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Biomolecules Dec 2023Metabolic myopathies are a group of genetic disorders that affect the normal functioning of muscles due to abnormalities in metabolic pathways. These conditions result... (Review)
Review
Metabolic myopathies are a group of genetic disorders that affect the normal functioning of muscles due to abnormalities in metabolic pathways. These conditions result in impaired energy production and utilization within muscle cells, leading to limitations in muscle function with concomitant occurrence of related signs and symptoms, among which fatigue is one of the most frequently reported. Understanding the underlying molecular mechanisms of muscle fatigue in these conditions is challenging for the development of an effective diagnostic and prognostic approach to test targeted therapeutic interventions. This paper outlines the key biomolecules involved in muscle fatigue in metabolic myopathies, including energy substrates, enzymes, ion channels, and signaling molecules. Potential future research directions in this field are also discussed.
Topics: Humans; Muscle Fatigue; Muscular Diseases; Metabolism, Inborn Errors; Muscles; Muscle Cells
PubMed: 38254650
DOI: 10.3390/biom14010050 -
European Journal of Applied Physiology Nov 2023Hamstring injuries in soccer reportedly increase towards the end of the matches' halves as well as with increased match frequency in combination with short rest periods,... (Randomized Controlled Trial)
Randomized Controlled Trial
PURPOSE
Hamstring injuries in soccer reportedly increase towards the end of the matches' halves as well as with increased match frequency in combination with short rest periods, possibly due to acute or residual fatigue. Therefore, this study aimed to investigate the effects of acute and residual muscle fatigue on exercise-induced hamstring muscle damage.
METHODS
A three-armed randomized-controlled trial, including 24 resistance-trained males, was performed allocating subjects to either a training group with acute muscle fatigue + eccentric exercise (AF/ECC); residual muscle fatigue + eccentric exercise (RF/ECC) or a control group with only eccentric exercise (ECC). Muscle stiffness, thickness, contractility, peak torque, range of motion, pain perception, and creatine kinase were assessed as muscle damage markers pre, post, 1 h post, and on the consecutive three days.
RESULTS
Significant group × time interactions were revealed for muscle thickness (p = 0.02) and muscle contractility parameters radial displacement (D) and contraction velocity (V) (both p = 0.01), with larger changes in the ECC group (partial η = 0.4). Peak torque dropped by an average of 22% in all groups; stiffness only changed in the RF/ECC group (p = 0.04). Muscle work during the damage protocol was lower for AF/ECC than for ECC and RF/ECC (p = 0.005).
CONCLUSION
Hamstring muscle damage was comparable between the three groups. However, the AF/ECC group resulted in the same amount of muscle damage while accumulating significantly less muscle work during the protocol of the damage exercise.
TRIAL REGISTRATION
This study was preregistered in the international trial registration platform (WHO; registration number: DRKS00025243).
Topics: Male; Humans; Muscle Fatigue; Hamstring Muscles; Muscle, Skeletal; Isometric Contraction; Arm; Torque
PubMed: 37330434
DOI: 10.1007/s00421-023-05234-z -
BMC Musculoskeletal Disorders Jan 2016The physiological background of exercise-induced muscle fatigue(EIMUF) is only poorly understood. Thus, monitoring of EIMUF by a single or multiple biomarkers(BMs) is... (Review)
Review
BACKGROUND
The physiological background of exercise-induced muscle fatigue(EIMUF) is only poorly understood. Thus, monitoring of EIMUF by a single or multiple biomarkers(BMs) is under debate. After a systematic literature review 91 papers were included.
RESULTS
EIMUF is mainly due to depletion of substrates, increased oxidative stress, muscle membrane depolarisation following potassium depletion, muscle hyperthermia, muscle damage, impaired oxygen supply to the muscle, activation of an inflammatory response, or impaired calcium-handling. Dehydration, hyperammonemia, mitochondrial biogenesis, and genetic responses are also discussed. Since EIMUF is dependent on age, sex, degree of fatigue, type, intensity, and duration of exercise, energy supply during exercise, climate, training status (physical fitness), and health status, BMs currently available for monitoring EIMUF have limited reliability. Generally, wet, volatile, and dry BMs are differentiated. Among dry BMs of EIMUF the most promising include power output measures, electrophysiological measures, cardiologic measures, and questionnaires. Among wet BMs of EIMUF those most applicable include markers of ATP-metabolism, of oxidative stress, muscle damage, and inflammation. VO2-kinetics are used as a volatile BM.
CONCLUSIONS
Though the physiology of EIMUF remains to be fully elucidated, some promising BMs have been recently introduced, which together with other BMs, could be useful in monitoring EIMUF. The combination of biomarkers seems to be more efficient than a single biomarker to monitor EIMUF. However, it is essential that efficacy, reliability, and applicability of each BM candidate is validated in appropriate studies.
Topics: Biomarkers; Clinical Trials as Topic; Exercise; Humans; Motor Activity; Muscle Fatigue; Muscle, Skeletal; Volatilization; Wettability
PubMed: 26790722
DOI: 10.1186/s12891-016-0869-2 -
Medicine and Science in Sports and... Nov 2016: During exercise, there is a progressive reduction in the ability to produce muscle force. Processes within the nervous system as well as within the muscles contribute... (Review)
Review
: During exercise, there is a progressive reduction in the ability to produce muscle force. Processes within the nervous system as well as within the muscles contribute to this fatigue. In addition to impaired function of the motor system, sensations associated with fatigue and impairment of homeostasis can contribute to the impairment of performance during exercise. This review discusses some of the neural changes that accompany exercise and the development of fatigue. The role of brain monoaminergic neurotransmitter systems in whole-body endurance performance is discussed, particularly with regard to exercise in hot environments. Next, fatigue-related alterations in the neuromuscular pathway are discussed in terms of changes in motor unit firing, motoneuron excitability, and motor cortical excitability. These changes have mostly been investigated during single-limb isometric contractions. Finally, the small-diameter muscle afferents that increase firing with exercise and fatigue are discussed. These afferents have roles in cardiovascular and respiratory responses to exercise, and in the impairment of exercise performance through interaction with the motor pathway, as well as in providing sensations of muscle discomfort. Thus, changes at all levels of the nervous system, including the brain, spinal cord, motor output, sensory input, and autonomic function, occur during exercise and fatigue. The mix of influences and the importance of their contribution vary with the type of exercise being performed.
Topics: Body Temperature Regulation; Brain; Feedback, Physiological; Hot Temperature; Humans; Motor Cortex; Motor Neurons; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Synaptic Transmission
PubMed: 27003703
DOI: 10.1249/MSS.0000000000000923 -
Experimental Physiology Feb 2016What is the topic of this review? Women are usually less fatigable than men for isometric fatiguing contractions of similar intensity, but whether this occurs for... (Review)
Review
What is the topic of this review? Women are usually less fatigable than men for isometric fatiguing contractions of similar intensity, but whether this occurs for dynamic tasks is less clear. This review presents evidence that the sex difference in muscle fatigue of repeated dynamic contractions is specific to the task requirements, including the velocity of shortening and the muscle group involved. What advances does it highlight? Contractile mechanisms are responsible for the sex differences in muscle fatigue for slow-velocity and low-load dynamic tasks. The variability of the sex difference in fatigability among dynamic tasks has implications for fatiguing contractions prescribed in training and rehabilitation to men and women. Women are usually less fatigable than men during single-limb isometric contractions, primarily because of sex-related differences in contractile mechanisms. It is less clear whether these sex differences in muscle fatigue occur for dynamic fatiguing tasks. This review highlights new findings that the sex difference in fatigability for dynamic shortening contractions with a single limb is dependent on the contraction velocity and the muscle group involved. Recent studies demonstrate that women are less fatigable than men for a dynamic task as follows: (i) the elbow-flexor muscles at slow- but not high-velocity contractions; and (ii) the knee-extensor muscles when muscle fatigue was quantified as a reduction in the maximal voluntary isometric contraction force after the dynamic fatiguing task. Contractile mechanisms are responsible for the sex difference in muscle fatigue of the dynamic contractions, with no evidence for a sex difference in the reduction in voluntary activation (i.e. central fatigue). Thus, these findings indicate that the sex difference in muscle fatigue of dynamic contractions is task specific. These data also challenge the assumption that men and women respond in a similar manner to training and rehabilitation that involve fatiguing contractions to overload the neuromuscular system. There is, however, a tremendous opportunity for conducting high-impact studies to gain insight into those factors that define the sex-based differences in muscle fatigue during dynamic tasks. Such studies can define the boundaries to human performance in both men and women during athletic endeavours, ergonomic tasks and rehabilitation.
Topics: Elbow Joint; Humans; Isometric Contraction; Knee Joint; Muscle Fatigue; Muscle, Skeletal; Physical Endurance; Sex Characteristics
PubMed: 26440505
DOI: 10.1113/EP085370 -
Cold Spring Harbor Perspectives in... Jul 2018Performance fatigability is characterized as an acute decline in motor performance caused by an exercise-induced reduction in force or power of the involved muscles.... (Review)
Review
Performance fatigability is characterized as an acute decline in motor performance caused by an exercise-induced reduction in force or power of the involved muscles. Multiple mechanisms contribute to performance fatigability and originate from neural and muscular processes, with the task demands dictating the mechanisms. This review highlights that (1) inadequate activation of the motoneuron pool can contribute to performance fatigability, and (2) the demands of the task and the physiological characteristics of the population assessed, dictate fatigability and the involved mechanisms. Examples of task and population differences in fatigability highlighted in this review include contraction intensity and velocity, stability and support provided to the fatiguing limb, sex differences, and aging. A future challenge is to define specific mechanisms of fatigability and to translate these findings to real-world performance and exercise training in healthy and clinical populations across the life span.
Topics: Aging; Athletic Performance; Female; Humans; Male; Motor Neurons; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Psychomotor Performance; Sex Characteristics
PubMed: 28507192
DOI: 10.1101/cshperspect.a029728 -
Experimental Physiology Jan 2021What is the central question of this study? Increasing severity of arterial hypoxaemia induces a shift towards greater central, relative to peripheral, mechanisms of...
NEW FINDINGS
What is the central question of this study? Increasing severity of arterial hypoxaemia induces a shift towards greater central, relative to peripheral, mechanisms of fatigue during exhaustive exercise. Does a similar pattern exist for 'all-out' repeated-sprint running? What is the main finding and its importance? Severe normobaric hypoxia [fraction of inspired oxygen ( ) = 0.13] did not induce a greater contribution from central fatigue, but indices of muscle fatigue were elevated compared with normoxia ( = 0.21) and moderate hypoxia ( = 0.17). This suggests a different fatigue response to repeated-sprint running versus other exercise modalities and, consequently, that task specificity might modulate the effect of hypoxia on the central versus peripheral contribution to fatigue.
ABSTRACT
We examined the effects of increasing hypoxia severity on repeated-sprint running performance and neuromuscular fatigue. Thirteen active males completed eight sprints of 5 s (recovery = 25 s) on a motorized sprint treadmill in normoxia (sea level, SL; = 0.21), in moderate hypoxia (MH; = 0.17) and in severe hypoxia (SH; = 0.13). After 6 min of passive recovery, in all conditions a second set of four sprints of 5 s was conducted in normoxia. Neuromuscular function of the knee extensors was assessed at baseline (Pre-) and 1 min after set 1 (Post-set 1) and set 2 (Post-set 2). In set 1, the mean distance covered in SL (22.9 ± 1.2 m) was not different to MH (22.7 ± 1.3 m; P = 0.71) but was greater than in SH (22.3 ± 1.3 m; P = 0.04). No significant differences between conditions for mean distance occurred in set 2. There was a decrease in maximal voluntary contraction torque (Δ = -31.4 ± 18.0 N m, P < 0.001) and voluntary activation (%VA; Δ = -7.1 ± 5.1%, P = 0.001) from Pre- to Post-set 1, but there was no effect of hypoxia. No further change from Post-set 1 to Post-set 2 occurred for either maximal voluntary contraction or %VA. The decrease in potentiated twitch torque in SL (Δ = -13.3 ± 5.2 N m) was not different to MH (Δ = -13.3 ± 6.3 N m) but was lower than in SH (Δ = -16.1 ± 4 N m) from Pre- to Post-set 1 (interaction, P < 0.003). Increasing severity of normobaric hypoxia, up to an equivalent elevation of 3600 m, can increase indices of peripheral fatigue but does not impact central fatigue after 'all-out' repeated-sprint running.
Topics: Adult; Athletic Performance; Bicycling; Exercise; Exercise Test; Humans; Hypoxia; Knee; Male; Muscle Fatigue; Muscle, Skeletal; Running
PubMed: 32557892
DOI: 10.1113/EP088485 -
International Journal of Environmental... Nov 2022Manual materials handling (MMH) contributes to musculoskeletal disorders (MSDs) in the workplace. The development and recovery of muscle fatigue are essential in...
Manual materials handling (MMH) contributes to musculoskeletal disorders (MSDs) in the workplace. The development and recovery of muscle fatigue are essential in work/rest arrangements for MMH tasks. A pulling experiment, including a muscle fatigue test and a muscle fatigue recovery test, was conducted. In the muscle fatigue test, the participant performed a pulling task on a treadmill with a walking velocity of 1 km/h until they could no longer do so. The load was either 30 or 45 kg. The maximum endurance time () was recorded. The pull strength () of the participant both before and after the pulling task was measured. The subjective ratings of muscle fatigue after the pulling task were recorded. In the muscle fatigue recovery test, the participant took a rest after performing the pulling task. The participants reported their subjective ratings of muscle fatigue on the scale after taking a rest for a time period where = 1, 2,…, 6 min. The of the participant was then measured again. It was found that the load significantly affected the for pulling tasks. The load was insignificant to the decrease of the , but was significant to the decrease rate ( decrease per min) of the . The decrease rate for the 45 kg condition (30.8 ± 16.5 N/min) was significantly higher ( < 0.05) than that of the 30 kg condition (15.4 ± 5.5 N/min). The recovery time significantly affected the and . Two models were established to explore the development of muscle fatigue in pulling tasks. A model was constructed to describe the recovery of muscle force. A model was proposed to show the subjective ratings of recovery. These models are beneficial for determining the work/rest allowance for pulling tasks.
Topics: Humans; Muscle Fatigue; Muscle, Skeletal; Walking; Exercise Test; Workplace
PubMed: 36429882
DOI: 10.3390/ijerph192215159 -
International Journal of Environmental... Jan 2022Manual demolition tasks are heavy, physically demanding tasks that could cause muscle fatigue accumulation and lead to work-related musculoskeletal disorders (WMSDs)....
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 () 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, 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 , 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 ( < 0.05). The weight of the tool was significant ( < 0.05) only on the CR-10 rating after the first pull. During the muscle fatigue recovery test, the increase and the CR-10 decrease were both significant ( < 0.05) after one or more breaks. Models of MET and 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 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.
Topics: Adult; Electromyography; Humans; Male; Muscle Fatigue; Muscle Strength; Muscle, Skeletal; Muscles; Musculoskeletal Diseases; Posture
PubMed: 35055755
DOI: 10.3390/ijerph19020930 -
Experimental Physiology Dec 2021What is the central question of this review? Is exposure to a hot environment detrimental to neuromuscular performance? What is the main finding and what is its... (Review)
Review
NEW FINDINGS
What is the central question of this review? Is exposure to a hot environment detrimental to neuromuscular performance? What is the main finding and what is its importance? Elevating body temperature improves peak power during short-duration, high-intensity exercise but trades off with an accelerated rate of decay. Higher muscle temperatures and cross-bridge cycling rate resemble a shift in contractile characteristic to a faster phenotype. Prolonged moderate-intensity exercise capacity is impaired in a hot environment. Fatigue appears to combine a reduced drive from the CNS and increased cardiovascular strain to maintain skeletal muscle perfusion and thermoregulation.
ABSTRACT
The effect of thermal stress on human work capacity and neuromuscular function has been of interest to physiologists since the 19th century. The aim of the present review is to examine the impact of exposure to heat stress on neuromuscular performance. Exposure to heat stress during exercise is known to increase strain on the cardiovascular system owing to the competing demands of skeletal muscle perfusion and homeostatic thermoregulation. The effects of exposure to heat stress on the neuromuscular system are more complex, because in some circumstances an elevation in muscle temperature leads to an improvement in function, whereas in other circumstances an increase in temperature leads to a decrement in function that is a consequence of the mode, metabolic demand and duration of the exercise. The ability to sustain isometric tension is impaired with an elevated muscle temperature and so too is locomotor capacity over prolonged periods of time. In contrast, peak power production is enhanced by increasing muscle temperature but is achieved at the expense of maintaining power output, owing to a higher rate of decay in power production. The different effects on neuromuscular function at an elevated muscle temperature are explained, in part, by a higher rate of energy turnover. In addition, the effect of an elevated core temperature also appears to impair neuromuscular performance either owing to a reduced voluntary drive in motor unit recruitment or to a failure in muscle afferent feedback, or a combination of the two.
Topics: Body Temperature Regulation; Heat Stress Disorders; Heat-Shock Response; Hot Temperature; Humans; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal
PubMed: 32608071
DOI: 10.1113/EP088191