| 1. |
- Coenen, Pieter, et al.
(author)
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Calibration of self-reported physical behaviours among office workers: A compositional data analysis
- 2019
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In: ICAMPAM 2019. - Maastricht : ICAMPAM.
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Conference paper (peer-reviewed)abstract
- The aim of this study was to develop and evaluate calibration models to predict objectively measured time spent sitting, standing and walking during office work from self-reported time-use compositions using a compositional data analysis (CoDA) approach. Ninety-nine office workers (49 women) at the Swedish Transport Administration participated in an intervention study on relocation to activity-based offices. At baseline and at a 3-months follow-up, physical behaviours (sitting, standing and walking) at work were assessed for five days using a thigh-mounted accelerometer (Actigraph) and by self-report (IPAQ). The time-use composition of the three behaviours was expressed in terms of isometric log-ratios (ILR). Calibration models predicting accelerometry-based time-use from self-reported compositions were constructed using linear regression on baseline data, and then validated using follow-up data. The accelerometer data showed that, on average, workers spent 69.9% of their day sitting, 23.7% standing, and 6.4% walking. The corresponding percentages for self-reports were 71.7%, 21.6%, and 7.4%, respectively. Non-calibrated self-reports were biased: the RMS errors obtained from the ILRs expressing sitting, standing and walking were 0.73, 1.09 and 1.05, respectively. Calibration models reduced these errors by 45% (sitting), 56% (standing), and 76% (walking). Validation of the calibration models using follow-up data from the same workers showed calibration remained equally effective; RMS errors were reduced by 55% (sitting), 58% (standing), and 75% (walking). In conclusion, calibration models for compositional time-use data were effective in reducing bias in self-reported physical behaviours at work, and the models remained effective when used on new data from the same workers. Calibrated self-reports may represent a cost-effective method for obtaining physical behaviour data with a satisfying accuracy in large-scale cohort and intervention studies.
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| 2. |
- Dempsey, Patrick G., et al.
(author)
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Influence of three principles of pacing on the temporal organisation of work during cyclic assembly and disassembly tasks
- 2010
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In: Ergonomics. - : Informa UK Limited. - 0014-0139 .- 1366-5847. ; 53:11, s. 1347-1358
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Journal article (peer-reviewed)abstract
- A study was conducted to investigate the influence of different approaches to arranging the pace and temporal organisation of repetitive assembly and disassembly tasks on both average performance and its variability and to compare assembly and disassembly times derived with psychophysical methods to a more traditional methods-time measurement (MTM) approach. The conditions studied were a traditional assembly line arrangement, where assemblies were started at a pace of 110 MTM (repeated on two occasions), a batch condition, where subjects were required to complete 36 assemblies within the total amount of time allowed at 110, MTM and a psychophysical condition, where subjects were allowed to choose their pace (repeated on two occasions). Overall, the results suggest that the mean time spent working in each cycle (the 'on-time') remained fairly constant across conditions, while the idle 'off-time' in between on-times was shorter and of less varied duration in the more autonomous batch and psychophysical conditions. During the second psychophysical (self-paced) condition, subjects completed a significantly higher number of assemblies than during the 110 MTM line condition. The higher pace was achieved through reduction in mean off-times and the potential implications for musculoskeletal risk are discussed. Statement of Relevance: Higher levels of autonomy over work pace, which intuitively would be beneficial from an ergonomics standpoint, actually led to subjects selecting to organise work such that off-times (idle times) were reduced. In contrast, active 'on' times were not affected much by autonomy. These results point to a reason that piecework would be associated with increased risk for musculoskeletal disorders.
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| 3. |
- Dempsey, P G, et al.
(author)
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Influence on work pace conditions of temporal organization of work and rest
- 2006
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In: Meeting diversity in ergonomics.
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Conference paper (other academic/artistic)abstract
- A study was conducted to investigate the influence of different approaches to arranging the pace and temporal organization of repetitive assembly and disassembly tasks on variability in performance, and to compare assembly and disassembly times derived with psychophysical methods to more traditional Methods- Time Measurement (MTM) approaches. The conditions studied were a traditional assembly line arrangement where assemblies were started at a pace of 110 MTM, a batch condition where subjects were required to complete 36 assemblies in the amount of time based on 110 MTM, a line condition where subjects were required to take a break after every 6 assemblies requiring theffi to work at a 120 MTM pace, and a psychophysical condition where subjects were allowed to choose their pace.Overall, the results suggest that the mean times spent working remained fairly constant a cross conditions, with more variation in pauses in between cycles. For the second self-paced condition, subjects selected a significantly higher pace than 1 10 MTM, which was the basis for the other conditions. The higher pace was achieved through reduction in mean pauses, and the potential implications for musculoskeletal risk are discussed.
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| 4. |
- Hallman, David, 1979-, et al.
(author)
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Calibration of self-reported time spent sitting, standing and walking among office workers: a compositional data analysis
- 2019
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In: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1661-7827 .- 1660-4601. ; 16:17
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Journal article (peer-reviewed)abstract
- We developed and evaluated calibration models predicting objectively measured sitting, standing and walking time from self-reported data using a compositional data analysis (CoDA) approach. A total of 98 office workers (48 women) at the Swedish Transport Administration participated. At baseline and three-months follow-up, time spent sitting, standing and walking at work was assessed for five working days using a thigh-worn accelerometer (Actigraph), as well as by self-report (IPAQ). Individual compositions of time spent in the three behaviors were expressed by isometric log-ratios (ILR). Calibration models predicting objectively measured ILRs from self-reported ILRs were constructed using baseline data, and then validated using follow-up data. Un-calibrated self-reports were inaccurate; root-mean-square (RMS) errors of ILRs for sitting, standing and walking were 1.21, 1.24 and 1.03, respectively. Calibration reduced these errors to 36% (sitting), 40% (standing), and 24% (walking) of those prior to calibration. Calibration models remained effective for follow-up data, reducing RMS errors to 33% (sitting), 51% (standing), and 31% (walking). Thus, compositional calibration models were effective in reducing errors in self-reported physical behaviors during office work. Calibration of self-reports may present a cost-e_ective method for obtaining physical behavior data with satisfying accuracy in large-scale cohort and intervention studies.
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| 5. |
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| 6. |
- Jackson, Jennie A, et al.
(author)
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Identification of individual working styles in a long-cycle assembly task using kinematic and EMG variables
- 2016
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Conference paper (peer-reviewed)abstract
- Background.Increased motor variability while performing repetitive tasks has been suggested to decrease the risk of developing musculoskeletal disorders. However, support for this positive effect is lacking outside of short, simple, highly controlled tasks. It is also currently unknown whether or not existing motor variability metrics are viable for characterising occupational tasks. The purpose of this study was to assess motor variability during a long-cycle simulated occupational task. Using metrics previously validated for short-cycle tasks, this study aimed to determine the extent to which: (1) individuals dif-fered in motor variability with respect to kinematics and/or EMG activation; (2) individual motor variability was consistent across days; and (3) kinematics and EMG motor variability were correlated.Methods.Following a stringent, three-day training regime, 15 females proved sufficiently proficient to participate. On two occasions, participants performed 36 cycles of an assembly task (combining gross and fine motor skills) at 110 MTM pacing (51 s per cycle). For each cycle, multiple upper arm kinematic and trapezius EMG summary mean and SD variables were calculated; for each variable, the variability across the 36 cycles was assessed. The relative size of variability across individuals, and the consistency of each individual’s motor behaviour across days were assessed using kinematic and EMG vari-ables. The correlation between kinematic and EMG variables was also assessed.Results.Distinct individual behaviours were observed across days: some participants were clearly more consistent in their motor behaviour than others. Further, a high correlation was found between some kinematic and muscle activation variables.Discussion. Using previously validated upper arm assessment metrics, we were able to differentiate between individuals performing a long-cycle assembly task based on their degree of motor variability. Given the nature of our study task, we believe the metrics that we found to be successful at identifying individual behaviours could be used for assessing field tasks.
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| 7. |
- Jackson, Jennie A., et al.
(author)
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Is what you see what you get? : Standard inclinometry of set upper arm elevation angles
- 2015
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In: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 47, s. 242-252
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Journal article (peer-reviewed)abstract
- Previous research suggests inclinometers (INC) underestimate upper arm elevation. This study was designed to quantify possible bias in occupationally relevant postures, and test whether INC performance could be improved using calibration. Participants were meticulously positioned in set arm flexion and abduction angles between 0 degrees and 150 degrees. Different subject-specific and group-level regression models comprising linear and quadratic components describing the relationship between set and INC-registered elevation were developed using subsets of data, and validated using additional data. INC measured arm elevation showed a downward bias, particularly above 600. INC data adjusted using the regression models were superior to unadjusted data; a subject-specific, two-point calibration based on measurements at 0 and 900 gave results closest to the 'true' set angles. Thus, inclinometer measured arm elevation data required calibration to arrive at 'true' elevation angles. Calibration to a common measurement scale should be considered when comparing arm elevation data collected using different methods.
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| 8. |
- Jackson, Jennie A., et al.
(author)
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Observer performance in estimating upper arm elevation angles under ideal viewing conditions when assisted by posture matching software
- 2016
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In: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 55, s. 208-215
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Journal article (peer-reviewed)abstract
- Selecting a suitable body posture measurement method requires performance indices of candidate tools. Such data are lacking for observational assessments made at a high degree of resolution. The aim of this study was to determine the performance (bias and between- and within-observer variance) of novice observers estimating upper arm elevation postures assisted by posture matching software to the nearest degree from still images taken under ideal conditions. Estimates were minimally biased from true angles: the mean error across observers was less than 2. Variance between observers was minimal. Considerable variance within observers, however, underlined the risk of relying on single observations. Observers were more proficient at estimating 0 and 90 postures, and less proficient at 60. Thus, under ideal visual conditions observers, on average, proved proficient at high resolution posture estimates; further investigation is required to determine how non-optimal image conditions, as would be expected from occupational data, impact proficiency.
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| 9. |
- Jackson, Jennie, et al.
(author)
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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
- 2023
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In: BMJ Open. - : BMJ. - 2044-6055. ; 13:5
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Journal article (peer-reviewed)abstract
- Introduction: Job rotation is a work organization 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. 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: The study is pre‐registered with the Open Science Framework (https://osf.io/zmdc8/).
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| 10. |
- Jackson, Jennie
(author)
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Bias and Precision in Biomechanical Exposure Assessment : Making the Most of our Methods
- 2017
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Doctoral thesis (other academic/artistic)abstract
- Background: Insufficient exposure assessment is a suggested contributing factor to the current lack of clearly characterised relationships between occupational biomechanical risk factors and musculoskeletal disorders. Minimal attention has been paid to the potential bias of measurement tools from expected true values (i.e. accuracy) or between measurement tools, and empirical data on the magnitudes of variance contributed by methodological factors for measurement tool precision are lacking.Aim: The aim of this thesis was to quantify aspects of bias and precision in three commonly employed biomechanical risk factor assessment tools - inclinometry, observation, and electromyography (EMG) - and provide recommendations guiding their use. Methods: Upper arm elevation angles (UAEAs) were assessed using inclinometers (INC) and by computer-based posture-matching observation, and bias relative to true angles was calculated. Calibration models were developed for INC data, and their efficacy in correcting measurement bias was evaluated. The total variance of trapezius and erector spinae (ES) EMG recordings during cyclic occupational work was partitioned into biological and methodological sources, including the variance uniquely attributable to sub-maximal normalisation. Using algorithms to estimate the precision of a group mean, the efficacy of different trapezius EMG study designs was evaluated. Using precision criteria, the efficacy of different normalisation methods was assessed for ES EMG recordings.Results and Discussion: Inclinometer measured UAEAs were biased from true angles, with increasing bias at higher angles. In contrast, computer based posture-matching observations were not biased from true angles. Calibration models proved effective at minimizing INC data bias. The dispersion of estimates between- and within- observers at any given set angle underlined the importance of repeated observations when estimating UAEAs. For EMG, a unique but relatively small component of the total variance was attributable to the methodological process of normalisation. Performing three repeats of the trapezius EMG normalisation task proved optimal at minimizing variance for one-day EMG studies, while two repeats sufficed for multi-day EMG studies. A prone normalisation task proved superior for maximizing normalised lumbar ES EMG precision.Conclusion: Key aspects of measurement tool accuracy, bias between tools, and tool precision were quantified, and recommendations were made to guide future research study design.
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