The influence of task design on upper limb muscles fatigue during low-load repetitive work: A systematic review

Ergonomic interventions such as increased scheduled breaks or job rotation have been proposed to reduce upper limb muscle fatigue in repetitive low-load work. This review was performed to summarize and analyze the studies investigating the effect of job rotation and work-rest schemes, as well as, work pace, cycle time and duty cycle, on upper limb muscle fatigue. The effects of these work organization factors on subjective fatigue or discomfort were also analyzed. This review was based on relevant articles published in PubMed, Scopus and Web of Science. The studies included in this review were performed in humans and assessed muscle fatigue in upper limbs. 14 articles were included in the systematic review. Few studies were performed in a real work environment and the most common methods used to assess muscle fatigue were surface electromyography (EMG). No consistent results were found related to the effects of job rotation on muscle activity and subjective measurements of fatigue. Rest breaks had some positive effects, particularly in perceived discomfort. The increase in work pace reveals a higher muscular load in specific muscles. The duration of experiments and characteristics of participants appear to be the factors that most have influenced the results. Future research should be focused on the improvement of the experimental protocols and instrumentation, in order to the outcomes represent adequately the actual working conditions.Relevance to industryIntroducing more physical workload variation in low-load repetitive work is considered an effective ergonomic intervention against muscle fatigue and musculoskeletal disorders in industry. Results will be useful to identify the need of future research, which will eventually lead to the adoption of best industrial work practices according to the workers capabilities.     

Low back strain in Danish semi-skilled construction work

Danish semi-skilled construction workers (SC-workers) perform a variety of tasks in building construction, civil engineering and rebuilding. A previous epidemiologic study indicated a high occurrence of low back pain (LBP) among these workers. The study was designed to quantify the major occupational risk factors associated with the development of LBP, i e, inclined postures, repetitive movements, heavy lifts, pushing/pulling motions, sudden unexpected strains and whole body vibrations in this group of construction workers. Firstly a study of occupational activity of 112 SC-workers on height construction sites during two separate five-days periods was carried out. This was followed by an observational study of the nine work tasks most common to SC-workers. Heavy lifts, pushing/pulling motions and sudden unexpected strain occurred most frequently in the work, while inclined postures, repetitive movements and whole body vibrations characterised different parts of the work. Assessments of the strain were made on the basis of techniques given in the literature.     

‘Best’ for whom?: the tension between ‘best practice’ ERP packages and diverse epistemic cultures in a university context

The idea that so-called ‘best’ business practices can be transferred to organizations when they purchase enterprise resource planning (ERP) software packages is a major selling point of these packages. Yet recent research has illustrated a gap between the espoused theory of a best practice solution and the theory-in-use experienced by those who install software with such a design. As researchers begin to examine the difficult process by which organizations recast the best practices model handed down to them by consultancies and software vendors in an effort to make the software ‘work for them’ in practice, it is equally important that we begin to understand the reasons that such a gap exists. To this end, we analyze the strategic partnership between a multinational software vendor and a university who together designed a ‘best practice’ ERP package for the higher education industry. Through the theoretical lens of ‘epistemic cultures’ we argue that in organizational contexts made up of more than one epistemic culture, the use of a best practice model will be problematic because, by definition, the model mandates one epistemological position through the software design. This is counter to a university's loosely coupled organizational form.     

The work load of warehouse workers in three different working systems

An investigation was conducted in five companies in the distribution branch. These companies were divided into three different working systems, i.e., highly mechanized (HM), moderately mechanized (MM), and slightly mechanized (SM). The three systems differed in logistics and kind of appliances used. The purpose of this study was to compare the three working systems with different degrees of mechanization concerning the time spent on tasks, activities during the working day, postures that occurred, physiological work load, perceived exertion and recovery from work. To investigate the different tasks, activities and working postures, 50 warehouse workers, originating from the three working systems, were observed by means of a direct observation method, called: ‘TRAC’. To investigate the physiological work load the heart rate was recorded continuously during the working day and related to the individually determined relation between heart rate and oxygen uptake. This relation was constructed with the results of a cycle ergometer test done in the laboratory. During lunch and at the end of the working day the warehouse workers filled in a questionnaire concerning their perceived exertion and recovery from work.

In the slightly mechanized system more time was spent with the trunk flexed more than 75° as compared with the other two systems. This posture was very common during lifting of objects, and lifting was done more often in this system than in the other systems. In the MM system the warehouse workers had the highest estimated oxygen uptake and reported the highest perceived exertion at the end of the working day. The workers in the HM system had a shorter working day and had less problems with recovery from work than the workers of the other two systems. Poor working postures like rotation and lateroflexion were commonly found in the HM working system. An important explanation was the difference in time spent driving an electric car. This activity was done mostly in the HM system. In conclusion, the HM system was considered most favourable when it concerned work load and recovery from work. The appliances used in the HM system, and especially the electric car, need to be designed according to ergonomic guidelines to avoid poor working postures.     

Standing, sitting and associated working conditions in the Quebec population in 1998

Working posture is an important determinant of musculoskeletal and vascular health. Knowledge of the context and type of postures is necessary in order to examine their associations with health-related outcomes. This study describes self-reported usual working postures in a population and their associations with other working conditions and demographic variables. The 1998 Quebec Health and Social Survey is a population-based survey of 11,986 private households in the province of Quebec. It contained a self-administered questionnaire, including an extensive occupational health section. The analyses in this study were limited to respondents with paid employment who had at least 6 months seniority in their current job, comprising 9,425 subjects. The overall prevalence of usual work in a standing posture is 58%; it is more common among men, workers under 25 years, those in the two lowest educational quintiles and those with incomes under 20,000 Canadian dollars. Only one person in six who works standing reports being able to sit at will. Women and men differ in the types of usual standing and sitting postures at work. Those who work standing and/or who work in more constrained postures are more likely to be exposed to other physical work demands, such as handling heavy loads, repetitive work, forceful exertion and low job decision latitude. The association between decision latitude and constrained postures is an important link between psychosocial and physical stressors in the workplace. In epidemiological studies, exposure covariation and interactions should be considered in the generation and interpretation of the associations between work postures and musculoskeletal disorders.     

Assessing the ‘insider–outsider threat’ duality in the context of the development of public–private partnerships delivering ‘choice’ in healthcare services: A sociomaterial critique

Containing the ‘outsider’ threat to the information systems of organisations as well as recognising the disruptive potential of ‘insiders’ are fundamentals of security management. However, the recent development of public–private partnerships in the UK requires a reassessment of the continuing utility of such dualities. This paper draws upon a sociological understanding of the complexities of organisational practices as well as a grounded case study of the implementation of the NHS ‘Choose and book’ service across both public and private healthcare organisations in order to challenge these essentialist forms of sociotechnical analysis. The paper proposes a sociomaterial understanding of information systems and organisational dynamics that does not seek to separate out distinct ‘human’ and ‘technical’ information security risks. Rather, it asserts that the organisational outcomes of the introduction of new information systems are necessarily emergent and contingent, and it is with these indeterminate realities that security analysts have to engage.     

Continuous exposure to noisy work environments does affect preferred leisure noise levels

Although noise research concentrates principally on the workplace, recent studies have shown that preferred leisure noise may be as loud as 10 dBA higher than workplace levels. This two-phase study compared leisure noise preferences for workers who were exposed to either a ‘loud’ (≥ 85 dBA) or ‘not loud’ (< 85 dBA) work environment. Phase 1 examined 110 subjects' noise level preferences that were recorded before and after work for a one-day observation. Phase 2 recorded 12 additional subjects' preferences for five consecutive days. Analysis of both phases' results determined that leisure noise levels prior to work were not significantly different. Those exposed to the ‘loud’ environment preferred noise levels significantly higher (6.5 to 9 dBA) than their before work levels. Over the five consecutive days (Phase 2) only the ‘loud’ group preferred noise levels significantly higher after work (Day 5 versus Day 1). Thus, it can be concluded that ‘loud’ work environments and consecutive daily exposure to these environments do influence preferred leisure noise levels.     

The performance of hand postures in front- and back-of-device interaction for mobile computing

Three studies of different mobile-device hand postures are presented. The first study measures the performance of postures in Fitts’ law tasks using one and two hands, thumbs and index fingers, horizontal and vertical movements, and front- and back-of-device interaction. Results indicate that the index finger performs well on both the front and the back of the device, and that thumb performance on the front of the device is generally worse. Fitts’ law models are created and serve as a basis for comparisons. The second study examines the orientation of shapes on the front and back of a mobile device. It shows that participants’ expectations of visual feedback for finger movements on the back of a device reverse the direction of their finger movements to favor a “transparent device” orientation. The third study examines letter-like gestures made on the front and back of a device. It confirms the performance of the index finger on the front of the device, while showing limitations in the ability for the index finger on the back to perform complex gestures. Taken together, these results provide an empirical foundation upon which new mobile interaction designs can be based. A set of design implications and recommendations are given based directly on the findings presented.     

Designing for operations: Towards a sociotechnical systems and cognitive engineering approach to concurrent engineering

In the practice of concurrent engineering, the factors that are considered early in the product design process include manufacturability, assembly, and cost. A set of issues that are not typically considered revolve around the operational requirements for human workers in the manufacturing system. What tasks will human workers accomplish? How will these tasks be organized and coordinated? What information and resources need to be shared? Will the workers have a coherent set of job responsibilities? How should the manufacturing environment be designed to support effective work practices? How can a manufacturing process be designed that also informs organizational structure and takes into account the quality of working life?

The field of sociotechnical systems theory (STS) focuses on exactly these kinds of issues. Rather than subscribing to the usual view of technological determinism — that a complex human-machine system is designed solely with respect to optimization of technical criteria — the goal of STS is to jointly optimize both human and technological considerations in system design and operation. The spirit of STS has much in common with recent work in cognitive systems engineering that advocates the design of joint cognitive systems in which machines serve as flexible, context-sensitive resources for human problem solving. Furthermore, a focus on design teams necessitates the study of the relationship between group work and technology as studied in the field of computer-supported cooperative work (CSCW). This paper briefly reviews current research in sociotechnical systems theory, computer-supported cooperative work, and cognitive systems engineering and proposes a framework for integrating operational concerns into the concurrent engineering process. Relevance to industry

To be competitive, organizations need to effectively manage human and technological resources. A key issue is the nature of the information and technological infrastructure that both enables and supports ‘best practice’ across the enterprise. This paper describes such an approach in the context of the ‘operational enterprise’ and provides both a philosophical stance as well as specific examples of software support.     

Using ergonomic digital human modeling in evaluation of workplace design and prevention of work‐related musculoskeletal disorders aboard small fishing vessels

This article seeks to present methods for preventing work‐related musculoskeletal disorders of Spanish fishermen and for redesigning the workplace aboard small fishing vessels. To achieve its objective, the research project was designed in four steps. First, the equipment and procedures for catching, handling, and storing fish were studied. Second, the work postures of all the fishermen were simulated and assessed by using an ergonomic digital human modeling system (ManneQuin Pro). Third, the work environment design aboard vessels was modified on the basis of acceptable simulated work postures to prevent repetitive movements, awkward working postures, and lower back biomechanical stresses. In the fourth step, ergonomic design parameters were provided to vessel designers. © 2011 Wiley Periodicals, Inc.     

A work measurement method for application in Indian agriculture

The usual scales of rating in work measurement practices are based on subjective assessment of effort and walking speed of workers. In the present paper an attempt was made to correlate walking speed and stride length with selected anthropometric and physiological measurements (heart rates), using three groups of farm workers. Linear simple and multiple regressions were obtained to identify the best possible correlation between the above parameters. Accordingly, a rating scale was developed and applied in ploughing, transplanting, reaping and sheafing operation in rice cultivation.

The result showed that the preferred speed of walking of the farm workers was 1.39 m/s and step frequency at that speed was 103 steps/min. On application of the suggested scale on the abovee four agricultural operations, it was observed that the majority of the workers' working loads and efforts were more than they should be.     

Information technology (IT) in Saudi Arabia: Culture and the acceptance and use of IT

The unified theory of acceptance and use of technology (UTAUT), a model of the user acceptance of IT, synthesizes elements from several prevailing user acceptance models. It has been credited with explaining a larger proportion of the variance of ‘intention to use’ and ‘usage behavior’ than do preceding models. However, it has not been validated in non-Western cultures. Using a survey sample collected from 722 knowledge workers using desktop computer applications on a voluntary basis in Saudi Arabia, we examined the relative power of a modified version of UTAUT in determining ‘intention to use’ and ‘usage behavior’. We found that the model explained 39.1% of intention to use variance, and 42.1% of usage variance. In addition, drawing on the theory of cultural dimensions, we hypothesized and tested the similarities and differences between the North American and Saudi validations of UTAUT in terms of cultural differences that affected the organizational acceptance of IT in the two societies.     

Estimation of model quality

This paper provides an introduction to recent work on the problem of quantifying errors in the estimation of models for dynamic systems. This is a very large field. We therefore concentrate on approaches that have been motivated by the need for reliable models for control system design. This will involve a discussion of efforts that go under the titles of ‘estimation in ’, ‘worst-case estimation’, ‘estimation in ℓ₁’ and ‘stochastic embedding of undermodelling’. A central theme of this survey is to examine these new methods with reference to the classic bias/variance tradeoff in model structure selection.     

Modernization of a laundry processing plant: is it really an improvement?

An ergonomics assessment was conducted in a modern, automated hospital-based laundry to investigate workers' complaints of musculoskeletal aches and pains and general fatigue. Numerous job stressors were identified requiring ergonomic solutions, including prolonged standing, excessive manual handling of transport units, non-adjustability of workstations, work pacing, awkward postures, lack of job rotation and excessive repetition of tasks. Associated health and safety issues such as noise, sharps, equipment maintenance and sanitation were also addressed. Potential mechanisms for repetitive strain injuries were substantiated and solutions for problematic areas were presented to management and the union for implementation. It was concluded that human factors must be taken into consideration when designing automated laundry systems to avoid mismatches resulting in potential injury to workers.     

Validity of self-reported duration of work postures obtained by interview

The aim of the study was to validate interview data concerning the duration of four work postures (1) sitting, (2) standing/walking with hands above shoulder level, (3) standing/walking with hands between shoulder and knuckle level, and (4) standing/walking with hands below knuckle level. The self-reported time spent in each posture was tested in relation to observations and technical measurements in 20 subjects during two full working days. The linear relationships between self-reports and observations were strong for the three postures; sitting (r²=0.55), hands above shoulder level (r²=0.58) and hands below knuckle level (r²=0.69). Thus, using this interview technique, self-reports concerning time spent in (1) sitting, (2) standing/walking with hands above shoulder level and, (3) standing/walking with hands below knuckle level may be accurate enough for studying these work postures in epidemiological studies.     

Long-duration assessment of upper arm posture and motion and their association with perceived symptoms among bakery workers

Awkward shoulder postures have been suggested to be a cause of shoulder discomfort among bakery workers. This study aimed at long-duration assessment of upper arms posture and motion and their association with perceived symptoms among bakery workers. Among workers in three types of bread systems, fifty-seven bakers were randomly selected. The self-reported rates for the perceived severity and frequency of shoulder discomfort were collected through questionnaires. Working postures and movements of the shoulders during work were continuously recorded with inclinometry measurements for three hours. Percentage of time spent with the upper arm right elevated more than 60° was significantly correlated with the perceived discomfort rate in the right shoulder for all bakery workers (r = 0.48 to 0.63, p ≤ 0.05). A significant correlation was found between angular velocity with the perceived discomfort intensity for right upper arm.(r = 0.60 to 0.87, ≤0.005) of all workers in the three baking systems. Physical exposure in bakers was characterized by significantly more awkward postures and the percentage of time spent with the upper arms elevated more than 60°. The current findings can facilitate more informed decisions with respect to both engineering (e.g.ergonomic workstation and tool design) and administration (e.g. work organization) control strategies.     

EPS: An ‘elementary’ programming system for the Delft Parallel Processor

A programming system for synchronous parallel processors, like the DPP-84 working in synchronous mode, is proposed. In EPS a program consists of a collection of well-defined and separate units, described in a conventional procedure-oriented language like PASCAL or MODULA-2. The connection between the ‘elementary’ program units is laid in a supervisory ‘configuration’ program, which defines both the spatial and time relations between the units. The concept of ‘virtual’ parallel processing is introduced, which enables the construction of logical parallel programs, independent of the number of processing elements actually available.     

Doing ‘organizational work’: Expanding the conception of professional practice in ergonomics

Literature on ergonomic practice contains many discussions of how ergonomists should work but far less attention has been paid to how they do work and the factors that influence their practice. In an effort to improve our understanding of ergonomic practice as it occurs and how it is conditioned by broader contexts, we conducted an interview study with 21 ergonomists in Canada. We were particularly interested to understand the different kinds of activities study participants engaged in during the course of their work, the challenges they faced and the strategies they employed for facing these challenges. Findings indicate that in the course of their professional practice ergonomists engage in a variety of types of activities. This includes consulting on risk factors as well as a proactive role of fostering the application of ergonomics in organizations. The process of advocating for ergonomics brought study participants into a variety of interactions and collaborations with workplace parties in a type of activity we have called “organizational work”. In the course of doing organizational work, ergonomists utilize different strategies, including “political manoeuvring”, tailoring data collection and report presentations to clients’ concerns and ‘goal hooking’ in order to make the case for implementing ergonomics in workplaces. The article concludes with a list of “tips” for practicing ergonomists that are suggested by the analysis.     

Physiological cost of apple-farming activities

Seventeen agricultural male workers, aged between 21 and 56 years, were investigated in the field during six different job-activities of apple-farming: pruning, weeding, hand and mechanical spraying, mowing and picking. Pulmonary ventilation and oxygen consumption were recorded for short periods by Oxylog, while heart rate was monitored for more than 24 hours by Holter's method. The farmers also rated the work intensity according to Borg's RPE scale.

Pulmonary ventilation ranged on average between 13 and 30 1/min and oxygen consumption between 500 and 1300 ml/min, with a relative aerobic cost between 15 and 40%, in the different work activities. Heart rate varied on average between 80 and 94 beats/min with a relative cardiac cost between 20 and 30%. The physiological criteria (oxygen uptake and cardiac response) and the subjective rating of fatigue gave a substantially similar evaluation of the work strain, ‘moderate-heavy’ for mowing, weeding and picking, ‘moderate’ for pruning and hand spraying, ‘light’ for mechanical spraying of pesticides. On the whole, apple-farming can be evaluated as ‘moderate’ intensity, thanks to the mechanisation implemented in reducing the work-load and the work-time of many job activities.     

Automated High Throughput Screening of Fluorescent Imaging Plate Reader (FLIPR) Assays Using Assay Platform™ Integrated with Activity Base for ‘on the fly’ Compound Reconfirmation

Advances in the field of automation have meant hitherto complex manual cell-based assays can now be automated. These improvements have brought significant enhancements in throughput, data fidelity and consistency, and allowed a reallocation of constrained resources.Building upon these improvements, we have linked our automated cell-based screening system, Assay Platform™, to Activity Base (IDBS), a software package designed to automate the analysis of HTS data. Customisation of this package has resulted in software that can identify ‘active’ compounds and re-pick them ‘on the fly’ from the original compound plates for triplicate re-testing without operator intervention.Based on an operator initially defining ‘normal’ parameters for assay activity in Activity Base, combined with an automated quality control software module that checks data fidelity, wells containing ‘active’ compounds can be re-picked and re-tested at the end of an automated screening run. Automating cell-based assays has significantly improved productivity, and, with the synergism of Activity Base, has given us greater power to complete each screening run and report ‘active’ compounds to Chemistry more rapidly. This article presents our approach to the automation of cell-based Fluorescent Imaging Plate Reader (FLIPR) screening together with automated active re-test confirmation using Activity Base.