The aim of the study was to evaluate the effects of individually prescribed physical exercise programmes on development of fatigue during the carrying of a loaded stretcher up and down the stairs. Nineteen ambulance personnel performed the training for 1 year. Testing occurred before and after 1 year of the training. Both the training group (n = 19) and the control group (n = 15) were assessed for physical capacity and lactate concentration in blood and ratings of perceived exertion during carrying a stretcher on the stairs. When comparisons were made between those who had been training three times/week for 1 year and the control group, lactate concentration was significantly decreased. In conclusion, markers of fatigue during stretcher carrying can be reduced by the use of individually prescribed physical exercise programmes.

The aim of the study was to evaluate the effects of individually prescribed physical exercise programmes on development of fatigue during the carrying of a loaded stretcher up and down the stairs. Nineteen ambulance personnel performed the training for 1 year. Testing occurred before and after 1 year of the training. Both the training group (n = 19) and the control group (n = 15) were assessed for physical capacity and lactate concentration in blood and ratings of perceived exertion during carrying a stretcher on the stairs. When comparisons were made between those who had been training three times/week for 1 year and the control group, lactate concentration was significantly decreased. In conclusion, markers of fatigue during stretcher carrying can be reduced by the use of individually prescribed physical exercise programmes.

Discomfort in the use of personal protective devices (PPD) has been one of the chief causes of their non-use. A field trial using industrial helmets was carried out to ascertain whether by training and repeated wearing subjects could experience a significant adaptation to discomfort. Ten subjects took part in the trial in a tropical environment by wearing helmets repeatedly (6 h a day) for one month. Subjective evaluations of discomfort were made at the end of the 1st, 3rd, 5th, 14th and 30th day. It was revealed that complaints of discomfort, viz. hotness, heaviness, bad fit, etc., decreased markedly throughout the 30 day period. Though positive responses of adaptation to discomfort seem to reach an optimum towards 30 days, it is difficult to draw any conclusions on the optimum period of adaptation for each discomfort factor. In relation to inherent discomforts that are extremely difficult to overcome without compromising the protection efficiency of a PPD, the principle of adaptation seems to be a very important facet which has to be developed for an effective PPD programme.

Hotness, weight, fitting problems etc., have been found to be the chief causes of the unpopularity of industrial safety helmets in tropical environments in developing countries (DC). Some selected safety helmets manufactured in industrialized countries (IC) were modified to provide extra head ventilation and to reduce weight, in order to make them more acceptable to users in hot environments. The modified helmets were subjected to ergonomics evaluation both objectively and subjectively in the laboratory (in simulated tropical conditions) as well as in the field situation. There was evidence that white helmets had some advantages in comfort, viz. reduction of hotness, compared to the other colours, e.g. red, green etc., when worn in the presence of radiant heat in the laboratory. Ventilation holes provided at the top of the shell seemed to reduce the greenhouse effect within the helmet shell which therefore felt less uncomfortable than a fully covered helmet. Even with a small reduction of weight, such as 45 g in helmets weighing about 350g, the difference in weight was perceived by the wearers. In adapting helmets made in IC for use in tropical climates, head ventilation and low weight perception are important aspects in comfort which need to be considered. In addition to low cost, a harness material suitable for sweat absorption is required. Adjustability and sizing to fit 90% of the user population also needs to be considered in the design and manufacture of safety helmets for people in DC.

The objective of this study was to assess the relationships between physical and psychosocial work exposures, engagement in domestic work and work-home imbalance in relation to symptoms of musculoskeletal disorders and emotional exhaustion in white- and blue-collar men and women. Three thousand employees from 21 companies were asked to answer a questionnaire on family structure, household and child care tasks, work exposure, work-home imbalance and symptoms of neck/shoulder disorders, low back disorders and emotional exhaustion. Women reported more musculoskeletal disorders and engagement in domestic work. Adverse at-work exposures were highest in blue-collar women. High engagement in domestic work was not separately associated with symptoms but paid work exposure factors were associated. High engagement in domestic work interacted with adverse work exposure and increased risk estimates for low back disorders and emotional exhaustion. Reported work-home imbalance was associated with neck/shoulder disorders in women and with emotional exhaustion in both women and men.

Practitioner Summary. The current article adds to earlier research by showing that high engagement in domestic work is not separately associated with increased symptoms, but interacts with psychosocial work exposure variables to produce emotional exhaustion in both women and men and low back disorders in women.

Underworking (i.e. shirking) and overworking of employees can have detrimental effects for the individual and the organisation. We develop a computational model to investigate how work structure, specifically the way in which managers distribute work tasks amongst employees, impacts work intensity and working time. The model draws on theories from economics, psychology and management, and on empirical observations. The simulations show that when managers correctly estimate task difficulty, but undervalue the employee's competence, opportunities for shirking are provided due to longer deadlines. Similarly, if managers overvalue the employee's competence, they set tighter deadlines leading to overwork. If task difficulty is misjudged, initially only influence on employee working time is observed. However, it gradually generates competence misjudgements, indirectly impacting the employee's effort level. An interaction between competence misjudgement and task uncertainty slows the manager's ability to correctly estimate employee competence and prolongs initial competence misjudgements. The study highlights the importance of applying dynamic modelling methods, which allows for testing theory assumptions in silico, generating new hypotheses and offers a foundation for future research. Practitioner summary: A computational model was developed to investigate how the structure of work allocation influences opportunities for shirking and overworking by employees. The paper demonstrates how dynamic modelling can be used to explain workplace phenomena and develop new hypotheses for further research.

The loading moment of force on the hip, knee, and ankle joints of nine healthy men rising from four different types of stools were compared, together with the levels of myoelectrical activity (EMG) in four leg muscles. Two types of stool (stand stools) had higher seats than a normal chair. The other two were of ordinary seat height, but one also had armrests. The bodyweight carried by the different stools when sitting was also measured, and the subject estimated the effort required for each trial. The mean maximum knee moment was over 60% lower when rising from the high stool than from 'ordinary' seat height. The difference between the high and low stand stool was also significant (p less than 0.001). Using the high stool or help of the arms reduced the mean maximum hip moment by about 50%. The mean maximum ankle moment was only marginally influenced by the different stools. Knee moment was influenced more by seat height than was hip moment. Vastus lateralis activity was significantly higher when subjects rose from 'ordinary' height than when rising from either stand stool (p less than 0.001). The rectus femoris muscle was little activated and the semitendinosus muscle was activated earlier when rising from higher seat heights. All subjects estimated the effort of rising from the higher stand stool to be lower than from the lower stand stool or from 'ordinary' height without arm rests. It was concluded that stand stools are good alternatives for workers who change frequently between sitting and standing work.

his paper is a follow-up of a field study of two military command teams and reports an experiment that tests three organizations (serial, parallel and optional) of co-operation and situation awareness within commander teams, as well as the communication between the commander team and the operative level. It was found that most groups in the optional condition performed worse than the groups in the other conditions. It was also found that members of teams in the parallel condition differed from members of teams in the serial condition in their situation awareness. The more successful commander team produced more planning in relation to hypothesis, as well as sending fewer messages in total between the units, than the less successful team.

Described is the cooperative work of constructing team situation awareness within two teams of a military command and control unit. Specifically discussed is how the distributed cognitive and cooperative work of decision-making of the two teams is structured. The situation enabled two different ways of distributing information within the team: one serial and one parallel. One team chose the parallel information transfer, the other the serial one. Discussed is the interaction patterns that emerge in the respective teams and their consequences for situation assessment and situation awareness. The differences are then discussed in terms of means of sharing information. Some hypotheses for future research are also offered.

Activity-based Flexible Offices (A-FOs) are offices with unassigned desks that provide a variety of workspaces. This paper presents desk-sharing and speech rules identified in A-FOs in four Swedish organisations, the emergence of and compliance with these rules, and their consequences for work conditions. Data collection involved 105 semi-structured interviews, document analyses, and observations. The identified rules were: (1) to remove belongings, (2) temporal restrictions on using the same workstations, (3) temporal restrictions on using scarce zones, (4) restrictions on verbal interactions, and (5) restrictions on phone conversations. The cases with extensive user involvement in their planning process had explicit unambiguous rules. A better compliance with rules occurred when (i) the employees were well-prepared and had a unified understanding regarding how and why to follow the rules, (ii) the rules were explicitly communicated and were regarded as easy to follow, and (iii) following the rules facilitated work and improved work conditions.

The effect on muscle activity variation of combining different office tasks is not known. We recorded electromyography from the upper trapezius (UT), wrist extensor (WE) and lumbar erector spinae (LES) in 24 office workers during five productive tasks, and breaks. Minute-to-minute variance was then estimated, by simulations, in a reference ‘job’ consisting of 85% sitting computer work and 15% breaks, and in ‘jobs’ where sitting computer work was replaced by different proportions of the other office tasks and breaks. Replacing sitting computer work with sitting non-computer work increased estimated variance by, in median, 23% (UT), 19% (WE) and 0% (LES). Replacing it by other tasks, in particular standing computer work and non-desk work, was less effective in increasing variance. Thus, some combinations of office tasks have a slight potential to increase muscle activity variation in the shoulder and lower arm, but not the lumbar back, while others will be ineffective.

Postures and muscle activity in the upper body were recorded from 50 academics office workers during 2 hours of normal work, categorised by observation into computer work (CW) and three non-computer (NC) tasks (NC seated work, NC standing/walking work and breaks). NC tasks differed significantly in exposures from CW, with standing/walking NC tasks representing the largest contrasts for most of the exposure variables. For the majority of workers, exposure variability was larger in their present job than in CW alone, as measured by the job variability ratio (JVR), i.e. the ratio between min–min variabilities in the job and in CW. Calculations of JVRs for simulated jobs containing different proportions of CW showed that variability could, indeed, be increased by redistributing available tasks, but that substantial increases could only be achieved by introducing more vigorous tasks in the job, in casu illustrated by cleaning.

The aims of this study were (1) to identify which physical performance tests could best explain the development of fatigue during a simulated ambulance work task, (2) to investigate the effect of height and weight and (3) to investigate in what respects these findings differ between female and male ambulance personnel. Forty-eight male and 17 female ambulance personnel completed a test battery assessing cardio-respiratory capacity, muscular strength and endurance, and co-ordination. The subjects also completed a simulated ambulance work task -- carrying a loaded stretcher. The work task was evaluated by development of fatigue. Univariate and multiple regression analyses were used to investigate to what extent the tests in the test battery were able to explain the variance of developed fatigue. The explained variance was higher for female than for male ambulance personnel (time > 70% of HRpeak: R2 = 0.75 vs 0.10, accumulated lactate: R2 = 0.62 vs 0.42, perceived exertion: R2 = 0.75 vs 0.10). Significant predictors in the models were VO2max, isometric back endurance, one-leg rising, isokinetic knee flexion and shoulder extension strength. Height, but not weight, could further explain the variance. The high physical strain during carrying the loaded stretcher implies the importance of investigating whether improved performance, matching the occupational demands, could decrease the development of fatigue during strenuous tasks.

The aims of this study were (1) to identify which physical performance tests could best explain the development of fatigue during a simulated ambulance work task, (2) to investigate the effect of height and weight and (3) to investigate in what respects these findings differ between female and male ambulance personnel. Forty-eight male and 17 female ambulance personnel completed a test battery assessing cardio-respiratory capacity, muscular strength and endurance, and co-ordination. The subjects also completed a simulated ambulance work task -- carrying a loaded stretcher. The work task was evaluated by development of fatigue. Univariate and multiple regression analyses were used to investigate to what extent the tests in the test battery were able to explain the variance of developed fatigue. The explained variance was higher for female than for male ambulance personnel (time > 70% of HRpeak: R2 = 0.75 vs 0.10, accumulated lactate: R2 = 0.62 vs 0.42, perceived exertion: R2 = 0.75 vs 0.10). Significant predictors in the models were VO2max, isometric back endurance, one-leg rising, isokinetic knee flexion and shoulder extension strength. Height, but not weight, could further explain the variance. The high physical strain during carrying the loaded stretcher implies the importance of investigating whether improved performance, matching the occupational demands, could decrease the development of fatigue during strenuous tasks.

Pictorial visualization is expected to facilitate communication between industrial professionals when planning working environments and production systems. This hypothesis was investigated by studying how 24 participants including managers, supervisors, machine operators, and occupational health and safety officials, judged three types of computer animated visualization varying in dimensional view (scale and scope of a production line): shop floor view/survey of shop floor; production unit view/semi-survey of production unit; and workplace view/close-up of workplace, in relation to a set of planning issues. The participants participated in a controlled 2-day planning workshop, redesigning a fictitious manufacturing process by means of computer graphics, and then responded to a questionnaire. It can be concluded that shop floor view as well as production unit view are significant for survey planning issues, while all 3-dimensional views are significant for close-up planning issues. Analogously, all dimensional views are significant for technocentric planning issues, whereas only the workplace view is valuable for anthropocentric planning issues.

It is assumed that pictorial visualization can be used to facilitate communication between industrial professionals when planning working environments and production. This article analyses how managers, supervisors, machine operators, and occupational health and safety officials, accustomed to using both paper drawings and computer animation of both shop floor and workplace view, evaluate these four types of visualization in relation to a set of planning issues. Twenty-four subjects participated in a controlled two-day planning workshop. They designed a new production layout by means of computer graphics, and responded to a questionnaire. From the analysis it may be concluded that the four types of visualization are unique enough to be evaluated differently with regard to some of the planning issues. Hence, great care should be devoted to analysing what features a visualization of a production layout or a working environment aims at illustrating. Furthermore, it can be concluded that each of the four types of visualization seems to be significant for planning activities in ways that can be anticipated. Shop floor view and workplace view is valuable for planning issues related to survey of a plant and specific machines, respectively. Computer animation is in general preferable to a paper drawing concerning dynamic planning issues. Computer animation of workplace viewis valuable for planning issues related to working environment considerations. All of the four types of visualization are less significant for illustrating or describing physical factors of the working environmen

The effect of office type on sickness absence among office employees was studied prospectively in 1852 employees working in (1) cell-offices; (2) shared-room offices; (3) small, (4) medium-sized and (5) large open-plan offices; (6) flex-offices and (7) combi-offices. Sick leaves were self-reported two years later as number of (a) short and (b) long (medically certified) sick leave spells as well as (c) total number of sick leave days. Multivariate logistic regression analysis was used, with adjustment for background factors. A significant excess risk for sickness absence was found only in terms of short sick leave spells in the three open-plan offices. In the gender separate analysis, this remained for women, whereas men had a significantly increased risk in flex-offices. For long sick leave spells, a significantly higher risk was found among women in large open-plan offices and for total number of sick days among men in flex-offices. Practitioner Summary: A prospective study of the office environment's effect on employees is motivated by the high rates of sick leaves in the workforce. The results indicate differences between office types, depending on the number of people sharing workspace and the opportunity to exert personal control as influenced by the features that define the office types.

This study investigated temporal changes in movement strategy and performance during fatiguing short-cycle work. Eighteen participants performed six 7-minutes work blocks with repetitive reaching movements at 0.5 Hz, each followed by a 5.5-minute rest break for a total duration of one hour. Electromyography (EMG) was collected continuously from the upper trapezius muscle, the temporal movement strategy and timing errors were obtained on a cycle-to-cycle basis, and perceived fatigue was rated before and after each work block. Clear signs of fatigue according to subjective ratings and EMG manifestations developed within each work block, as well as during the entire hour. For most participants, timing errors gradually increased, as did the waiting time at the near target. Changes in temporal movement strategy were negatively correlated with changes in the level and variability of EMG, suggesting that an adaptive temporal strategy offset the development of unstable motor solutions in this fatiguing, short-cycle work

This study investigated the effect of work pace on workload, motor variability and fatigue during light assembly work. Upper extremity kinematics and electromyography (EMG) were obtained on a cycle-to-cycle basis for eight participants during two conditions, corresponding to "normal" and "high" work pace according to a predetermined time system for engineering. Indicators of fatigue, pain sensitivity and performance were recorded before, during and after the task. The level and variability of muscle activity did not differ according to work pace, and manifestations of muscle fatigue or changed pain sensitivity were not observed. In the high work pace, however, participants moved more efficiently, they showed more variability in wrist speed and acceleration, but they also made more errors. These results suggest that an increased work pace, within the range addressed here, will not have any substantial adverse effects on acute motor performance and fatigue in light, cyclic assembly work. STATEMENT OF RELEVANCE: In the manufacturing industry, work pace is a key issue in production system design and hence of interest to ergonomists as well as engineers. In this laboratory study, increasing the work pace did not show adverse effects in terms of biomechanical exposures and muscle fatigue, but it did lead to more errors. For the industrial engineer, this observation suggests that an increase in work pace might diminish production quality, even without any noticeable fatigue being experienced by the operators.

This paper analyses information and communication technology (ICT) and its relation to work organizations, human communication, stress, allocation issues, knowledge transfer and global villages. An interdisciplinary research programme on 'Computer technology and work life' was initiated and led by the author at Stockholm University in 1974, followed by many programmes in Sweden in the held. A theoretical framework was developed including two theoretical models, one more general, the other where the concepts and their interrelationships were specified. The models were tested empirically in three large work organizations in Sweden, representing three main historical periods of computer technology. It was also used as a model in discussing what might be desirable goats in the information society. The present fourth period, the 'Network period', is characterized by a convergence of three main technologies: computer, telecommunication and media. TCT is used in almost every activity and is embedded in many things. The author proposes a superimposed theoretical model reflecting 'ICT and the psychosocial life environment', a revised model of her initial models. Finally, future research is discussed with reference to theoretical models revised, and conclusions address major psychosocial processes, psychosocial life environments and a call for synthesis.

A possible basis for the risk assessment for hand-transmitted vibration may be to determine the amount of energy absorbed in the human hand and arm. In the present study, the mechanical energy absorption in the hand-arm system was measured within the frequency range of 4 to 1000 Hz. The study was carried out on ten healthy subjects during exposure to sinusoidal vibration. The influence of various experimental conditions, such as vibration direction (Xh, Yh, Zh), grip force (25-75 N), vibration level (8-45 mm/srms), and hand-arm posture were studied. The outcome shows that the energy absorption in the human hand and arm depended mainly on the frequency and direction of the vibration stimulus. Higher vibration levels, as well as firmer handgrips, resulted in higher absorption of energy. Varying hand-arm postures had only a small influence on the amount of absorbed energy, while the constitution of the hand and arm affected the energy absorption to a larger extent.

This paper seeks to address questions related to friction measurement such as how friction is related to human-centred assessment and actual slipping, and how repeatable friction measurements are. Commonly used devices for slipperiness measurement are surveyed and their characteristics compared with suggested test conditions from biomechanical observations summarized in Part 1. The issues of device validity, repeatability, reproducibility and usability are examined from the published literature. Friction assessment using the mechanical measurement devices described appears generally valid and reliable. However, the validity of most devices could be improved by bringing them within the range of human slipping conditions observed in biomechanical studies. Future studies should clearly describe the performance limitations of any device and its results and should consider whether the device conditions reflect these actual human slipping conditions. There is also a need for validation studies of more devices by walking experiments.

Friction has been widely used as a measure of slipperiness. However, controversies around friction measurements remain. The purposes of this paper are to summarize understanding about friction measurement related to slipperiness assessment of shoe and floor interface and to define test conditions based on biomechanical observations. In addition, friction mechanisms at shoe and floor interface on dry, liquid and solid contaminated, and on icy surfaces are discussed. It is concluded that static friction measurement, by the traditional use of a drag-type device, is only suitable for dry and clean surfaces, and dynamic and transition friction methods are needed to properly estimate the potential risk on contaminated surfaces. Furthermore, at least some of the conditions at the shoe/floor interface during actual slip accidents should be replicated as test conditions for friction measurements, such as sliding speed, contact pressure and normal force build-up rate.

Background: Musculoskeletal disorders have been associated with computer use among office workers and lack of variation caused by too little exposure diversity between work tasks has been proposed as an important etiological factor. However there is little information on the diversity of occupations and information and communication technologies (ICT) used by office workers and none which extends beyond the traditional workday. Whilst direct observation is expected to provide the most accurate data, it is resource intensive and self report and sampling alternatives may be a viable alternative.

Method: This paper describes direct observation and self-report data on the occupations and ICT use of 24 Australian office workers in their natural environments at work and away-from-work, over 12 hours of a working day.

Results: Participants were observed for a mean [SD] for 642[40] minutes, 67% of which was at the workplace. Productive occupations (405[122] minutes) accounted for 63% of the observation period, compared to 17% for instrumental (106[57] minutes), 12% for self-care (75[46] minutes) and 8% for leisure occupations (54[39] minutes). Non ICT tasks occurred during 44% of the observation period (285[89] minutes); New ICT accounted for 36 % (234[118] minutes), Old ICT accounted for 15% (98[73] minutes), and Combined ICT tasks 4% (24[30] minutes). The proportions of occupations and ICT use differed between work and away-from-work. Computer-based New ICT was most used for work tasks. Observed and self-reported time on occupations and ICT were similar, though with some differences. Self-reported time on occupations and ICT was similar for the first day and the subsequent 4 days.

Conclusion: The first detailed description of occupations and ICT used by office workers at work and away-from-work shows that the variety of Old, New, Combined and Non-ICT used for performing typical work and non-work tasks offered a diversity of exposures for the workers. This information provides an important step for further investigations into exposure variation in this group, and possible musculoskeletal health risks.

Office workers perform tasks using different information and communication technologies (ICT) involving various postures. Adequate variation in postures and muscle activity is generally believed to protect against musculoskeletal complaints, but insufficient information exists regarding the effect on postural variation of using different ICT. Thus, this study among office workers aimed to determine and compare postures and postural variation associated with using distinct types of ICT. Upper arm, head and trunk postures of 24 office workers were measured with the Physiometer® over a whole day in their natural work and away-from-work environments. Postural variation was quantified using two indices; APDF_(90-10) and EVA_(sd).Various ICT had different postural means and variation. Paper-based tasks had more non-neutral, yet also more variable postures. Electronics-based tasks had more neutral postures, with less postural variability. Tasks simultaneously using paper- and electronics-based ICT had least neutral and least variable postures. Tasks without ICT usually had the most posture variability. Interspersing tasks involving different ICT could increase overall exposure variation among office workers and may thus contribute to musculoskeletal risk reduction.

The study evaluated the efficiency of two heat dissipation strategies under simulated desert patrol missions. Ten men participated in four trials, during which they walked on a treadmill (45°C, 20% relative humidity), carrying a load of 35 kg; two 50-min walks were separated by a 20-min rest. Cooling strategies, provided by an ambient air-ventilated vest (active cooling condition, AC), or water spraying of the skin during the rest (passive cooling condition, PC), in addition to reduced clothing and open zippers, were compared to conditions with full protective (FP) clothing and naked condition (NC). Skin temperature was higher during NC (37.9 ± 0.4°C; p < 0.001), and rectal temperature and heart rate were higher during FP (38.6 ± 0.4°C, p < 0.001 and 145 ± 12, p < 0.001, respectively), compared to other conditions. Four subjects terminated the trial prematurely due to signs of heat exhaustion in FP. Both cooling strategies substantially improved evaporative cooling.

A series of standardized tasks, isometric trunk flexion and extension and maximal Valsalva manoeuvres, were used to evaluate the role of the abdominal musculature in developing an increased intra-abdominal pressure (IAP). Seven male subjects were measured for IAP, myoelectric activity of rectus abdominis (RA), obliquus externus and internus (OE and OI respectively), erector spinae (ES) and isometric trunk torque. IAPs in all experimental conditions were markedly greater than those that occurred while relaxed. In isometric trunk flexion, IAPs were increased with accompanying high levels of activity from the abdominal muscles. In contrast, little activity from the abdominal muscles occurred during isometric trunk extension, although levels of IAP were similar to those found in the isometric flexion condition. With maximal voluntary pressurization (Valsalva manoeuvre) slightly higher levels of IAP than those found in torque conditions were recorded, this pressure being produced with abdominal activities (OE and OI) less than one fourth their recorded maximum. When isometric torque tasks were added to the Valsalva manoeuvre, patterns of muscle activity (RA, OE, OI and ES) were significantly altered. For Valsalva with isometric trunk extension, activity from OE and OI was reduced while IAPs remained fairly constant. These findings indicate that in tasks where an IAP extension moment is warranted, abdominal pressure can be increased without the development of a large counter-moment produced by the dual action of the trunk flexors. Activation of other muscles such as the diaphragm and transversus abdominis is suggested as helping provide control over the level of IAP during controlled trunk tasks.

One of the challenges with working from home (WFH) is the question of its effect on health and well-being. The impact of home working on health has so far not been studied extensively. We address this gap by investigating the association between internal recovery, operationalised as rest break frequency (low, medium, and high) during the working day, on self-reported musculoskeletal pain, and post-work recovery symptoms in WFH knowledge workers (n = 382). The analysis showed that failing to take frequent breaks was associated with a dose-response increased risk of reporting headaches. For post-work recovery symptoms, failing to take rest breaks throughout the day was associated with an increased risk of reporting psychological fatigue, physical fatigue, and sleep problems, and a decreased risk of psychologically detaching from work and experiencing adequate rest. Our findings emphasise the importance of remote workers taking recovery breaks from work demands in the maintenance of health and well-being.

Ergonomics design is about the creation of future work. So how can ergonomics research support and inform design if its findings are cast in a language oriented towards current work derived from field observations or laboratory settings? In this paper we assess instances of three different strands (experimental, ethnomethodological, and surveys) of ergonomics research on paper flight strips in air traffic control, for how they analytically confront future work and how they make the findings relevant or credible with respect to future work. How these justifications come about, or how valid (or well argued for) they are, is rarely considered in the ergonomics literature. All three strands appear to rely on rhetoric and argument as well as method and analysis, to justify findings in terms of their future applicability. Closing the gap between research results and future work is an important aim of the ergonomic enterprise. Better understanding of the processes necessary to bridge this gap may be critical for progress in ergonomics research and for the use of its findings in actual design processes. © 2004 Taylor & Francis Ltd.

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.

There are likely to be individual differences in bus driver behaviour when adhering to strict schedules under time pressure. A reliable and valid assessment of these individual differences would be useful for bus companies keen to mitigate risk of crash involvement. This paper reports on three studies to develop and validate a self-report measure of bus driver behaviour. For study 1, two principal components analyses of a pilot questionnaire revealed six components describing bus driver behaviour and four bus driver coping components. In study 2, test-retest reliability of the components were tested in a sub-sample and found to be adequate. Further, the 10 components were used to predict bus crash involvement at three levels of culpability with consistently significant associations found for two components. For study 3, avoidance coping was consistently associated with celeration variables in a bus simulator, especially for a time-pressured drive. Statement of Relevance: The instrument can be used by bus companies for driver stress and fatigue management training to identify at-risk bus driver behaviour. Training to reduce the tendency to engage in avoidance coping strategies, improve evaluative coping strategies and hazard monitoring when under stress may improve bus driver safety.

The study examined the effects of manual control locations on two groups of randomly selected young and old drivers in relation to visual time off road, steering wheel deviation and safety perception. Measures of visual time off road, steering wheel deviations and safety perception were performed with young and old drivers during real traffic. The results showed an effect of both driver's age and button location on the dependent variables. Older drivers spent longer visual time off road when pushing the buttons and had larger steering wheel deviations. Moreover, the greater the eccentricity between the normal line of sight and the button locations, the longer the visual time off road and the larger the steering wheel deviations. No interaction effect between button location and age was found with regard to visual time off road. Button location had an effect on perceived safety: the further away from the normal line of sight the lower the rating. © 2006 Taylor & Francis.

The study examined the effects of manual control locations on two groups of randomly selected young and old drivers in relation to visual time off road, steering wheel deviation and safety perception. Measures of visual time off road, steering wheel deviations and safety perception were performed with young and old drivers during real traffic. The results showed an effect of both driver's age and button location on the dependent variables. Older drivers spent longer visual time off road when pushing the buttons and had larger steering wheel deviations. Moreover, the greater the eccentricity between the normal line of sight and the button locations, the longer the visual time off road and the larger the steering wheel deviations. No interaction effect between button location and age was found with regard to visual time off road. Button location had an effect on perceived safety: the further away from the normal line of sight the lower the rating.

Although buttons are a frequently used type of control in car interiors, little research has been undertaken on how the usage of buttons affects the visual behaviour of the driver. In this study, the aim was to analyse the effect of push button location and auditory feedback on drivers' visual time off road and safety perception when driving in a real traffic situation. The effect of six button locations (five on the centre stack, one near the gear stick) was tested. Drivers' visual behaviour was studied in real traffic on a motorway. An eye tracking system recorded the visual behaviour of eight drivers who, in 96 repeated trials each, were instructed to press a specific button. Data analysis focused on the drivers' visual time off road and safety perception in relation to the location of the button to be pressed. Auditory feedback did not show a significant effect on visual time off road. The time off road increased significantly as the angle increased between the normal line of sight and button location for the five buttons placed on the centre stack. Results for the button located close to the gear stick, with the highest eccentricity, produced a short time off road. This unexpected finding is discussed in terms of three potential explanations: 1) the role of perceptual discrimination; 2) risk perception; and 3) motor control.

A mouth-borne heat and moisture exchanger (HME) was tested. Nine healthy subjects performed an incremental-load cycle ergometry test to exhaustion, breathing once through the HME and once through a similar device without heat-exchange function (control). HME substantially increased inspired gas temperatures and decreased expired gas temperatures measured at the mouth; at 260 W (pulmonary ventilation (VE) approximately 1001 min-1) these changes amounted to + 15 degrees C and -5 degrees C, respectively. The breathing resistance was increased by HME but remained well within tolerable levels even during severe exercise. This was reflected in the subjective assessments of breathing resistance and breathing discomfort which, at any given workload, were rated similarly in the HME and control conditions. Also, time to exhaustion as well as oxygen uptake and VE at a given workload were unaffected by HME. That even at high pulmonary ventilations HME provided a good heat-exchange function while keeping breathing resistance relatively low suggests HME to be a useful aid for individuals suffering from cold-induced bronchospasm.

Swedish recycling centres are manned facilities for waste collection. There is no special category in the official injury statistics for employees at recycling centres, which precludes a straightforward analysis of reported occupational injuries. This study aimed at identifying the frequency of reported accidents and diseases and the type of events that contribute to such injuries at recycling centres, based on official injury statistics. The employees were identified as being affected by more than three to five times as many accidents compared with the total workforce in Sweden. The reported accidents had occurred during a wide range of situations, but most frequently during manual handling of waste. Reported work-related diseases were mostly associated with musculoskeletal disorders, mainly due to heavy lifting. A more detailed classification of sanitation professions and workplaces in the official injury statistics would facilitate future studies of injuries in a specific professional category, e.g. employees at recycling centres. Suggestions for prevention are given. Statement of Relevance: The present article describes all reported work accidents and diseases among employees at recycling centres from 1992 to February 2005. It also highlights the problem of identifying new working groups in the official statistics and gives advice for a detailed classification to facilitate such future studies of injuries.

Swedish recycling centres are manned facilities for waste collection. There is no special category in the official injury statistics for employees at recycling centres, which precludes a straightforward analysis of reported occupational injuries. This study aimed at identifying the frequency of reported accidents and diseases and the type of events that contribute to such injuries at recycling centres, based on official injury statistics. The employees were identified as being affected by more than three to five times as many accidents compared with the total workforce in Sweden. The reported accidents had occurred during a wide range of situations, but most frequently during manual handling of waste. Reported work-related diseases were mostly associated with musculoskeletal disorders, mainly due to heavy lifting. A more detailed classification of sanitation professions and workplaces in the official injury statistics would facilitate future studies of injuries in a specific professional category, e.g. employees at recycling centres. Suggestions for prevention are given.

Statement of Relevance: The present article describes all reported work accidents and diseases among employees at recycling centres from 1992 to February 2005. It also highlights the problem of identifying new working groups in the official statistics and gives advice for a detailed classification to facilitate such future studies of injuries.

The time saving bias predicts that the time saved when increasing speed from a high speed is overestimated, and underestimated when increasing speed from a slow speed. In a questionnaire, time saving judgements were investigated when information of estimated time to arrival was provided. In an active driving task, an alternative meter indicating the inverted speed was used to debias judgements. The simulated task was to first drive a distance at a given speed, and then drive the same distance again at the speed the driver judged was required to gain exactly 3 min in travel time compared with the first drive. A control group performed the same task with a speedometer and saved less than the targeted 3 min when increasing speed from a high speed, and more than 3 min when increasing from a low speed. Participants in the alternative meter condition were closer to the target. The two studies corroborate a time saving bias and show that biased intuitive judgements can be debiased by displaying the inverted speed.

Practitioner Summary: Previous studies have shown a cognitive bias in judgements of the time saved by increasing speed. This simulator study aims to improve driver judgements by introducing a speedometer indicating the inverted speed in active driving. The results show that the bias can be reduced by presenting the inverted speed and this finding can be used when designing in-car information systems.

The time saving bias predicts that the time saved when increasing speed from a high speed is overestimated, and underestimated when increasing speed from a slow speed. In a questionnaire, time saving judgements were investigated when information of estimated time to arrival was provided. In an active driving task, an alternative meter indicating the inverted speed was used to debias judgements. The simulated task was to first drive a distance at a given speed, and then drive the same distance again at the speed the driver judged was required to gain exactly three minutes in travel time compared to the first drive. A control group performed the same task with a speedometer and saved less than the targeted three minutes when increasing speed from a high speed, and more than three minutes when increasing from a low speed. Participants in the alternative meter condition were closer to the target. The two studies corroborate a time saving bias and show that biased intuitive judgements can be debiased by displaying the inverted speed.

The time saving bias predicts that the time saved when increasing speed from a high speed is overestimated, and underestimated when increasing speed from a slow speed. In a questionnaire, time saving judgements were investigated when information of estimated time to arrival was provided. In an active driving task, an alternative meter indicating the inverted speed was used to debias judgements. The simulated task was to first drive a distance at a given speed, and then drive the same distance again at the speed the driver judged was required to gain exactly three minutes in travel time compared to the first drive. A control group performed the same task with a speedometer and saved less than the targeted three minutes when increasing speed from a high speed, and more than three minutes when increasing from a low speed. Participants in the alternative meter condition were closer to the target. The two studies corroborate a time saving bias and show that biased intuitive judgements can be debiased by displaying the inverted speed.

The aim of this study was to evaluate different arm supports by comparing the activity of shoulder and arm muscles during various work tasks, with and without the lower arm supported. Twelve female subjects, aged between 23 and 37 years, were asked to perform three types of tasks: typing, simulated assembly work (in two different positions), and pipetting. The supports used were: fixed arm support (FIX), horizontal movable arm support (HOR), and spring-loaded arm support (SLA). During the experiments, the electromyograms (EMG) of four muscles were simultaneously recorded: m. deltoideus anterior and lateralis, m. trapezius pars descendens and m. extensor carpi radialis brevis. Normalization was made against maximum isometric contraction. The mean values of the normalized EMG levels showed a reduced EMG level of the shoulder muscles when using arm supports in all the tasks, and for all muscles but the wrist extensor, compared to the EMG levels without arm supports. The horizontal movable support was more effective in reducing the EMG levels of the shoulder muscles than other arm supports, in tasks at table height. Thus, it is possible to reduce muscle activity of the shoulder region by using arm supports. Further research is needed to make biomechanical calculations to compare the EMG level of these muscles using suspension and the effects of inclination of work task.

The present aim was to measure and quantify upper-arm elevation and to find how changed work organization and work tasks influence arm movement during a working day. Sixteen female office workers participated in the study. Their main work was statistical data entry. Upper-arm elevation was measured on two occasions separated by 18 months, i.e., before and after a change of work organization. The measurements were performed during the whole of one ordinary working day. The differences between the two measurements were mostly non-significant. Arm elevation remained essentially below 30 degrees during the main time of the working day, and the subjects worked with limited arm movements. Despite new alternative office tasks, they did not achieve a change in their habitual arm postures, or in their neck-and-shoulder disorders.

This study investigated how ergonomic design influences neck-and-shoulder muscle strain, through keyboard assessment. Muscular activity was measured electromyographically (EMG) from six muscles in the forearm and shoulders of eight experienced typists using each of five different types of keyboard: one mechanical, one electromechanical, and one electronic typewriter; one personal computer/word processor (PC-XT) keyboard; and one angled at 20 degrees in the horizontal plane. The impact on muscular activity of using a palmrest was also studied. The mechanical typewriter induced a higher strain in the forearm and finger muscles than did the modern typewriters and keyboards. These induced no different strain on the neck-and-shoulder muscles, except for the right shoulder muscle, which was more active with the electronic typewriter than with the other machines. Using a palmrest did not decrease the strain on the muscles investigated. Use of the 'angled' PC-XT keyboard did not influence the measured muscular load on the forearm and finger muscles compared to typing on an ordinary PC-XT keyboard, but decreased the extensor muscular strain compared to the electronic typewriter.

In trauma teams, coordination can be established through a centralised leader. The team can also use a decentralised strategy. In this descriptive study of video-recorded trauma resuscitations, using quantification of qualitative data, Social Network analysis of all real-time communications of eight in-real-life (IRL) and simulated trauma teams explained team social structure. The communication network structures in the simulated scenarios were more centralised using individually directed speech and had a high proportion of communication to update all team members. Such a structure might be the result of work performed in a complexity-stripped simulation environment where simplified task-executions required less interactions, or from work revolving around a deteriorating patient, imposing high demands on rapid decision-making and taskwork. Communication IRL was mostly decentralised, with more variability between cases, possibly due to unpredictability of the IRL case. The flexibility to act in a decentralised manner potentiates adaptability and seems beneficial in rapidly changing situations.Practitioner summary: Efficient collaboration in trauma teams is essential. Communication in in-real-life and simulated trauma teams was analysed using social network analysis. The simulation teams were overall more centralised compared to the IRL teams. The flexibility to act decentralised seems beneficial for emergency teams as it enables adaptability in unpredictable situations.

Current research on slips and falls has mainly focused on floors and/or contaminated floors. Although icy and snowy surfaces near melting temperature are more slippery, more important still, slip and falls on icy and snowy surfaces involve not only outdoor workers, but also pedestrians and the general public; and occur in cold regions and in the winter season in many parts of the world. However, in comparison with the size of the problem, research work done so far in this area has been limited. The objective of this paper is to present a systems perspective of slip and fall accidents, with special focus on its occurrence on icy and snowy surfaces. In order to explore the aetiology of slip and fall accidents further, and to provide the basis for prevention, the authors put forward a systems model towards the slips and falls on icy and snowy surfaces based on a review of literature and current knowledge. Various contributing factors are systematically discussed to highlight the multi-factorial nature of the problem, providing the possibility of a multi-faceted approach to reach systematic prevention. Unresolved issues related to slips and falls on ice and snow are also identified, which necessitate further research.

Current research on slipperiness of footwear has mainly focused on floors and lubricated floors. Slips and falls on icy and snowy surfaces involve not only outdoor workers, but also pedestrians and the general public; and occur in cold regions and in winter season in many parts of the world. However, in comparison with the size of the problem, research on slips and falls on icy and snowy surfaces has been scarce. The objective of this paper is to explore the slip resistant properties of footwear (soling materials, roughness and hardness) on ice. The coefficients of kinetic friction of four different soling materials (synthetic rubber, nitrile rubber, natural rubber and polyurethane) were measured on ice (-12°C). The outsole roughness and hardness were also measured. Results showed that the polyurethane soling did not perform better than synthetic rubber, nitrile rubber and natural rubber on pure hard ice (-12°C). Soling roughness was positively correlated with the coefficient of kinetic friction. The most slip resistant soling material (polyurethane) on floors and lubricated floors may not provide sufficient slip resistance on ice.

The main objective of this paper is to give an overview of basic concepts and definitions of terms related to the 'measurement of slipperiness' from the onset of a foot slide to a gradual loss of balance and a fall. Other unforeseen events prior to falls (e.g. tripping) are sparingly dealt with. The measurement of slipperiness may simply comprise an estimation of slipping hazard exposures that initiate the chain of events ultimately causing an injury. However, there is also a need to consider the human capacity to anticipate slipperiness and adapt to unsafe environments for avoiding a loss of balance and an injury. Biomechanical and human-centred measurements may be utilized for such an approach, including an evaluation of relevant safety criteria for slip/fall avoidance and procedures for validation of slip test devices. Mechanical slip testing approaches have been readily utilized to measure slipperiness in terms of friction or slip resistance but with conflicting outcomes. An improved understanding of the measurement of slipperiness paradigm seems to involve an integration of the methodologies used in several disciplines, among others. injury epidemiology, psychophysics, biomechanics, motor control, materials science and tribology.