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International Journal of Molecular... Oct 2021Muscle fatigue (MF) declines the capacity of muscles to complete a task over time at a constant load. MF is usually short-lasting, reversible, and is experienced as a... (Review)
Review
Muscle fatigue (MF) declines the capacity of muscles to complete a task over time at a constant load. MF is usually short-lasting, reversible, and is experienced as a feeling of tiredness or lack of energy. The leading causes of short-lasting fatigue are related to overtraining, undertraining/deconditioning, or physical injury. Conversely, MF can be persistent and more serious when associated with pathological states or following chronic exposure to certain medication or toxic composites. In conjunction with chronic fatigue, the muscle feels floppy, and the force generated by muscles is always low, causing the individual to feel frail constantly. The leading cause underpinning the development of chronic fatigue is related to muscle wasting mediated by aging, immobilization, insulin resistance (through high-fat dietary intake or pharmacologically mediated Peroxisome Proliferator-Activated Receptor (PPAR) agonism), diseases associated with systemic inflammation (arthritis, sepsis, infections, trauma, cardiovascular and respiratory disorders (heart failure, chronic obstructive pulmonary disease (COPD))), chronic kidney failure, muscle dystrophies, muscle myopathies, multiple sclerosis, and, more recently, coronavirus disease 2019 (COVID-19). The primary outcome of displaying chronic muscle fatigue is a poor quality of life. This type of fatigue represents a significant daily challenge for those affected and for the national health authorities through the financial burden attached to patient support. Although the origin of chronic fatigue is multifactorial, the MF in illness conditions is intrinsically linked to the occurrence of muscle loss. The sequence of events leading to chronic fatigue can be schematically denoted as: trigger (genetic or pathological) -> molecular outcome within the muscle cell -> muscle wasting -> loss of muscle function -> occurrence of chronic muscle fatigue. The present review will only highlight and discuss current knowledge on the molecular mechanisms that contribute to the upregulation of muscle wasting, thereby helping us understand how we could prevent or treat this debilitating condition.
Topics: Autophagy; COVID-19; Critical Illness; Humans; Insulin Resistance; Lysosomes; Muscle Fatigue; Muscle Proteins; Muscle, Skeletal; Muscular Atrophy; Sarcopenia
PubMed: 34769017
DOI: 10.3390/ijms222111587 -
The Journal of Physiology Jan 2008Much is known about the physiological impairments that can cause muscle fatigue. It is known that fatigue can be caused by many different mechanisms, ranging from the... (Review)
Review
Much is known about the physiological impairments that can cause muscle fatigue. It is known that fatigue can be caused by many different mechanisms, ranging from the accumulation of metabolites within muscle fibres to the generation of an inadequate motor command in the motor cortex, and that there is no global mechanism responsible for muscle fatigue. Rather, the mechanisms that cause fatigue are specific to the task being performed. The development of muscle fatigue is typically quantified as a decline in the maximal force or power capacity of muscle, which means that submaximal contractions can be sustained after the onset of muscle fatigue. There is even evidence that the duration of some sustained tasks is not limited by fatigue of the principal muscles. Here we review experimental approaches that focus on identifying the mechanisms that limit task failure rather than those that cause muscle fatigue. Selected comparisons of tasks, groups of individuals and interventions with the task-failure approach can provide insight into the rate-limiting adjustments that constrain muscle function during fatiguing contractions.
Topics: Electromyography; Female; Humans; Male; Motor Activity; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Task Performance and Analysis
PubMed: 17702815
DOI: 10.1113/jphysiol.2007.139477 -
Physiological Measurement May 2017In a broad view, fatigue is used to indicate a degree of weariness. On a muscular level, fatigue posits the reduced capacity of muscle fibres to produce force, even in... (Review)
Review
In a broad view, fatigue is used to indicate a degree of weariness. On a muscular level, fatigue posits the reduced capacity of muscle fibres to produce force, even in the presence of motor neuron excitation via either spinal mechanisms or electric pulses applied externally. Prior to decreased force, when sustaining physically demanding tasks, alterations in the muscle electrical properties take place. These alterations, termed myoelectric manifestation of fatigue, can be assessed non-invasively with a pair of surface electrodes positioned appropriately on the target muscle; traditional approach. A relatively more recent approach consists of the use of multiple electrodes. This multi-channel approach provides access to a set of physiologically relevant variables on the global muscle level or on the level of single motor units, opening new fronts for the study of muscle fatigue; it allows for: (i) a more precise quantification of the propagation velocity, a physiological variable of marked interest to the study of fatigue; (ii) the assessment of regional, myoelectric manifestations of fatigue; (iii) the analysis of single motor units, with the possibility to obtain information about motor unit control and fibre membrane changes. This review provides a methodological account on the multi-channel approach for the study of myoelectric manifestation of fatigue and on the experimental conditions to which it applies, as well as examples of their current applications.
Topics: Electromyography; Electrophysiological Phenomena; Humans; Muscle Fatigue; Signal Processing, Computer-Assisted
PubMed: 28199218
DOI: 10.1088/1361-6579/aa60b9 -
European Journal of Applied Physiology Mar 2021This review integrates from the single muscle fibre to exercising human the current understanding of the role of skeletal muscle for whole-body potassium (K) regulation,... (Review)
Review
This review integrates from the single muscle fibre to exercising human the current understanding of the role of skeletal muscle for whole-body potassium (K) regulation, and specifically the regulation of skeletal muscle [K]. We describe the K transport proteins in skeletal muscle and how they contribute to, or modulate, K disturbances during exercise. Muscle and plasma K balance are markedly altered during and after high-intensity dynamic exercise (including sports), static contractions and ischaemia, which have implications for skeletal and cardiac muscle contractile performance. Moderate elevations of plasma and interstitial [K] during exercise have beneficial effects on multiple physiological systems. Severe reductions of the trans-sarcolemmal K gradient likely contributes to muscle and whole-body fatigue, i.e. impaired exercise performance. Chronic or acute changes of arterial plasma [K] (hyperkalaemia or hypokalaemia) have dangerous health implications for cardiac function. The current mechanisms to explain how raised extracellular [K] impairs cardiac and skeletal muscle function are discussed, along with the latest cell physiology research explaining how calcium, β-adrenergic agonists, insulin or glucose act as clinical treatments for hyperkalaemia to protect the heart and skeletal muscle in vivo. Finally, whether these agents can also modulate K-induced muscle fatigue are evaluated.
Topics: Exercise; Humans; Muscle Fatigue; Muscle, Skeletal; Potassium
PubMed: 33392745
DOI: 10.1007/s00421-020-04546-8 -
Nutrients Jun 2022Recovery strategies, both in the general population and in athletes, must be aimed at the main causes of fatigue [...].
Recovery strategies, both in the general population and in athletes, must be aimed at the main causes of fatigue [...].
Topics: Athletes; Fatigue; Humans; Muscle Fatigue; Muscle, Skeletal; Nutritional Status
PubMed: 35745146
DOI: 10.3390/nu14122416 -
Physical Medicine and Rehabilitation... May 2000The purpose of this review is to acquaint the reader with the neurobiology of muscle fatigue. Muscle fatigue is a complex, multifactorial process. The authors have... (Review)
Review
The purpose of this review is to acquaint the reader with the neurobiology of muscle fatigue. Muscle fatigue is a complex, multifactorial process. The authors have covered the chain of events bringing about skeletal muscle contraction and the manner in which fatigue may affect each step. Advances in technology continue to increase understanding of central fatigue. Many excellent studies of peripheral fatigue have been designed to delineate the mechanisms that influence the excitation-contraction coupling, energy supply, and force generation processes. Although much of this work has considered mechanisms in isolation, different mechanisms may be responsible under different conditions. Fatigue is a common complaint among patients with a variety of neuromuscular and metabolic diseases. Armed with an enhanced knowledge of the mechanisms of muscle fatigue, one can more fully recognize the signs and symptoms of metabolic disorders and neuromuscular diseases and use diagnostic testing. The clinician should anticipate the role of muscle fatigue in injury and focus on injury prevention strategies, especially during the restorative phase of rehabilitation. As a clinician-scientist concerned with optimizing patients' and athletes' performance, one must design ways to identify, measure, and treat muscle fatigue. Beyond illustrating what is currently known about muscle fatigue, the authors hope this review inspires the reader to solve problems of great clinical importance to patients and athletes alike.
Topics: Animals; Energy Metabolism; Humans; Muscle Fatigue; Muscle, Skeletal; Musculoskeletal Physiological Phenomena; Nervous System Physiological Phenomena; Physical Endurance
PubMed: 10810767
DOI: No ID Found -
Journal of Applied Physiology... May 2017Sustained physical exercise leads to a reduced capacity to produce voluntary force that typically outlasts the exercise bout. This "fatigue" can be due both to impaired... (Review)
Review
Sustained physical exercise leads to a reduced capacity to produce voluntary force that typically outlasts the exercise bout. This "fatigue" can be due both to impaired muscle function, termed "peripheral fatigue," and a reduction in the capacity of the central nervous system to activate muscles, termed "central fatigue." In this review we consider the factors that determine the of voluntary force generating capacity after various types of exercise. After brief, high-intensity exercise there is typically a rapid restitution of force that is due to recovery of central fatigue (typically within 2 min) and aspects of peripheral fatigue associated with excitation-contraction coupling and reperfusion of muscles (typically within 3-5 min). Complete recovery of muscle function may be incomplete for some hours, however, due to prolonged impairment in intracellular Ca release or sensitivity. After low-intensity exercise of long duration, voluntary force typically shows rapid, partial, recovery within the first few minutes, due largely to recovery of the central, neural component. However, the ability to voluntarily activate muscles may not recover completely within 30 min after exercise. Recovery of peripheral fatigue contributes comparatively little to the fast initial force restitution and is typically incomplete for at least 20-30 min. Work remains to identify what factors underlie the prolonged central fatigue that usually accompanies long-duration single joint and locomotor exercise and to document how the time course of neuromuscular recovery is affected by exercise intensity and duration in locomotor exercise. Such information could be useful to enhance rehabilitation and sports performance.
Topics: Animals; Central Nervous System; Exercise; Humans; Muscle Fatigue; Muscle, Skeletal; Peripheral Nerves
PubMed: 27932676
DOI: 10.1152/japplphysiol.00775.2016 -
Sports Medicine (Auckland, N.Z.) 2008One of the consequences of sustaining exercise for 90 minutes of football match-play is that the capability of muscle to generate force declines. This impairment is... (Review)
Review
One of the consequences of sustaining exercise for 90 minutes of football match-play is that the capability of muscle to generate force declines. This impairment is reflected in the decline of work-rate towards the late part of the game. Causes of this phenomenon, which is known as fatigue, and some of its consequences are considered in this article. The stores of muscle glycogen may be considerably reduced by the end of the game, especially if there has not been a tapering of the training load. Thermoregulatory strain may also be encountered, resulting in a fall in physical performance, or there may be a reduced central drive from the nervous system. The decline in muscle strength may increase the predisposition to injury in the lower limbs. Central fatigue may also occur with implications for muscle performance. Strategies to offset fatigue include astute use of substitutions, appropriate nutritional preparation and balancing pre-cooling and warm-up procedures. There is also a role for endurance training and for a pacing strategy that optimizes the expenditure of energy during match-play.
Topics: Exercise Tolerance; Football; Humans; Muscle Fatigue
PubMed: 18416591
DOI: 10.2165/00007256-200838050-00001 -
Advances in Experimental Medicine and... 1995Ventilatory failure may accompany a variety of pulmonary and neuromuscular diseases. There has been much controversy about whether this failure is due to respiratory... (Review)
Review
Ventilatory failure may accompany a variety of pulmonary and neuromuscular diseases. There has been much controversy about whether this failure is due to respiratory muscle fatigue at peripheral sites or a failure of drive at sites within the central nervous system. The chapter reviews this topic.
Topics: Animals; Diaphragm; Electromyography; Humans; Muscle Fatigue; Pulmonary Ventilation; Respiratory Muscles
PubMed: 8585468
DOI: 10.1007/978-1-4899-1016-5_32 -
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