Motricité, Motricity, Motricidad, Flexion, Bending, Flexión, Homme, Human, Hombre, Membre supérieur, Upper limb, Miembro superior, Mâle, Male, Macho, Pincement, Pinching, Desmoche, Poignet, Wrist, Muñeca, Préhension, Gripping, Prension, Supination, Supinación, Torsion, Torsión, Travailleur, Worker, Trabajador, handgrip, maximum acceptable torques, maximum isometric torque, pinch extension and flexion, screw driving, supination, ulnar deviation, upper extremity, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Psychologie. Psychophysiologie, Psychology. Psychophysiology, Niveaux d'activité. Psychomotricité, Activity levels. Psychomotricity, Activités psychomotrices, Psychomotor activities, Psychologie. Psychanalyse. Psychiatrie, Psychology. Psychoanalysis. Psychiatry, Cognition, Genetics, Génétique, Applied physiology, ergonomics sports medicine, Physiologie appliquée, ergonomie, sport, Psychology, psychopathology, psychiatry, and Psychologie, psychopathologie, psychiatrie

Objective: The purpose of the study was to quantify maximum acceptable torques (MATs) in 16 healthy male industrial workers while performing six motions: screw driving clockwise with a 40 mm handle and a 39 mm yoke handle,flexion and extension with a pinch grip, ulnar deviation with a power grip (similar to knife cutting), and a handgrip task (similar to a pliers task). Background: Psychophysical studies on repetitive motions of the wrist and hand were previously reported on women; however, it is not clear how men will psychophysically respond to similar motions. Method: A psychophysical methodology was used in which the participant adjusted the resistance on the handle. Repetition rates for these tasks were 15 and 25 per minute. Participants performed the tasks for 7 hours per day, 5 days per week, and for 12 days. Symptoms were recorded by the subjects at the end of each hour. Results: The mean MATs ranged from 1.15 Nm to 1.88 Nm for screw driving, 2.26 Nm to 3.71 Nm for pinch flexion and extension, 3.88 Nm to 4.07 Nm for ulnar deviation, and 11.47 Nm to 13.98 Nm for the handgrip task.The higher the repetition rate, the lower the MAT. Depending on the type of task and repetition rate, these values represented 15% to 35% (median of 23%) of their maximum isometric torque. Application: Based on aforementioned findings, a table of MATs and derived acceptable forces for six tasks at different percentage capabilities of the male industrial populations is formulated.

Environment, Environnement, Hygiene and public health, epidemiology, occupational medicine, Hygiène et santé publique, épidémiologie, médecine du travail, Toxicology, Toxicologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Sante publique. Hygiene-medecine du travail, Public health. Hygiene-occupational medicine, Médecine du travail, Occupational medicine, Divers, Miscellaneous, Ergonomie, Ergonomics, Ergonomía, Etude comparative, Comparative study, Estudio comparativo, Exposition professionnelle, Occupational exposure, Exposición profesional, Homme, Human, Hombre, Industrie, Industry, Industria, Manutention, Handling, Manutención, Médecine du travail, Occupational medicine, Medicina ocupacional, Psychophysique, Psychophysics, Psicofísica, Recommandation, Recommendation, Recomendación, Sexe, Sex, Sexo, Travailleur, Worker, Trabajador, Charge physique, Genre, Gender, Género, Carrying, Ergonomic redesign, Lifting and lowering, Manual materials handling guidelines, and Pushing and pulling

Purpose In the year 1991, manual materials handling guidelines were published by Liberty Mutual Research Institute for Safety. In these guidelines, maximum acceptable weights (MAWs) and forces (MAFs) for lifting, lowering, pushing, pulling, and carrying were derived from studies conducted in a 20 year span before the above publication date. The question is whether the present generation of workers has retained the same gender differences and absolute values in psychophysically determined MAWs and MAFs as those reflected in the guideline. Methods Twenty-four female industrial workers performed 20 variations of lifting, lowering, pushing, pulling, and carrying. A psychophysical methodology was used whereby the workers chose a workload they could sustain for 8 h without straining themselves or without becoming unusually tired, weakened, overheated or out of breath. Results In females, MAWs of lifting, lowering, and carrying averaged 53% of the present-day male values, similar to the 55% in the guideline. MAFs of pushing and pulling were 83 and 86% of the present-day male values but slightly higher than the 73 and 78% in the guideline, respectively for initial and sustained forces. Conclusions The similarity of gender differences between the guideline and the present findings was coupled with dramatic decreases in MAWs of lifting, lowering, and carrying. Such decreases may reflect a new psychophysical set point; however, considerations about adjusting existing guidelines on lifting, lowering, and carrying may not be appropriate until additional data from other sources inside and outside the US confirm the present findings.

Education, Éducation, Applied physiology, ergonomics sports medicine, Physiologie appliquée, ergonomie, sport, Psychology, psychopathology, psychiatry, Psychologie, psychopathologie, psychiatrie, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Physiologie humaine appliquee a l'etude des populations et des conditions de vie. Ecophysiologie humaine, Human physiology applied to population studies and life conditions. Human ecophysiology, Physiologie appliquée, Applied physiology, Ergonomie. Poste de travail. Physiologie du travail, Ergonomics. Work place. Occupational physiology, Démontage, Desassembly, Desmontaje, Ergonomie, Ergonomics, Ergonomía, Etude en laboratoire, Laboratory study, Estudio en laboratorio, Gestion production, Production management, Gestión producción, Homme, Human, Hombre, Montage, Assembly, Montaje, Méthodologie, Methodology, Metodología, Organisation travail, Job engineering, Organización trabajo, Production, Producción, Tâche manuelle, Manual task, Tarea manual, laboratory study, management of production, and work organisation

A study was conducted to investigate the influence of different approaches to arranging the pace and temporal organisation of repetitive assembly and disassembly tasks on both average performance and its variability and to compare assembly and disassembly times derived with psychophysical methods to a more traditional methods-time measurement (MTM) approach. The conditions studied were a traditional assembly line arrangement, where assemblies were started at a pace of 110 MTM (repeated on two occasions), a batch condition, where subjects were required to complete 36 assemblies within the total amount of time allowed at 110, MTM and a psychophysical condition, where subjects were allowed to choose their pace (repeated on two occasions). Overall, the results suggest that the mean time spent working in each cycle (the 'on-time') remained fairly constant across conditions, while the idle 'off-time' in between on-times was shorter and of less varied duration in the more autonomous batch and psychophysical conditions. During the second psychophysical (self-paced) condition, subjects completed a significantly higher number of assemblies than during the 110 MTM line condition. The higher pace was achieved through reduction in mean off-times and the potential implications for musculoskeletal risk are discussed.

Ecology, Ecologie, Environment, Environnement, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Pollution, Traitement et pollution des eaux, Water treatment and pollution, Pollution des eaux naturelles, Natural water pollution, Eaux continentales superficielles, Continental surface waters, Analyse risque, Risk analysis, Análisis riesgo, Eau surface, Surface water, Agua superficie, Evaluation risque, Risk assessment, In vitro, Inhalation, Inhalación, Oxyde de titane, Titanium oxide, Titanio óxido, Risque santé, Health hazards, Riesgos contra salud, Réglementation, Regulation, Reglamentación, Santé publique, Public health, Salud pública, Statistique rang, Rank statistic, Estadística rango, Toxicité, Toxicity, Toxicidad, Nanomaterials, environmental risk, human health risk, and risk ranking

As nanomaterials find increased application in commercial and industrial products and processes so too the potential for release of these novel materials into the environment increases. The characteristics of these materials also may result in novel toxicological actions related to their nanoscale, which will have implications on their ecotoxicological and toxicological limits of exposure and eventual regulation. A framework for nanomaterial risk assessment on regulatory, ecotoxicological and toxicological bases developed from recent exposure and toxicity studies is presented. The release of nanoscale TiO2, Ag and CeO2 to the atmosphere and surface waters is assessed against provisional toxicological bench mark doses (BMDs) and critical effect doses (CEDs) developed from best available data. Predicted levels of nanomaterial release to surface waters and the atmosphere resulted in regulatory risk rankings of moderate concern based on worst case provisional regulatory limits. Inhalation and ingestion risk rankings were of very low concern based on the provisional inhalation and ingestion toxicity BMDLs and CEDLs determined for the nanomaterials in question. More toxicological data is needed on nanoscale CeO2 inhalation to develop a true dose response as in vitro cytotoxicity studies yielded an inhalation risk ranking of lower concern. The moderate to high ecotoxicological risk rankings posed by the release of nanoscale TiO2 and Ag to surface waters highlights the need for guidance and restriction on the usage and disposal of commercial products containing nanomaterial. The risk rankings presented in this assessment give a first indication of the relative risks posed by the usage and release of these materials into the environment and indicate what materials require further investigation into their nano-specific toxicological actions. As more nano-relevant toxicity studies are published, end-points and risk levels related to nano-specific toxicity actions may be determined and the provisional BMDLs developed as part of this framework refined, resulting in more confident risk rankings.

Applied physiology, ergonomics sports medicine, Physiologie appliquée, ergonomie, sport, Psychology, psychopathology, psychiatry, Psychologie, psychopathologie, psychiatrie, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Physiologie humaine appliquee a l'etude des populations et des conditions de vie. Ecophysiologie humaine, Human physiology applied to population studies and life conditions. Human ecophysiology, Physiologie appliquée, Applied physiology, Ergonomie. Poste de travail. Physiologie du travail, Ergonomics. Work place. Occupational physiology, Ergonomie, Ergonomics, Ergonomía, Femelle, Female, Hembra, Force, Fuerza, Homme, Human, Hombre, Industrie, Industry, Industria, Manutention, Handling, Manutención, Poussée, Thrust, Empujón, Psychophysique, Psychophysics, Psicofísica, Recommandation, Recommendation, Recomendación, Reproductibilité, Reproducibility, Reproductividad, Travail dynamique, Dynamic work, Trabajo dinámico, Travailleur, Worker, Trabajador, Cart pushing, and Manual materials handling

Using psychophysics, the maximum acceptable forces for pushing have been previously developed using a magnetic particle brake (MPB) treadmill at the Liberty Mutual Research Institute for Safety. The objective of this study was to investigate the reproducibility of maximum acceptable initial and sustained forces while performing a pushing task at a frequency of 1 min-1 both on a MPB treadmill and on a high-inertia pushcart. This is important because our pushing guidelines are used extensively as a ergonomic redesign strategy and we would like the information to be as applicable as possible to cart pushing. On two separate days, nineteen female industrial workers performed a 40-min MPB treadmill pushing task and a 2-hr pushcart task, in the context of a larger experiment. During pushing, the subjects were asked to select a workload they could sustain for 8 h without straining themselves or without becoming unusually tired, weakened, overheated or out of breath. The results demonstrated that maximum acceptable initial and sustained forces of pushing determined on the high inertia pushcart were 0.8% and 2.5% lower than the MPB treadmill. The results also show that the maximum acceptable sustained force of the MPB treadmill task was 0.5% higher than the maximum acceptable sustained force of Snook and Ciriello (1991). Overall, the findings confirm that the existing pushing data developed by the Liberty Mutual Research Institute for Safety still provides an accurate estimate of maximal acceptable forces for the selected combination of distance and frequency of push for female industrial workers.

Cognition, Genetics, Génétique, Applied physiology, ergonomics sports medicine, Physiologie appliquée, ergonomie, sport, Psychology, psychopathology, psychiatry, Psychologie, psychopathologie, psychiatrie, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Physiologie humaine appliquee a l'etude des populations et des conditions de vie. Ecophysiologie humaine, Human physiology applied to population studies and life conditions. Human ecophysiology, Physiologie appliquée, Applied physiology, Ergonomie. Poste de travail. Physiologie du travail, Ergonomics. Work place. Occupational physiology, Pathologie du muscle strié, Striated muscle disease, Músculo estriado patología, Activité professionnelle, Professional activity, Actividad profesional, Charge travail, Workload, Carga trabajo, Chariot industriel, Industrial truck, Carro industrial, Ergonomie, Ergonomics, Ergonomía, Exposition professionnelle, Occupational exposure, Exposición profesional, Femelle, Female, Hembra, Frottement, Friction, Frotamiento, Homme, Human, Hombre, Poussée, Thrust, Empujón, Psychophysiologie, Psychophysiology, Psicofisiología, Surface sol, Ground surface, Superficie suelo, Trouble musculosquelettique, Musculoskeletal disorder, Patología sistema musculoesqueletico, Tâche manuelle, Manual task, and Tarea manual

Objective: The aim of this study was to evaluate psychophysically determined acceptable forces, cardiopulmonary, and calf muscle metabolic responses in 15 workers while they pushed an instrumented cart on two walkways. Background: In addition to the potential for increased musculoskeletal disorders in workers, pushing on various terrains is associated with occurrence of slips and falls at the workplace. Method: Using a psychophysical approach, participants chose the maximum acceptable cart weight they could push without strain on walkways with coefficient of friction equaling 0.68 (plywood) and 0.26 (Teflon-coated.). Then, while participants pushed their psychophysically chosen cart weight for 2 hr on each walkway, horizontal and vertical forces applied on the cart handle and physiological responses were collected. Cardiopulmonary responses were measured using a telemetric metabolic cart. A tissue hemoglobin index (THI) and a tissue oxygenation index (TOI) from the right and left calf muscles were obtained using near-infrared spectroscopy. Results: Participants generated higher horizontal forces (by 26%) on plywood than that on Teflon. Cardiopulmonary and TOI and THI responses were similar between walkways. However, greater ratios of absolute oxygen uptake per force (by 19%) and TOI per force (by 24%) on Teflon were demonstrated in the horizontal direction than on plywood. Conclusions: This increased muscle oxygenation―force ratio, coupled with increased oxygen uptake per force generated on Teflon, might suggest that pushing on the slippery surface results in higher metabolic demand. Application: Findings from the present study will assist in revising previously established acceptable forces and in relating these forces to physiological responses with respect to pushing on different frictional walkways.