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PloS One 2022Muscle fatigue is a crucial indicator to determine whether training is in place and to protect trainers.
BACKGROUND
Muscle fatigue is a crucial indicator to determine whether training is in place and to protect trainers.
PURPOSE
To make full use of morphological information of surface EMG and ECG signals in the time domain, a new idea and method for the fatigue assessment of exercise muscles based on data fusion is proposed in this paper.
METHODS
sEMG and ECG time series with the same length were obtained by signal preprocessing and sequence normalization, feature extraction of sequence tenses was realized by a deep learning network based on sequential convolution and signal fusion model of muscle fatigue evaluation was established by D-S evidence theory.
EXPERIMENT
Thirty volunteers were recruited and divided into three groups. ECG signals and sEMG signals at the biceps brachii of the right upper limb were monitored in a 20-minute exercise cycle.
RESULTS
The prediction result of TCN based on time domain signal is better than the commonly used KNN and SVM recognition algorithm, and the recognition accuracy of relaxed, excessive and fatigue by D-S fusion was 89%, 86%, 88.5%. The accuracy was 0.9055, 0.9494 and 0.9269, respectively. The recall rates of the three conditions were 0.9303, 0.9570 and 0.9435. The F-score of the three conditions was 0.8911, 0.8764 and 0.8837, respectively.
CONCLUSION
Based on time series and time series convolutional network, sEMG and ECG fusion of motor muscle recognition method can better distinguish different state information and has certain practical value in the fields of muscle evaluation, clinical diagnosis, wearable devices and so on.
Topics: Humans; Muscle Fatigue; Exercise; Electromyography; Time Factors; Electrocardiography
PubMed: 36454887
DOI: 10.1371/journal.pone.0276921 -
Sports Biomechanics Jun 2021This study determined the effect of skill level (ITN 3 vs. ITN 8) on the tennis serve biomechanics and analysed the impact of forearm fatigue on dominant arm mechanisms...
This study determined the effect of skill level (ITN 3 vs. ITN 8) on the tennis serve biomechanics and analysed the impact of forearm fatigue on dominant arm mechanisms between the two groups (expert vs. non-expert tennis players). The motion capture system with 17 reflective markers attached on anatomic landmarks of the participant was used for data collection. A total of 12 expert and 11 non-expert tennis players performed the required serving tasks. The ball speed of the expert group was significantly faster than that of the non-expert group during non-fatigued and fatigued states ( < 0.001). The wrist radial/ulnar deviation angle at impact was significantly different between non-fatigued and fatigued states for top-spin ( = 0.030) and flat serves ( = 0.018). A significant increase in extensor carpi ulnaris (ECU) and extensor carpi radialis (ECR) muscle activity during extension ( < 0.010) was observed, with that of the ECU being an ulnar deviation. Both the ECU and ECR might contribute to wrist joint and racket handle stability for the coming acceleration and impact while fatigue occurs. Fatigue might substantially influence non-experts' dominant forearms because of the significantly different elbow joint angles and dominant arm syndromes they displayed as compared with the experts.
Topics: Adult; Athletic Performance; Biomechanical Phenomena; Electromyography; Forearm; Humans; Middle Aged; Muscle Fatigue; Muscle, Skeletal; Tennis; Young Adult
PubMed: 30729865
DOI: 10.1080/14763141.2018.1560492 -
Clinics (Sao Paulo, Brazil) 2022Fatigue of the ankle's stabilizing muscles may influence the performance of functional activities and postural control. The purpose of this study was to evaluate the...
OBJECTIVE
Fatigue of the ankle's stabilizing muscles may influence the performance of functional activities and postural control. The purpose of this study was to evaluate the performance of healthy young adults using functional jump tests and static posturography control under pre- and post-fatigue conditions of the ankle invertor and evertor muscles.
METHODS
Thirty physically active healthy male and female (15 male and 15 female) volunteers (24.3 years) were enrolled in this prospective cross-sectional study. Participants performed tests on one day under a non-fatigued state of invertor and evertor muscles and on the second day in a fatigued state. Tests included static posturography on a force platform in a bipedal stance with eyes open and closed and in one-legged support with eyes open and functional jump tests (figure-of-8, side hop, 6-m crossover hop, and square hop). Fatigue of the ankle invertor and evertor muscles was induced using isokinetic dynamometry with 30 repetitions at 120°/s.
RESULTS
Participants had an average age of 24.3 years (SD ± 2.08), the height of 1.73 m (SD ± 0.08), and a weight of 68.63 kg (SD ± 10.29). The average Body Mass Index (BMI) was 22.88 (SD ± 2.46). A decrease in performance was observed in functional activities and postural control under all conditions after the induction of muscle fatigue, except for the speed at a bipedal stance with eyes open.
CONCLUSIONS
Functional jump tests are low cost and useful for clinical practice and evaluation of the effects of muscle fatigue and could be used in clinical practice.
Topics: Adult; Ankle Joint; Cross-Sectional Studies; Female; Humans; Male; Muscle Fatigue; Muscle, Skeletal; Postural Balance; Prospective Studies; Young Adult
PubMed: 35231777
DOI: 10.1016/j.clinsp.2022.100011 -
Experimental Physiology Apr 2022What is the central question of this study? Does the work done above critical power (W') or muscle activation determine the degree of peripheral fatigue induced by...
NEW FINDINGS
What is the central question of this study? Does the work done above critical power (W') or muscle activation determine the degree of peripheral fatigue induced by cycling time trials performed in the severe-intensity domain? What is the main finding and its importance? Peripheral fatigue increased when power output and muscle activation increased, whereas W' did not change between the time trials. Therefore, no relationship was found between W' and exercise-induced peripheral fatigue such as previously postulated in the literature. In contrast, we found a significant association between EMG amplitude during exercise and exercise-induced reduction in the potentiated quadriceps twitch, suggesting that muscle activation plays a key role in determining peripheral fatigue during severe-intensity exercise.
ABSTRACT
In order to determine the relationship between peripheral fatigue, muscle activation and the total work done above critical power (W'), 10 men and four women performed, on separated days, self-paced cycling time trials of 3, 6, 10 and 15 min. Exercise-induced quadriceps fatigue was quantified using pre- to postexercise (15 s to 15 min recovery) changes in maximal voluntary contraction (MVC) peak force, voluntary activation and potentiated twitch force (QT). Voluntary activation was measured using the interpolated twitch technique, and QT was evoked by electrical stimulations of the femoral nerve. Quadriceps muscle activation was determined using the root mean square of surface EMG of vastus lateralis (VL ), vastus medialis (VM ) and rectus femoris (RF ). Critical power and W' were calculated from the power-duration relationship from the four time trials. Mean power output and mean VL , VM and RF were greater during shorter compared with longer exercise periods (P < 0.05), whereas no significant between-trial change in W' was found. The magnitude of exercise-induced reductions in QT increased with the increase in power output (P < 0.001) and was associated with mean VL VM and RF (P < 0.001, r > 0.369) but not W' (P > 0.150, r < 0.044). Reduction in voluntary activation tended (P = 0.067) to be more pronounced with the lengthening in time trial duration, whereas no significant between-trial changes in MVC peak force were found. Our data suggest that peripheral fatigue is not related to the amount of work done above the critical power but rather to the level of muscle activation during exercise in the severe-intensity domain.
Topics: Electromyography; Exercise; Exercise Tolerance; Female; Humans; Male; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Quadriceps Muscle
PubMed: 35137992
DOI: 10.1113/EP090043 -
International Journal of Occupational... Jul 2019The objective of this study was to assess the postures that were commonly used in automobile chassis repair operations, and to evaluate shoulder girdle muscle fatigue...
OBJECTIVES
The objective of this study was to assess the postures that were commonly used in automobile chassis repair operations, and to evaluate shoulder girdle muscle fatigue for different combinations of the weight of hand-tools.
MATERIAL AND METHODS
Two right muscles, including upper trapezius (UT) and middle deltoid (MD), were selected. Surface electromyography (SEMG) and a perceived level of discomfort (PLD) were used to assess the degree of shoulder girdle fatigue. Fifteen healthy young male subjects from the Northwestern Polytechnical University participated in the test. The test consisted of assuming 4 different postures and maintaining each of them for 60 s. The 4 postures varied in terms of dumbbell weights, standing for the hand-tools weight: W1 was 0.48 kg and W2 was 0.75 kg; the 4 shoulder postures were shoulder flexions of 150°, 120°, 90°, and 60°, combined with an included elbow angle of 180°, 150°, 120° and 90°, respectively. The experimental sequences were randomly selected. The signals of SEMG and the values of PLD in the shoulder girdle were recorded in 60 s. All subjects completed the whole test. The repeated measure analysis of variance (ANOVA) was performed to ascertain differences between dumbbell weight (0.48 kg and 0.75 kg) and shoulder postures (150°/180°, 120°/150°, 90°/120° and 60°/90°). The Friedman test was utilized to determine the significant differences for UT(PLD) and MD(PLD) on shoulder postures. Spearman’s correlation was used to analyze the relationship between the subjective and objective measurements.
RESULTS
Significant correlational relationships existed between the UT percentage of the maximal voluntary electrical activation (%MVE) and UT(PLD) (r = 0.459, p < 0.01), between MD(%MVE) and MD(PLD) (r = 0.821, p < 0.01). The results showed that SEMG and PLD of the 4 postures under analysis differed significantly (p < 0.05).
CONCLUSIONS
It was indicated that posture T4 (shoulder forward flexion 60° and included elbow angle 90°) resulted in the lowest fatigue, both in terms of the objective measure and the subjective perception, which meant that this posture was more ergonomic. Int J Occup Med Environ Health. 2019;32(4):537–52
Topics: Adult; Automobiles; Electromyography; Ergonomics; Humans; Male; Muscle Fatigue; Muscle, Skeletal; Posture; Shoulder; Workload
PubMed: 31309815
DOI: 10.13075/ijomeh.1896.01387 -
Experimental Physiology Oct 2021What is the topic of this review? Physiological complexity in muscle force and torque fluctuations, specifically the quantification of complexity, how neuromuscular... (Review)
Review
NEW FINDINGS
What is the topic of this review? Physiological complexity in muscle force and torque fluctuations, specifically the quantification of complexity, how neuromuscular complexityis altered by perturbations and the potential mechanism underlying changes in neuromuscular complexity. What advances does it highlight? The necessity to calculate both magnitude- and complexity-based measures for the thorough evaluation of force/torque fluctuations. Also the need for further research on neuromuscular complexity, particularly how it relates to the performance of functional activities (e.g. manual dexterity, balance, locomotion).
ABSTRACT
Physiological time series produce inherently complex fluctuations. In the last 30 years, methods have been developed to characterise these fluctuations, and have revealed that they contain information about the function of the system producing them. Two broad classes of metrics are used: (1) those which quantify the regularity of the signal (e.g. entropy metrics); and (2) those which quantify the fractal properties of the signal (e.g. detrended fluctuation analysis). Using these techniques, it has been demonstrated that ageing results in a loss of complexity in the time series of a multitude of signals, including heart rate, respiration, gait and, crucially, muscle force or torque output. This suggests that as the body ages, physiological systems become less adaptable (i.e. the systems' ability to respond rapidly to a changing external environment is diminished). More recently, it has been shown that neuromuscular fatigue causes a substantial loss of muscle torque complexity, a process that can be observed in a few minutes, rather than the decades it requires for the same system to degrade with ageing. The loss of torque complexity with neuromuscular fatigue appears to occur exclusively above the critical torque (at least for tasks lasting up to 30 min). The loss of torque complexity can be exacerbated with previous exercise of the same limb, and reduced by the administration of caffeine, suggesting both peripheral and central mechanisms contribute to this loss. The mechanisms underpinning the loss of complexity are not known but may be related to altered motor unit behaviour as the muscle fatigues.
Topics: Electromyography; Isometric Contraction; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Torque
PubMed: 34472160
DOI: 10.1113/EP089711 -
Gait & Posture Mar 2022Muscle fatigue of the lower limbs is considered a main contributor to the perceived fatigue in children with cerebral palsy (CP) and is expected to occur during...
BACKGROUND
Muscle fatigue of the lower limbs is considered a main contributor to the perceived fatigue in children with cerebral palsy (CP) and is expected to occur during prolonged walking. In adults without disabilities, muscle fatigue has been proposed to be associated with adaptations in complexity of neuromuscular control.
RESEARCH QUESTION
What are the effects of prolonged walking on signs of muscle fatigue and complexity of neuromuscular control in children with CP?
METHODS
Ten children with CP and fifteen typically developing (TD) children performed a standardised protocol on an instrumented treadmill consisting of three stages: six-minutes walking at preferred speed (6 MW), moderate-intensity walking (MIW, with two minutes at heart rate > 70% of predicted maximal heart rate) and four-minutes walking at preferred speed (post-MIW). Electromyography (EMG) data were analysed for eight muscles of one leg during three time periods: 6 MW-start, 6 MW-end and post-MIW. Signs of muscle fatigue were quantified as changes in EMG median frequency and EMG root mean square (RMS). Complexity of neuromuscular control was quantified by total variance accounted for by one synergy (tVAF1). Muscle coactivation was assessed for antagonistic muscle pairs.
RESULTS
EMG median frequency was decreased at 6 MW-end and post-MIW compared to 6 MW-start in children with CP (p < 0.05), but not in TD children. In both groups, EMG-RMS (p < 0.01) and muscle coactivation (p < 0.01) were decreased at 6 MW-end and post-MIW compared to 6 MW-start. tVAF1 decreased slightly at 6 MW-end and post-MIW compared to 6 MW-start in both groups (p < 0.05). Changes were most pronounced from 6 MW-start to 6 MW-end.
SIGNIFICANCE
Children with CP presented signs of muscle fatigue after prolonged walking, while no effects were found for TD. Both groups showed minimal changes in tVAF1, suggesting signs of muscle fatigue are not associated with changes in complexity of neuromuscular control.
Topics: Adult; Cerebral Palsy; Child; Electromyography; Gait; Humans; Muscle Fatigue; Muscle, Skeletal; Walking
PubMed: 35042058
DOI: 10.1016/j.gaitpost.2022.01.004 -
European Journal of Sport Science Aug 2023Neuromuscular electrical stimulation (NMES) in combination with blood flow restriction (BFR) enhances muscle hypertrophy and force-generating capacity. The present study...
Neuromuscular electrical stimulation (NMES) in combination with blood flow restriction (BFR) enhances muscle hypertrophy and force-generating capacity. The present study aimed to investigate the acute effects of BFR and NMES, both in isolation and in combination, on muscle thickness (MT) and fatigue in the lower body of 20 young healthy subjects. Different stimuli were applied for 25 min, defined by the combination of BFR with high- and low-frequency NMES, and also isolated BFR or NMES. Changes in MT were then evaluated by ultrasound of the (RF) and (VL) muscles at the end of the session (POST) and 15 min later (POST 15'). Lower limb fatigue was evaluated indirectly by strength performance. Results showed that RF MT was higher under the combined protocol (BFR + NMES) or isolated BFR than under NMES - regardless of the frequency - both at POST ( ≤ 0.018) and POST 15' ( ≤ 0.016). No significant changes in MT were observed under isolated NMES or BFR at POST 15' when compared with basal values ( ≥ 0.067). No significant differences were observed for VL MT between conditions ( = 0.322) or for fatigue between conditions ( ≥ 0.258). Our results indicate that a combination of BFR and NMES acutely increases MT in sedentary subjects. Also, although not significantly, BFR conditions had a greater tendency to induce fatigue than isolated NMES.The combination of blood flow restriction (BFR) and neuromuscular electrical stimulation (NMES) produces higher acute cell swelling than the isolated application of either NMES or BFR.BFR in isolation appears to produce greater cell swelling than NMES, regardless of the frequency used.BFR conditions had a greater tendency to induce fatigue than isolated NMES.
Topics: Humans; Muscle, Skeletal; Electric Stimulation; Quadriceps Muscle; Hemodynamics; Regional Blood Flow; Electric Stimulation Therapy; Muscle Strength; Muscle Fatigue
PubMed: 35965445
DOI: 10.1080/17461391.2022.2113145 -
Journal of Neural Engineering Aug 2022Exercise-induced muscle fatigue is a complex physiological phenomenon involving the central and peripheral nervous systems, and fatigue tolerance varies across...
Exercise-induced muscle fatigue is a complex physiological phenomenon involving the central and peripheral nervous systems, and fatigue tolerance varies across individuals. Various studies have emphasized the close relationships between muscle fatigue and the brain. However, the relationships between the resting-state electroencephalogram (rsEEG) brain network and individual muscle fatigue tolerance remain unexplored.Eighteen elite water polo athletes took part in our experiment. Five-minute before- and after-fatigue-exercise rsEEG and fatiguing task (i.e. elbow flexion and extension) electromyography (EMG) data were recorded. Based on the graph theory, we constructed the before- and after-task rsEEG coherence network and compared the network differences between them. Then, the correlation between the before-fatigue rsEEG network properties and the EMG fatigue indexes when a subject cannot keep on exercising anymore was profiled. Finally, a prediction model based on the before-fatigue rsEEG network properties was established to predict fatigue tolerance.. Results of this study revealed the significant differences between the before- and after-exercise rsEEG brain network and found significant high correlations between before-exercise rsEEG network properties in the beta band and individual muscle fatigue tolerance. Finally, an efficient support vector regression (SVR) model based on the before-exercise rsEEG network properties in the beta band was constructed and achieved the accurate prediction of individual fatigue tolerance. Similar results were also revealed on another 30 subject swimmer data set further demonstrating the reliability of predicting fatigue tolerance based on the rsEEG network.Our study investigates the relationship between the rsEEG brain network and individual muscle fatigue tolerance and provides a potential objective physiological biomarker for tolerance prediction and the regulation of muscle fatigue.
Topics: Brain; Electroencephalography; Electromyography; Humans; Muscle Fatigue; Muscle, Skeletal; Reproducibility of Results
PubMed: 35901723
DOI: 10.1088/1741-2552/ac8502 -
Mathematical Biosciences and... Mar 2020Muscle fatigue is an important field of study in sports medicine and occupational health. Several studies in the literature have proposed methods for predicting muscle...
Muscle fatigue is an important field of study in sports medicine and occupational health. Several studies in the literature have proposed methods for predicting muscle fatigue in isometric con-tractions using three states of muscular fatigue: Non-Fatigue, Transition-to-Fatigue, and Fatigue. For this, several features in time, spectral and time-frequency domains have been used, with good performance results; however, when they are applied to dynamic contractions the performance decreases. In this paper, we propose an approach for analyzing muscle fatigue during dynamic contractions based on time and spectral domain features, Permutation Entropy (PE) and biomechanical features. We established a protocol for fatiguing the deltoid muscle and acquiring surface electromiography (sEMG) and biomechanical signals. Subsequently, we segmented the sEMG and biomechanical signals of every contraction. In order to label the contraction, we computed some features from biomechanical signals and evaluated their correlation with fatigue progression, and the most correlated variables were used to label the contraction using hierarchical clustering with Ward's linkage. Finally, we analyzed the discriminant capacity of sEMG features using ANOVA and ROC analysis. Our results show that the biomechanical features obtained from angle and angular velocity are related to fatigue progression, the analysis of sEMG signals shows that PE could distinguish Non-Fatigue, Transition-to-Fatigue and Fatigue more effectively than classical sEMG features of muscle fatigue such as Median Frequency.
Topics: Cluster Analysis; Electromyography; Entropy; Muscle Fatigue; Muscle, Skeletal
PubMed: 32233556
DOI: 10.3934/mbe.2020142