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A comparison of lumbar spine and muscle loading between male and female workers during box transfers
There is a clear relationship between lumbar spine loading and back musculoskeletal disorders in manual materials handling. The incidence of back disorders is greater in women than men, and for similar work demands females are functioning closer to their physiological limit. It is crucial to study loading on the spine musculoskeletal system with actual handlers, including females, to better understand the risk of back disorders. Extrapolation from biomechanical studies conducted on unexperienced subjects (mainly males) might not be applicable to actual female workers. For male workers, expertise...
Two-dimensional biomechanical thumb model for pipetting
Manual pipetting imposes repetitive movements, high force, and awkward postures on the thumb, fingers, and wrist, increasing the risk of musculoskeletal injuries. The purpose of this study is to provide a linear regression model to estimate the optimal pipetting grip height based on the two-dimensional biomechanical static thumb model developed in this study. This biomechanical static thumb model uses hand anatomy and static equilibrium conditions to estimate internal tendon forces against a given external force. Based on the model, we conclude that the optimal grip height is 3 cm in males and...
The influence of external load configuration on trunk biomechanics and spinal loading during sudden loading
Sudden loading is a major risk factor for work-related lower back injuries among occupations involving manual material handling (MMH). The current study explored the effects of external weight configuration on trunk biomechanics and trunk rotational stiffness in the sagittal plane during sudden loading. Fifteen asymptomatic volunteers experienced sudden loadings using the same magnitude of weight (9 kg) with two different configurations (medially- or laterally-distributed) at three levels of height (low, middle and high). Results of this study showed that the medially distributed weight...
Occupational biomechanical risk factors for surgically treated ulnar nerve entrapment in a prospective study of male construction workers
Evidence was provided for forceful hand-grip work, with and without vibration, as a risk factor for ulnar nerve entrapment (UNE) surgery in a large cohort of Swedish construction workers. Several individual biomechanical factors comprising such work were associated with increased risk of UNE, including: increased grip force, upper extremity load, frequency of hand-held tool use, and hand arm vibration. Source: Jackson, J. A., Olsson, D., Punnett, L., Burdorf, A., Järvholm, B. et Wahlström, J. (2018). Scandinavian journal of work, environment & health . http://dx.doi.org/10.5271/sjweh...
Surface electromyography for risk assessment in work activities designed using the “revised NIOSH lifting equation”
The aims of this study were: to identify surface electromyography (sEMG)-based indices of trunk muscles acquired during the execution of lifting tasks designed using the revised NIOSH lifting equation and featuring a progressively increasing lifting index (LI); to study changes of these indices in relation to the LI; to evaluate the relationship between the identified indices and forces (FL5−S1) and moments (ML5−S1) at the L5-S1 joint. sEMG, kinematic and kinetic data of 20 male workers were recorded in three conditions. We computed the average rectified value (ARV), root mean square...
How does the biomechanical exposure of the upper body in manual box handling differ from exposure in other tasks in the real industrial context?
The assessment of biomechanical exposure during handling tasks in relation to other activities that are performed in industrial settings can be crucial to understand the biomechanical demands of manual box handling for the upper limbs. This study aims to evaluate the representativeness of the handling task to the upper body in comparison with the other tasks in a real setting, compare the biomechanical exposure between tasks, and identify the differences in exposure during manual box handling from job exposure. Twelve workers had biomechanical exposure assessed through trapezius muscle activity...
Accuracy, precision and reliability in anthropometric surveys for ergonomics purposes in adult working populations
A literature review Anthropometric surveys are the most common method of gathering human morphometric data, used to design clothing, products and workspaces. The aim of this paper was to assess how current peer reviewed literature addresses the accuracy, reliability and precision regarding manual anthropometric surveys applied to adult working populations in the field of ergonomics. A literature review was performed in two electronic databases for finding relevant papers. A total of 312 papers were reviewed, of which 79 met the inclusion criteria. The results shown that the subjects of these publications...
Développement d’un système de mesures et d’un protocole de mesures permettant de quantifier l’exposition physique des manutentionnaires
L'objectif principal de ce projet était de combiner différents senseurs et instruments pour expérimenter, en laboratoire et sur le terrain, un système de mesures permettant d'estimer quantitativement l'exposition physique des manutentionnaires. Ce type de système pourrait éventuellement servir à évaluer objectivement l'efficacité d'approches de prévention. Un second objectif consistait à mettre au point une stratégie d'échantillonnage pour optimiser la mesure de l'exposition physique...
Inter-day reliability of surface electromyography recordings of the lumbar part of erector spinae longissimus and trapezius descendens during box lifting
Background: Low back pain and neck-shoulder pain are the most reported types of work-related musculoskeletal disorders, and performing heavy lifting at work and working with trunk rotation increase the risk of developing work-related musculoskeletal disorders. Surface electromyography (sEMG) provides information about the electrical activity of muscles. Thus it has the potential to retrieve indirect information about the physical exposure of specific muscles of workers during their actual work. This study aimed to investigate the inter-day reliability of absolute and normalized amplitude of sEMG...
Proceedings of the 5th International Digital Human Modeling Symposium
The proceedings present the the peer-reviewed articles of the 5th International Digital Human Modeling Symposium. The symposium was held from June 26-28, 2017 at the Fraunhofer-Institute for Communication, Information Processing and Ergonomics (FKIE), in cooperation with the unit "Human factors and ergonomics" of the Federal Institute for Occupational Safety and Health (BAuA). Source: https://www.baua.de/EN/Service/Publications/Report/Gd91.html
NIOSH Lifting Equation App: NLE Calc
The National Institute for Occupational Safety and Health (NIOSH) Lifting Equation mobile application, NLE Calc, is a tool to calculate the overall risk index for single and multiple manual lifting tasks. This application provides risk estimates to help evaluate lifting tasks and reduce the incidence of low back injuries in workers. Source: https://www.cdc.gov/niosh/topics/ergonomics/nlecalc.html
Cumulative occupational mechanical exposures during working life and risk of sickness absence and disability pension
Prospective cohort study Using a biomechanical job exposure matrix combined with Danish registers, cumulative occupational mechanical exposures throughout life (ie, more years with heavy and frequent lifting, and kneeling work) predicted risk of long-term sickness absence among older workers. Importantly, heavy lifting throughout working life was associated with disability pension. Source: Sundstrup E, Hansen ÅM, Mortensen EL, Poulsen OM, Clausen T, Rugulies R, Møller A, Andersen LL. (2017). Scand J Work Environ Health . http://dx.doi.org/10.5271/sjweh.3663
Qualitative ergonomics/human factors research in health care
Current state and future directions The objective of this systematic review was to understand the current state of Ergonomics/Human Factors (E/HF) qualitative research in health care and to draw implications for future efforts. This systematic review identified 98 qualitative research papers published between January 2005 and August 2015 in the seven journals endorsed by the International Ergonomics Association with an impact factor over 1.0. The majority of the studies were conducted in hospitals and outpatient clinics, were focused on the work of formal health care professionals, and were classified...
Difference between male and female workers lifting the same relative load when palletizing boxes
A few biomechanical studies have contrasted the work techniques of female and male workers during manual material handling (MMH). A recent study showed that female workers differed from males mostly in the strategy they used to lift 15-kg boxes from the ground, especially regarding task duration, knee and back postures and interjoint coordination. However, the lifting technique difference observed in females compared to males was perhaps due to a strength differences. The objective of this study was to test whether female workers would repeat the same lifting technique with a load adjusted to their...
Evaluating the low back biomechanics of three different office workstations: Seated, standing, and perching
The objective of this study was to evaluate how different workstations may influence physical behavior in office work through motion and how that may affect spinal loads and discomfort. Twenty subjects performed a typing task in three different workstations (seated, standing, and perching) for one hour each. Measures of postural transitions, spinal loads, discomfort, and task performance were assessed in order to understand the effects of workstation interaction over time. Results indicated that standing had the most amount of motion (6–8 shifts/min), followed by perching (3–7 shifts...
Estimation of lumbar spinal loading and trunk muscle forces during asymmetric lifting tasks
Application of whole-body musculoskeletal modelling in OpenSim Large spinal compressive force combined with axial torsional shear force during asymmetric lifting tasks is highly associated with lower back injury (LBI). The aim of this study was to estimate lumbar spinal loading and muscle forces during symmetric lifting (SL) and asymmetric lifting (AL) tasks using a whole-body musculoskeletal modelling approach. Thirteen healthy males lifted loads of 7 and 12 kg under two lifting conditions (SL and AL). Kinematic data and ground reaction force data were collected and then processed by a whole-body...
Estimation du chargement au dos
Développement d'une méthode ambulatoire intégrant la cinématique du dos et de l'électromyographie De nombreux travailleurs1 sont atteints de maux de dos chaque année. La région lombaire est de loin celle qui est la plus fréquemment atteinte, et ce type de troubles musculosquelettiques est principalement occasionné par des efforts excessifs, surtout en soulevant quelque chose, et les chargements aux tissus de la colonne qu'ils engendrent. Il n'existe pas de méthode de mesure directe de ces chargements qui puisse...
Estimation du chargement lombaire au moyen de modèles biomécaniques articulaires
Évaluation et application Les troubles musculosquelettiques (TMS) et tout particulièrement les affections vertébrales constituent un fardeau autant pour la société que pour les personnes qui en sont affectées. Au Québec, le nombre d'affections vertébrales s'établissait en 2011 à 21 228 et elles représentaient près de 30 % de l'ensemble des lésions professionnelles indemnisées. C'est la région lombaire de la colonne vertébrale qui est la zone la plus touchée (60...
Effect of firefighters' personal protective equipment on gait
The biomechanical experiment with eight male and four female firefighters demonstrates that the effect of adding essential equipment: turnout ensemble, self-contained breathing apparatus, and boots (leather and rubber boots), significantly restricts foot pronation. This finding is supported by a decrease in anterior-posterior and medial-lateral excursion of center of plantar pressure (COP) trajectory during walking. The accumulation of this equipment decreases COP velocity and increases foot-ground contact time and stride time, indicating increased gait instability. An increase in the flexing resistance...
Revised NIOSH Lifting Equation May generate spine loads exceeding recommended limits
The 1991 NIOSH Lifting Equation (NLE) is widely used to assess the risk of injury to spine by providing estimates of the recommended weight limit (RWL) in hands. The present study uses the predictive equations developed based on a detailed trunk musculoskeletal biomechanical model to verify whether the RWL generates L5-S1 loads within the limits (e.g., 3400 N for compression recommended by NIOSH and 1000 N for shear recommended in some studies). Fifty lifting activities are simulated here to evaluate the RWL by the NLE and the L5-S1 loads by the predictive equations. In lifting activities involving...
Psychometric properties evaluation of a new ergonomics-related job factors questionnaire developed for nursing workers
The objectives of this study were to develop a questionnaire that evaluates the perception of nursing workers to job factors that may contribute to musculoskeletal symptoms, and to evaluate its psychometric properties. Internationally recommended methodology was followed: construction of domains, items and the instrument as a whole, content validity, and pre-test. Psychometric properties were evaluated among 370 nursing workers. Construct validity was analyzed by the factorial analysis, known-groups technique, and convergent validity. Reliability was assessed through internal consistency and stability...
Effects of work experience on work methods during dynamic pushing and pulling
Pushing and pulling are potential risk factors for work-related low back disorders (WRLBDs). While several studies have evaluated differences in work methods related to work experience, such evidence for dynamic pushing and pulling is limited. Eight novices and eight experienced workers completed dynamic push/pull tasks using a cart weighted to 250% of individual body mass in two different configurations (preferred vs. elbow handle heights). Multiple measures [hand forces, torso kinematics and kinetics, and required coefficient of friction (RCOF)] were obtained to assess WRLBD and slip risks. Experienced...
Cinématique et modélisation biomécanique de l’épaule lors de tâches de manutention
De récentes revues de la littérature épidémiologique montrent que travailler avec les bras en position levée augmente la probabilité de développer des troubles musculosquelettiques (TMS) aux épaules. Bien que l’origine et les mécanismes de TMS à l’épaule manquent d’évidence dans la littérature scientifique, réaliser une tâche avec les bras en position levée cause un chargement de la musculature de l’épaule plus important. Cependant, peu d’éléments...
Determining Safe Limits for Significant Task Parameters During Manual Lifting
This experimental study investigated the effect of lifting task parameters (i.e., lifting weight, frequency, coupling, asymmetric angle, and vertical, horizontal, and travel distances) for various dynamic human lifting activities on the ground reaction forces of workers. Ten male workers loaded containers from different levels asymmetrically during experimental trials. The experimental design evolved using Taguchi's Fractional Factorial Experiments. Three factors (lifting weight, frequency, and vertical distance) were observed to be significant. The results showed that vertical reaction forces...
The assessment of material handling strategies in dealing with sudden loading
The effects of load handling position on trunk biomechanics Back injury caused by sudden loading is a significant risk among workers that perform manual handling tasks. The present study investigated the effects of load handling position on trunk biomechanics (flexion angle, L5/S1 joint moment and compression force) during sudden loading. Eleven subjects were exposed to a 6.8 kg sudden loading while standing upright, facing forward and holding load at three different vertical heights in the sagittal plane or 45° left to the sagittal plane (created by arm rotation). Results showed that the increase...
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