific changes in the introduction of a new air traffic control system, we believe that the findings are applicable to similar technological developments in other settings. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
- Arvidsson, Inger, et al.
(author)
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Neck postures in air traffic controllers with and without neck/shoulder disorders.
- 2008
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In: Applied Ergonomics. - : Elsevier BV. - 1872-9126 .- 0003-6870. ; 39:2, s. 255-260
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Journal article (peer-reviewed)abstract
- Prolonged computer work with an extended neck is commonly believed to be associated with an increased risk of neck–shoulder disorders. The aim of this study was to compare neck postures during computer work between female cases with neck–shoulder disorders, and healthy referents. Based on physical examinations, 13 cases and 11 referents were selected among 70 female air traffic controllers with the same computer-based work tasks and identical workstations. Postures and movements were measured by inclinometers, placed on the forehead and upper back (C7/Th1) during authentic air traffic control. A recently developed method was applied to assess flexion/extension in the neck, calculated as the difference between head and upper back flexion/extension. Results: cases and referents did not differ significantly in neck posture (median neck flexion/extension: −10° vs. −9°; p=0.9). Hence, the belief that neck extension posture is associated with neck–shoulder disorders in computer work is not supported by the present data.
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| 3. |
- Hansson, Gert-Åke, et al.
(author)
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Precision of measurements of physical workload during standardised manual handling. Part II: Inclinometry of head, upper back, neck and upper arms
- 2006
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In: Journal of Electromyography & Kinesiology. - : Elsevier BV. - 1050-6411 .- 1873-5711. ; 16:2, s. 125-136
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Journal article (peer-reviewed)abstract
- For measuring the physical exposure/workload in studies of work-related musculoskeletal disorders, direct measurements are valuable. However, the between-days and between-subjects variability, as well as the precision of the method per se, are not well known. In a laboratory, six women performed three standardised assembly tasks, all of them repeated on three different days. Triaxial inclinometers were applied to the head, upper back and upper arms. Between-days (within subjects) and between-subjects (within tasks) variance components were derived for the 10th, 50th and 90th percentiles of the angular and the angular velocity distributions, and for the proportion of time spent in predefined angular sectors. For percentiles of the angular distributions, the average between-days variability was 3.4 degrees , and the between-subjects variability 4.0 degrees . For proportion of time spent in angular sectors, the variability depended on the percentage of time spent in the sector; the relative variability was scattered and large, on average 103% between days and 56% between subjects. For the angular velocity percentiles, the average between-days variability was 7.9%, and the average between-subjects variability was 22%. The contribution of the measurement procedure per se to the between-days variability, i.e., the imprecision of the method, was small: less than 2 degrees for angles and 3% for angular velocity.
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| 4. |
- Holtermann, Andreas, et al.
(author)
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A practical guidance for assessments of sedentary behavior at work: A PEROSH initiative
- 2017
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In: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 63, s. 41-52
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Journal article (peer-reviewed)abstract
- Sedentary behavior is defined as sitting or lying with low energy expenditure. Humans in industrialized societies spend an increasing amount of time in sedentary behaviors every day. This has been associated with detrimental health outcomes. Despite a growing interest in the health effects of sedentary behavior at work, associations remain unclear, plausibly due to poor and diverse methods for assessing sedentary behavior. Thus, good practice guidance for researchers and practitioners on how to assess occupational sedentary behavior are needed. The aim of this paper is to provide a practical guidance for practitioners and researchers on how to assess occupational sedentary behavior. Ambulatory systems for use in field applications (wearables) are a promising approach for sedentary behavior assessment. Many different small-size consumer wearables, with long battery life and high data storage capacity are commercially available today. However, no stand-alone commercial system is able to assess sedentary behavior in accordance with its definition. The present paper offers decision support for practitioners and researchers in selecting wearables and data collection strategies for their purpose of study on sedentary behavior. Valid and reliable assessment of occupational sedentary behavior is currently not easy. Several aspects need to be considered in the decision process on how to assess sedentary behavior. There is a need for development of a cheap and easily useable wearable for assessment of occupational sedentary behavior by researchers and practitioners
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| 5. |
- Kazmierczak, Karolina, et al.
(author)
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An integrated analysis of ergonomics and time consumption in Swedish 'craft-type' car disassembly.
- 2005
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In: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 36:3, s. 263-73
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Journal article (peer-reviewed)abstract
- Car disassembly is at the edge of extensive rationalisations due to increased legislative demands for recycling. This study focused on (1) assessing current mechanical exposures (physical work loads) for comparison with future rationalised systems, with particular emphasis on time aspects, (2) analysing disassembly work in terms of time consumption and exposures in constituent tasks as defined by a loss analysis technique, and (3) predicting the consequences of car disassembly rationalisation for mechanical exposures. The study showed that disassembly implied pronounced circulatory loads, and that more walking and higher lumbar peak loads were found than in studies of assembly work. Value-adding tasks comprised 30% of the total working time, and implied higher postural exposures for the head, arm, trunk and wrist, as well as less opportunities to recover, as compared to non-value-adding tasks. Organisational-type rationalisations can be expected to increase the time spent in value-adding work, thus increasing local exposures for the average worker, while a concurrent increase in mechanisation level might reduce circulatory exposures, the amount of walking, and peak lumbar loads.
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| 6. |
- Kazmierczak, Karolina, et al.
(author)
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Observer reliability of industrial activity analysis based on video recordings
- 2006
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In: International Journal of Industrial Ergonomics. - : Elsevier BV. - 0169-8141 .- 1872-8219. ; 36:3, s. 275-282
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Journal article (peer-reviewed)abstract
- The aim of this study was to assess the agreement between observers analyzing activity patterns during truck engine assembly work based on video recordings. Two observers observed the recordings of nine workers, on the average 2.2 h long, assigning activities to four activity categories. For each activity category data were obtained on the mean duration of uninterrupted sequences of activities and their relative time proportion in the job. This data was analyzed with 2-way crossed ANOVA algorithms to derive the components of variance attributed to disagreement between observers, to differences between filmed subjects, and to residual "unexplained" variance. The latter was interpreted as an estimate of within-observer variability and possible interactions between subject and observer. While the observers disagreed about the overall time proportions for the four activity categories by no more than 3.7% of time, their second-to-second classification disagreed for 13% of the total analysis time. The between-observer variance was small as compared to within-observer variance and the variance between Subjects performing the same job. Simulations based oil the variance components showed that a group mean of the proportion of direct work could be determined with a standard deviation within 5% of the mean by having two observers analyzing one 2-h video recording once, each. Relevance to industry The results of this study may support decision making when designing a reliable video-based analysis of industrial work. Thus, the study helps production engineers, ergonomics practitioners and researchers allocate resources between data collection and data analysis, based on their preferences for precision and power of a particular study. (c) 2006 Elsevier B.V. All rights reserved.
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| 7. |
- Mathiassen, Svend Erik, et al.
(author)
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Optimizing cost-efficiency in mean exposure assessment – cost functions reconsidered
- 2011
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In: BMC Medical Research Methodology. - : Springer Science and Business Media LLC. - 1471-2288. ; 11:76
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Journal article (peer-reviewed)abstract
- Background. Reliable exposure data is a vital concern in medical epidemiology and intervention studies. The present study addresses the needs of the medical researcher to spend monetary resources devoted to exposure assessment with an optimal cost-efficiency, i.e. obtain the best possible statistical performance at a specified budget. A few previous studies have suggested mathematical optimization procedures based on very simple cost models; this study extends the methodology to cover even non-linear cost scenarios. Methods. Statistical performance, i.e. efficiency, was assessed in terms of the precision of an exposure mean value, as determined in a hierarchical, nested measurement model with three stages. Total costs were assessed using a corresponding three-stage cost model, allowing costs at each stage to vary non-linearly with the number of measurements, according to a power function. Using these models, procedures for identifying the optimally cost-efficient allocation of measurements under a constrained budget were developed, and applied on 225 scenarios combining different sizes of unit costs, cost function exponents, and exposure variance components. Results. Explicit mathematical rules for identifying optimal allocation could be developed when cost functions were linear, while non-linear cost functions implied that parts of or the entire optimization procedure had to be carried out using numerical methods. For many of the 225 scenarios, the optimal strategy consisted in measuring on one occasion from each of as many subjects as allowed by the budget. Significant deviations from this principle occurred if costs for recruiting subjects were large compared to costs for setting up measurement occasions, and, at the same time, the between-subjects to within-subject variance ratio was small. In these cases, non-linearities had a profound influence on the optimal allocation and on the eventual size of the exposure data set. Conclusions. The analysis procedures developed in the present study can be used for informed design of exposure assessment strategies, provided that data are available on exposure variability and the costs of collecting and processing data. The present shortage of empirical evidence on costs and appropriate cost functions however impedes general conclusions on optimal exposure measurement strategies in different epidemiologic scenarios.
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| 8. |
- Mathiassen, Svend Erik, et al.
(author)
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Task-based estimation of mechanical job exposure in occupational groups
- 2005
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In: Scandinavian Journal of Work, Environment and Health. - 0355-3140 .- 1795-990X. ; 31:2, s. 138-51
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Journal article (peer-reviewed)abstract
- OBJECTIVES: This study examined the validity of a common belief in epidemiology with respect to work-related musculoskeletal disorders, that individual mechanical job exposure is better estimated from tasks performed in the job than from the mean exposure of the occupational group. METHODS: Whole-day recordings of upper trapezius electromyography were obtained from 24 cleaners and 23 office workers. Trapezius activity was analyzed in the level (gap time) and frequency (jerk time) dimensions. On the same day, the job of each person was divided into periods of active work and breaks by means of continuous observations. The bootstrap re-sampling technique was used with this database to compare task-based job exposure estimates with estimates based on the occupational mean. For a particular person, the task-based estimate was obtained by combining the average work and break exposures in the occupation with the personal time proportions of the two tasks in the job. RESULTS: The task-based estimates were, in general, equivalent to, or less correct than, occupation-based estimates for both exposure parameters in both occupations and for individual exposures, as well as for group means. This was the result in spite of significant and consistent exposure differences between work and breaks, in particular among the cleaners. CONCLUSIONS: Even if task exposure contrasts are large, task-based estimates of job exposures can be less correct than estimates based on the occupational mean. Since collecting and processing task information is costly, it is recommended that task-based modeling of mechanical exposure be implemented in studies only after careful examination of its possible benefits.
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| 9. |
- Neumann, W. P., et al.
(author)
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Production system design elements influencing productivity and ergonomics - A case study of parallel and serial flow strategies
- 2006
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In: International Journal of Operations & Production Management. - : Emerald. - 0144-3577 .- 1758-6593. ; 26:8, s. 904-923
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Journal article (peer-reviewed)abstract
- Purpose - The purpose of this paper is to investigate a strategic change from parallel cell-based assembly (old) to serial-line assembly (new) in a Swedish company with special reference to how production system design elements affect both productivity and ergonomics. Design/methodology/approach - Multiple methods, including records and video analysis, questionnaires, interviews, biomechanical modelling, and flow simulation were applied. Findings - The new system, unlike the old, showed the emergence of system and balance losses as well as vulnerability to disturbances and difficulty handling all product variants. Nevertheless, the new system as realised partially overcame productivity barriers in the operation and management of the old system. The new system had impaired ergonomics due to decreased physical variation and increased repetitiveness with cycle times that were 6 per cent of previous thus increasing repetitiveness, and significantly reducing perceived influence over work. Workstations' uneven exposure to physical tasks such as nut running created a potential problem for workload management. The adoption of teamwork in the new system contributed to significantly increased co-worker support - an ergonomic benefit. Practical implications - Design decisions made early in the development process affect both ergonomics and productivity in the resulting system. While the time pattern of physical loading appeared to be controlled by flow and work organisation elements, the amplitude of loading was determined more by workstation layout. Psychosocial conditions appear to be affected by a combination of system elements including layout, flow, and work organisation elements. Strategic use of parallelisation elements in assembly, perhaps in hybrid forms from configurations observed here, appears to be a viable design option for improved performance by reducing the fragility and ergonomic problems of assembly lines. Originality/value - The interacting design elements examined here pose potential "levers" of control by which productivity and ergonomics could be jointly optimised for improved total system performance.
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| 10. |
- Svendsen, Susanne Wulff, et al.
(author)
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Work above shoulder level and degenerative alterations of the rotator cuff tendons : a magnetic resonance imaging study.
- 2004
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In: Arthritis and rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 50:10, s. 3314-22
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To determine whether work performed with the arms in a highly elevated position is associated with alterations in the rotator cuff tendons as assessed by magnetic resonance imaging (MRI). METHODS: A cross-sectional study was performed in a historical cohort of male machinists, car mechanics, and house painters. The participants were right-handed, ages 40-50 years, and had been employed in their trades for not less than 10 years. Seventy-one percent of invited subjects participated (136 of 192). Lifetime upper arm elevation was assessed by direct measurements combined with individual work histories obtained by questionnaire and from registry data. Supraspinatus tendinopathy was evidenced by MRI signal intensity changes and morphologic alterations. Infraspinatus and subscapularis tendinopathy were also assessed. Additional outcomes were acromioclavicular joint degeneration and humeral head cysts. The MRI findings were evaluated by radiologists who were blinded to exposure status and symptoms. RESULTS: An exposure-response relationship was found between lifetime upper arm elevation and supraspinatus tendinopathy, with an age-adjusted odds ratio of 1.27 (95% confidence interval 1.02-1.60) for a 5-month increase in the total number of full-time working months spent with the arm elevated >90 degrees . CONCLUSION: Work with the arms in a highly elevated position is associated with MRI-diagnosed alterations in the supraspinatus tendon. By demonstrating the first part of a possible biologic pathway, the study corroborates the work-relatedness of rotator cuff disorders.
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