Manual Lifting Tasks Research Articles

Work System Improvement of Evacuation Process Conducted by Emergency Medical Technicians Using Virtual Environment Modeling

The work of emergency medical technicians (EMT) during patient evacuation involves lifting task in an emergency situation, which results in the increasing risk of musculoskeletal disorders such as low back pain. The purpose of this research was to investigate the workplace and ergonomic aspect that influence work posture of the EMT using simulation approach in a virtual environment. Biomechanic model (mannequin) of the EMT had been simulated and analyzed by using LBA and OWAS method. The mannequin was given an improvement based on ergonomic principle of manual lifting task and then was reanalyzed. Improvement that can be used for the work system of the evacuation process conducted by EMT considering its nature situation is the work posture of personnel during the process of lifting the patient into the stretcher. The technique that can be used is the proper lifting techniques. The results of this research can be used as a recommendation to the work system of the EMT.

Experimental simulated study on the break for manual lifting task by surface electromyography and electrocardiogram

To investigate the recovery duration of manual lifting tasks. 30 college student volunteers with gender equally distributed were involved in the simulated stoop-, squart- and semi squart-lifting tasks in the laboratory. Signals of electromyography (EMG) at the back muscles (left and right thorax m. erector spinae, LT(10) and RT(10); left and right lumbar m. erector spinae, LL(3) and RL(3)) and electrocardiography (ECG) were recorded during the rest intervals. The percentage of maximum voluntary electrical activation (MVE%), EMG median frequency (MF), and heart rate (HR) were analyzed to predict the recovery time required. During the break, MVE% at 4 back muscles of all the male subjects were recovered to resting level within 5 minutes and 91.8% were within 2 minutes. Except for RL(3) after squat- and stoop-lifting task, the MVE% of female subjects went back to resting level within 3 minutes and 67.8% were within 2 minutes. The MF of male subjects were recovered in 10 minutes and 74.9% within 2 minutes, with the exception of RL(3) after stoop- and squat-lifting tasks. All the female MF were recovered in 8 minutes and 83.4% were within 2 minutes. However, during the last 20 minute break after the lifting tasks, the MVE% and MF of all male and female subjects were recovered, while HR came back to resting level within 14 and 5 minutes, respectively. For the three manual lifting tasks with 25% MVC workload lasting for 4.5 min, a break of 15 minutes is sufficient for most erectors spinae to recover from local muscle load. However, in terms of the HR, a break of 15 minutes is enough for the recovery of systematic load.

The development of a model to predict the effects of worker and task factors on foot placements in manual material handling tasks

Accurate prediction of foot placements in relation to hand locations during manual materials handling tasks is critical for prospective biomechanical analysis. To address this need, the effects of lifting task conditions and anthropometric variables on foot placements were studied in a laboratory experiment. In total, 20 men and women performed two-handed object transfers that required them to walk to a shelf, lift an object from the shelf at waist height and carry the object to a variety of locations. Five different changes in the direction of progression following the object pickup were used, ranging from 45° to 180° relative to the approach direction. Object weights of 1.0 kg, 4.5 kg, 13.6 kg were used. Whole-body motions were recorded using a 3-D optical retro-reflective marker-based camera system. A new parametric system for describing foot placements, the Quantitative Transition Classification System, was developed to facilitate the parameterisation of foot placement data. Foot placements chosen by the subjects during the transfer tasks appeared to facilitate a change in the whole-body direction of progression, in addition to aiding in performing the lift. Further analysis revealed that five different stepping behaviours accounted for 71% of the stepping patterns observed. More specifically, the most frequently observed behaviour revealed that the orientation of the lead foot during the actual lifting task was primarily affected by the amount of turn angle required after the lift (R 2 = 0.53). One surprising result was that the object mass (scaled by participant body mass) was not found to significantly affect any of the individual step placement parameters. Regression models were developed to predict the most prevalent step placements and are included in this paper to facilitate more accurate human motion simulations and ergonomics analyses of manual material lifting tasks. Statement of Relevance: This study proposes a method for parameterising the steps (foot placements) associated with manual material handling tasks. The influence of task conditions and subject anthropometry on the foot placements of the most frequently observed stepping pattern during a laboratory study is discussed. For prospective postural analyses conducted using digital human models, accurate prediction of the foot placements is critical to realistic postural analyses and improved biomechanical job evaluations.

Multi-response optimization and empirical modeling of cardiopulmonary responses during manual lifting tasks

An experimental study involving five independent lifting variables (namely weight, lift frequency, horizontal distance from the object, operator, and vertical distance) and their interactions was conducted using the Taguchi L27 design. Two responses—heart rate and oxygen uptake—were measured during each trial. To optimize both responses simultaneously, the signal‐to‐noise ratio was normalized to obtain a multi‐response signal‐to‐noise (MRSN) ratio for each trial. The MRSN ratio was analyzed using analysis of variance to identify the optimal condition in which both responses were optimized at the same time. Lift frequency was found to be the most significant factor, and operator and horizontal distance were found to be least significant. The empirical modeling equation was developed and can be used to predict the response values during experimental trials involving similar work conditions. © 2010 Wiley Periodicals, Inc. © 2011 Wiley Periodicals, Inc.

Hand Placement and Risk Assessment by the LMM Model

Previous studies have shown a variety of hand placement locations employed by workers performing manual lifting tasks in industry. In this study, participants used four different hand placement locations to lift a box of variable weight and starting height. As they performed these lifts, the motions of their torso were captured using the lumbar motion monitor and these trunk kinematics were then input into the LMM low back injury risk assessment model. The results showed significant effects of all three independent variables with asymmetric hand placement locations generating the highest level of risk: 20% in the symmetric, 5kg condition as compared to a high of nearly 40% under the asymmetric, 10kg condition. These results indicate that hand placement is a relevant variable to consider when designing manual materials handling tasks.

Bottom-up estimation of joint moments during manual lifting using orientation sensors instead of position sensors

L5/S1, hip and knee moments during manual lifting tasks are, in a laboratory environment, frequently established by bottom-up inverse dynamics, using force plates to measure ground reaction forces (GRFs) and an optoelectronic system to measure segment positions and orientations. For field measurements, alternative measurement systems are being developed. One alternative is the use of small body-mounted inertial/magnetic sensors (IMSs) and instrumented force shoes to measure segment orientation and GRFs, respectively. However, because IMSs measure segment orientations only, the positions of segments relative to each other and relative to the GRFs have to be determined by linking them, assuming fixed segment lengths and zero joint translation. This will affect the estimated joint positions and joint moments. This study investigated the effect of using segment orientations only (orientation-based method) instead of using orientations and positions (reference method) on three-dimensional joint moments. To compare analysis methods (and not measurement methods), GRFs were measured with a force plate and segment positions and/or orientations were measured using optoelectronic marker clusters for both analysis methods. Eleven male subjects lifted a box from floor level using three lifting techniques: a stoop, a semi-squat and a squat technique. The difference between the two analysis methods remained small for the knee moments: <4%. For the hip and L5/S1 moments, the differences were more substantial: up to 8% for the stoop and semi-squat techniques and up to 14% for the squat technique. In conclusion, joint moments during lifting can be estimated with good accuracy at the knee joint and with reasonable accuracy at the hip and L5/S1 joints using segment orientation and GRF data only.

Web-based expert system prototype: applications for workplace improvement

The purposes of this research are to extend the existing guidelines for manual lifting tasks and to evaluate the impacts from the web-based and interactive features on workers' preference. This web-based tool, the ML-Expert System was designed to address the safety and health of workers. A comparison was made between the two groups, in accordance with the National Institute for Occupational Safety and Health (NIOSH) and the ML-Expert system, over a period of five months. The overall result indicates the need to extend the existing basic guidelines for manual-lifting work by adapting to a unique working environment. Finally, the web-based and interactive features of the ML-Expert appeared to help increase satisfaction and workplace learning.

Proposed procedures for measuring the lifting task variables required by the Revised NIOSH Lifting Equation – A case study

This study aims to contribute to a better understanding of the Revised NIOSH Lifting Equation applied to field conditions by providing a detailed description of the procedures for measuring its variables. These procedures were adopted during the evaluation of a lifting/lowering task of steel sheets in an auto parts manufacturing plant. The Revised NIOSH Lifting Equation is a tool for assessing two-handed manual lifting tasks. A review of the existing literature failed to come up with a detailed description of procedures for obtaining the equation variables at a worksite. A systematic approach for data collection was therefore proposed, since this is a key step to apply the equation correctly. Both films and photographs were used throughout the evaluation, following the load from its origin to its final destination. Measurements were taken with several instruments, i.e., tape measures, meter sticks, set squares, protractors, etc. The evaluated task presented a Recommended Weight Limit of 5.73 kg and a Lifting Index of 5.8. This survey found that the NIOSH Lifting Equation is an inexpensive and very useful methodology. However, the researcher must be thoroughly familiar with the methodology and the criteria underpinning its design. Furthermore, the analyst must be trained in handling the devices employed in determining the variables at the work site. Relevance to industry This study shows a practical application to obtain data for use Revised NIOSH Lifting Equation in industrial company. As didactic element to industry, contributes to the achievement of the measures in workstations that involving of a lifting task. Presenting systematic and reliable procedures to ensure the reproducibility and reliability of the method proposed by the Revised NIOSH Lifting Equation (NIOSH (National Institute for Occupational Safety and Health), 1994. Applications Manual for the Revised NIOSH Lifting Equation. Technical Report No. 94-110. U.S. Department of Health and Human Services (NIOSH), Public Health Service, Cincinnati, OH.).

WHEN IS IT SAFE TO MANUALLY LIFT A PATIENT?

In 1994 the National Institute for Occupational Safety and Health (NIOSH) released the Revised NIOSH Lifting Equation-an ergonomics assessment tool that can be used to calculate the recommended weight limit for two-handed manual-lifting tasks. However, NIOSH excluded assessment of patient-handling tasks from the uses of the revised equation, arguing that such tasks involve too many variables. The equation in fact can be used to calculate a recommended weight limit for a limited range of patient-handling tasks in which the patient is cooperative and unlikely to move suddenly during the task. In general, the revised equation yields a recommended 35-lb. maximum weight limit for use in patient-handling tasks. When weight to be lifted exceeds this limit, assistive devices should be used.

A fuzzy relational rule network modeling of electromyographical activity of trunk muscles in manual lifting based on trunk angels, moments, pelvic tilt and rotation angles

The main objective of the study was to model the electromyographic (EMG) responses for 10 trunk muscles in manual-lifting tasks using the fuzzy relational rule network (FRRN). The FRRN utilized trunk-related variables, including sagittal and lateral trunk moments, pelvic tilt and pelvic rotation angles, and sagittal, lateral, and twist trunk angles as model inputs. The EMG data for model training and testing were randomly selected from a set collected for 20 college students. The data represented a total of 24 combinations of weight lifted (15, 30, 50 lbs), asymmetry (0°, 60°), and the origin and destination of lift (floor-waist, floor-102 cm, knee-waist, knee-102 cm), with two replications of each condition. The primary data-driven fuzzy model with relational input partition was trained using the laboratory EMG data for 10 subjects, and was then tested based on the EMG data for another 10 subjects. The model allowed for estimating EMG responses for the 10 trunk muscles with the average value of mean absolute error (MAE) of 9.9% (SD=1.44%). This study demonstrates that application of fuzzy modeling techniques allows for estimating time domain EMG responses of trunk muscles due to manual lifting under limited task conditions. Relevance to industry Estimation of EMG responses using the proposed fuzzy-based system opens new opportunities for biomechanical modeling of manual-lifting tasks aimed at prevention of low back disorders at the workplace.

Theoretical and experimental evaluation of the multiplicative lifting equation and the general lifting index

The Revised NIOSH Lifting Equation [13] integrated the findings of different approaches reported in the scientific literature into a single mathematical formulation based on the empirical model proposed by Drury and Pfeil [5]. This simple model was tested on a limited basis and the model generalizations have not been examined. The primary objectives of this study were to investigate the performance of the NIOSH lifting equation with general formulations reported by Karwowski [7], and to examine the structure of the lifting index and the relative importance of physical factors (as defined by the lifting index) and non-physical factors (as defined by perceived risk of injury and work dissatisfaction) with respect to workers' perceived effort associated with the lifting conditions. A cross-sectional study was conducted on 217 experienced manual handling workers in the Hong Kong area to validate the study objectives. In this investigation, information was collected on lifting task parameters, perceived effort, perceived risk of injury, and work dissatisfaction. The results suggest that a multiplicative model is better than an additive model in evaluating the effort associated with lifting task performance. In this regard, the exponents of the parameters in the lifting index should be different from 1.0. The best model for evaluating effort emerged from perceived risk of injury and the general lifting index (GLI). Given the limitations of our observational study, the main findings from this research suggest that the multiplicative structure of the NIOSH lifting equation is better than an additive model. In addition, the weighing of lifting task multipliers may need further investigation, and the study of manual lifting tasks should include both physical and non-physical factors when examining the etiologic factors leading to musculoskeletal symptoms and disorders.

Upper body kinematic and low-back kinetic responses to precision placement challenges and cognitive distractions during repetitive lifting

Exposure to cognitive distractions and precision placement challenges during manual lifting exertions may alter lumbar spine loading by influencing movement and/or motor patterns. In this study, the impact of such demands on upper body kinematics, trunk muscle activation, and lumbar spine loading during a repetitive lifting task was examined. Nine male volunteers performed four different sagittal plane lifting tasks in which a 15.9 kg mass was lifted repetitively at a fixed rate of 7.5 lifts/min for a total duration of 30 min (216 lifts/task). The physical dimensions of the experimental setup remained constant between tasks. Tasks differed based on the presence or absence of simultaneous cognitive distractions and/or precision placement challenges. Upper body kinematics and trunk muscle activation levels were monitored, and a two-dimensional dynamic biomechanical model was used to estimate L4/L5 joint loads. Reductions in elbow flexion (14.3%), elbow extension (16.6%), shoulder flexion (11.7%), and shoulder extension (10.2%) velocities were observed when precision placement challenges were imposed during lifting, and mean lift times increased by 27% as a result. This led to greater cumulative L4/L5 moments (23%), joint compression (15%), reaction shear (17%), and joint shear (10%) forces when precision placement constraints were imposed. Performing a cognitive distraction challenge while lifting had no impact on cumulative L4/L5 joint loads. The magnitude of cumulative L4/L5 loads was highly dependent on the preferred time taken to perform single-lift exertions, as there were no differences in peak L4/L5 loads between the tasks examined. This was further supported in that very few biomechanically significant changes were observed in trunk muscle activation levels or three-dimensional trunk kinematics as a function of the tasks performed. The results suggest that upper limb kinematic adaptations to precision placement constraints in repetitive lifting may alter the risk of reporting low back pain. Relevance to Industry The results of this study indicate that often overlooked task demands, particularly precision placement constraints, may modify the level of risk associated with the performance of repetitive manual lifting tasks. There was no evidence to suggest that exposure to simultaneous cognitive distractions while lifting would modify the level of risk under the conditions examined. Accordingly, these findings may be relevant in the design and biomechanical risk assessment of industrial lifting tasks.

Maximum acceptable weight of lift for manual lifting tasks

To explore the maximum acceptable weight of lift (MAWL) in different lifting conditions and the suitable lifting equation for the stipulation of occupational health standard of manual lifting tasks in China. The MAWL was investigated among the thirteen male and ten female students using psychophysical methodology and the recommended weight of limit (RWL) was compared. The MAWL of male and female subjects was decreased gradually with the increase of lifting height. Once the height of lifting was over shoulder, the MAWL was decreased dramatically. The RWL was greater than the MAWL at 25 cm horizontal distance in male subjects, but the RWL was smaller than the MAWL at the distance of 45 cm and 63 cm. The average MAWL of male subjects was 30.8% greater than that of female subjects. The MAWL was decreased gradually with increase of the horizontal distance at the same height of lifting. The result of the male subjects was consistent with that of the female subjects. For the asymmetric lifting tasks of the male subjects, the bigger the angle of rotation was, the less the MAWL became. The angle of rotation had negative correlation with the capability of lifting (r = -0.996 6, P < 0.01). When the subjects performed asymmetric lifting tasks, the RWL was smaller than the MAWL and the difference was significant. The revision is sufficient for the horizontal distance and asymmetric lifting in the NIOSH lifting equation, but it is not suitable for height, especially for the task of lifting over shoulder. The RWL for the task of lifting over shoulder should be lowered. The factor of gender should be taken into account in the lifting equation and the constant of gender S can be added. Then S = 1 for male while S = 0.692 for female.

A Field Evaluation Method for Assessing Whole Body Biomechanical Joint Stress in Manual Lifting Tasks

Work-related musculoskeletal injuries are often associated with overexertion of the body at work. The manual materials handling activity of lifting is a major source of work-related musculoskeletal disorders. Biomechanical evaluation offers useful information about the physical stress imposed on the worker's body joints; however, biomechanical analysis is usually tedious and complex. For evaluation purpose, the biomechanical method needs to be easy to apply in a field environment. Manual lifting occurs as one of the most common manual materials handling tasks in the workplace. A biomechanical evaluation method was developed based on the ratio of joint moment to joint capacity. The method was applied to evaluate the physical stress of manual lifting in truck loading jobs using a nine-link whole body joint model. Thirty eight industrial tasks were evaluated using the developed joint moment ratio. The moment ratio was compared with subjectively rated body discomfort, overall workload, and the NIOSH lifting index. The moment ratio was found to have a high correlation with the NIOSH lifting index. The biomechanical method can be used with relatively simple equipment and procedure which may be suitable for on-site ergonomic evaluation.

The application of surface electromyography in the assessment of ergonomic risk factors associated with manual lifting tasks.

The purpose of this study was to evaluate the ergonomic risk factors associated with manual lifting tasks using surface electromyography (EMG). 13 volunteers lifted loads of 6 and 13 kg at two speeds and at two horizontal distances in 3 different postures and three boxes of different sizes, from floor to knuckle height, performing 72 lifting tasks. For each lift, the surface electromyography signals from the erector spinae muscles, bilaterally at T10 and L3, was recorded. The ergonomic risk factors associated with manual lifting tasks were evaluated by comparing the average amplitude of EMG signals from the erector spinae muscles. The EMG average amplitude for lifting the load of 13 kg was 14.3% greater than that for lifting the load of 6 kg (t=-10.93, P<0.01). The EMG average amplitude at the site of L3 was 10.3% greater than that at the site of T10 (t=-7.98, P<0.01). The EMG average amplitude when performing "fast" lift was 5.9% greater than the "slow" lift (t=-4.63, P<0.01). The posture of lifting affected the EMG average amplitude. It was lowest with semi-squat posture and greatest with squat posture (F=27.76, P<0.01). The result of multiple stepwise regression analysis showed that the loads of lifting, the size of box, horizontal distance, posture of lifting, the site of the spine subjected to force, lifting speed were the factors affecting the EMG average amplitude. The most significant factor was the loads of lifting, followed by the site of the spine subjected to force and the lifting speed in terms of risk. The ergonomic risk factors associated with manual lifting tasks includes the loads, posture, lifting speed, horizontal distance, the site of the spine subjected to force etc. The results of signal amplitude of EMG from the erector spinae muscles showed that semi-squat posture is the best posture for lifting tasks.

Static lifting strengths at different exertion heights

Twelve healthy right-handed male subjects were recruited to investigate their maximum static lifting strengths for right-handed, left-handed and two-handed exertions at five different exertion heights (10, 45, 75, 105, and 140 cm). The results showed that the highest lifting strength occurred in the interval of exertion height between 10 and 45 cm while the lowest lifting strength at the exertion height of 105 cm. The hand dexterity seemed to have little connection with lifting strengths especially for higher exertion heights. This study suggests that two-handed lifting should be encouraged since it resulted in both higher lifting strengths and less strains on load-bearing shoulder, elbow and wrist structures compared with one-handed lifting. Additionally, the sum of right-handed and left-handed lifting strengths was greater than the two-handed lifting strength for exertion height below 75 cm, while it was smaller than the two-handed lifting strength at 140 cm exertion height. Relevance to industry This study provides the lifting strength data for one-handed and two-handed manual lifting tasks. Practitioners can use the results of this study for ergonomic design of manual lifting tasks and equipments in industry.

Estimation of EMG Activity of Trunk Muscles in Manual Lifting Tasks Based on Trunk Dynamics Using the Fuzzy Relational Rule Network

The main objective of this study was to demonstrate feasibility of predicting the electromyographic (EMG) activities of trunk muscles in manual lifting tasks. The applied data-driven fuzzy model with relational rule network utilized trunk dynamics as input variables, including sagittal and lateral trunk moments, pelvic tilt and rotation angles, and sagittal, lateral, and twist trunk angles. The data for model training and testing were randomly selected from a data set of EMG time domain values collected for 20 male college students. The utilized EMG data represented a total of 24 combinations of weight (15, 30, 50) lifted, asymmetry (0–60 degrees), and the origin and destination of lift (floor-waist, floor-102 cm, knee-waist, knee-102 cm), with two replications of each condition. The model was trained using the data for ten subjects and 18 randomly selected trials, and was then tested based on the EMG data for another ten subjects using randomly selected 6 trials. The model allowed for estimating EMG responses (in time domain) for the ten trunk muscles with the mean absolute error ranging from 0.91% to 11.8%. The study showed that it is feasible to estimate the time domain EMG responses of human trunk muscles due to manual lifting tasks with the acceptable level of accuracy.

A computerized video coding system for biomechanical analysis of lifting tasks

This paper illustrates the design of a computerized postural coding system using information from field survey videotapes and limited input (e.g., load, weight, and height) to provide a timely estimation of kinematic and kinetic data for biomechanical analysis of sagittal lifting task evaluation and design. The main objectives of the study were to report the development of this technique, assess its applicability, and examine its prediction tolerance under several lifting conditions. A computer graphical user interface was developed, relying on interactive graphical three-dimensional animation to assist the prediction of a subject's lifting movement. The subject's motion was predicted based on the identification of major joint angles of key posture events extracted from the lifting video clips of the analyzed task. The key prediction outcome of this approach is the estimation of joint loading over time, including the compressive force on the lumbosacral (L5/S1) joint. Biomechanical experiments were conducted to evaluate the proposed method under several sagittal lifting conditions. The results showed that the proposed method is comparable to the use of a complex system. While there existed a tolerance between both systems in estimation of the lower back compressive force, the maximum error percentage (≈10%) is considered within a reasonable range. The implication of this approach is to provide a feasible method for performing on-site evaluations of the biomechanics of lifting tasks which cannot be performed otherwise due to the limitations of time and resources. It can also be used for pilot studies to timely identify and select the most critical tasks for more detailed analyses. Relevance to industry This study presents a design that is capable of performing the biomechanical assessment of manual lifting tasks using only the field survey videotapes and limited input data. For industrial-based in situ analyses, this approach may provide an alternative for biomechanical assessment of manual lifting tasks while still maintaining the quality of results.

Workers' assessments of manual lifting tasks: cognitive strategies and validation with respect to objective indices and musculoskeletal symptoms.

To determine the different cognitive strategies adopted by workers in assessing the effects of lifting-task parameters on effort, and to validate workers' assessments. Questionnaires were administered to 217 male workers with varied levels of experience in manual handling. Workers were asked to assess the effects of lifting on perceived effort, using linguistic descriptors (e.g., light, heavy), and to determine the physical meaning of such descriptors. In addition, each worker assessed on-the-job effort, perceived risk of injury and work dissatisfaction, and musculoskeletal outcomes in a cross-sectional design. Perceived physical effort was significantly associated with lifting variables. Results indicated that the three-cluster strategy is the best performer. Weight of load emerged as the most influential factor that impacted on effort in the most dominant cluster (close to 50% of the observations). The second cluster (25% of the observations) demonstrated that weight, horizontal distance, and twisting angle, contributed equally to effort, and the third cluster had weight and vertical travel distance as the most important variables (with travel distance being more important). Perceived effort was significantly associated with objective indices (i.e., biomechanical lifting equivalent and NIOSH lifting index), and musculoskeletal symptoms in eight body parts. Cognitive reasoning of experienced workers may be used as an active device for the evaluation of strenuous physical activities such as lifting tasks. Lifting activities are significantly associated with musculoskeletal symptoms, not only in the lower-back region, but also in seven other body parts; and effort may integrate the effects of both physical (lifting tasks) and non-physical (i.e., work dissatisfaction) factors, as well as perception of risk.

Empirical evaluation of training and a work analysis tool for participatory ergonomics

A controlled laboratory experiment was performed to test the effects of ergonomics training and the NIOSH lifting equation on the participatory redesign of a simulated manual material handling job. Before performing the job, 16 subjects were given ergonomics training and 16 were instructed on how to use the NIOSH lifting equation for manual lifting tasks. Compared to a control group, subjects who received the ergonomics instruction identified and eliminated more risk factors in the simulated job. While subjects who used the NIOSH lifting equation also identified more risk factors, they did not eliminate any more risk factors than the control group. No additive benefit was found using both the training and the lifting equation over either method alone. Ergonomics training led to better improvements than use of the lifting equation in terms of risk factors identified and eliminated. Implications for use of training and tools in participatory ergonomics approaches are discussed. Relevance to industry This study supports that ergonomics training should be a requisite for any participatory ergonomics approach. Given a fundamental level of ergonomics training, subjects demonstrated that they were better capable of identifying and eliminating risk factors in the job.