Effects of different block designs on low back and shoulders biomechanical loads and postural stability during crab pot handling.

In commercial Dungeness crab fishing vessels, the block pulls crab pots for harvesting and typically positions them to the side of vessels, rather than the sorting tables on board. Consequently, fishermen must reach outside the vessel to grab the pots, posing increased risk of musculoskeletal and fall-related injuries. To investigate the effects of block design on these risks, 25 participants in a repeated-measures laboratory study handled a pot under two block conditions: away-from-table (conventional setting) and above-table (intervention).

Vertical-dominant and multi-axial vibration associated with heavy vehicle operation: Effects on dynamic postural control.

Heavy vehicle operators suffer from increased fall risk, potentially due to exposure to whole-body vibration (WBV) that compromises postural control. This study aimed to characterize the relative impacts of multi-axial WBV vs. vertical-dominant WBV on dynamic postural control during sit-to-stand transition and stair descent, following prolonged vibration exposures.

Effects of error rates and target sizes on neck and shoulder biomechanical loads during augmented reality interactions.

Augmented reality (AR) interactions have been associated with increased biomechanical loads on the neck and shoulders. To provide a better understanding of the factors that may impact such biomechanical loads, this repeated-measures laboratory study evaluated the effects of error rates and target sizes on neck and shoulder biomechanical loads during two standardized AR tasks (omni-directional pointing and cube placing). Twenty participants performed the two AR tasks with different error rates and target sizes.

A fishermen-developed intervention reduced musculoskeletal load associated with commercial Dungeness crab harvesting.

This study characterized physical risk factors associated with injuries during a Dungeness crab harvesting task and evaluated the efficacy of a fishermen-developed ergonomic control (banger bar) in mitigating physical risk factors, including biomechanical loads in the low back, shoulders, and upper extremities, and postural instability. In a repeated-measures laboratory study, 25 healthy male participants performed manual crab harvesting tasks in five conditions: without any banger bar (control) and with 4 bars of differing heights or designs. The results showed that the ergonomic control reduced trunk and shoulder angles, L5/S1, and shoulder moments; muscle activities in low back, shoulders, and upper extremities; perceived exertion ratings; and postural sway measures.

A passive upper-limb exoskeleton reduced muscular loading during augmented reality interactions.

The aim of this study was to evaluate a passive upper-limb exoskeleton as an ergonomic control to reduce the musculoskeletal load in the shoulders associated with augmented reality (AR) interactions. In a repeated-measures laboratory study, each of the 20 participants performed a series of AR tasks with and without a commercially-available upper-limb exoskeleton. During the AR tasks, muscle activity (anterior, middle, posterior deltoid, and upper trapezius), shoulder joint postures/moment, and self-reported discomfort were collected.

Evaluation of vertical and multi-axial suspension seats for reducing vertical-dominant and multi-axial whole body vibration and associated neck and low back joint torque and muscle activity.

The primary aim of this laboratory-based human subject study was to evaluate the biomechanical loading associated with mining vehicles' multi-axial whole body vibration (WBV) by comparing joint torque and muscle activity in the neck and low back during three vibration conditions: mining vehicles' multi-axial, on-road vehicles' vertical-dominant, and no vibration. Moreover, the secondary aim was to determine the efficacy of a vertical passive air suspension and a prototype multi-axial active suspension seat in reducing WBV exposures and associated biomechanical loading measures. The peak joint torque and muscle activity in the neck and low back were higher when exposed to multi-axial vibration compared to the vertical-dominant or no vibration condition.

The effects of target size and error rate on the cognitive demand and stress during augmented reality interactions.

This study investigated the effects of target size and error rate on cognitive demand during augmented reality (AR) interactions. In a repeated-measures laboratory study, twenty participants performed two AR tasks (omni-directional pointing and cube placing) with different target sizes and error rates. During the AR tasks, we measured cerebral oxygenation using functional near-infrared spectroscopy (fNIRS), perceived workload using the NASA-TLX questionnaire, stress using the Short Stress State Questionnaire, and task performance (task completion time).

The effects of different seat suspension types on occupants' physiologic responses and task performance: implications for autonomous and conventional vehicles.

This study evaluated whole body vibration (WBV), non-driving task performance, muscle activity, and self-reported discomfort and motion sickness between different seat suspension systems in a simulated vehicle environment. In a repeated-measures laboratory experiment where field-measured 6-degree-of-freedom (6-DOF) passenger vehicle vibration was replicated on a 6-DOF motion platform, we measured WBV, non-driving task (pointing, typing, web-browsing, and reading) performance, low back (erector spinae), shoulders (trapezius) and neck (splenius capitis and sternocleido-mastoid) muscle activity, and self-reported discomfort and motion sickness from three different seats: a vertical (z-axis) active suspension, multi-axial active suspension [vertical (z-axis) + lateral (y-axis)], and a static suspension-less seat (current seat type in all passenger cars). Both the vertical and multi-axial active suspension seats significantly reduced the vertical WBV exposure (p < 0.

Postural balance effects from exposure to multi-axial whole-body vibration in mining vehicle operation.

Twenty participants (18 males and 2 females) completed postural stability assessments before and after 4-h exposure to whole body vibration (WBV) in four experimental conditions: (a) vertical-dominant WBV with vertical passive air suspension, (b) multi-axial WBV with vertical passive air suspension, (c) multi-axial WBV with multi-axial active suspension, and (d) no WBV condition. Center of pressure (COP)-based postural sway measures significantly increased following multi-axial WBV exposure. Increase in COP velocity and displacement following multi-axial WBV was significantly higher than the increase in all the other exposure conditions.

Effect of whole-body vibration exposures on physiological stresses: Mining heavy equipment applications.

The aim of this study was to employ validated biological markers to quantify the physiologic consequences of exposure to whole-body vibration (WBV) and evaluate the relative impact of mining vehicle operator vibration exposure on physiological responses as compared to vertical-axial dominant WBV. In a laboratory-based study with a repeated-measures design, we played actual field-measured floor vibration profiles into a 6-degree-of-freedom motion platform to create different realistic WBV exposures: 1) vertical-dominant vibration collected from long-haul trucks, 2) multi-axial vibration collected from mining heavy equipment vehicles, and 3) no vibration (control condition). Circulating biomarkers of interest were cortisol and catecholamines (epinephrine and norepinephrine) to assess physiological stress, interleukin-6 (IL-6) and tumor necrosis factor-α (TNFα) to test for inflammation, thiobarbituric acid reactive substances (TBARS) to measure oxidative stress, and myoglobin and plasma creatine kinase to assess muscle damage.

Differences in typing forces, muscle activity, wrist posture, typing performance, and self-reported comfort among conventional and ultra-low travel keyboards.

This study investigated the relative impact of ultra-low travel keyboards on typing force, muscle activity, wrist posture, typing performance, and self-reported comfort/preference as compared to a conventional keyboard. In a repeated-measures laboratory-based study, 20 subjects were invited to type for 10 min on each of five keyboards with different travel distances of 0.5, 0.