Physical workload of ambulance assistants

Abstract

The physical workload of ambulance assistants was assessed by means of the Ovako Working posture Analysis System (OWAS) observation method and a Work and Health Questionnaire (WHQ) for measuring perceived workload. In addition, a biomechanical model was applied to several specifically strenuous conditions that were simulated in a laboratory situation. Bad postures were identified for a number of activities: 16% to 29% of a work shift was spent in harmful positions. Strenuous situations occur particularly during rides in emergency situations. The results of observed and perceived workload are generally in agreement. A number of practical recommendations are made. They concern, for example, the equipment in ambulance cars, training of ambulance assistants and adaptations in working procedures.     

Physical workload of lorry drivers: a comparison of four methods of transport

Abstract

Four groups of eight lorry drivers, transporting goods on wheeled cages, as packed goods, on pallets, or as bulk cargo, were studied during a complete working day. The drivers working with bulk cargo served as a reference group. Manual materials handling and the working postures were studied by observation. The heart rate (HR) was continuously recorded and related to observed tasks. The relationship between HR and oxygen uptake during a simulation of loading and unloading and the maximal oxygen uptake ([Vdot]O2 max) were measured in a laboratory for every driver. The lorry drivers worked long hours, only the group transporting wheeled cages worked less than 11 hd^-1 on average. Driving made up almost half of the total working time in all groups. In general, the highest HR was found during loading and unloading. Loading and unloading of wheeled cages was done for 2nd^-1, at 50% of [Vdot]O2max. The drivers transporting packed goods and pallets loaded and unloaded for around 100mind^-1, at 48% and 35% of [Vdot]O2 max respectively. When the drivers of these two groups lifted, their trunks were flexed for more than 60% of the time. The most important difference between the reference group and the other groups was that the drivers of the former rarely pushed or pulled anything. It is suggested that the required pushing and pulling forces were largely responsible for the high physical workload during loading and unloading.     

The effect of police cruiser restraint cage configuration on shoulder discomfort,muscular demands,upper limb postures,and task performance during simulated police patrol

Advances in police-specific technology have led to changes in work layout and physical occupational demands of mobile police officers. This study investigated the influence of police cruiser compartment configuration on perceived discomfort, muscle activation, shoulder kinematics, and typing performance during simulated police patrol. Participants completed a one-hour session including simulated driving and 2-min typing trials in a standard compartment configuration with a fixed mobile data terminal (MDT) location (ST), and in a modified compartment configuration with an MDT in front of the user and a rearward translated seat (MOD). The MOD configuration resulted in reductions of 55–65% in perceived shoulder discomfort, up to 3.4% MVC in shoulder muscle demands, and more neutral humeral orientations (shoulder elevation reduced by 13–25°). These improvements associated with the MOD configuration may have ergonomic implications for future police car designs, particularly as new technology is introduced in the mobile environment and advanced solutions are sought.     

Musculoskeletal symptoms and workload in 12 branches of Dutch agriculture

A postal questionnaire survey was carried out in Dutch agriculture to identify high risk branches with respect to musculoskeletal symptoms and workload. The study population comprised a sample 2580 male employees and employers, with a response rate of 49%. A total of 75% of the employees and 71 % of the employers reported musculoskeletal symptoms during the past 12 months. Low-back pain was most prevalent (one-year prevalence rate of 51% among employees, 47% among employers), followed by symptoms of the neck-shoulder (one-year prevalence rate of 35% among employees, 30% among employers) and knees (one-year prevalence rate of 22% among employees, 17% among employers). There were marked differences between specific branches in the size and nature of musculoskeletal morbidity as well as in self-reported musculoskeletal workload. In particular protective vegetables growing and arboriculture showed both relatively high rates of symptoms and relatively high exposure levels. The results of this study were used to decide which agricultural branches and workload factors should have priority in the ergonomic interventions that followed.     

Effect of block weight on work demands and physical workload during masonry work

The effect of block weight on work demands and physical workload was determined for masons who laid sandstone building blocks over the course of a full work day. Three groups of five sandstone block masons participated. Each group worked with a different block weight: 11 kg, 14 kg or 16 kg. Productivity and durations of tasks and activities were assessed through real time observations at the work site. Energetic workload was also assessed through monitoring the heart rate and oxygen consumption at the work site. Spinal load of the low back was estimated by calculating the cumulated elastic energy stored in the lumbar spine using durations of activities and previous data on corresponding compression forces. Block weight had no effect on productivity, duration or frequency of tasks and activities, energetic workload or cumulative spinal load. Working with any of the block weights exceeded exposure guidelines for work demands and physical workload. This implies that, regardless of block weight in the range of 11 to 16 kg, mechanical lifting equipment or devices to adjust work height should be implemented to substantially lower the risk of low back injuries.     

The relationship between physical workload and quality within line-based assembly

Reducing costs and improvement of product quality are considered important to ensure productivity within a company. Quality deviations during production processes and ergonomics have previously shown to be associated. This study explored the relationship between physical workload and real (found during production processes) and potential (need of extra time and assistance to complete tasks) quality deviations in a line-based assembly plant. The physical workload on and the work rotation between 52 workstations were assessed. As the outcome, real and potential quality deviations were studied during 10 weeks. Results show that workstations with higher physical workload had significantly more real deviations compared to lower workload stations. Static work posture had significantly more potential deviations. Rotation between high and low workload was related to fewer quality deviations compared to rotation between only high workload stations. In conclusion, physical ergonomics seems to be related to real and potential quality deviation within line-based assembly.

Practitioner Summary: To ensure good productivity in manufacturing industries, it is important to reduce costs and improve product quality. This study shows that high physical workload is associated with quality deviations and need of extra time and assistance to complete tasks within line-based assembly, which can be financially expensive for a company.     

Effects of concurrent physical and mental demands for a short duration static task

The purpose of this study was to quantify the effects of concurrent physical and mental demands on the upper extremity muscle activity during static exertions. Seventeen healthy participants performed isometric upper extremity exertions at five levels of physical intensity (5%, 25%, 45%, 65%, and 85% maximum voluntary contraction (MVC)) in the presence and absence of a mental task (Stroop color word test). Muscular responses were quantified using surface electromyography (EMG) and motor performance was measured through force fluctuations. Subjective assessments were obtained through the NASA-TLX tool and the Borg CR-10 Scale. In general, a decrease in mean anterior and posterior deltoid muscle activity and co-contraction index (CCI) of the shoulder was observed in the presence of the mental task. However, these changes were more prominent at higher physical exertion levels compared to the lower levels. Furthermore, the additional mental task resulted in decreased upper and lower arm muscle activity, specifically at the 45% MVC level. Motor performance improved at the middle exertion levels, but was adversely affected by the mental task at higher exertion levels. Decreased motor performance at higher loads may have been a result of decreased muscular effort to maintain the loads in a steady posture. Both mental and physical demand adversely affected the NASA-TLX ratings, however, ratings using the Borg CR-10 Scale were only sensitive to changes in physical demand.

Relevance to industry

Workplace tasks, such as jobs performed by healthcare workers, assembly line workers, and computer operators, have become more multidimensional in the recent years; with workers experiencing combined physical and mental demands in their daily jobs, yet their effect on muscular responses is not clearly understood. Results from this study suggest that certain physical exertion levels are more susceptible to interference by mental demands than others.     

Physical workload of flight attendants when pushing and pulling trolleys aboard aircraft

The musculoskeletal loads from moving trolleys aboard aircraft were assessed by observation of trolley handling on planes and by physical workload analyses of pushing and pulling of trolleys in a laboratory set up. Trolley handling by a total of 15 female flight attendants was observed on 10 short- and medium-distance flights in different types of aircraft. About 25 selected flight attendants (22 females; 3 males) of five German airlines took part in the laboratory study, which comprised three-dimensional (3D) measurements of posture and hand forces during pushing and pulling of trolleys in a variety of configurations. From the on-flight observations performed, between 150 and 250 trolley movements can be projected for a work shift. The greatest physical workload is to be expected at the beginning of service: The trolleys are fully laden then, and the cabin floor can still be inclined up to 8°, as the aircraft is still climbing, particularly on short-distance flights. The laboratory investigation revealed that the musculoskeletal workload from pushing and pulling depends essentially on the trolley load and on the gradient of the cabin floor. In addition, the degree of stressing depends significantly on the trolley type, mode of handling and personal dexterity. The up/down force component perpendicular to the direction of motion often achieved considerable amplitudes-in some cases equal to or exceeding the force in the direction of movement. The posture analysis demonstrated that pulling forced the flight attendants to adopt ergonomically unfavourable postures such as pronounced flexion of the back, particularly among female subjects. The highest values for flexion of the back occurred while pulling the half-size trolley. The results demonstrate that female flight attendants are likely to overload themselves if they frequently have to move heavily laden trolleys unaided on an inclined cabin floor.

Relevance to industry

On short distance flights, flight attendants have been complaining increasingly of high physical workload from manoeuvring trolleys. On the basis of the presented data airline companies may improve the trolley handling skills of their flight attendances by practical trainings and may ergonomically optimize the general service procedures aboard aircrafts.     

Job stress management and ergonomic intervention for work-related upper extremity symptoms

In practice the secondary prevention of work-related upper extremity (WRUE) symptoms generally targets biomechanical risk factors. Psychosocial risk factors have also been shown to play an important role in the development of WRUE symptom severity and future disability. The addition of a stress management component to biomechanically focused interventions may result in greater improvements in WRUE symptoms and functional limitations than intervening in the biomechanical risk factors alone. Seventy office workers with WRUE symptoms were randomly assigned to an ergonomics intervention group (assessment and modification of work station and stretching exercises) or a combined ergonomic and job stress intervention group (ergonomic intervention plus two 1-h workshops on the identification and management of workplace stress). Baseline, 3- and 12-month follow-up measures of observed ergonomic risks and self-reported ergonomic risks, job stress, pain, symptoms, functional limitation, and general physical and mental health were obtained from all participants. While both groups experienced significant decreases in pain, symptoms, and functional limitation from baseline to three months with improvements continuing to 12 months post baseline, no significant differences between groups were observed for any outcome measures. Findings indicate that the additional two-session job stress management component did not significantly enhance the short- or long-term improvements brought about by the ergonomic intervention alone.     

Computer mouse use and cumulative trauma disorders of the upper extremities

The computer mouse is now present in virtually every office environment because of the recent adoption of the graphical user interface. However, Karlqvist et al. (1994) pointed out that there still remains a paucity of work on the musculoskeletal problems associated specifically with computer mouse use. Likewise, there have been no published data on the magnitude of upper extremity musculoskeletal disorders associated with computer mouse use. In order to ascertain this magnitude, claims data from the Liberty Mutual Group were reviewed for the years 1986 to 1993, inclusive. Count, total cost and average cost per claim for all claims associated with computer use and computer mouse use were determined for the years in question. It was concluded that although there are few claims related to computer mouse use, it appears to be a growing problem, and therefore, perhaps, deserves more research and intervention attention. However, the present magnitude is less than for other musculoskeletal disorders.     

Effect of horizontal position of the computer keyboard on upper extremity posture and muscular load during computer work

The distance of the keyboard from the edge of a work surface has been associated with hand and arm pain; however, the variation in postural and muscular effects with the horizontal position have not been explicitly explored in previous studies. It was hypothesized that the wrist approaches more of a neutral posture as the keyboard distance from the edge of table increases. In a laboratory setting, 20 adults completed computer tasks using four workstation configurations: with the keyboard at the edge of the work surface (NEAR), 8 cm from the edge and 15 cm from the edge, the latter condition also with a pad that raised the work surface proximal to the keyboard (FWP). Electrogoniometers and an electromagnetic motion analysis system measured wrist and upper arm postures and surface electromyography measured muscle activity of two forearm and two shoulder muscles. Wrist ulnar deviation decreased by 50% (4°) as the keyboard position moved away from the user. Without a pad, wrist extension increased by 20% (4°) as the keyboard moved away but when the pad was added, wrist extension did not differ from that in the NEAR configuration. Median values of wrist extensor muscle activity decreased by 4% maximum voluntary contraction for the farthest position with a pad (FWP). The upper arm followed suit: flexion increased while abduction and internal rotation decreased as the keyboard was positioned further away from the edge of the table. In order to achieve neutral postures of the upper extremity, the keyboard position in the horizontal plane has an important role and needs to be considered within the context of workstation designs and interventions.     

The nature of work-related neck and upper limb musculoskeletal disorders

The nature of work-related musculoskeletal disorders of the neck and upper limbs is reviewed using both scientific data and the consensus view of experts, union bodies and government agencies across the European Union. Work-related musculoskeletal disorders describe a wide range of inflammatory and degenerative diseases and disorders. These conditions result in pain and functional impairment and may affect, besides others, the neck, shoulders, elbows, forearms, wrists and hands. They are work-related when the work activities and work conditions significantly contribute to their development or exacerbation but are not necessarily the sole determinant of causation. The classification and the need for standardised diagnostic methods for assessment of neck and upper limb musculoskeletal disorders are reviewed. These disorders are a significant problem within the European Union with respect to ill health, productivity and associated costs. The pathomechanisms of musculoskeletal disorders affecting tendons, ligaments, nerves, muscle, circulation and pain perception are reviewed and conceptual models for the pathogenesis of musculoskeletal disorders affecting the neck and upper limbs are presented. The epidemiological evidence on the work-relatedness of these disorders is discussed. A relationship between the performance of work and the occurrence of neck and upper limb musculoskeletal disorders is evident. Intervention strategies in the workplace for the reduction of both exposure and effect should focus upon factors within the work organisation as well as actively involving the individual worker. The current knowledge is sufficient to enable informed decisions to be made on future research needs and prevention strategies at the societal, organisational and individual level.     

Physical workload and psychosocial working conditions in Swedish pig transport drivers

Working conditions of 20 Swedish pig transport drivers (PTD) were assessed by a questionnaire, a workshop, and recorded postures and movements during on-farm loading, driving, unloading at abattoir and vehicle cleaning. High arm positions and high frequencies of shoulder problems indicated an excessive physical load on shoulders. Extreme crouching postures inside vehicles and high frequencies of lower back problems indicated high load on the back of PTDs. Inadequate design of on-farm loading areas was associated with knee discomfort. Observed variation in workload between PTDs could be explained by differences in physical working environment and pig handling practices. PTDs reported high job satisfaction and commitment although conflicts with farmers and official veterinarians, as well as regulatory conflicts were emphasized. We conclude that issues of inadequate farm and abattoir facilities, stakeholder conflicts and insufficient training in animal handling need to be addressed to ensure sustainable PTD working conditions.     

云计算环境下负载—功耗特征测试与分析

为了实现云计算数据中心的高效节能的工作负载调度,必须首先研究虚拟机层面不同的工作负载和功率消耗之间的关系.在现有研究的基础上,通过对服务器虚拟机层面的功耗度量与分析,研究多种硬件、软件、负载条件下,虚拟机中不同类型的工作负载对功耗的影响特性,这对于能耗的度量、建模、管理、优化等都具有重要的意义.     

Exploration on the Integration of CAD Course and National CAD Grade Certification Training

Based on the syllabus and standard of National CAD Grade Certification issued by the Ministry of Education and China Figure Association, this paper discusses the teaching model of combining classroom teaching with skill grade certification in voca- tional college. To achieve the unity of classroom teaching and skill training can save training costs and increase the significance of classroom teaching. Implementation of integrating mechanical CAD curriculum and national CAD grade certification training is the extension of teaching reform. It can make the vocational college students obtain the professional qualification certificates besides di-plomas.     

Impact of physical exposure on neck and upper limb disorders in female workers

Physical workload [muscular load of the trapezius and infraspinatus muscles using electromyography (EMG), wrist positions and movements by electrogoniometers] and neck and upper limb disorders (from, for example, a physical examination) were studied in women with repetitive industrial work (n = 95) and referents (n = 74). The repetitive work displayed higher ratings for wrist movements, but not for EMG. The prevalences of neck, shoulder and wrist/hand disorders were elevated for women with repetitive work [age-adjusted prevalence odds ratios (PORs) 2.0-7.5]. For the left hand, high frequency of wrist movements (mean power frequency 0.53 Hz) was associated with a high prevalence of disorders (56%), as compared to low (0.28 Hz and 26%; POR 3.5). We found no consistent and significant effect of muscular load, on either neck or shoulder disorders. However, selection and other bias may have diminished our possibility to observe such effects. Psychosocial work environment factors were not confounding the results. Measurements of wrist movements may be used for identification of high-risk work tasks.     

基于交换树的多机器人任务协调与负荷平衡方法

针对多机器人任务分工与协调过程中,未能有效解决的带任务偏序关系的负荷平衡问题,提出一种基于交换树的多机器人任务协调与负荷平衡方法。首先,通过有向赋权图（约束图）对带偏序关系约束的多机器人任务分工问题进行描述;其次,根据有向赋权图提出了初始任务分工策略,通过改进Dijkstra算法解决多机器人之间任务协调问题;最后,提出负荷平衡策略,通过交换树竞拍的方法解决机器人之间任务负荷不平衡问题。仿真结果表明,与一般Dijkstra方法相比,执行完任务负荷平衡策略之后,工作效率明显提高了12%,机器人之间的任务负荷差也减少了30%,验证了该方法的有效性。     

Evaluation and prediction mental workload in user interface of maritime operations using eye response

Eye response measurement is one of the objective measure methods and useful for assessing of operators' mental workload (MWL). The main objectives of this paper are to consider the relationship between operators' MWL and eye responses in the task of operating marine engine interface. Also, an artificial neural network (ANN) model was developed to predict the operators' MWL based on integrating eye response data. Eye response indices (pupil dilation, blink rate, fixation rate, and saccadic rate) were recorded, and two subjective rating methods (The National Aeronautics and Space Administration's Task Load Index [NASA-TLX] and subjective workload assessment technique [SWAT]) were used for 27 participants. The results again confirm that the eye response is sensitive to MWL in workload levels of the task when using the interface control. The ANN model developed by measuring these indices can predict the operators' MWL with the determination coefficient (R²) of 0.971, 0.912 and 0.918 for training, validation, and testing, respectively. These results indicated that the ANN approach is quite accurate for the prediction of operators' MWL based on eye response indices.Relevance to industryThe developed model is expected to provide the operator with a reference value of their MWL by evaluating their physiological indices. This result might be applied for developing an intelligent prediction model in the actual work environment to inform or support the operator in a variety of ways. From this, the manager can organize the human resources for each task to sustain the appropriate MWL as well as to improve the work performance.     

基于几何矩的CAD模型形状匹配算法及应用

基于矩方法及其理论,提出了一个基于几何矩的形状匹配算法,用于识别CAD模型中具有相似形状特征的几何体.该算法采用一组满足平移、旋转、缩放不变性的几何矩不变量对三维几何体的形状特征进行描述,并根据形状特征向量的相似程度评估几何体之间的相似性.为提高几何矩计算的准确性和效率,对CAD模型的三角面片数据进行了预处理,并采用递...