Manual Lifting Research Articles

Understanding outcome metrics of the revised NIOSH lifting equation

The interpretation of the calculated result of the revised NIOSH Lifting Equation (RNLE) has been problematic because the relationship of the calculated result to back injury risk has not always been either well understood nor consistently interpreted. During the revision of the ISO standard 11228–1 (Manual lifting, lowering and carrying), an extensive literature review was conducted on validation studies of the RNLE. A systematic review of exposure-risk associations between the LI metrics and various low-back health outcomes from peer-reviewed epidemiological studies was conducted. Risk interpretations for different levels of calculated result of the RNLE are added to the ISO standard. Rationale for the risk interpretations is presented in this paper.

Using visual aids to influence manual lifting techniques: acute effects of viewing static images on spine motion

Purpose. This study aimed to determine whether untrained observers alter their spine as directed via static images of different lifting techniques. Methods. Ten men and eight women, who had no lifting or visual observation training, performed box lifts. Following a self-selected lifting technique trial, participants performed four experimental lifting trials (in randomized order) wherein they were instructed to execute lifts in accordance with the techniques pictured. These techniques differed by the amount of knee, trunk and spine flexion modeled. Peak lumbar flexion angles and flexion/extension velocities were quantified, and then statistically analyzed via general linear models with two within-participant factors (condition = technique; phase = lift/lower). Results. Lumbar flexion angles and flexion/extension velocities differed between conditions (p < 0.001), although the effects depended on the combination of postural characteristics pictured. A main effect of phase was observed for peak lumbar flexion velocity only (p = 0.001). No condition × phase interaction effects were detected for any dependent variables (p > 0.050). Conclusions. Acute changes in lifting mechanics can be elicited via visual observation of pictured techniques. However, if using pictures to attenuate peak lumbar flexion displacements and velocities when lifting, auxiliary instruction may be needed to direct observers’ attention to the spine curvature displayed.

Design and material selection for a patient transport device in field hospitals

ACKGROUND: A major cause of patient and hospital worker injuries occurs transferring patients between two planes. The main aim of this paper was to propose a design of patient’s lift and transfer apparatus for use in field hospitals. The assumption was to design lightweight, durable and ergonomic device using innovative material. The authors concentrated on partial elimination of manual lifting in order to device could work both in two situations: with or without electricity. The paper includes mechanical design, material selection and analytical calculation. METHODS: In order to carry out strength calculations, the shape and size of device was designed using AutoCAD. Based on a comparison of composite material properties, an epoxy-carbon laminate was selected. The strength calculations were performed in the following order: determination of elementary stresses, determination of the most dangerous cross-section, calculation of tensile strength, calculation of Young’s modulus, selection of channel dimensions, determination of material parameters (thickness, fiber mass), determination of substitute stresses. RESULTS: To design a lightweight, durable and ergonomic patient lift with lifting capacity of 150 kg an epoxy-carbon laminate composed of three layers was chosen. A profile in a C-shape and dimension of 138x90x14 mm has been designed. Patient lift includes an arm of 1.6 m height and 1m length of the horizontal beam. The designed transport mechanism uses rollers, a linear electric actuator and a crank with a worm gear. CONCLUSIONS: The designed device fulfil the most important criterion, which is to ensure the safety of patients and medical personnel. The height adjustment mechanism partially eliminates the manual transfer of patients and is adapted to the conditions existing in a field hospital.

Implementation of the lean ergonomics approach to process performance improvement

Actually market is subject to constant change which forces organizations to innovate with new strategies that provide greater productivity to maintain a competitive advantage, one of the flexible tools used are Lean systems. However, in most of the improvements registered in these systems, the non-ergonomic elements have not been considered as waste, which have high costs for companies. This document presents an approach to integrating Lean systems with Ergonomics, the main tools used were Value Stream Mapping, SIPOC, Kaizen, REBA Method and NIOSH. As a result, a risk identification was obtained in 86% of the 26 activities of three processes analyzed, mainly by postures, manual lifting of loads and repetitiveness, with the improvements developed, the 25 controlled risks were reduced high to medium or low and obtained an average reduction of 32% in the cycle time of operations, making each process more efficient.

Relationship of Musculoskeletal Discomforts with the Permissible Levels of Manual Load Lifting and Postural Assessment Score (Case Study of a Printing Industry)

Relationship of Musculoskeletal Discomforts with the Permissible Levels of Manual Load Lifting and Postural Assessment Score (Case Study of a Printing Industry)

Characterizing Regional Methane Emissions from Natural Gas Liquid Unloading.

A "bottom-up" probabilistic model was developed using engineering first-principles to quantify annualized throughput normalized methane emissions (TNME) from natural gas liquid unloading activities for 18 basins in the United States in 2016. For each basin, six discrete liquid-unloading scenarios are considered, consisting of combinations of well types (conventional and unconventional) and liquid-unloading systems (nonplunger, manual plunger lift, and automatic plunger lift). Analysis reveals that methane emissions from liquids unloading are highly variable, with mean TNMEs ranging from 0.0093% to 0.38% across basins. Automatic plunger-lift systems are found to have significantly higher per-well methane emissions rates relative to manual plunger-lift or non-plunger systems and on average constitute 28% of annual methane emissions from liquids unloading over all basins despite representing only ∼0.43% of total natural gas well count. While previous work has advocated that operational malfunctions and abnormal process conditions explain the existence of super-emitters in the natural gas supply chain, this work finds that super-emitters can arise naturally due to variability in underlying component processes. Additionally, average cumulative methane emissions from liquids unloading, attributed to the natural gas supply chain, across all basins are ∼4.8 times higher than those inferred from the 2016 Greenhouse Gas Reporting Program (GHGRP). Our new model highlights the importance of technological disaggregation, uncertainty quantification, and regionalization in estimating episodic methane emissions from liquids unloading. These insights can help reconcile discrepancies between "top-down" (regional or atmospheric studies) and "bottom-up" (component or facility-level) studies.

Understanding Anthropometric Characteristics Associated With Performance in Manual Lifting Tasks.

Beck, B, Middleton, KJ, Billing, DC, Caldwell, JN, and Carstairs, GL. Understanding anthropometric characteristics associated with performance in manual lifting tasks. J Strength Cond Res 33(3): 755-761, 2019-Manual lifting is an essential military job task and is commonly linked to occupational injury. Methods to reduce injury risk focus on ensuring that employees have the requisite physical capacity to safely conduct critical job tasks. The aim of this study was to investigate which anthropometric characteristics are associated with lifting performance to inform targeted training programs for job-critical lifting tasks. Sixty-three (42 men and 21 women) participants conducted 3 maximal lifts to a platform (pack lift to 1.5 m, box lift to 1.3 m and box lift to 1.5 m). A dual-energy x-ray absorptiometry scan was used to quantify anthropometric characteristics (body region-specific lean mass and fat mass). Although anthropometric measures were strongly associated with each other, multivariable linear regression revealed that a significant proportion of the total variation in lifting performance in each of the 3 tasks was explained by upper-arm lean mass (pack lift: β = 5.42, p < 0.001; box lift 1.3 m: β = 5.64, p < 0.001; box lift 1.5 m: β = 7.00, p < 0.001). Leg lean mass also significantly contributed to the variation of pack lift performance (β = 0.93, p = 0.01). When controlling for key anthropometric characteristics in these 3 tasks, separate analyses showed no significant effect of sex or stature on lift performance. These results suggest that the perceived limitations of stature and sex may be overcome by targeted training programs to improve specific physical characteristics associated with lifting performance.

Risk Perception and Occupational Accidents among a Group of Egyptian Construction Workers in Cairo, Egypt

Background: Construction sector is one of the risky businesses in which fatal and non-fatal occupational injuries occur frequently. Information about workers’ awareness about health hazards, risk perception, and safe work practices can help in implementing prevention strategies. Unfortunately, construction sites had limited access for research, accounting only for 2.28% of all available researches. Objectives: The current study aimed to estimate the perception of construction workers to the occupational hazards. Also, it aimed at identifying types of common occupational accidents involving construction workers in an Egyptian company, and to identify the workers’ personal and work-related characteristics of their risk perception. Methods: A cross-sectional study was conducted among construction workers in one of the projects in Cairo. During the period from January to August 2018, 104 workers were interviewed using a structured questionnaire inquiring about sociodemographic characteristics and work-related variables together with assessment of workers’ risk perception. Results: The majority of the workers had low risk perception for falls, contact with chemicals, being struck by objects, sharp objects, manual lifting, repetitive movements, and heat stress, while noise was reported to be in “no or acceptable risk” category. The study identified age, health and safety training, working hours, and the use of Personal Protective Equipment (PPE) as significantly related factors to risk perception. Conclusion: Risk perception among studied workers in average is low. Older age, prolonged working hours, lack of training, and not wearing PPE are significant risk factors shaping workers’ perception. Safety training and change of work environment may reduce the risk of injuries.

Use of Assistive Devices to Lift, Transfer, and Reposition Hospital Patients.

Devices to lift, transfer, and reposition patients are recommended for healthcare workers' and patients' safety, but their intended use has yet to be fully realized. The aim of this study was to describe hospital nursing staff use of lift/transfer devices and the presence of factors at the time of lifts/transfers with potential to influence whether devices are used. Participants were 108 US nursing staff in a university-based medical center and two community hospitals. A self-completed questionnaire was used to collect demographic and work characteristics, typical frequency of patient lifts/transfers, training in and typical use of lift equipment, and specific factors that could influence use. Proportional distributions of lifting/transferring and repositioning frequencies in a typical shift, amount of equipment use, and factors present were examined overall and across worker and work-related characteristics. Although trained in equipment use, only 40% used equipment for at least half of lifts/transfers. During lifts/transfers, factors often present included patient unable to help with lift/transfer (91.3%) or of a size/weight where participant needed assistance to help lift/transfer (87.5%); availability of others who could assist with manual lift (86.3%) or use of lift equipment (82.4%); and equipment functioning properly (86.4%), having supplies available (82.5%), and being easy to retrieve from storage (81.6%). During repositioning tasks, physical assistance was "always/almost always" provided from coworkers (83.3%) and often perceived as "very helpful" (92.6%) in reducing physical demands. Physical assistance from patients was less common (14.0% "always/almost always") yet perceived as "very helpful" by 66.3%. One fifth always used friction-reducing devices. Despite training in their use, nursing staff use of available lift equipment and assistive devices is limited. Factors present at the time of lifts/transfers that may influence equipment/device use reflect a complex mix of patient, worker, equipment, and situational characteristics.

Assessment of Usability and Task Load Demand Using a Robot-Assisted Transfer Device Compared With a Hoyer Advance for Dependent Wheelchair Transfers.

Manual lifting can be burdensome for people who care for power wheelchair users. Although technologies used for dependent transfers are helpful, they have shortcomings of their own. This study compares the usability and task load demand of a novel robot-assisted transfer device to a clinical standard when performing dependent transfers. A cross-sectional study was conducted to assess caregivers (N = 21) transferring a 56-kg mannequin with the Strong Arm and Hoyer Advance at three transfer locations. Feedback was gathered through qualitative surveys. Usability was significant in multiple areas important for transfers. Caregiver fatigue and discomfort intensity were reduced, and the Strong Arm was preferred at the three transfer locations. Device ease and efficiency favored Strong Arm at two stations as was discomfort frequency. In addition, physical demand, frustration, and effort were significantly lower using Strong Arm compared with the Hoyer Advance. Compared with the Hoyer, participants favored Strong Arm for transfer usability and task load demand. However, further Strong Arm developments are needed.

Estimation of exerted force in manual lifting task using wearable device

Estimation of exerted force in manual lifting task using wearable device

A SYSTEMATIC REVIEW ON IDENTIFYING ASSOCIATED FACTORS IN DECIDING WORK- RELATEDNESS OF CHRONIC BACK PAIN AMONG EMPLOYEE

Chronic low back pain is a common and preventable complain among workers. Large amount of financial and benefit cost has been spent by the developed countries to prevent, treat and rehabilitate a large number of workers that are exposed to hazards attributing to low back pain. Efforts on primary prevention of low back pain has been challenging due to difficulties in affirming work- relatedness of chronic back pain among workers. As such, efforts have to be focused on the existing literatures to propose acceptable variables to define work- relatedness specific to occupational low back pain. Evidences suggest twisting, frequent manual lifting of objects, duration of daily exposure, coping mechanism towards the pain, body mass index (BMI), smoking status and physical activity are associated with occupational back pain. However, further research efforts are needed to establish stronger evidence and improve the occupational safety and health of our workers that are exposed to all these hazards throughout the day on a daily basis.

Psychological working conditions and predictors of occupational stress among nurses, Salaga Government Hospital, Ghana, 2016.

IntroductionOccupational stress is a recognized health problem among nurses. Globally, its prevalence varies between 9.2% and 68.0%. It detracts from nurses' quality of life and efficiency of job performance. In Ghana, we do not know the important contributory factors to this problem. Our study sought to identify the important predictors of occupational stress among nurses.MethodsIn January 2016, we conducted an institutional-based survey among nurses of Salaga Government Hospital. They completed a five-point Likert type questionnaire adopted from the British Psychological Working Conditions Survey, and the Nurse Stress Index. Across 30 predictor variables, a mean score of 4.00 to 5.00 represented high to extreme occupational stress. We performed bivariate and multivariate analyses to identify important predictors of occupational stress at 95% confidence level.ResultsOf 167 nurses, 58.1% (97) were females. Respondents who experienced high to extreme stress levels had a 2.3 times odds of reporting sickness absence (CI: 1.03-5.14). Sources of occupational stress included: manual lifting of patients and pieces of equipment (OR: 16.23; CI: 6.28 - 41.92), the risks of acquiring infections (OR: 14.67; CI 5.90 - 36.46), receiving feedback only upon unsatisfactory performance (OR: 28.00; CI: 9.72 - 80.64), and inadequate opportunities for continuous professional development (OR: 63.50; CI: 19.99 - 201.75).ConclusionThe working conditions of nurses were stressful. The most significant predictors of occupational stress were poor supportive supervision by superiors, lack of adequate skills to perform routine tasks, uncertainty about their job role, and the lack of adequate opportunities for career advancements.

Forces Loaded on the Back of Manual Material Handling Tasks' Workers of Food Industries in Malard Using"3D Static Strength Prediction Program”

Introduction: Manual Material Handling tasks can cause fatigue in the short term and increase physical workload and musculoskeletal injuries in the long term. The present study was conducted to determine the amount of forces entered to the lower back in workers with manual material handling tasks.Methods: This descriptive-analytic study was conducted on 100 workers in food industries in Malard city in 2017. The Nordic questionnaire was used to determine the frequency of musculoskeletal disorders. The 3DSSPP was also applied to determine the amount of forces entered to the lower back of manual material handling tasks workers. Data analysis was conducted using SPSS (version 23)Results: we found that 24percent of workers had discomfort in at least one of their nine musculoskeletal muscles. The results of 3DSSPP showed that 30 and 34 percent of the compressive forces entered into L5/S1 and L4/L5 discs, respectively. In addition, the shearing force loaded on the L5/S1 disc was also found to be higher than the permissible limit eight percent of the participants. No significant relationship was found between the frequency of musculoskeletal disorders and the amount of compressive and shear forces entered to the lower back of workers.Conclusion: Based on NIOSH recommended limits, the amount of compressive and shear forces entered to the lower back in 3DSSPP showed that in 30 percent of manual lifting load tasks, the risk of injury to the lower back was moderate and this risk was low in 70 percent of tasks.

Risk Perception and Occupational Accidents among a Group of Egyptian Construction Workers in a Construction Company in Cairo.

Background: Construction sector is one of the main pillars of the global economy, even though it is a risky business in which fatal and non-fatal occupational injuries occur frequently. Information about workers’ awareness about health and safety hazards, risk perception and safe work practices can help to understand where to apply prevention strategies. Unfortunately, construction sites are workplaces with limited access for research; studies at work level represent 2.28% of all available research. Objectives: To estimate the perception of construction workers to the occupational hazards, to identify types of common occupational accidents involving construction workers in an Egyptian company and to identify the workers’ personal and work related characteristics determinants on their risk perception. Material and methods: A cross sectional study was conducted among construction workers in one of the projects in Cairo. During the period from January to August 2018; a sample of 104 workers were interviewed using a structured questionnaire inquiring about socio-demographic characteristics, work related variables together with assessment of workers’ risk perception. Results: the majority of the workers had low risk perception for falls, contact with chemicals, struck by objects, sharp objects, manual lifting, repetitive movements and heat stress, while the noise was reported as “ no or acceptable risk category”. The study identified age, health and safety training, working hours and the use of PPEs as significantly related factors to risk perception. Conclusion:risk perception among studied workers in average is low. Older age, prolonged working hours, lack of training and not wearing PPEs are significant risk factors shaping workers’ perception. Recommendation: safety training and change of work environment may improve workers’ perception toward occupational accidents and subsequently reduce the risk of injuries.

Comparative Analysis of Multi-Trade Prefabrication Construction Methods

This paper proposes a construction method for efficient application of multi-trade prefabrication (MTP). The currently most advanced prefabrication method, MTP was recently introduced in North America and Europe. However, there have been few reports and studies of MTP in Asia. This paper discusses MTP construction method application in a workshop and presents solutions to identified problems. MTP pilot test 1 was performed using combinations of conventional chain block and scissor lift. Productivity analysis indicated that on-site MTP construction increased an extra labor input which was 19.6% compared to the total labor input of the conventional method. Pilot test 2 used manual material lifts for on-site MTP construction. Labor input per MTP module was reduced to 75.8% of that required for pilot test 1, but the manual lifts extended overall construction time. Pilot test 3 used a proposed optimized stacker based lifting device. Labor input for on-site MTP construction was reduced to 47.0% of that for pilot test 1. These results will be the basis for development of best practices for future MTP construction and provide better understanding as well as directions for improving MTP construction.

Riesgo lumbar en la manipulación de barras de hierro en una empresa siderúrgica

Sr. Editor. El dolor lumbar por manipulación de carga constituye un problema de salud ocupacional que trae como consecuencia la reducción de la movilidad, y discapacidad1,2,3. Así, le comunicamos acerca de un estudio descriptivo y transversal que tuvo como objetivo determinar el nivel de riesgo lumbar en el conteo de barras de hierro, que realizamos el año 2015 en el almacén de la ciudad de Pisco de la empresa siderúrgica Aceros Arequipa. Participaron 40 trabajadores que tuvieron como actividad diaria el conteo de barras de hierro en posición parada y flexión, levantando barras de 30 kg. Se utilizó el método INSHT (Instituto Nacional de Seguridad e Higiene en el Trabajo de España)1 en la determinación del nivel de riesgo lumbar con los datos: peso de la carga, postura, desplazamiento vertical, giro del tronco, agarre de la carga, frecuencia, distancia transportada, según la ecuación de NIOSH que permite calcular un índice de levantamiento que proprciona el nivel de riesgo asociado a una tarea de levantamiento manual (cociente entre peso de carga levantada y límite de peso recomendado).

Comparisons with subjective and objective indexes of lifting risk among different combinations of lifting weight and frequency

It is evident that the lifting risk increases with both the lifting weight and frequency. However, little is known whether or not different combinations of lifting weight and frequency cause different risks even lifting the same total weight over a period of time. Therefore, the purpose of this study was to investigate the effects of lifting weight and frequency combinations on the lifting risk in the same amount of weight lifted over a period of time. Oxygen consumption, heart rate, and NIOSH’s (US National Institute for Occupational Safety and Health) Lifting Index (LI) were measured and considered as objective risk indexes. The rating of perceived exertion (RPE) was collected as subjective risk index. Sixteen young adults participated in the experiment. Each participant performed four lifting trials with different combinations of lifting weight and frequency, i.e. 12 kg & 2 lift/min, 8 kg & 3 lift/min, 6 kg & 4 lift/min, and 4 kg & 6 lift/min. Each lifting trial last 16 min. Each participant’s oxygen consumption and heart rate were measured during the lifting trial. After each trial, the participant’s RPE and LI were collected. The results indicated the combination of weight and frequency had a significant effect on RPE and LI, but had little effect on oxygen consumption and heart rate. The larger lifting weight accompanied with lower frequency (12 kg & 2 lift/min) had a significant greater RPE and LI than the other three lifting trials. This study provided useful information to determine proper risk predictors for manual lifting tasks with different combinations of object weight and lifting frequency.

Estimation of physical workload of the low-back based on exposure variation analysis during a full working day among male blue-collar workers. Cross-sectional workplace study

This study aims to quantify physical workload of the low-back using exposure variation analysis (EVA) during a full working day among blue-collar workers with manual lifting tasks. One hundred and ten male employees (39 warehouse workers, 27 operators, 24 postal workers and 20 slaughterhouse workers) with manual lifting tasks from 12 workplaces participated. The workers performed standardized box lifts using 5, 10, 20 and 30 kg before and after a working day. Muscular activity of the low-back was measured throughout the working day using surface electromyography (sEMG). Corresponding sEMG-values for 0–30 kg lifts were identified using linear regression. EVA at exposure levels corresponding to “lifting periods” of [1-5, 5-10, 10-20, 20-30 and >30] kg in time intervals [0–0.5, 0.5–1, 1-2, 2-5, 5-10, >10] sec was computed. Back inclination was measured using tri-axial accelerometers. Compared to the other job groups, the operators’ low-back muscles were exposed to more short duration “lifting periods” with varying loads and more frequent medium duration high load “lifting periods”, respectively. The operators also worked more with their back inclined (>30°, >60°, and >90°) than the remaining job groups. Nonetheless, more than 41% of the workers performed heavy “lifting periods” that exceeded Danish lifting guidelines. This EVA demonstrates that almost half of the blue-collar workers were exposed to heavy low-back loading which puts them at risk of developing musculoskeletal disorders and low-back injury. Operators are, in particular, exposed to more short duration and medium duration “lifting periods” with varying load compared to warehouse-, postal- and slaughterhouse workers.

Load-embedded inertial measurement unit reveals lifting performance

Manual lifting of loads arises in many occupations as well as in activities of daily living. Prior studies explore lifting biomechanics and conditions implicated in lifting-induced injuries through laboratory-based experimental methods. This study introduces a new measurement method using load-embedded inertial measurement units (IMUs) to evaluate lifting tasks in varied environments outside of the laboratory. An example vertical load lifting task is considered that is included in an outdoor obstacle course. The IMU data, in the form of the load acceleration and angular velocity, is used to estimate load vertical velocity and three lifting performance metrics: the lifting time (speed), power, and motion smoothness. Large qualitative differences in these parameters distinguish exemplar high and low performance trials. These differences are further supported by subsequent statistical analyses of twenty three trials (including a total of 115 total lift/lower cycles) from fourteen healthy participants. Results reveal that lifting time is strongly correlated with lifting power (as expected) but also correlated with motion smoothness. Thus, participants who lift rapidly do so with significantly greater power using motions that minimize motion jerk.