Validation of pitchAI markerless motion capture using marker-based 3D motion capture.

This study sought to compare and validate baseball pitching mechanics, including joint angles and spatiotemporal parameters, from a single camera markerless motion capture solution with a 3D optical marker-based system. Ten healthy pitchers threw 2-3 maximum effort fastballs while concurrently using marker-based optical capture and pitchAI (markerless) motion capture. Time-series measures were compared using -squared (r), and root mean square error (RMSE).

Usefulness of the Rapid Office Strain Assessment (ROSA) tool in detecting differences before and after an ergonomics intervention.

Background: Most ergonomics studies on office workstations evaluate the effects of an intervention only by subjective measures such as musculoskeletal pain and discomfort. Limited evidence has been provided regarding risk factor reduction in office environments through standardized methods assessments. The Rapid Office Strain Assessment (ROSA) tool can provide an estimation of risk factor exposure for office workers as a means by which the outcome of interventions can be quantified.

Influence of muscle fatigue on motor task performance of the hand and wrist: A systematic review.

Muscle fatigue is represented as a reduction in force production capability; however, fatigue does not necessarily result in performance impairments. As the distal upper limb serves as the end effector when interacting or manipulating objects, it is important to understand how muscle fatigue may impact motor functionality. The aim of this study was to systematically review the literature to identify how various aspects of motor performance of the distal upper limb are impaired following muscle fatigue.

Assessment of Joint Angle and Reach Envelope Demands Using a Video-Based Physical Demands Description Tool.

Background: Current methods for describing physical work demands often lack detail and format standardization, require technical training and expertise, and are time-consuming to complete. A video-based physical demands description (PDD) tool may improve time and accuracy concerns associated with current methods.

Methods: Ten simulated occupational tasks were synchronously recorded using a motion capture system and digital video.

Manifestations of muscle fatigue in baseball pitchers: a systematic review.

Background: Fatigue in baseball pitchers is a process linked to lowered physical and mental performance, injury, and changes in kinematics. Numerous studies have associated fatigue with overuse, high ball velocities, lack of rest time, poor mechanics, and degree of self-satisfaction. The aim of this study was to systematically review the literature to identify a theoretical framework for the relationship between outcomes and the manifestation of fatigue on baseball pitching.

Muscle fibre activation is unaffected by load and repetition duration when resistance exercise is performed to task failure.

Key Points: Performing resistance exercise with heavier loads is often proposed to be necessary for the recruitment of larger motor units and activation of type II muscle fibres, leading to type II fibre hypertrophy. Indirect measures [surface electromyography (EMG)] have been used to support this thesis, although we propose that lighter loads lifted to task failure (i.e.

Ratings of perceived fatigue predict fatigue induced declines in muscle strength during tasks with different distributions of effort and recovery.

The purpose of this study was to quantify the relationship between ratings of perceived fatigue (RPF), using a modified Borg CR-10 scale, and muscle fatigue accumulation, as defined by maximal voluntary contraction strength (MVC) declines, during two complex MVC-relative tasks (conditions) that cause muscle fatigue and allow recovery. Nine female participants completed the fatiguing tasks, composed of a series of submaximal, isometric efforts (task plateaus) requiring isometric flexion at the distal interphalangeal joint of the thumb. Significant partial correlations between RPF and MVC, while controlling for task plateau intensity (%MVC), were found in 6/9 participants.

Evaluation of a virtual reality head mounted display as a tool for posture assessment in digital human modelling software.

The purpose of this work was to assess the feasibility of using a head mounted display with a motion capture system to simulate real world occupational tasks. Participants performed a pointing task under 3 conditions: (1) real environment (REA), (2) virtual environment with auditory stimulus (VEA) and (3) virtual environment with visual stimulus (VEV). End point error, movement time and peak fingertip velocity were calculated for each discrete point event.

Rapid office strain assessment (ROSA): Cross cultural validity, reliability and structural validity of the Brazilian-Portuguese version.

Forty-three occupational health professionals (observers) and 90 workers were enrolled in this study to perform the cross-cultural adaptation of the Rapid Office Strain Assessment into Brazilian Portuguese (ROSA-Br) and evaluate its psychometric properties. After cross-cultural adaptation, the measurement properties were checked in three stages: study 1: pre-testing (27 observers rated 15 office worker videos), study 2: intra- and inter-observer reliability (26 observers rated 15 office worker videos), and study 3: validity and accuracy of ROSA-Br final scores (90 office workers). For the ROSA scores, acceptable intraclass correlation coefficients were found for 75% and 86% of the intra-observer reliability comparisons for non-trained and trained observers, respectively, and for 100% of the inter-observer reliability comparisons (0.

Grip Type Alters Maximal Pinch Forces in Syringe Use.

Objective: The purpose of this study was to determine maximum forces during syringe use for different grips found in the field.

Background: Prolonged syringe use in chemotherapy drug delivery is associated with pain and injury in nurses and technicians.

Method: Twenty healthy female hospital workers generated isometric maximum voluntary force using a 30 cc syringe with four pinch grips (chuck, chuck variation, thenar, two-handed).

Physiological responses to incremental, interval, and continuous counterweighted single-leg and double-leg cycling at the same relative intensities.

Purpose: We compared physiological responses to incremental, interval, and continuous counterweighted single-leg and double-leg cycling at the same relative intensities. The primary hypothesis was that the counterweight method would elicit greater normalized power (i.e.

Major League Baseball pace-of-play rules and their influence on predicted muscle fatigue during simulated baseball games.

Major League Baseball (MLB) has proposed rule changes to speed up baseball games. Reducing the time between pitches may impair recovery from fatigue. Fatigue is a known precursor to injury and may jeopardise joint stability.

A modified version of the three-compartment model to predict fatigue during submaximal tasks with complex force-time histories.

Unlabelled: The three-compartment model (3CM) was validated previously for prediction of endurance times by modifying its fatigue and recovery rates. However, endurance times do not typically represent work demands, and it is unknown if the current version of the 3CM is applicable for ergonomics analysis of all occupational tasks. The purpose of this study was to add biological fidelity to the 3CM, and validate the model against a series of submaximal force plateaus.

Fatigue accumulation and twitch potentiation during complex MVC-relative profiles.

Fatigue accumulation can be significantly influenced by post-activation potentiation (PAP). This phenomenon leads to increased force generating capacity after a series of conditioning efforts. The purpose of our study was to examine how the order of force demands impacted muscle fatigue accumulation, and how fatigue was affected by potentiation.

Force time-history affects fatigue accumulation during repetitive handgrip tasks.

Muscle fatigue is associated with a higher risk of workplace injury, in particular during repetitive tasks. This study aimed to identify the effect of a complex force-time history (a task with multiple different submaximal effort levels) on fatigue accumulation and recovery during a handgrip task. We measured surface electromyography of the brachioradialis (BRD) and flexor carpi ulnaris (FCU) of ten right hand dominant females with no history of upper limb injury while they performed a complex submaximal visually targeted gripping task.

A psychophysical study to determine maximum acceptable efforts for a thumb abduction task with high duty cycles.

Potvin (2012, 'Predicting Maximum Acceptable Efforts for Repetitive Tasks: An Equation Based on Duty Cycle', Human Factors: The Journal of the Human Factors and Ergonomics Society, 54 (2), 175-188) developed an equation using psychophysical data to estimate maximum acceptable efforts (MAEs) as a function of duty cycle (DC). However, only ∼6% of the data featured DCs ≥ 0.50.

It wears me out just imagining it! Mental imagery leads to muscle fatigue and diminished performance of isometric exercise.

The purpose of this study was to investigate the aftereffects of self-generated mental imagery of an effortful task on physical self-control endurance and muscle fatigue. Participants performed two isometric handgrip endurance trials (50% of maximum contraction) separated by either an imagery manipulation or a quiet rest period. The imagery group showed greater negative changes in endurance performance from trial 1 to trial 2 (p=.

Development and evaluation of an office ergonomic risk checklist: ROSA--rapid office strain assessment.

The Rapid Office Strain Assessment (ROSA) was designed to quickly quantify risks associated with computer work and to establish an action level for change based on reports of worker discomfort. Computer use risk factors were identified in previous research and standards on office design for the chair, monitor, telephone, keyboard and mouse. The risk factors were diagrammed and coded as increasing scores from 1 to 3.