Comparison of multi-task ergonomic assessment methods for risk of upper extremity and low back musculoskeletal disorders.

Work-related musculoskeletal disorder of upper extremity multi-task assessment methods (Revised Strain Index [RSI], Distal Upper Extremity Tool [DUET]) and manual handling multi-task assessment methods (Revised NIOSH Lifting Equation [RNLE], Lifting Fatigue Failure Tool [LiFFT]) were compared. RSI and DUET showed a strong correlation (r = 0.933, p < 0.

The ACGIH TLV for lifting: Estimated TLVs for torso asymmetry beyond 30 degrees.

Background: The American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) for Lifting is a manual material handling (MMH) assessment method to identify weight limits that nearly all workers may be exposed to without developing work-related low back disorders (LBD). However, this assessment method only applies to lifting with the torso within 30° asymmetry of the sagittal plane.

Objective: Estimate TLV weight limits while lifting with torso asymmetry greater than 30° beyond the sagittal plane.

Influence of different passive shoulder exoskeletons on shoulder and torso muscle activation during simulated horizontal and vertical aircraft squeeze riveting tasks.

Aircraft manufacturing involves riveting utilizing squeeze riveting tools at heights from below elbow to overhead levels. This study assessed utilization of passive shoulder exoskeletons on shoulder and torso muscle activation during simulated squeeze riveting. Horizontal and vertical riveting tasks using squeeze riveting tools were performed by 16 aircraft workers wearing three different shoulder exoskeletons and a no-exoskeleton condition capturing electromyographic signals from shoulder and torso muscles.

The Reliability and Validity of Gluteal Endurance Measures (GEMs).

Background: The gluteals have unique morphology related to muscle endurance, including moderate fiber sizes and a majority of Type I endurance fibers. Evidence suggests gluteal endurance is related to low back pain, running kinematics, balance, posture, and more. However, reliable and valid measures specific to gluteal endurance are lacking in the literature.

Torso Kinematics in Human Rolling Do Not Change When Upper Extremity Motion Is Constrained.

Human rolling, as turning in bed, is a fundamental activity of daily living. A quantitative analysis of rolling could help identify the neuromusculoskeletal disorders that prohibit rolling and develop interventions for individuals who cannot roll. This study sought to determine whether crossing the arms over the chest would alter fundamental coordination patterns when rolling.

Gluteal Muscle Activation During Common Yoga Poses.

Background: Approximately 24% of physical therapists report regularly using yoga to strengthen major muscle groups. Although clinicians and athletes often use yoga as a form of strength training, little is known about the activation of specific muscle groups during yoga poses, including the gluteus maximus and medius.

Hypothesis/purpose: The purpose of this study was to measure gluteus maximimus and gluteus medius activation via electromyography (EMG) during five common yoga poses.

Simulation of Exoskeleton Alignment and its Effect on the Knee Extensor and Flexor Muscles.

This study presents the analysis of different knee joint impairments and their effects on the knee extensor and flexor muscles. Joint impairments can result from stroke, musculoskeletal diseases, or misalignment of an attached exoskeleton joint. Understanding the correlation between parameters involved in joint movement mechanisms as well as force interactions could provide insight to establish an appropriate design for exoskeletons.

The effects of a fatiguing lifting task on postural sway among males and females.

Lifting and falls comprise a large proportion of work related injuries. Repetitive lifting to the point of fatigue can affect postural sway, which is associated with fall risk. To investigate the effects of lifting and fatigue on postural sway in males and females, 35 participants (18 male, 17 female) were asked to lift a weighted box in sets of 25 lifts at 5 different incremental weights (10, 15, 20, 25, and 30 kg) until fatigue.

BUILDING A BETTER GLUTEAL BRIDGE: ELECTROMYOGRAPHIC ANALYSIS OF HIP MUSCLE ACTIVITY DURING MODIFIED SINGLE-LEG BRIDGES.

Background: Gluteal strength plays a role in injury prevention, normal gait patterns, eliminating pain, and enhancing athletic performance. Research shows high gluteal muscle activity during a single-leg bridge compared to other gluteal strengthening exercises; however, prior studies have primarily measured muscle activity with the active lower extremity starting in 90 ° of knee flexion with an extended contralateral knee. This standard position has caused reports of hamstring cramping, which may impede optimal gluteal strengthening.

Can the efficacy of electrically stimulated pedaling using a commercially available ergometer BE improved by minimizing the muscle stress-time integral?

Introduction: The cardiorespiratory and muscular strength benefits of functional electrical stimulation (FES) pedaling for spinal cord injury (SCI) subjects are limited because the endurance of electrically stimulated muscle is low.

Methods: We tested new electrical stimulation timing patterns (Stim3, designed using a forward dynamic simulation to minimize the muscle stress-time integral) to determine whether SCI subjects could increase work and metabolic responses when pedaling a commercial FES ergometer. Work, rate of oxygen uptake (VO(2)), and blood lactate data were taken from 11 subjects (injury level T4-T12) on repeated trials.

Effects of fast functional electrical stimulation gait training on mechanical recovery in poststroke gait.

Stroke leads to gait impairments that can negatively influence quality of life. Functional electrical stimulation (FES) applied during fast walking (FastFES) is an effective gait rehabilitation strategy that can lead to improvements in gait performance, walking speed and endurance, balance, activity, and participation poststroke. The effect of FastFES gait training on mechanical energy utilization is not well understood.

The effects of stimulating lower leg muscles on the mechanical work and metabolic response in functional electrically stimulated pedaling.

Functional electrical stimulation (FES) pedaling with the muscles of the upper leg has been shown to provide benefit to spinal cord injured (SCI) individuals. FES pedaling with electrical stimulation timing patterns that minimize the stress-time integral of activated muscles has been shown to increase the work individuals can perform during the exercise compared to existing FES stimulation timing patterns. Activation of the lower leg muscles could further enhance the benefit of FES pedaling by increasing the metabolic response to the exercise.

Muscle stimulation waveform timing patterns for upper and lower leg muscle groups to increase muscular endurance in functional electrical stimulation pedaling using a forward dynamic model.

Functional electrical stimulation (FES) of pedaling provides a means by which individuals with spinal cord injury can obtain cardiorespiratory exercise. However, the early onset of muscle fatigue is a limiting factor in the cardiorespiratory exercise obtained while pedaling an FES ergometer. One objective of this study was to determine muscle excitation timing patterns to increase muscle endurance in FES pedaling for three upper leg muscle groups and to compare these timing patterns to those used in a commercially available FES ergometer.

Influence of pedaling rate on muscle mechanical energy in low power recumbent pedaling using forward dynamic simulations.

An understanding of the muscle power contributions to the crank and limb segments in recumbent pedaling would be useful in the development of rehabilitative pedaling exercises. The objectives of this work were to 1) quantify the power contributions of the muscles to driving the crank and limb segments using a forward dynamic simulation of low-power pedaling in the recumbent position, and 2) determine whether there were differences in the muscle power contributions at three different pedaling rates. A forward dynamic model was used to determine the individual muscle excitation amplitude and timing to drive simulations that best replicated experimental kinematics and kinetics of recumbent pedaling.

How changing the inversion/eversion foot angle affects the nondriving intersegmental knee moments and the relative activation of the vastii muscles in cycling.

Nondriving intersegmental knee moment components (i.e., varus/valgus and internal/external axial moments) are thought to be primarily responsible for the etiology of overuse knee injuries such as patellofermoral pain syndrome in cycling because of their relationship to muscular imbalances.

Functional roles of the leg muscles when pedaling in the recumbent versus the upright position.

An understanding of the coordination of the leg muscles in recumbent pedaling would be useful to the design of rehabilitative pedaling exercises. The objectives of this work were to (i) determine whether patterns of muscle activity while pedaling in the recumbent and upright positions are similar when the different orientation in the gravity field is considered, (ii) compare the functional roles of the leg muscles while pedaling in the recumbent position to the upright position to the upright position and (iii) determine whether leg muscle onset and offset timing for recumbent and upright pedaling respond similarly to changes in pedaling rate. To fulfill these objectives, surface electromyograms were recorded from 10 muscles of 15 subjects who pedaled in both the recumbent and upright positions at 75, 90, and 105 rpm and at a constant workrate of 250 W.