BACKGROUND: Laser imaging provides an alternative to manual measurements in the collection of general anthropometric surveys focused on 1-D measures. This study aimed to develop a systematic method of comparing manual and digital anthropometric measurements and validate a commercial three-dimensional laser scanner for anthropometric measurements. OBJECTIVE: The purpose of this preliminary project is to validate a laser scanner for selected length and girth measurements. METHODS: A variety of linear and circumferential segmental measures from 20 participants were either extracted from a 3D commercial laser imaging device scans or measured manually. Error between manual and scan-extracted measurements was compared based on ISO20685, and clinical standards. Regression analysis improved the quality of the measurements and residuals were again compared to the standards. RESULTS: After regression, 7 of the 9 the measurements were within, or close to (two times standard), standards. Error was caused by a combination of image quality issues associated with the laser scanner, as well as algorithmic issues associated with larger participants. CONCLUSIONS: Overall, the results are promising, and given the indicated population, a small number of minor improvements may very quickly allow the scanner to collect measurements on a clinical population.
BACKGROUND: Manual patient handling completed by nurses can include unexpected or strenuous exertions, potentially leading to injury. Lifting guidelines focus on mitigating primarily limiting low back exposures, and the influence of these techniques on the shoulder is unknown. OBJECTIVE: To quantify shoulder loading during manual patient handling tasks and determine whether approaches intended to limit low back exposures negatively affect shoulder demands. METHODS: Twenty novice university-aged females completed five manual patient handling tasks before and after a training session. Participants simulated handling a partial weight bearing patient, and joint load magnitudes were calculated. Strength demands were interpreted in the context of available population capability ranges. RESULTS: Using recommended techniques decreased peak low back loading in most scenarios (p = 0.01–0.02), but had variable effects on shoulder loading. Peak loading in the shoulders increased by 97–107% in the Sit-to-Chair task following training. Using recommended techniques for Turn Toward decreased mean population strength requirements at the back to 35% of capability while increasing shoulder requirements to 100% capability. CONCLUSIONS: Recommended manual patient handling techniques mitigate low back exposures but likely transfer demands to other body regions, specifically the shoulder.
BACKGROUND:The paper is a printed version of keynotes and plenary addresses which have been presented during international ergonomics conferences to which the author had been invited.It focuses on human work performance influenced by an advanced age.Aging of the workforce, productivity, or work and health, today must be regarded as important research topics for ergonomics and for realizing age-differentiated work design.OBJECTIVE: A scientific survey of the various human performance potentials impacted by age.METHODS: A comprehensive literature review of scientific papers dealing with age-dependent work performance was carried out.The results were garnished with suitable aphorisms, sentences and wisdoms on age which stem from wise old men and prominent philosophers and poets.RESULTS: The results comprise physical age-related performance potentials, e.g., muscle strength and assembly performance.Also the impact of age on vision and on the hearing is described in detail and it is visualized in figures and tables.Furthermore, important age-dependent changes in the central nervous system and in mental-cognitive performance areas are reported.Fortunately, also positive issues of aging on the working performance could be detected.The paper ends with a meditative discourse about length and quality of life.CONCLUSIONS: Age-differentiated work design has to be based on specific knowledge about age-dependent performance potentials of the employees.A comprehensive literature review revealed a lot of already existing and sustainable facts which can be applied in work design.However, further fundamental and especially applied research is necessary since today substantial changes in the working conditions occur very quickly.
BACKGROUND: Joystick operators often experience constant low level muscle loading in the upper limb when using joysticks, which can lead to repetitive strain injuries. It has been hypothesized that the strain on the muscles may be reduced by supporting the arm during joystick manipulation. OBJECTIVE: To design a horizontally dynamic armrest which appropriately supports the motion of the forearm during sideto-side joystick movements. METHODS: The paper describes the process used to design a dynamic armrest which appropriately supports an operator’s arm throughout the range of side-to-side joystick movements. RESULTS: The trajectory of the elbow and wrist during these joystick movements was determined, and a new horizontally dynamic armrest designed and built. CONCLUSIONS: Most heavy mobile equipment seat armrests fail to provide appropriate support throughout the range of joystick motion resulting in constant upper body muscle loading. Our paper describes the development of a dynamic armrest which is designed to provide appropriate support throughout side-to-side joystick movements.
BACKGROUND: Ever deeper mining is exposing workers to increasing heat and humidity, which can threaten their health and safety. OBJECTIVE: The objective of this research is to create a matrix of criteria that will eventually be used to design a perso
BACKGROUND: There is an extensive body of research reviewing the effect of task factors on the Maximum Acceptable Weight of Lift (MAWL) or heart beats elevation as a result of a manual material handling task.However, there are now studies that investigate the effect of task factors on the heart rate recovery time (HRR).OBJECTIVE: The purpose of the study was twofold: (1) to determine the HRR for a series of lifting tasks based on the activity heart rate and by using a set of task variables, (2) to compare the effect of three task factors on the HRR following a lifting task.METHODS: This research was constituted of capturing the duration that heart rate needs to get to a steady state following a lifting task, along with conducting the survey of perceived exertion (Borg).Three independent variables of this study (taskfactors) were weight of the lift (10 and 20 kg), frequency of the lift (6 and 9 lifts per minute), and the duration of the lift (5 and 10 minutes).Given the possible treatment combinations, a total of 8 treatments was obtained.Twenty-four university male students performed the lifting tasks in a between-subject design.Each participant performed one treatment by lifting a box from knuckle to shoulder height at a certain frequency, duration and weight.All eight treatments were equally replicated with three observations per treatment group.RESULTS: Increasing weight and frequency of the lift significantly increased the HRR (respectively by 37% and 34%), while the HRR had a slight decrease when duration was doubled (approximately -2.7%).Weight of the lift was the only factor led to a significant change in the perceived difficulty of the task among participants (approximately 20%).CONCLUSIONS: Among main factors, frequency and weight of the lift had a significant effect on the HRR (p-values < 0.1).Among the interaction effects, the interaction of frequency and duration had a significant effect on the HRR.The only factor that had a significant effect on the Borg-rating was weight of the lift (p-value < 0.1).
BACKGROUND: The torque required to manually turn a handwheel-valve typically exceeds operators' capabilities, requiring them to use a valve-wrench.Although valve-wrenches are commonly used, an ergonomic wrench has not yet been developed.OBJECTIVE: To introduce an ergonomically designed valve-wrench and evaluate it with respect to conventional valve opening methods.METHODS: Four methods were compared including: bare hands, restricted conventional wrench (assumes presence of obstructions), unrestricted conventional wrench, and ergonomically-modified wrench.Each method was performed at two torque settings, 15 Nm and 30 Nm. Electromyography activities were measured from eight trunk and shoulder muscles.The time to fully open the valve and Borg-ratings were recorded for each method.RESULTS: The modified wrench resulted in the lowest average time and Borg-rating; however, these averages were not significantly different from the averages of the unrestricted conventional wrench.The method that was associated with the lowest overall electromyography activities was restricted conventional wrench, followed subsequently by bare hands, modified wrench, and unrestricted conventional wrench.CONCLUSIONS: Although the ergonomically-modified wrench was associated with relatively high electromyography activities, it was the most time-efficient method, allowing the muscles to sustain physical loads for shorter periods of time.Overall, participants rated this method as the least physically demanding.
BACKGROUND: Thermal discomfort is mentioned as one of the major causes of dissatisfaction in workplaces when people are exposed to extremely hot or cold thermal environments in the industrial context. Studies evaluating the comfort of the thermal environment are becoming increasingly important, but this kind of studies is time-consuming and it becomes expensive and difficult to implement for many organizations. OBJECTIVE: The purpose of this study was to evaluate thermal comfort in a metalworking industry located in Portugal, applying user-friendly thermal indexes supported by real data collected using inexpensive measuring tools. METHODS: To this end, this study was conducted using objective measurements of air temperature T (◦C), and relative humidity RH (%), collected using a pen data acquisition (Easy Log USB). Simultaneously, subjective answers about the perception of thermal comfort by the workers in the section studied were collected based on a questionnaire survey. RESULTS: The results revealed a high risk of heat stress for some workstations, which required the intervention of the Health and Safety Department. CONCLUSIONS: The indexes applied in this work, namely the WMO diagram and the EsConTer index, offer a sound model for thermal stress risk evaluation, minimizing difficult and time-consuming investigations to identify thermal comfort problems in workplaces, each emphasizing particular aspects, in order to create value.
BACKGROUND: Motorbikes are a cost effective and fuel efficient mode of transport but at the same time they account for huge number of Road Traffic Accidents (RTA). Bike riders are exposed to postural, psychosocial stress which may lead to accidents.
BACKGROUND: There is an extensive body of research reviewing the ergonomics needs of industrial office workers. However, very few studies have considered evaluating the working postures of students or professors in universities who are exposed to pro
BACKGROUND: Asymmetric and dynamic lifting is known to be one of the leading causes of occupational lower back disorders (LBDs). Biomechanical modeling has been utilized to investigate lifting task characteristics so that the task demands can be kept within a limit, and internal muscles and joints are not injured. OBJECTIVE: This study implemented AnyBody to analyze internal torso loading in asymmetric and dynamic lifting tasks. METHODS: A six-camera motion capture (mocap) system collected dynamic motion data of lifting 30 lb (13.6 kg) weight at 0o, 30o and 60o asymmetry. The mocap data drove the AnyBody model, and the study investigated the effect of the asymmetry. RESULTS: Erector spinae was the most activated muscle for both symmetric and asymmetric lifting. When lifting origin became more asymmetric toward right, erector spinae activity was reduced, but oblique muscles increased their share of activity to counter the external moment. Most muscle tensions peaked at the lift initiation phase except left external oblique and right internal oblique. Left external oblique played a minor role in the right asymmetric lifting task, and the difference of activation for right internal oblique may be due to variance of the motion. Surprisingly the lift asymmetry decreased both compression and shear forces at the L5/S1 joint. CONCLUSIONS: This finding contradicted the results obtained from other research studies. The reduction in spine forces is postulated to have resulted from the increased oblique muscles’ share in the production of back extensor moment. Since these muscles have longer moment arms, they generated lesser spine force to counteract the external moment. The subject also tended to squat as lifting origin became asymmetric, which effectively reduced the load moment on the spine.
BACKGROUND: Passenger seats need to be designed according to ergonomic guidelines for long hour sitting travel. In Bangladesh, passenger seats are designed and fabricated by the local manufacturers who have no knowledge about anthropometry. As a result, passenger has to face stress, fatigue, headac he and other disorders. OBJECTIVE: To compare passengers' anthropometric measurements and relevant existing seat dimensions for identifying possible discrepancy and recommending an optimum design. METHODS: In this study the passengers' anthropometric measurements and relevant existing seat dimensions were compared to identify possible discrepancy. RESULTS: The result represented a considerable mismatch between body dimensions of passengers and the existing seat dimensions. The recommended new seat dimensions would enhance match percentage. CONCLUSIONS: The design and allocation of passenger seats were given on the basis of passenger's anthropometry. The proposed seat dimensions would ensure a safe and comfortable journey for the passengers.
BACKGROUND: Static postures and heavy helmets elicit neck pain in many aircraft personnel during or after flight. Helmet-mounted equipment can further increase neck loading and injury risk. OBJECTIVE: To quantify neck muscle activity changes as a function of helmet configuration and static neck pos tures. METHODS: Eight male participants participated. Neck surface EMG was measured bilaterally in each combination of 7 neck postures (neutral, flexed, extended, twisted, laterally flexed, and two combination postures) and 5 helmet-mounted equipment configurations (combinations of a helicopter helmet, night-vision goggles (NVG), and a 600 g counterweight (CW)). RESULTS: Helmet configuration alone did not influence activity for any muscle. Peak muscle activity was less than 5% of maximum voluntary exertion for most trials. The highest neck extensor activity occurred when wearing the helmet with CW and NVG engaged, while the lowest activity occurred in the same setup but NVG in a disengaged position, and helmet configuration effects varied by target posture. Muscle activity tended to be greatest in extension and combination movements for the lateral muscles and in flexion and flexion with rotation for the neck extensors. CONCLUSION: Neck posture influenced neck muscular demands more than the configuration of helmet-mounted equipment. As such, cockpit layout may play a primary role in mitigating neck injury risk factors.
BACKGROUND: Firefighting is a physically demanding occupation where workers are exposed to a significantly increased risk of injuries. OBJECTIVE: The purpose of this narrative review was to examine the literature surrounding protective firefighting boots and their relationship to lower body and lum bar biomechanics and potential injury. METHODS: An exhaustive search of peer reviewed firefighting literature was undertaken across 300 databases with 12 articles fitting the inclusion criteria and subsequently synthesised for the purposes of this review. RESULTS: The evidence suggested that protective firefighting boots restricted the range of motion at both the ankle and the metatarsophalangeal joints, with changes subsequently observed for centre of pressure traces as well as at the knee and hip joints. These changes influenced gait characteristics during the stance and swing phases, with the potential to alter landing strategies adopted during occupational specific activities, all of which place firefighters at an increased risk of lower body and lumbar injuries. CONCLUSIONS: As a majority of the research was conducted with firefighters wearing personal protective equipment in conjunction with standard issue boots, to date, it remains unclear as to how protective firefighting boots in isolation or design differences influence lower body movement and injury.
BACKGROUND: Forceful exertions of the arm/shoulder are common during material handling and many other industrial tasks. Determination of how the risk of shoulder injury changes in conjunction with direction of force exertion could provide useful guidance on the design of workplaces and tasks. OBJEC TIVE: This research was conducted to determine how direction of force exertion and muscle recruitment algorithm effect shoulder strain computed by musculoskeletal modeling. METHODS: Musculoskeletal modeling software was used to perform simulations of static force exertions of the right upper limb. A series of 36 force exertions in directions at 30° intervals in the transverse, sagital, and frontal planes were performed using three muscle recruitment optimization algorithms. A previously validated strain index equation was used to calculate risk injury for each force exertion based on the magnitude and direction of the resultant glenohumeral force. RESULTS: Generally, highest strain values were found in the downward, backward, and leftward direction and lowest strain values were found in the upward, forward, and rightward direction, or, in other words, during force exertions opposing forces in those directions. CONCLUSIONS: When designing workplace tasks that involve forceful exertions of the shoulder, pulling and downward pushing exertions should be given preference over pushing and lifting exertions.
Ergonomics is the science of fitting the workplace to the worker to reduce the risk of injury. In order to reduce the risk of developing work-related musculoskeletal disorders (WMSDs), it is important to change posture frequently. The neutral posture is the optimal body position, which provides the greatest strength and control and minimizes stress. Even a neutral posture can be fatiguing if held all day; therefore, microchanges in posture and stretching are recommended. This chapter identifies physical workplace risk factors associated with laboratory environments. The physical risk factor checklist is a tool used to identify ergonomics stressors in the workplace. Reduce to the lowest level feasible significant contributing physical risk factors and consider contributing personal risk factors in the evaluation. The workers should have a basic understanding of ergonomic principles and handling techniques, recognize risk factors and injury or illness symptoms.
BACKGROUND: Exposure to foot-transmitted vibration (FTV) has been linked to injury; however, the biodynamic response of the foot to FTV has not been quantified. OBJECTIVE: The objective was to measure vibration transmissibility from the floor-to-ankle, and the floor-to-metatarsal, during exposure to FTV while standing, and to determine if FTV exposure frequency, or participant mass or arch index (AI) influence the transmission of FTV through the foot. METHODS: Participants’ AI was measured. Four ADXL326, tri-axial accelerometers were utilized to measure vibration on the platform medial to distal head of first metatarsal, on the distal head of first metatarsal, on the platform paralleling the medial malleolus, and on the lateral malleolus. Participants were randomly exposed to FTV at 25 Hz, 30 Hz, 35 Hz, 40 Hz, 45 Hz, and 50 Hz for 45 seconds. RESULTS: Neither the three-way interaction of location*frequency*AI [λ = 0.816, F(5,24) = 1.080, p = 0.396] or location*frequency*mass [λ = 0.959, F(5,24) = 0.203, p = 0.958] were significant ( p< 0.05). The location*frequency interaction was significant [λ = 0.246, F(5,25) = 15.365, p = 0.0001]. Differences in mean transmissibility between the ankle and metatarsal were significant at 40 Hz, 45 Hz, and 50 Hz ( p< 0.001). CONCLUSIONS: The greatest transmissibility magnitude measured at the metatarsal and ankle occurred at 50 Hz and 25– 30 Hz respectively, suggesting the formation of a local resonance at each location.
This chapter talks about hand tool designs and describes the key principles of hand tool selection and how they interact to affect performance and safety. It presents ergonomic basics of hand tool use. A tool becomes ergonomic only when it fits the task one is performing and fits one's hand without causing awkward postures, harmful contact pressures or other safety and health risks. When using tools one should know the job, look at the workspace, improve the work posture and select the tool. The chapter discusses the analysis of the traditional splicing task, and the analysis of using the Melni connector to perform the splicing task. The use of the Melni connector provides great ergonomic benefit over the traditional method of splicing 4/0 cable and takes considerably less time to perform. Melni connector can be used whenever possible and electricians should be trained on the ergonomic risk factors.
BACKGROUND: Exposure to hand operated vibrating tools in the construction industry places workers at risk for developing hand-arm vibration syndrome (HAVS), which is a common occupational disease. OBJECTIVE: To outline health and safety training obtained by construction workers and to assess which factors influence anti-vibration (AV) glove utilization following an educational intervention provided during a clinical assessment for HAVS at an occupational health clinic. METHODS: One hundred participating workers from the construction industry referred for a HAVS assessment at a hospitalbased ambulatory occupational health clinic in Toronto, Ontario, Canada. A baseline and two-month follow-up questionnaire were completed. RESULTS: Almost all of the participants indicated that they had completed health and safety training within their workplace. However, few received training specific regarding HAVS or AV gloves. Participants’ AV glove use improved from 4.3% at baseline to 53.3% at follow-up two months later. Key predictors of participants wearing AV gloves was sharing the educational intervention information with their supervisors and working in a workplace with 20 or more employees. CONCLUSIONS: Training specific to HAVS and AV gloves is lacking in the construction industry. The educational intervention proved most effective in increasing AV glove use when the information was shared within the workplace.
