scholarly journals Modeling and Validation of Fatigue and Recovery of Muscles for Manual Demolition Tasks

Author(s):  
Cannan Yi ◽  
Fan Tang ◽  
Kai-Way Li ◽  
Hong Hu ◽  
Huali Zuo ◽  
...  

Manual demolition tasks are heavy, physically demanding tasks that could cause muscle fatigue accumulation and lead to work-related musculoskeletal disorders (WMSDs). Fatigue and recovery models of muscles are essential in understanding the accumulation and the reduction in muscle fatigue for forceful exertion tasks. This study aims to explore the onset of muscle fatigue under different work/rest arrangements during manual demolition tasks and the offset of fatigue over time after the tasks were performed. An experiment, including a muscle fatigue test and a muscle fatigue recovery test, was performed. Seventeen male adults without experience in demolition hammer operation were recruited as human participants. Two demolition hammers (large and small) were adopted. The push force was either 20 or 40 N. The posture mimicked that of a demolition task on a wall. In the muscle fatigue test, the muscle strength (MS) before and after the demolition task, maximum endurance time (MET), and the Borg category-ratio-10 (CR-10) ratings of perceived exertion after the demolition task were measured. In the muscle fatigue recovery test, MS and CR-10 at times 1, 2, 3, 4, 5, and 6 min were recorded. Statistical analyses were performed to explore the influence of push force and the weight of the tool on MS, MET, and CR-10. Both muscle fatigue models and muscle fatigue recovery models were established and validated. The results showed that push force affected MET significantly (p < 0.05). The weight of the tool was significant (p < 0.05) only on the CR-10 rating after the first pull. During the muscle fatigue recovery test, the MS increase and the CR-10 decrease were both significant (p < 0.05) after one or more breaks. Models of MET and MS prediction were established to assess muscle fatigue recovery, respectively. The absolute (AD) and relative (RD) deviations of the MET model were 1.83 (±1.94) min and 34.80 (±31.48)%, respectively. The AD and RD of the MS model were 1.39 (±0.81) N and 1.9 (±1.2)%, respectively. These models are capable of predicting the progress and recovery of muscle fatigue, respectively, and may be adopted in work/rest arrangements for novice workers performing demolition tasks.

Author(s):  
Alessandra Moreira-Reis ◽  
José Luis Maté-Muñoz ◽  
Juan Hernández-Lougedo ◽  
Pablo García-Fernández ◽  
Eulogio Pleguezuelos-Cobo ◽  
...  

Background: Aerobic dance (AD) is an appropriate physical activity for improving cardiorespiratory fitness. This study aimed to compare cardiorespiratory and metabolic responses, and muscle fatigue between an air dissipation platform (ADP) and a hard surface during a video-recorded AD session. Methods: 25 healthy young women (23.3 ± 2.5 years) completed three sessions. In session 1, participants performed an incremental test to exhaustion on a treadmill. One week after session 1, participants were randomly assigned in a crossover design to perform video-recorded AD sessions on an ADP and on a hard surface (sessions 2 and 3). Cardiorespiratory and metabolic responses were assessed during AD sessions. Muscular fatigue was measured before and after AD sessions by a countermovement jump test. Results: Significantly higher heart rate, respiratory exchange ratio, pulmonary ventilation, ventilatory oxygen equivalent, and ventilatory carbon dioxide equivalent were observed on an ADP than on a hard surface (p < 0.05). Despite a significant increase in lactate levels on an ADP (p ≤ 0.01), muscular fatigue and perceived exertion rating were similar on both surfaces (p > 0.05). Conclusions: Video-recorded AD on an ADP increased the cardioventilatory and metabolic responses compared to a hard surface, preventing further muscle fatigue.


2021 ◽  
Vol 7 ◽  
pp. 237796082110579
Author(s):  
Seyed Abolfazl Zakerian ◽  
Mansooreh Afzalinejhad ◽  
Mahmood Mahmodi ◽  
Niloofar Sheibani

Introduction Nursing personnel are always at risk for work-related musculoskeletal disorders, and patient transportation is one of the major risk factor for these disorders. Objective The aim of this study was to evaluate the ergonomic belt to improve patient transferring conditions. Methods The subjects included 60 health care workers (HCW) of a hospital with patient transfer experience. The ergonomic belt was examined to help move the patient from one bed to another. The prevalence of musculoskeletal disorders was assessed through the Nordic questionnaire, the degree of perceived exertion through the Borg criterion, and the patient's movement through the MAPO index before and after the intervention. Results The results showed a significant decrease in Borg scale scores and MAPO index in two factors of education and auxiliary tools and overall scores of this index. We also saw a significant reduction in musculoskeletal disorders in the neck, shoulders and arms, waist, hands and wrists, thighs, knees and legs. There were no significant differences in the elbow and forearm before and after using the ergonomic belt. Conclusion In general, it can be concluded that the use of ergonomic belt had helped to reduce the risk of musculoskeletal disorders, as well as reducing the perceived exertion of nurses and other relevant personnel.


Work ◽  
2021 ◽  
pp. 1-10
Author(s):  
Kai Way Li ◽  
Wenbao Li ◽  
Lu Peng

BACKGROUND: Manual demolition tasks are heavy physical demanding tasks which involve forceful exertion of sustained pushing. They result in muscle fatigue which could lead to musculoskeletal disorders. Assessments of maximum endurance time (MET) are essential in understanding the developing of muscle fatigue for these tasks. OBJECTIVE: The objectives of this study were to determine the effects of handle height and load conditions on the MET, and to establish MET models for the simulated demolition tasks. METHODS: Twenty three male participants performed simulated demolition tasks under three loads and three handle heights conditions until they could not do so any longer. Their METs and ratings of perceived exertion were recorded and analyzed. RESULTS: The results showed that both load and handle height were significant (p <  0.0001) factors affecting the MET. Regression models to predict the MET under handle height and load conditions were established. The mean absolute deviations of these models were between 1.91 and 4.84 min. CONCLUSION: The MET models established may be used to estimate the MET which may be adopted in work/rest arrangement for demolition tasks using a handheld demolition hammer.


2017 ◽  
Vol 124 (3) ◽  
pp. 649-661 ◽  
Author(s):  
P. C. Caetano Júnior ◽  
M. L. Castilho ◽  
L. Raniero

This study compared the effects of an official rugby match and a fatigue test on the salivary cortisol responses of 13 rugby players. We also examined the relationship between this cortisol response and session ratings of perceived exertion (session-RPE). We collected saliva before and after the match and fatigue test and assessed physical effort intensity via session-RPE using a CR-10 scale. We measured cortisol concentration by enzyme-linked immunosorbent assays. Results were greater session-RPE and cortisol concentrations for the rugby match, compared with the fatigue test. There was a significant difference between cortisol concentrations obtained pre- and postmatch ( p < .022) and significant correlations between cortisol response and session-RPE sampling in both the rugby match ( r = .81; p < .001) and fatigue test ( r = .91; p < .001). This study provides evidence of greater perceived effort and higher cortisol concentrations in actual competition versus a fatigue test. Our data further support session-RPE as a relatively inexpensive close correlate of a stress biomarker (cortisol response). Thus, session-RPE can be used by coaches as a valid indication of training loads and adequate recovery time after exertion.


2017 ◽  
Vol 33 (2) ◽  
pp. 105-111 ◽  
Author(s):  
Víctor Torreblanca-Martinez ◽  
Fernando M. Otero-Saborido ◽  
José A. Gonzalez-Jurado

The purpose was to study the effects of muscle fatigue induced by countermovement jumps (CMJ) on instep kick foot velocity in young male soccer players. Fifteen under-18 soccer players from a professional club performed maximal velocity instep kicks before and after a fatigue protocol that consisted of continuous CMJ. Foot velocity at impact without fatigue, foot velocity at impact with fatigue, CMJ height without fatigue, maximum jump height in fatigue test, and CMJ height change in fatigue test on a dynamometric platform were measured. There was a significant difference between jump height with and without fatigue (P = .00; ES = 0.8), but there were no significant differences between kicking with fatigue and without fatigue (P = .580, ES = 0.10). In conclusion, although the protocol was intense enough to generate fatigue in the muscles involved in CMJ, there were no significant differences in kicking velocity under fatigue conditions with respect to kicking without fatigue in the soccer players studied.


2000 ◽  
Vol 44 (30) ◽  
pp. 5-614-5-614 ◽  
Author(s):  
Simon S. Yeung ◽  
Ella W. Yeung ◽  
Rachel FM Chan ◽  
CY Chow ◽  
Glory PS Lee ◽  
...  

This study aimed to investigate the muscle fatigue and self-perceived exertion level on violin players before and after a training session. Fourteen professional violin players volunteered in this study. Surface electromyography (EMG) was used to record the fatigue level of the upper trapezius muscles before and after a training session. Medium Frequency (MF) of the EMG signals was used to document the fatigue rate of this muscle. Regression analysis and paired sample t-tests revealed no significant difference in the slopes of MF on both sides of trapezius muscle, before and after the training sessions. However, the Borg Scale ratings of perceived exertion revealed significant increase in fatigue level (p=0.003) after the training session. The disparity in the subjective perception with the objective findings indicated that the violists' self-perceived exertion arises from multiple sources. The high prevalence of playing-related musculoskeletal complaints (79%) in this group of players warrants further ergonomic investigation of possible work-related risk factors.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Helena Eri Shimizu ◽  
Josierton Cruz Bezerra ◽  
Luciano José Arantes ◽  
Edgar Merchán-Hamann ◽  
Walter Ramalho

Abstract Background Since 2004, Brazil has had a national policy for occupational health and safety. This policy means companies’ tax burden is altered according to the numbers of work-related accidents and ill-health amongst their workers. In 2010, a multiplication factor was introduced to this policy, called the Accident Prevention Factor. The idea of this new multiplication factor is to encourage individual employers to take initiatives to prevent accidents and ill health in the workplace. This study was designed to investigate the incidence of work-related accidents and ill-health in Brazil according to their causes, their severity, and the economic activity in which they occur, and to compare the data before and after the introduction of the Accident Prevention Factor. Methods An ecological study was conducted by analyzing the time series of work-related accidents/ill-health between 2008 and 2014 from the Brazilian social security system (Previdência Social) statistical yearbooks. Incidences were calculated per cause, economic activity, and severity of the accident/ill-health. Data from before and after the introduction of the Accident Prevention Factor were compared using the Mann-Whitney test per cause and per economic activity. Statistical analyses were made using the SPSS software, with significance set at 5%. Results A reduction in the incidence of work-related accidents/ill-health was found across all the groups of causes analyzed, except for the groups “external causes of morbidity and mortality” and “factors influencing health status and contact with health services.” Greater reductions were found for diseases of the musculoskeletal system and connective tissue and diseases of the nervous system. Reductions in work-related accidents/ill-health were found in the different economic activities and in the different severity groups. The highest reduction after the introduction of the Accident Prevention Factor was in manufacturing and production (p < 0.05). Conclusions Overall, the incidence of accidents/ill-health was found to be on decline, except those with external causes of morbidity and mortality and those involving factors influencing health status and contact with health services. The biggest reduction was found in manufacturing and production. However, generally speaking progress still needs to be made in accident prevention and occupational health across a whole range of work environments.


Neuroreport ◽  
2017 ◽  
Vol 28 (3) ◽  
pp. 115-122 ◽  
Author(s):  
Feng Guo ◽  
Yong-Jun Sun ◽  
Ri-Hui Zhang

2009 ◽  
Vol 25 (4) ◽  
pp. 293-303 ◽  
Author(s):  
Yi-Ming Huang ◽  
Ya-Ju Chang ◽  
Miao-Ju Hsu ◽  
Chia-Ling Chen ◽  
Chia-Ying Fang ◽  
...  

The purpose of this study was to evaluate whether agonist muscle fatigue changed the coactivation time and the co-contraction magnitude of the agonist and antagonist muscle, and if the agonist muscle fatigue produced bias (constant error: CE) and inconsistency (variable error: VE) of the force. Subjects are 10 healthy people and one person with impaired proprioception. EMG and force for fast (0.19 ± 0.06 s) and slow (1.20 ± 0.44 s) targeted isometric dorsiflexions were recorded before and after fatigue of the dorsiflexors. The results revealed that the coactivation time increased after fatigue only in the slow contractions but the co-contraction magnitude did not change. The postfatigue increment of the CE was greater in the fast contractions than in the slow ones. We conclude that the postfatigue compensatory strategy can reduce the fatigue-induced bias. The change of muscles activation level after fatigue might be under the influence of the common drive. Impaired proprioception is a possible cause of the fatigue-related increase in bias and inconsistency.


2005 ◽  
Vol 99 (1) ◽  
pp. 141-153 ◽  
Author(s):  
Micaela Schmid ◽  
Marco Schieppati

Neck proprioceptive input, as elicited by muscle vibration, can produce destabilizing effects on stance and locomotion. Neck muscle fatigue produces destabilizing effects on stance, too. Our aim was to assess whether neck muscle fatigue can also perturb the orientation in space during a walking task. Direction and amplitude of the path covered during stepping in place were measured in 10 blindfolded subjects, who performed five 30-s stepping trials before and after a 5-min period of isometric dorsal neck muscle contraction against a load. Neck muscle electromyogram amplitude and median frequency during the head extensor effort were used to compute a fatigue index. Head and body kinematics were recorded by an optoelectronic system, and stepping cadence was measured by sensorized insoles. Before the contraction period, subjects normally stepped on the spot or drifted forward. After contraction, some subjects reproduced the same behavior, whereas others reduced their forward progression or even stepped backward. The former subjects showed minimal signs of fatigue and the latter ones marked signs of fatigue, as quantified by the dorsal neck electromyogram index. Head position and cadence were unaffected in either group of subjects. We argue that the abnormal fatigue-induced afferent input originating in the receptors transducing the neck muscle metabolic state can modulate the egocentric spatial reference frame. Notably, the effects of neck muscle fatigue on orientation are opposite to those produced by neck proprioception. The neck represents a complex source of inputs capable of modifying our orientation in space during a locomotor task.


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