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1.
J Occup Environ Hyg ; 20(3-4): 136-142, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36799881

RESUMEN

The goal of this study was to evaluate the relationship between ratings of perceived exertion (RPE) and relative strength with respect to baseline for a fatiguing free dynamic task targeting the upper extremity, namely simulated order picking, and determine whether the relationship remains the same for different conditions (i.e., pace and weight) and with fatigue. Fourteen participants (seven males, seven females) performed four sessions that included two 45-min work periods separated by 15 min of rest. The work periods involved picking weighted bottles from shoulder height and packaging them at waist height for four combinations of bottle mass and picking rate: 2.5 kg-15 bottles per minute (bpm), 2.5 kg-10 bpm, 2.5 kg-5 bpm, and 1.5 kg-15 bpm. Participants reported their RPEs every 5 min and performed a maximum isometric shoulder flexion exertion every 9 min. Pearson product-moment correlation was used to evaluate the linear relationship between RPE and relative strength for each subject and work period. Then, the effects of condition and work period on the average relationship were assessed using a repeated-measures analysis of variance (ANOVA). For the first 45-min period, there were no significantly different correlations between RPE and relative strength across conditions (average r = -0.62 (standard deviation = 0.38); p = 0.57). There was a significant decrease in average correlation for the second work period (r = -0.39 (0.53)). These results suggest that individual subjective responses consistently increase while relative strength declines when starting from a non-fatigued state. However, correlations are weaker when re-engaging in work following incomplete recovery. Thus, starting fatigue levels should be accounted for when considering the expected relationship between RPE and relative strength.


Asunto(s)
Esfuerzo Físico , Extremidad Superior , Masculino , Femenino , Humanos , Esfuerzo Físico/fisiología , Hombro , Descanso
2.
Sensors (Basel) ; 22(15)2022 Jul 28.
Artículo en Inglés | MEDLINE | ID: mdl-35957219

RESUMEN

Repetitive task performance is a leading cause of musculoskeletal injuries among order-picking workers in warehouses. The repetition of lifting tasks increases the risk of back and shoulder injuries among these workers. While lifting in this industry is composed of loaded and unloaded picking and placing, the existing literature does not address the separate analysis of the biomechanics of the back and shoulder for these events. To that end, we investigated the kinematics of the back and shoulder movements of nine healthy male participants who performed three sessions of a simulated de/palletization task. Their back and shoulder kinematics were sensed using an optical motion capture system to determine the back inclination and shoulder flexion. Comparison of the kinematics between the first and last sessions indicated statistically significant changes in the timings, angles, coordination between the back and shoulder, and moments around the shoulder (p<0.05). The majority of the significant changes were observed during the loaded events, which confirms the importance of the separation of these events for biomechanical analysis. This finding suggests that focusing worker evaluation on the loaded periods can provide important information to detect kinematic changes that may affect musculoskeletal injury risk.


Asunto(s)
Enfermedades Musculoesqueléticas , Hombro , Fenómenos Biomecánicos , Humanos , Masculino , Rango del Movimiento Articular , Análisis y Desempeño de Tareas , Extremidad Superior
3.
Sensors (Basel) ; 21(19)2021 Oct 08.
Artículo en Inglés | MEDLINE | ID: mdl-34641001

RESUMEN

Human activity recognition has been extensively used for the classification of occupational tasks. Existing activity recognition approaches perform well when training and testing data follow an identical distribution. However, in the real world, this condition may be violated due to existing heterogeneities among training and testing data, which results in degradation of classification performance. This study aims to investigate the impact of four heterogeneity sources, cross-sensor, cross-subject, joint cross-sensor and cross-subject, and cross-scenario heterogeneities, on classification performance. To that end, two experiments called separate task scenario and mixed task scenario were conducted to simulate tasks of electrical line workers under various heterogeneity sources. Furthermore, a support vector machine classifier equipped with domain adaptation was used to classify the tasks and benchmarked against a standard support vector machine baseline. Our results demonstrated that the support vector machine equipped with domain adaptation outperformed the baseline for cross-sensor, joint cross-subject and cross-sensor, and cross-subject cases, while the performance of support vector machine equipped with domain adaptation was not better than that of the baseline for cross-scenario case. Therefore, it is of great importance to investigate the impact of heterogeneity sources on classification performance and if needed, leverage domain adaptation methods to improve the performance.


Asunto(s)
Aprendizaje , Máquina de Vectores de Soporte , Humanos , Reconocimiento en Psicología
4.
Hum Factors ; 63(1): 151-191, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-31596613

RESUMEN

OBJECTIVE: We present a literature review on workplace physical fatigue interventions, focusing on evaluating the methodological quality and strength of evidence. BACKGROUND: Physical fatigue is a recognized workplace problem, with negative effects on performance and health-related complaints. Although many studies have focused on the mechanisms and consequences of fatigue, few have considered the effectiveness of interventions to mitigate fatigue. METHOD: A systematic review of the workplace safety literature for controlled trials of physical fatigue interventions was conducted. Data on intervention type, subject characteristics, targeted tasks and body locations, outcome measures, and study design were extracted. The methodological quality for each study was evaluated using the PEDro scale, and the level of evidence was based on quality, amount, and consistency. RESULTS: Forty-five controlled trials were reviewed, examining 18 interventions. We categorized those interventions into individual-focused (N = 28 studies, nine interventions), workplace-focused (N = 12 studies, five interventions), and multiple interventions (N = 5 studies, four interventions). We identified moderate evidence for interventions related to assistive devices and task variation. There was moderate evidence supporting no fatigue attenuation for the garment change category of interventions. The interventions in the remaining categories had limited to minimal evidence of efficacy. The heterogeneity of the included trials precludes the determination of effect size. CONCLUSION: This review showed a lack of high levels of evidence for the effectiveness of most physical fatigue interventions. APPLICATION: Due to a lack of high levels of evidence for any category of reviewed physical fatigue interventions, further high-quality studies are needed to establish the efficacy of others.


Asunto(s)
Fatiga Muscular , Lugar de Trabajo , Humanos , Examen Físico
5.
BJU Int ; 125(4): 553-560, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-31901213

RESUMEN

OBJECTIVES: To develop and evaluate the feasibility of an objective method using artificial intelligence (AI) and image processing in a semi-automated fashion for tumour-to-cortex peak early-phase enhancement ratio (PEER) in order to differentiate CD117(+) oncocytoma from the chromophobe subtype of renal cell carcinoma (ChRCC) using convolutional neural networks (CNNs) on computed tomography imaging. METHODS: The CNN was trained and validated to identify the kidney + tumour areas in images from 192 patients. The tumour type was differentiated through automated measurement of PEER after manual segmentation of tumours. The performance of this diagnostic model was compared with that of manual expert identification and tumour pathology with regard to accuracy, sensitivity and specificity, along with the root-mean-square error (RMSE), for the remaining 20 patients with CD117(+) oncocytoma or ChRCC. RESULTS: The mean ± sd Dice similarity score for segmentation was 0.66 ± 0.14 for the CNN model to identify the kidney + tumour areas. PEER evaluation achieved accuracy of 95% in tumour type classification (100% sensitivity and 89% specificity) compared with the final pathology results (RMSE of 0.15 for PEER ratio). CONCLUSIONS: We have shown that deep learning could help to produce reliable discrimination of CD117(+) benign oncocytoma and malignant ChRCC through PEER measurements obtained by computer vision.


Asunto(s)
Adenoma Oxifílico/diagnóstico por imagen , Carcinoma de Células Renales/diagnóstico por imagen , Aprendizaje Profundo , Procesamiento de Imagen Asistido por Computador , Neoplasias Renales/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodos , Diagnóstico Diferencial , Estudios de Factibilidad , Humanos , Estudios Retrospectivos
6.
Hum Factors ; 60(3): 351-362, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29320232

RESUMEN

OBJECTIVE: To gather information on the (a) types of wearable sensors, particularly personal activity monitors, currently used by occupational safety and health (OSH) professionals; (b) potential benefits of using such technologies in the workplace; and (c) perceived barriers preventing the widespread adoption of wearable sensors in industry. BACKGROUND: Wearable sensors are increasingly being promoted as a means to improve employee health and well-being, and there is mounting evidence supporting their use as exposure assessment and personal health tools. Despite this, many workplaces have been hesitant to adopt these technologies. METHODS: An electronic survey was emailed to 28,428 registered members of the American Society of Safety Engineers (ASSE) and 1,302 professionals certified by the Board of Certification in Professional Ergonomics (BCPE). RESULTS: A total of 952 valid responses were returned. Over half of respondents described being in favor of using wearable sensors to track OSH-related risk factors and relevant exposure metrics at their respective workplaces. However, barriers including concerns regarding employee privacy/confidentiality of collected data, employee compliance, sensor durability, the cost/benefit ratio of using wearables, and good manufacturing practice requirements were described as challenges precluding adoption. CONCLUSION: The broad adoption of wearable technologies appears to depend largely on the scientific community's ability to successfully address the identified barriers. APPLICATION: Investigators may use the information provided to develop research studies that better address OSH practitioner concerns and help technology developers operationalize wearable sensors to improve employee health and well-being.


Asunto(s)
Ergonomía , Personal de Salud , Enfermedades Musculoesqueléticas , Enfermedades Profesionales , Salud Laboral , Dispositivos Electrónicos Vestibles , Adulto , Ergonomía/estadística & datos numéricos , Personal de Salud/estadística & datos numéricos , Humanos , Enfermedades Musculoesqueléticas/diagnóstico , Enfermedades Musculoesqueléticas/prevención & control , Enfermedades Profesionales/diagnóstico , Enfermedades Profesionales/prevención & control , Salud Laboral/estadística & datos numéricos , Privacidad , Dispositivos Electrónicos Vestibles/estadística & datos numéricos , Lugar de Trabajo
7.
Ergonomics ; 61(12): 1646-1656, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30317942

RESUMEN

The purpose of this study was to examine task and sex differences in forearm muscle oxygenation, measured using near infrared spectroscopy, during sustained submaximal handgrip exercises. Forty-eight adults (50% males) performed fatiguing handgrip exercises at 20, 40, 60 and 80% of their maximum handgrip strength. While males and females exhibited similar levels of relative fatigability, forearm oxygenation was found to be task (i.e. contraction intensity and phase of fatigue development) and sex dependent. Higher contraction intensities were associated with greater desaturation over time. Compared to females, males exhibited greater desaturation as fatigue progressed and this was augmented at higher contraction intensities. These may be likely affected by sex differences in muscle mass, morphology and strength differences during exercises at relative intensities. Future work that explores sex differences in muscle oxygenation during absolute force intensities are needed, which may have implications for muscle fatigue development and potential fatigue mitigation strategies. Practitioner Summary: Muscle oxygenation impacts fatigue development that can in turn affect worker health and productivity. Males exhibit greater forearm desaturation than females at higher relative work intensities, despite similar fatigue levels. Females may be predisposed to greater muscle delivery and oxygenation challenges that can increase their fatigability during work at absolute load levels.


Asunto(s)
Fuerza de la Mano , Fatiga Muscular , Músculo Esquelético/metabolismo , Oxígeno/metabolismo , Adulto , Ejercicio Físico , Femenino , Antebrazo , Humanos , Contracción Isométrica , Masculino , Factores Sexuales , Espectroscopía Infrarroja Corta , Adulto Joven
8.
Ergonomics ; 61(8): 1116-1129, 2018 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-29452575

RESUMEN

The purpose of this study is to provide a method for classifying non-fatigued vs. fatigued states following manual material handling. A method of template matching pattern recognition for feature extraction ($1 Recognizer) along with the support vector machine model for classification were applied on the kinematics of gait cycles segmented by our stepwise search-based segmentation algorithm. A single inertial measurement unit on the ankle was used, providing a minimally intrusive and inexpensive tool for monitoring. The classifier distinguished between states using distance-based scores from the recogniser and the step duration. The results of fatigue detection showed an accuracy of 90% across data from 20 recruited subjects. This method utilises the minimum amount of data and features from only one low-cost sensor to reliably classify the state of fatigue induced by a realistic manufacturing task using a simple machine learning algorithm that can be extended to real-time fatigue monitoring as a future technology to be employed in the manufacturing facilities. Practitioner Summary: We examined the use of a wearable sensor for the detection of fatigue-related changes in gait based on a simulated manual material handling task. Classification based on foot acceleration and position trajectories resulted in 90% accuracy. This method provides a practical framework for predicting realistic levels of fatigue.


Asunto(s)
Biometría/métodos , Fatiga/diagnóstico , Marcha/fisiología , Aprendizaje Automático , Enfermedades Profesionales/diagnóstico , Adulto , Algoritmos , Tobillo , Fenómenos Biomecánicos , Biometría/instrumentación , Fatiga/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Enfermedades Profesionales/fisiopatología , Dispositivos Electrónicos Vestibles
9.
BMC Musculoskelet Disord ; 18(1): 314, 2017 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-28732481

RESUMEN

BACKGROUND: Fatigue increases the likelihood of developing work-related musculoskeletal disorders and injury. Due to the physiological and neuromuscular changes that accompany obesity, it may alter the fatigue development mechanism and exacerbate injury risk. The upper extremities have the highest incidence rates for work-related musculoskeletal disorders. Therefore, the goals of this study were to investigate the effect of obesity on central vs. peripheral fatigue as well as on the physical signs of fatigue on the middle deltoid muscle. METHODS: A measure of central activation ratio was used to quantify central fatigue by considering the increment in the torque output by superimposed twitch relative to its corresponding maximum voluntary contraction. For this purpose, electrical stimulation was delivered at the middle deltoid muscles of 22 non-obese (18 < body mass index (BMI) < 25 kg/m2) and 17 obese (30 < BMI < 40 kg/m2) individuals aged 18-32 years old. Participants completed superimposed maximum voluntary isometric contractions of shoulder abduction before and after a sustained isometric fatiguing task at either 30 or 60% of the muscle capacity. Differences in endurance time, torque fluctuation, torque loss, and muscle activity measured by an electromyography sensor were also investigated. RESULTS: A greater reduction of voluntary activation of motor units (p = 0.001) with fatigue was observed for individuals who are obese. Contrary to the effect of obesity on central fatigue, a trend toward reduced peripheral fatigue (p = 0.06) was observed for the obese group compared to the non-obese group. On average, a 14% higher rate of torque loss per second was observed among individuals with obesity in comparison to non-obese participants. CONCLUSIONS: The observed greater contribution of central fatigue during the sustained endurance tasks suggests that among young healthy obese individuals, the faster fatigue development with obesity, commonly reported in the literature, is most likely due to the central elements rather than the peripheral factors. This finding has implications for fatigue prevention programs during sustained exertions and can help to develop training, work, and rest schedules considering obesity.


Asunto(s)
Músculo Deltoides/fisiología , Contracción Isométrica/fisiología , Fatiga Muscular/fisiología , Obesidad/fisiopatología , Resistencia Física/fisiología , Adolescente , Adulto , Estimulación Eléctrica/métodos , Electromiografía/métodos , Femenino , Humanos , Masculino , Hombro/fisiología , Adulto Joven
10.
J Occup Environ Hyg ; 14(3): 180-186, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-27715653

RESUMEN

The objective of this study was to assess the effect of obesity on postural stability during a standardized lifting task. Twelve young males, six obese and six non-obese, completed three replications of repeated six lifts (at a rate of six lifts per minutes) at two levels of loads (10% and 25% of capacity) crossed with two levels of orientation (0° and 45° from sagittal plane). Postural stability measures showed that center of pressure sway path and sway area were ∼21% and ∼53% lower with obesity, respectively. Additionally, frequency band of amplitude spectrum in the medial lateral direction at 0° lifting orientation was significantly lower with obesity. The results suggest that obesity, as measured by body mass index, does not impair balance control in healthy young males when lifting load is relative to the capacity.


Asunto(s)
Elevación , Obesidad/fisiopatología , Equilibrio Postural/fisiología , Soporte de Peso/fisiología , Índice de Masa Corporal , Ergonomía , Humanos , Masculino , Adulto Joven
11.
J Occup Environ Hyg ; 14(10): 786-792, 2017 10.
Artículo en Inglés | MEDLINE | ID: mdl-28636453

RESUMEN

This study evaluates whether the existing force-endurance relationship models are predictive of endurance time for overweight and obese individuals, and if not, provide revised models that can be applied for ergonomics practice. Data was collected from 141 participants (49 normal weight, 50 overweight, 42 obese) who each performed isometric endurance tasks of hand grip, shoulder flexion, and trunk extension at four levels of relative workload. Subject-specific fatigue rates and a general model of the force-endurance relationship were determined and compared to two fatigue models from the literature. There was a lack of fit between previous models and the current data for the grip (ICC = 0.8), with a shift toward lower endurance times for the new data. Application of the revised models can facilitate improved workplace design and job evaluation to accommodate the capacities of the current workforce.


Asunto(s)
Músculo Esquelético/fisiopatología , Obesidad/fisiopatología , Resistencia Física/fisiología , Adulto , Ergonomía , Femenino , Fuerza de la Mano/fisiología , Humanos , Contracción Isométrica , Masculino , Modelos Teóricos , Hombro/fisiopatología , Torso/fisiopatología
12.
Eur J Appl Physiol ; 115(9): 1905-17, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-25896283

RESUMEN

PURPOSE: The goal of this study was to quantify obesity-related differences in systemic physiologic responses and cerebral hemodynamics during physical work to exhaustion. METHODS: Twenty men, ten who are obese and ten of healthy weight, completed an incremental exercise lifting a box from 25 cm below to 25 cm above knuckle height at 10 lifts/min. The lifting started with a load of 5 kg and was increased by 2 kg every 2 min until participants reached either voluntary fatigue or two of the American College of Sports Medicine endpoints for maximum aerobic capacity. Cardiorespiratory and prefrontal hemodynamic responses were measured simultaneously during rest, incremental lifting, and recovery. RESULTS: The non-obese group lifted for ~64 % longer than the obese group. Both groups reached similar peak pulmonary oxygen uptake at the termination of exercise; however, when these responses were expressed relative to their body mass, the obese group had ~60 % reduced oxygen uptake. As the load increased, steady increases in cerebral oxygenation and blood volume responses were observed in both groups up to ~90 % of the lifting trial. In contrast, at higher intensities (near 100 % of the lifting trial), cerebral oxygenation and blood volume decreased in the obese group, whereas it plateaued or slightly increased in the non-obese group, with greatest cerebral oxygen extraction occurring at the cessation of lifting trial. CONCLUSION: These findings suggest that acute exposure to repetitive lifting exercise decreases cardiorespiratory responses and cerebral hemodynamics in the group who are obese, which may contribute to their reduced lifting capacity.


Asunto(s)
Velocidad del Flujo Sanguíneo , Circulación Cerebrovascular , Frecuencia Cardíaca , Obesidad/fisiopatología , Resistencia Física , Levantamiento de Peso , Adulto , Humanos , Elevación , Masculino , Consumo de Oxígeno , Esfuerzo Físico , Valores de Referencia
13.
J Occup Environ Hyg ; 11(9): 583-90, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24484265

RESUMEN

In this study, the main and interactive effects of obesity and age on functional performance were assessed during intermittent exertions involving the upper extremity. The prevalence of obesity has doubled over the past 30 years and this increase is associated with higher health care costs, rates of workplace injury, and lost workdays. Obesity and aging can modify job demands and affect worker capacity in terms of muscular and psychomotor function. However, there is a lack of empirical studies quantifying the work-relevant (or ergonomic) impacts related to task demands, capacities, and their potential imbalance. Eight obese and eight non-obese participants from each of two age groups (18-25 and 50-65 years) completed three endurance tasks involving fixed levels of task demands: hand grip, shoulder flexion, and a simulated assembly task using the upper extremity. Measures of functional performance including endurance, discomfort, motor control, and task performance were recorded for each of the task conditions. Endurance times were ∼60% longer for the non-obese group, and older participants had longer endurance times; however there was no evidence of interactive effects of obesity and age. Obesity also impaired functional performance, as indicated by higher rates of strength loss, increases in discomfort, and declines in task performance. These observed impairments may reflect underlying physiological differences among individuals who are obese, but that are independent of age. Obesity-related impairments may have implications for the design of work duration and demand level to prevent fatigue development for workers who are obese.


Asunto(s)
Obesidad/fisiopatología , Resistencia Física , Análisis y Desempeño de Tareas , Extremidad Superior/fisiología , Adolescente , Adulto , Factores de Edad , Anciano , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Persona de Mediana Edad , Fatiga Muscular , Adulto Joven
14.
IISE Trans Occup Ergon Hum Factors ; 11(3-4): 123-135, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38536045

RESUMEN

OCCUPATIONAL APPLICATIONSMusculoskeletal disorders are prevalent among warehouse workers who engage in repetitive and dynamic tasks. To prevent such injuries, it is vital to identify the factors that influence fatigue in the upper extremities during these repetitive activities. Our study reveals that task factors, namely the bottle mass and picking rate, significantly influence upper extremity fatigue. In most cases, the fatigue indicator is a functional variable, meaning that the fatigue score or measurement is a curve captured over time, which could be modeled as a function. In this study, we demonstrate that functional data analysis tools, such as functional analysis of variance (FANOVA), prove more effective than traditional methods in specifying how task factors contribute to the development of fatigue in the upper extremities. Furthermore, since there are inherent differences among workers that could affect their fatigue development process, the data heterogeneity could be tackled by employing clustering methods.


Background: Preventing musculoskeletal disorders is a paramount safety concern for industries, with order pickers in warehouses being particularly vulnerable due to their repetitive and dynamic tasks. Understanding the factors contributing to upper-extremity fatigue in such settings is crucial. Purpose: This paper investigates the impact of task-related factors on two upper-extremity fatigue indicators: ratings of perceived fatigue and relative muscle strength. Several statistical approaches were used and compared in terms of their capability in eliciting these effects. Methods: Simulated over-shoulder, order-picking lab experiments were conducted under different combinations of two bottle loads and three picking paces. Fourteen participants, evenly distributed between genders, completed the experiment. A FANOVA was executed as the principal analytical approach, considering the functional nature of the two fatigue indicators measured over the work period. To underscore the benefits of considering the whole functional curve instead of discrete variables, we also conducted repeated-measures and two-way ANOVA as benchmark analyses. Results: FANOVA outcomes affirmed that both task factors (load and pace) significantly influenced both fatigue indicators. The FANOVA method identified larger effect sizes (0.11< ηp2 < 0.19) for both task factors compared to the conventional methods (0< ηp2 < 0.11), supporting the efficacy of FANOVA in identifying the importance of these factors. Conclusions: The FANOVA approach proved effective in detecting the impact of task factors on fatigue indicators, yielding superior results compared to conventional benchmark methods. To address participant heterogeneity, functional clustering and gender-based clustering were introduced into the FANOVA framework, both effectively mitigating this challenge. Notably, FANOVA with functional clusters had superior performance compared to the one with gender clustering, suggesting functional clustering as a more suitable method in overcoming participant heterogeneity.


Asunto(s)
Fatiga Muscular , Enfermedades Profesionales , Humanos , Extremidad Superior , Enfermedades Profesionales/epidemiología , Enfermedades Profesionales/prevención & control , Análisis de Varianza
15.
Appl Ergon ; 102: 103732, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35287084

RESUMEN

Existing ergonomic risk assessment tools require monitoring of multiple risk factors. To eliminate the direct observation, we investigated the effectiveness of an end-to-end framework that works with the data from a single wearable sensor. The framework is used to identify the performed task as the major contextual risk factor, and then estimate the task duration and number of repetitions as two main indicators of task intensity. For evaluation of the framework, we recruited 37 participants to complete 10 simulated work tasks in a laboratory setting. In testing, we achieved an average accuracy of 92% for task identification, 7.3% error in estimation of task duration, and 7.1% error for counting the number of task repetitions. Moreover, we showed the utility of the framework outputs in two ergonomic tools to estimate the risk of injury. Overall, we indicated the feasibility of using data from wearable sensors to automate the ergonomic risk assessment in workplaces.


Asunto(s)
Ciencia de los Datos , Dispositivos Electrónicos Vestibles , Ergonomía , Humanos , Factores de Riesgo , Lugar de Trabajo
16.
Appl Ergon ; 90: 103262, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32927403

RESUMEN

Advancements in sensing and network technologies have increased the amount of data being collected to monitor the worker conditions. In this study, we consider the use of time series methods to forecast physical fatigue using subjective ratings of perceived exertion (RPE) and gait data from wearable sensors captured during a simulated in-lab manual material handling task (Lab Study 1) and a fatiguing squatting with intermittent walking cycle (Lab Study 2). To determine whether time series models can accurately forecast individual response and for how many time periods ahead, five models were compared: naïve method, autoregression (AR), autoregressive integrated moving average (ARIMA), vector autoregression (VAR), and the vector error correction model (VECM). For forecasts of three or more time periods ahead, the VECM model that incorporates historical RPE and wearable sensor data outperformed the other models with median mean absolute error (MAE) <1.24 and median MAE <1.22 across all participants for Lab Study 1 and Lab Study 2, respectively. These results suggest that wearable sensor data can support forecasting a worker's condition and the forecasts obtained are as good as current state-of-the-art models using multiple sensors for current time prediction.


Asunto(s)
Esfuerzo Físico , Dispositivos Electrónicos Vestibles , Fatiga/diagnóstico , Predicción , Humanos , Proyectos de Investigación
17.
PLoS One ; 14(7): e0219090, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31260477

RESUMEN

The main goal of this study was to investigate the reliability of muscle strength across different levels of obesity. A sample of 142 healthy subjects performed maximum voluntary isometric contractions for shoulder flexion and trunk extension on each of four days. Subjects were recruited into one of three groups, non-obese, overweight, or obese, based on body mass index (BMI). Reliability of the strength measurements within each session and across the four sessions was determined from the intraclass correlation coefficient, coefficient of repeatability, coefficient of variation, and standard error of measurement. For the shoulder flexion measures, the coefficient of variation was < 10% and intraclass correlation coefficient was > 0.75. The absolute reliability of trunk extension strength measurement was rejected due to a high variability across sessions. For both tasks, comparable strengths across the BMI groups were found.


Asunto(s)
Índice de Masa Corporal , Fuerza Muscular/fisiología , Obesidad/fisiopatología , Adulto , Femenino , Voluntarios Sanos , Humanos , Contracción Isométrica/fisiología , Masculino , Persona de Mediana Edad , Dinamómetro de Fuerza Muscular , Sobrepeso/fisiopatología , Reproducibilidad de los Resultados , Hombro , Torso , Adulto Joven
18.
Int J Comput Assist Radiol Surg ; 14(4): 697-707, 2019 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-30460490

RESUMEN

PURPOSE: To develop and validate an automated assessment of surgical performance (AASP) system for objective and computerized assessment of pelvic lymph node dissection (PLND) as an integral part of robot-assisted radical cystectomy (RARC) using console-feed videos recorded during live surgery. METHODS: Video recordings of 20 PLNDs were included. The quality of lymph node clearance was assessed based on the features derived from the computer vision process which include: the number and cleared area of the vessels/nerve (N-Vs); image median color map; and mean entropy (measures the level of disorganization) in the video frame. The automated scores were compared to the validated pelvic lymphadenectomy appropriateness and completion evaluation (PLACE) scoring rated by a panel of expert surgeons. Logistic regression analysis was employed to compare automated scores versus PLACE scores. RESULTS: Fourteen procedures were used to develop the AASP algorithm. A logistic regression model was trained and validated using the aforementioned features with 30% holdout cross-validation. The model was tested on the remaining six procedures, and the accuracy of predicting the expert-based PLACE scores was 83.3%. CONCLUSIONS: To our knowledge, this is the first automated surgical skill assessment tool that provides an objective evaluation of surgical performance with high accuracy compared to expert surgeons' assessment that can be extended to any endoscopic or robotic video-enabled surgical procedure.


Asunto(s)
Cistectomía/educación , Educación de Postgrado en Medicina/métodos , Procedimientos Quirúrgicos Robotizados/métodos , Cirujanos/educación , Neoplasias de la Vejiga Urinaria/cirugía , Urología/educación , Grabación en Video/métodos , Biopsia , Cistectomía/métodos , Femenino , Humanos , Escisión del Ganglio Linfático , Ganglios Linfáticos/patología , Masculino , Cirujanos/normas , Neoplasias de la Vejiga Urinaria/diagnóstico
19.
Opt Express ; 16(18): 13738-51, 2008 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-18772985

RESUMEN

Corneal birefringence affects polarization-sensitive optical measurements of the eye. Recent literature supports the idea that corneal birefringence is biaxial, although with some disagreement among reports and without considering corneas with very low values of central retardance. This study measured corneal retardation in eyes with a wide range of central corneal retardance by means of scanning laser polarimetry (GDx-VCC, Carl Zeiss Meditec, Inc.), which computes the retardance and slow axis of the cornea from images of the bow tie pattern formed by the radial birefringence of the macula. Measurements were obtained at many points on the cornea by translating the instrument. Data were compared to calculations of the retardation produced by a curved biaxial material between two spherical surfaces. Most corneas showed one or two small areas of zero retardance where the refracted ray within the cornea aligned with an optical axis of the material. The retardation patterns in these corneas could be mimicked, but not accurately described, by the biaxial model. Two corneas with large areas of low retardance more closely resembled a uniaxial model. We conclude that the cornea, in general, behaves as a biaxial material with its fastest axis perpendicular to its surface. Some locations in a few corneas can be uniaxial with the optical axis perpendicular to the surface. Importantly, corneal birefringence varies greatly among people and, within a single cornea, significantly with position.


Asunto(s)
Algoritmos , Topografía de la Córnea/métodos , Interpretación de Imagen Asistida por Computador/métodos , Microscopía Confocal/métodos , Refractometría/métodos , Birrefringencia , Humanos , Sensibilidad y Especificidad
20.
J Workplace Behav Health ; 33(1): 24-42, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29599663

RESUMEN

This study explored concurrent effects of six work psychosocial factors on current participation and the self-reported likelihood of future participation in workplace wellness programs using a cross-sectional survey, an ad hoc focus group, and structured interviews. Classification and regression tree analysis was used to analyze survey responses from 343 employees (194 nonparticipants, 95 participants, and 54 engaged participants). A thematic analysis of focus group (n = 7) and interview (n = 5) narratives was also undertaken. In combination with high work control, high superior support was associated with an engaged participant profile. Job demand was the third important variable with low and very high levels associated with participation. With regard to high likelihood of future participation, among respondents with age older than 50, high predictability of occupational activities and control were identified as a significant factor, and among others, high superior support and control. The analysis of narratives revealed peer relations and flexible working hours to be positively linked to participation and general job stress was identified as having a bidirectional relationship. Employees stated that stress led them to take advantage of these programs as a source of relief and that their availability/participation has contributed to lowering their stress. These findings inform practitioners about the importance of addressing poor psychosocial factors as a participation barrier and having a holistic approach to employee well-being.

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