Maximal acceptable torques of six highly repetitive hand-wrist motions for male industrial workers.

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.

Influence of three principles of pacing on the temporal organisation of work during cyclic assembly and disassembly tasks.

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.

Gender differences in psychophysically determined maximum acceptable weights and forces for industrial workers observed after twenty years.

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.

Gender comparison of psychophysical forces, cardiopulmonary, and muscle metabolic responses during a simulated cart pushing task.

The purpose was to compare psychophysiological responses between healthy male and female workers during dynamic pushing. Using a psychophysical approach, 27 participants chose an acceptable force that they could push over a 7.6m distance at a frequency of 1 push per min on a treadmill.

Psychophysiological responses in women during cart pushing on different frictional walkways.

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.

Psychophysically determined forces of dynamic pushing for female industrial workers: Comparison of two apparatuses.

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 1min(-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.

Dynamic pushing on three frictional surfaces: maximum acceptable forces, cardiopulmonary and calf muscle metabolic responses in healthy men.

Pushing is an important materials handling activity in many occupations; however, pushing-related physiological investigations are still in infancy. The purpose was to evaluate maximum acceptable forces and physiological responses while pushing on: treadmill (TREAD); plywood floor (PLY); and Teflon floor (TEF). Acceptable forces, cardiopulmonary and calf muscle oxygenation and blood volume responses were collected simultaneously while 12 men (age 39 +/- 13 years; height 178 +/- 6 cm; and body mass 91.

Oxygen consumption prediction models for individual and combination materials handling tasks.

An experiment was conducted to develop models to predict oxygen consumption of males and females engaged in common materials handling tasks including lifting, lowering, pushing, pulling, (de)palletising and combination tasks involving lifting or lowering a box and carrying it a set distance and lifting or lowering it to the destination. Nineteen male and 19 female subjects participated in the study. A psychophysical approach was used to set load limits for individual subjects for the oxygen consumption protocol.

Secular changes in psychophysically determined maximum acceptable weights and forces over 20 years for male industrial workers.

The most frequent and expensive cause of compensable workplace injuries loss is manual material handling (MMH). In an attempt to minimise these losses, refinement of existing MMH guidelines is a component of redesigning high risk MMH jobs. In the development of the present MMH 1991 guidelines (Snook and Ciriello 1991), maximum acceptable weights (MAWs) and forces (MAFs) were derived from studies conducted in a 21 year time span before the above publication date.

The effect of workstation and task variables on forces applied during simulated meat cutting.

The purpose of the study was to investigate factors related to force and postural exposure during a simulated meat cutting task. The hypothesis was that workstation, tool and task variables would affect the dependent kinetic variables of gripping force, cutting moment and the dependent kinematic variables of elbow elevation and wrist angular displacement in the flexion/extension and radial/ulnar deviation planes. To evaluate this hypothesis a 3 x 3 x 2 x 2 x 2 (surface orientation by surface height by blade angle by cut complexity by work pace) within-subject factorial design was conducted with 12 participants.