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 work stations. 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

The aim of this study was to determine the extent of upper arm, neck and trunk posture variation that can be obtained by combining seated and standing computer work, compared to performing only seated computer work. Posture data were recorded for two hours during each of three days of ordinary work from 24 office workers that had been using a sit-stand station for two months. Periods with sitting and standing computer work were identified using on-site observations, and posture means and minute-to-minute variance were determined for both. Expected minute-to-minute posture variability in different temporal combinations of sitting and standing computer work were determined by simulation, and expressed in terms of a Job Variance Ratio, i.e. the relative increase in variability compared to sitting-only work. For all three postures, mean values differed between sitting and standing computer work, and both showed a notable minute-to-minute variability. For most workers, posture variability was larger when combining sitting and standing than when sitting only, and simulations suggested to introduce more standing than what the worker currently practiced. The results indicate that introducing a sit-stand table could, for most office workers, have a positive effect on upper arm, neck and trunk posture variability.

Activity-based workplaces (ABWs) are becoming popular in Western countries and were implemented at four office sites of a large Swedish government agency. A fifth office was used as a control group. The study aim was to examine the effects of relocation to ABW on perceived productivity among employees and to determine if perceived change-oriented leadership behavior prior to relocation moderates potential effects. Data were collected three months prior to relocation, and three and 12 months after. 407 respondents were included in linear mixed regression models. Perceived productivity decreased significantly after relocation compared to the control group and these effects persisted 12 months after the relocation. However, the decrease in perceived productivity was significantly smaller among employees perceiving high change-oriented leadership before relocation. Our results point out the importance of a change-oriented leadership behavior during the implementation to avoid productivity loss among employees when implementing ABWs.

This systematic review updates a previous systematic review on work-related physical and psychosocial risk factors for elbow disorders. Medline, Embase, Web of Science, Cochrane Central and PsycINFO were searched for studies on associations between work-related physical or psychosocial risk factors and the occurrence of elbow disorders. Two independent reviewers selected eligible studies and assessed risk of bias (RoB). Results of studies were synthesized narratively. We identified 17 new studies and lateral epicondylitis was the most studied disorder (13 studies). Five studies had a prospective cohort design, eight were cross-sectional and four were case-control. Only one study had no items rated as high RoB. Combined physical exposure indicators (e.g. physical exertion combined with elbow movement) were associated with the occurrence of lateral epicondylitis. No other consistent associations were observed for other physical and psychosocial exposures. These results prevent strong conclusions regarding associations between work-related exposures, and the occurrence of elbow disorders.

The aim was to investigate if the method of normalizing surface electromyography (sEMG) can change results on sex differences in the muscular activation of the shoulder girdle muscles during a simulated work task. sEMG was recorded in 36 asymptomatic participants (17 females, 19 males) from four parts of trapezius and from serratus anterior muscles during a simulated work task. Four normalization methods, one involving maximal voluntary contractions (MVCs) and three involving submaximal voluntary contractions were applied. Sex differences in absolute and normalized amplitude of sEMG were analyzed. The normalization method had a significant influence on the observed sex differences. Females only showed higher sEMG amplitude than males when the sEMGs were normalized to MVC and to a submaximal contraction based on 20% of MVC for the upper trapezius (acromial fibers). Researchers and practitioners should be aware of the impact of the sEMG normalization method in sex differences investigation.

The aim was to describe occupational physical activity (OPA) and examine the role of psychosocial job resources among blue-collar workers. In a sample of 198 workers (57% male; mean age 44.9 (SD 9.9) year) from 7 companies in Denmark, two accelerometers (Actigraph) were placed on the thigh and trunk during 1-5 consecutive days, to determine working time spent standing, walking, on feet and in activity of moderate to vigorous intensity level (MVPA). The level of influence and social support at work were assessed by questionnaire. The exposure to OPA significantly varied by particular job type, especially in male predominant occupations. Overall, psychosocial job resources did not affect the exposure to OPA. These findings suggest that workplace interventions aiming to prevent adverse outcomes of OPA among blue-collars workers ought to focus on task redesign and target work organizational factors related to specific job type.

The industrial revolution significantly changed the way work was organized and analyzed by the introduction and widespread implementation of the division of labor philosophy. This philosophy has continued to dominate work design, and has evolved beyond the factory to include many facets of service industries, and even professional occupations. The analysis of manual work, particularly materials handling tasks, remains an active domain of ergonomics research and practice. Many of the task-analytic tools used for workplace analysis are rooted in the philosophy of dividing work into elements, analyzing the individual elements, and synthesizing the results into conclusions about the entire job, including the risk of contracting musculoskeletal disorders (MSDs). The authors discuss the notion that the nature of modern work, which is characterized by multiple tasks in a complex time pattern, and the complex nature of MSDs, which are influenced by biomechanical as well as psychological, political, and economic factors, may limit the effectiveness of classical task analytic techniques in preventing MSDs.

In the present study, we assessed the wrist kinetics (range of motion, mean position, velocity and mean power frequency in radial/ulnar deviation, flexion/extension, and pronation/supination) associated with performing a mouse-operated computerized task involving painting rectangles on a computer screen. Furthermore, we evaluated the effects of the painting task on subjective perception of fatigue and wrist position sense. The results showed that the painting task required constrained wrist movements, and repetitive movements of about the same magnitude as those performed in mouse-operated design tasks. In addition, the painting task induced a perception of muscle fatigue in the upper extremity (Borg CR-scale: 3.5, p<0.001) and caused a reduction in the position sense accuracy of the wrist (error before: 4.6 degrees , error after: 5.6 degrees , p<0.05). This standardized painting task appears suitable for studying relevant risk factors, and therefore it offers a potential for investigating the pathophysiological mechanisms behind musculoskeletal disorders related to computer mouse use.

The aim of this study was to assess postures andmovements of the trunk and upper arm during paper mill work, and to determinethe extent to which they differ depending on method of assessment. For each oftwenty-eight paper mill workers, postures and movements were assessed duringthree full shifts using inclinometer registration and observation from video. Summary metrics for each shift, e.g.,10^th, 50^th, and 90^th posture percentile, were averagedacross shifts and across workers. In addition, the standard deviation between workers,and the standard deviation between shifts within worker were computed. The resultsshowed that trunk and arm postures during paper mill work were similar to otheroccupations involving manual materials handling, but the velocity of armmovements were lower. While postures determined by inclinometry and observationwere similar on a group level, substantial differences were found betweenresults obtained by the two methods for individual workers, particularly for extremepostures. Thus, measurements by either method on individuals or small groupsshould be interpreted with caution.

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 industrialized world 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 of 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.

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.

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° and 150°. 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 60°.  INC data adjusted using the regression models were superior to un-adjusted data; a subject-specific, two-point calibration based on measurements at 0° and 90° 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.

Research suggests an association between motor variability (MV) during repetitive work and work-related musculoskeletal disorders (MSDs). However, whether MV is a consistent individual trait, even across working conditions or tasks, remains unknown. This study assessed whether individual MV traits were consistent during complex work performed under different temporal conditions. Fifteen women performed cyclic assembly under four conditions differing in pace and organisation (line-type, batch-type). MV of trapezius muscle activity and upper arm elevation was quantified and partitioned into variance components. For all MV metrics, a non-zero between-subjects variance was found, indicating consistent individual MV traits across conditions. Variance between subjects was higher for electromyography (EMG) MV metrics compared with kinematic metrics. Our results showed individuals exhibited consistent MV traits across working conditions differing in pace and production process. Further research is needed to understand whether MV is an individual predictive factor for MSD onset or progression.

We evaluated differences in work environment conditions and health by gender and place of birth in a commercial laundromat prior to (baseline) and at the end of the first wave of the COVID-19 pandemic (follow-up). Using survey data, including dimensions from the Copenhagen Psychosocial Questionnaire, from forty-one workers, we assessed work environment conditions and health at baseline, follow-up and in change scores between baseline and follow-up. At baseline, men and women reported similar scores, while foreign-born (FB) workers reported better work environment conditions than Swedish-born (SB) workers. During the pandemic, conditions generally declined for all workers, but FB reported smaller declines than SB. A consistent inequality hierarchy across the 4 groups was not clear at baseline, follow-up or in change scores between time points. The study suggests potential cultural differences may exist in how work environment conditions are experienced. This should be considered in future studies and when managing future crises

The aim of this project was to develop a direct observation instrument to assess the work technique of nursing personnel during patient transfers and to test the validity and reliability of the instrument. An expert group developed this instrument, called DINO (Direct Nurse Observation instrument for assessment of work technique during patient transfers), which contains 16 items divided into three phases of a transfer: the preparation, performance and result phases. To quantify the assessments a scoring system was constructed, giving an overall score for each transfer, depending on the level of musculoskeletal health and safety. Four observers assessed 45 patient transfers at hospital wards and showed in an evaluation that the inter-observer reliability and criterion-related validity of DINO was satisfactory. The assessments with the DINO instrument are done directly when the transfer occurs, without costly equipment. Therefore, it has a wide range of applications. For example, when evaluating training in work technique or when identifying an unsafe work technique as a risk factor for musculoskeletal problems in epidemiological studies. (C) 2004 Elsevier Ltd. All rights reserved.

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.

This study aimed at determining the extent to which individuals with neck-shoulder pain and non-symptomatic individuals differ in muscle activation patterns, when performing computer work, as quantified by exposure variation analysis (EVA). As a secondary aim, we also aimed to quantify the day-to-day reliability of EVA variables describing trapezius muscle activation in a non-symptomatic control group. Thirteen touch-typing computer users (pain: n=5, non-symptomatic: n=8) completed three pre-selected computer tasks in the laboratory.

Upper trapezius muscle activity was recorded using electromyography and analyzed using EVA with five amplitude and five duration categories. Individuals with neck-shoulder pain spent less time at low amplitudes and exhibited longer uninterrupted periods of muscle activation compared to their non-symptomatic counterparts. Thus, non-symptomatic workers tended to switch between exposure levels more often than individuals with pain. For a majority of EVA variables, ICCs ranged from 0.6 to 0.9, and between-days coefficients of variation were between 0.4 and 2.2.

The study aim was to determine the effects of input device type, texting style, and screen size on upper extremity muscle activity and neck and wrist posture during a short texting task in college students. Users of a physical keypad produced greater thumb and wrist extensor muscle force than when texting with a touch screen; using a touch screen required greater wrist extension. Texting on either device produced greater finger flexor and wrist extensor muscle force and greater radial deviation when 1 hand/thumb was used, compared to both hands/thumbs. As touch screen size increased, more participants held the device on their lap, and there was a trend for greater muscle force in finger flexors, wrist extensors, and trapezius, and greater wrist extension, ulnar deviation, and cervical spine flexion. Future research can help inform whether the ergonomic stressors observed during texting are associated with the risk of musculoskeletal disorders.

Trends in global working life suggest that the occurrence of jobs characterized by long-lasting low-level loads or repetitive operations is increasing. More physical "variation" is commonly believed to be a remedy against musculoskeletal disorders in such jobs. One aim of the present paper was to shortly review the validity of this conviction. An examination of the available epidemiologic literature pointed out that the effectiveness of initiatives like job rotation or more breaks is weakly supported by empirical evidence, and only for short-term psychophysical outcomes. Only a limited number of studies have been devoted to physical variation, and concepts and metrics for variation in biomechanical exposure are not well developed. Thus, as a second objective, the paper proposes a framework for investigating and evaluating aspects of exposure variation, based on explicit definitions of variation as "the change in exposure across time" and diversity as "the extent that exposure entities differ". Operational methods for assessing these concepts are also discussed.

Assessment of workingpostures by observation is a common practice in ergonomics. The present studyinvestigated whether monetary resources invested in a video-based posture observationstudy should preferably be spent in collecting many video recordings of thework and have them observed once by one observer, or in having multipleobservers rate postures repeatedly from fewer videos. The study addressed thisquestion from a practitioner’s perspective by focusing two plausible scenarios:documenting the mean exposure of one individual, and of a specific occupationalgroup. Using a data set of observed working postures among hairdressers, empiricalvalues of posture variability, observer variability, and costs for recordingand observing one video were entered into equations expressing the total costof data collection and the information (defined as 1/SD) provided by theresulting estimates of two variables: percentage time with the arm elevated<15 degrees and >90 degrees. Sixteen measurement strategies involving 1-4observers repeating their posture ratings 1-4 times were examined for budgetsup to €2000.  For both posture variablesand in both the individual and group scenario, the most cost-efficient strategyat any specific budget was to engage 3-4 observers and/or having observer(s)rate postures multiple times each. Between 17% and 34% less information wasproduced when using the commonly practiced approach of having one observer ratea number of video recordings one time each. We therefore recommend observationalposture assessment to be based on video recordings of work, since this allowsfor multiple observations; and to allocate monetary resources to repeated observationsrather than many video recordings.

Ergonomics interventions often focus on reducing exposure in those parts of the job with the highest exposure levels, while leaving other parts unattended. A successful intervention will thus change the form of the job exposure distribution. This disqualifies standard methods for assessing the ability of various exposure measurement strategies to correctly detect the intervention effect on mean job exposure. This study used a non-parametric simulation procedure to evaluate the relationship between the number of measurements collected during a self-paced manufacturing job undergoing ergonomics interventions of varying effectiveness and the probability of correctly determining whether and to which extent the interventions reduced the overall occurrence of trunk flexion. Sixteen video-recordings taken at random times on multiple days for each of 3 workers were used to estimate the time distribution of each worker's exposure to trunk flexion of at least 20°. Nine ergonomics intervention scenarios were simulated in which the upper 1/8, 1/4, and 1/2 of the exposure distribution was reduced by 10%, 30% and 50%. Ten exposure measurement strategies were explored, collecting from 1 to 10 pre- and post-intervention exposure samples. For each worker, intervention scenario and sampling strategy, data were bootstrapped from the measured (pre-intervention) and simulated (post-intervention) exposure distributions to develop empirical data of the estimated intervention effect. Results showed that for the one to three most effective intervention scenarios, depending on worker, one to four pre- and post-intervention exposure samples were sufficient to reach an 80% probability of detecting that the intervention did, indeed, have an effect. However, even for these effective scenarios, seven or more samples were needed to obtain a probability larger than 50% of estimating the magnitude of the intervention effect to within ±50% of its true size. For less effective interventions, limited exposure sampling led to low probabilities of detecting any intervention effect, let alone its correct size.

The aim of this case study was to (1) investigate differences in mechanical exposure (i.e. mechanical forces arising in the body of the operator) between two production strategies: long-cycle parallelised flow assembly (OLD) and conventional serial flow assembly (NEW), and (2) estimate potential changes in job exposure as a consequence of waste reduction when rationalising a line system.

Data on postures, movements and whole body exposure were collected during an ordinary working shift, by means of video recordings synchronised to direct technical measurements of six professional operators.

The results revealed the machine paced NEW system to have slower movements with less time spent in movements of high velocity compared to the self-paced OLD system. No significant differences were found between time-median posture levels. ‘Disturbances’ in the NEW system offered lower mechanical risk exposures compared to direct assembly work. Modelling the removal of wasteful ‘disturbances’ revealed both an increase in risk-implying fast movements and decrease in recovery-implying periods at low velocity – effectively isolating a work intensification. This study helps expose the complex relationship between rationalizations and mechanical exposure for system operators

Objective. Sedentary behavior is an independent risk factor for obesity, diabetes, and all cause mortality. With adults in occupational settings spending two thirds or more of their time in sedentary behavior, novel strategies are required to intervene with occupational sitting. To investigate whether or not use of sit-stand desks and awareness of the importance of postural variation and breaks are associated with the pattern of sedentary behavior in office workers.

Method. The data came from a cross-sectional observation study of Swedish call centre workers. Inclinometers recorded ‘seated’ or ‘standing/walking’ episodes of 131 operators over a full work shift. Differences in sedentary behavior based on desk type and awareness of the importance of posture variation and breaks were assessed by non-parametric analyses.

Results. 90 (68.7%) operators worked at a sit-stand desk. Working at a sit-stand desk, as opposed to a sit desk, was associated with less time seated (78.5 vs 83.8%, p=0.010), and less time taken to accumulate 5 minutes of standing/walking (36.2 vs 46.3 minutes, p=0.022), but no significant difference to sitting episode length or the number of switches between sitting and standing/walking per hour. Ergonomics awareness was not associated with any sedentary pattern variable among those using a sit-stand desk.

Conclusion. Use of sit-stand desks was associated with better sedentary behavior in call centre workers, however ergonomics awareness did not enhance the effect. Further investigation into how best to intervene with occupational sitting is required.

We investigated the extent to which observers rate clearly visible postures on video differently from postures that are only partly visible, and whether this would have an effect on full-shift posture summaries. Trunk and upper arm postures were observed from 10,413 video frames representing 80 shifts of baggage handling; observers reported whether postures were fully or only partly visible.  Postures were summarized for each shift into several standard metrics using all available data, only fully visible frames, or only partly visible frames. 78% of trunk and 71% of upper arm postural observations were inferred.  When based on all data, mean and 90^th percentile trunk postures were 1.3° and 5.4° lower, respectively, than when based only on fully visible situations.  For the arm; differences in mean and 90^thpercentile were 2.5° and 8.1°.  Daily posture summaries can, thus, be significantly influenced by whether partly visible postures are included or not

Observers rank partly visible postures on video frames differently than fully visible postures, but it’s not clear if this is due to differences in observer perception. This study investigated the effect of posture visibility on between-observer variability in assessments of trunk and arm posture.  Trained observers assessed trunk and arm postures from video recordings of 84 pulp mill shifts using a work sampling approach; postures were also categorized as ‘fully’ or ‘partly’ visible.  Between-worker, between-day, and between-observer variance components and corresponding confidence intervals were calculated. Although no consistent gradient was seen for the right upper arm, trunk posture showed smaller between-observer variance when all observers rated a posture as fully visible. This suggests that, partly- visible data, especially when observers disagree as to the level of visibility, introduces more between-observer variability when compared to fully visible data.  Some previously-identified differences in daily posture summaries may be related to this phenomenon.

Four methods assessing the physical demands of manual lifting were compared. The scaffolding job was evaluated and three distinct scaffolding tasks were ranked using: (1) the revised NIOSH lifting equation (NIOSH method), (2) lifting guidelines for the Dutch construction industry (Arbouw method), (3) rapid appraisal of the NIOSH lifting equation (practitioners' method), and (4) systematic observations. For the three first-mentioned methods the same dataset was used; observation took place in a different setting in the same company. At job level, all methods indicated that ergonomic interventions are required to protect scaffolders from an increased risk for low back pain. The NIOSH, Arbouw and practitioners' method resulted in a similar ranking order of tasks (transport>construction>dismantlement). In contrast, the observational method gave transport the lowest ranking. The underlying cause was probably that the observational method is more sensitive to durations of tasks and lifting within tasks than the three other methods.

The objective of this study, based on an extensive dataset on manual materials handling during scaffolding, was to explore whether routinely collected company data can be used to estimate exposure to manual lifting.The number of manual lifts of scaffold parts while constructing/dismantling scaffolds was well predicted by the number of scaffolders in the team and the type of worksite, in combination with company data of either the number of scaffold parts or the scaffold volume. The proportion of explained variance in the number of lifts ranged from 77% to 92%, depending on the variables in the model. Data on scaffold parts and scaffold volume can easily be obtained from the company’s administration, since this is its usual paperwork supporting logistics and customer invoicing, respectively.We conclude that company data can be a promising source of information for ergonomic practitioners and researchers, to support assessment of manual lifting in scaffolding.

This review is an update of a previous systematic review and assesses the evidence for the association of work-related physical and psychosocial risk factors and specific disorders of the shoulders. Medline, Embase, Web of Science Core Collection, Cochrane Central and PsycINFO were searched and study eligibility and risk of bias assessment was performed by two independent reviewers. A total of 14 new articles were added with the majority focusing on rotator cuff syndrome (RCS) with seven studies. Nine articles reported psychosocial exposures in addition to physical exposures. The strongest evidence was found for the association between elevation, repetition, force and vibration and the occurrence of SIS and tendinosis/tendonitis. Evidence also suggests that psychosocial exposures are associated with the occurrence of RCS and tendinosis/tendonitis. Other findings were inconsistent which prevents drawing strong conclusions.

Objective: To assess uncertainty in cost estimates for collecting posture data by inclinometry, observations and self-report.

Method: In a study addressing physical workloads at a paper mill, costs were calculated for measuring postures of twenty-eight workers during three shifts. Uncertainty in costs was assessed for all three methods as the range between an assumed best case (lowest cost) and worst case (highest cost) using scenario analysis.

Results: The cost for observation was larger, but also more uncertain (€16506 and €89552 in the best and worst case, respectively) than that of inclinometry (€7613 - €45896). Self-report costs were both lower and less uncertain (€3743 - €23368).

Conclusions: The extent of uncertainty in cost estimates implies that observation could be less expensive than inclinometry, e.g., in a scenario where experienced observers could use existing software, while inclinometers would have to be purchased. We propose adding uncertainty assessments to cost estimates when selecting a method for measuring working postures, and offer guidance in how to proceed in a specific setting.

Time is a key issue for both ergonomists and engineers when they engage in production system interventions. While not their primary purpose, the actions of engineers have major effects on biomechanical exposure; possibly of much greater magnitude than many ergonomics interventions. This paper summarises the aims, actions and tools of engineers and ergonomists, emphasising time-related outcomes. Activities of the two groups when attempting to manipulate time aspects of work may be contradictory; engineers wishing to improve production and ergonomists aiming at better health as well as contributing to production. Consequently, tools developed by ergonomists for assessing time aspects of work describe rest patterns, movement velocities or daily duration of exposures, while engineering tools emphasise time-efficient production. The paper identifies measures that could be used to communicate time-relevant information between engineers and ergonomists. Further cooperation between these two stakeholders as well as research on the topic are needed to enable ergonomists to have a larger impact on the design of production systems.