scholarly journals Convective oxygen transport and fatigue

2008 ◽  
Vol 104 (3) ◽  
pp. 861-870 ◽  
Author(s):  
Markus Amann ◽  
Jose A. L. Calbet
Keyword(s):  
Central Fatigue ◽  
Peripheral Fatigue ◽  
Healthy Human ◽  
Reduction In Force ◽  
Fatigue Development ◽  
Inhibitory Feedback ◽  
Generating Capacity ◽  
Exercise Fatigue ◽  
Acute And Chronic Exposure ◽  
Rate Of Accumulation

During exercise, fatigue is defined as a reversible reduction in force- or power-generating capacity and can be elicited by “central” and/or “peripheral” mechanisms. During skeletal muscle contractions, both aspects of fatigue may develop independent of alterations in convective O2delivery; however, reductions in O2supply exacerbate and increases attenuate the rate of accumulation. In this regard, peripheral fatigue development is mediated via the O2-dependent rate of accumulation of metabolic by-products (e.g., inorganic phosphate) and their interference with excitation-contraction coupling within the myocyte. In contrast, the development of O2-dependent central fatigue is elicited 1) by interference with the development of central command and/or 2) via inhibitory feedback on central motor drive secondary to the peripheral effects of low convective O2transport. Changes in convective O2delivery in the healthy human can result from modifications in arterial O2content, blood flow, or a combination of both, and they can be induced via heavy exercise even at sea level; these changes are exacerbated during acute and chronic exposure to altitude. This review focuses on the effects of changes in convective O2delivery on the development of central and peripheral fatigue.

scholarly journals Recovery of central and peripheral neuromuscular fatigue after exercise

2017 ◽  
Vol 122 (5) ◽  
pp. 1068-1076 ◽  
Author(s):  
T. J. Carroll ◽  
J. L. Taylor ◽  
S. C. Gandevia
Keyword(s):  
Muscle Function ◽  
Time Course ◽  
Central Fatigue ◽  
Exercise Bout ◽  
Complete Recovery ◽  
Peripheral Fatigue ◽  
Partial Recovery ◽  
Long Duration ◽  
Intracellular Ca ◽  
Generating Capacity

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 recovery 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 Ca2+ 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.

scholarly journals Effect of carbohydrate ingestion on central fatigue during prolonged running exercise in moderate hypoxia

2019 ◽  
Vol 126 (1) ◽  
pp. 141-151 ◽  
Author(s):  
Hunter L. Paris ◽  
Timothy J. Fulton ◽  
Robert F. Chapman ◽  
Alyce D. Fly ◽  
David M. Koceja ◽  
...  
Keyword(s):  
Central Fatigue ◽  
Branched Chain Amino Acids ◽  
Peripheral Fatigue ◽  
Carbohydrate Ingestion ◽  
Moderate Hypoxia ◽  
Free Tryptophan ◽  
Fatigue Development ◽  
Branched Chain ◽  
Trained Runners ◽  
Placebo Drink

To determine whether acute exposure to moderate hypoxia alters central and peripheral fatigue and to test whether carbohydrate ingestion impacts fatigue characteristics, 12 trained runners completed three running trials lasting 1 h each at 65% of normoxic maximum oxygen uptake. The first trial was performed in normoxia [inspired O2 fraction ([Formula: see text]) = 0.21], and the last two trials were completed in hypoxia ([Formula: see text] = 0.15). Participants ingested a placebo drink in normoxia (NORM-PLA), a placebo drink in hypoxia (HYP-PLA), or a carbohydrate solution in hypoxia (HYP-CHO). HYP conditions were randomized. Peripheral [change in potentiated quadriceps twitch force (ΔQtw,pot)] and central [change in voluntary activation (ΔVA)] fatigue were assessed via preexercise-to-postexercise changes in magnetically evoked quadriceps twitch. In HYP, blood was drawn to determine the ratio of free-tryptophan (f-TRP) to branched-chain amino acids (BCAA). After exercise, peripheral fatigue was reduced to a similar degree in normoxia and hypoxia (ΔQtw,pot = −4.5 ± 1.3% and −4.0 ± 1.5% in NORM-PLA and HYP-PLA, respectively; P = 0.61). Central fatigue was present after normoxic and hypoxic exercise but to a greater degree in HYP-PLA compared with NORM-PLA (ΔVA: −4.7 ± 0.9% vs. −1.9 ± 0.7%; P < 0.01). Carbohydrate ingestion did not influence central fatigue (ΔVA in HYP-CHO: −5.7 ± 1.2%; P = 0.51 vs. HYP-PLA). After exercise, no differences were observed in the ratio of f-TRP to BCAA between HYP-PLA and HYP-CHO ( P = 0.67). Central fatigue increased during prolonged running exercise in moderate hypoxia although the ratio of f-TRP to BCAA remained unchanged. Ingesting carbohydrates while running in hypoxia did not influence fatigue development. NEW & NOTEWORTHY Hypoxic exposure influences the origin of exercise-induced fatigue and the rate of fatigue development depending on the severity of hypoxia. Our data suggest that moderate hypoxia increases central, but not peripheral, fatigue in trained runners exercising at 65% of normoxic maximum oxygen uptake. The increase in central fatigue was unaffected by carbohydrate intake and occurred although the ratio of free tryptophan to branched-chain amino acids remained unchanged.

Distinct profiles of neuromuscular fatigue during muscle contractions below and above the critical torque in humans

2012 ◽  
Vol 113 (2) ◽  
pp. 215-223 ◽  
Author(s):  
Mark Burnley ◽  
Anni Vanhatalo ◽  
Andrew M. Jones
Keyword(s):  
Vastus Lateralis ◽  
Central Fatigue ◽  
Neuromuscular Fatigue ◽  
Voluntary Activation ◽  
Peripheral Fatigue ◽  
Critical Threshold ◽  
Task Failure ◽  
Fatigue Development ◽  
The Right ◽  
Experimental Trials

Whether the transition in fatigue processes between “low-intensity” and “high-intensity” contractions occurs gradually, as the torque requirements are increased, or whether this transition occurs more suddenly at some identifiable “threshold”, is not known. We hypothesized that the critical torque (CT; the asymptote of the torque-duration relationship) would demarcate distinct profiles of central and peripheral fatigue during intermittent isometric quadriceps contractions (3-s contraction, 2-s rest). Nine healthy men performed seven experimental trials to task failure or for up to 60 min, with maximal voluntary contractions (MVCs) performed at the end of each minute. The first five trials were performed to determine CT [∼35–55% MVC, denoted severe 1 (S1) to severe 5 (S5) in ascending order], while the remaining two trials were performed 10 and 20% below the CT (denoted CT-10% and CT-20%). Dynamometer torque and the electromyogram of the right vastus lateralis were sampled continuously. Peripheral and central fatigue was determined from the fall in potentiated doublet torque and voluntary activation, respectively. Above CT, contractions progressed to task failure in ∼3–18 min, at which point the MVC did not differ from the target torque (S1 target, 88.7 ± 4.3 N·m vs. MVC, 89.3 ± 8.8 N·m, P = 0.94). The potentiated doublet fell significantly in all trials, and voluntary activation was reduced in trials S1–S3, but not trials S4 and S5. Below CT, contractions could be sustained for 60 min on 17 of 18 occasions. Both central and peripheral fatigue developed, but there was a substantial reserve in MVC torque at the end of the task. The rate of global and peripheral fatigue development was four to five times greater during S1 than during CT-10% (change in MVC/change in time S1 vs. CT-10%: −7.2 ± 1.4 vs. −1.5 ± 0.4 N·m·min−1). These results demonstrate that CT represents a critical threshold for neuromuscular fatigue development.

scholarly journals Peripheral Modulators of the Central Fatigue Development and Their Relationship with Athletic Performance in Jumper Horses

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 743
Author(s):  
Francesca Arfuso ◽  
Claudia Giannetto ◽  
Elisabetta Giudice ◽  
Francesco Fazio ◽  
Michele Panzera ◽  
...  
Keyword(s):  
Blood Lactate ◽  
Athletic Performance ◽  
Lactate Concentration ◽  
Indirect Evidence ◽  
Blood Lactate Concentration ◽  
Central Fatigue ◽  
Serotoninergic System ◽  
Stressful Situation ◽  
Passive Behavior ◽  
Fatigue Development

The current study aimed to investigate whether peripheral modulators of serotoninergic function and neurohumoral factors’ changes in athletic horses during an official jumping competition, and to evaluate their relationship with the physical performance of competing horses. From 7 Italian Saddle mares (6–9 years; mean body weight 440 ± 15 kg), performing the same standardized warm-up and jumping course during an official class, heart rate (HR) was monitored throughout the competition. Rectal temperature (RT) measurement, blood lactate and glucose concentration, serum tryptophan, leucine, valine, the tryptophan/branched-chain amino-acids ratio (Try/BCAAs), dopamine, prolactin, and non-esterified fatty acids (NEFAs) were assessed before the exercise event (T0), at the end of the competition stage (5 min ± 10 s following the cessation of the exercise, TPOST5), and 30 min after the end of competition (TPOST30). Highest HR values were recorded during the course and at the outbound (p < 0.0001); blood lactate concentration and RT increased after exercise with respect to the rest condition (p < 0.0001). Lower leucine and valine levels (p < 0.01), and higher tryptophan, Try/BCAAs ratio, and NEFAs values were found at TPOST5 and TPOST30 with respect to T0 (p < 0.0001). A higher prolactin concentration was found at TPOST5 and TPOST30 compared to T0 (p < 0.0001), whereas dopamine showed decreased values after exercise compared to rest (p < 0.0001). Statistically significant correlations among the peripheral indices of serotoninergic function, neurohumoral factors, and athletic performance parameters were found throughout the monitoring period. The findings provide indirect evidence that the serotoninergic system may be involved in fatigue during jumper exercise under a stressful situation, such as competition, in which, in addition to physical effort, athletic horses exhibit more passive behavior.

Electrically-induced quadriceps fatigue in the contralateral leg impairs ipsilateral knee extensors performance

2021 ◽  
Author(s):  
Fabio Giuseppe Laginestra ◽  
Markus Amann ◽  
Emine Kirmizi ◽  
Gaia Giuriato ◽  
Chiara Barbi ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Central Fatigue ◽  
Endurance Performance ◽  
Voluntary Exercise ◽  
Peripheral Fatigue ◽  
Knee Extensors ◽  
Motor Drive ◽  
Time To Exhaustion ◽  
Crossover Effect ◽  
The Impact

Muscle fatigue induced by voluntary exercise, which requires central motor drive, causes central fatigue that impairs endurance performance of a different, non-fatigued muscle. This study investigated the impact of quadriceps fatigue induced by electrically-induced (no central motor drive) contractions on single-leg knee-extension (KE) performance of the subsequently exercising ipsilateral quadriceps. On two separate occasions, eight males completed constant-load (85% of maximal power-output) KE exercise to exhaustion. In a counterbalanced manner, subjects performed the KE exercise with no pre-existing quadriceps fatigue in the contralateral leg on one day (No-PreF), while on the other day, the same KE exercise was repeated following electrically-induced quadriceps fatigue in the contralateral leg (PreF). Quadriceps fatigue was assessed by evaluating pre- to post-exercise changes in potentiated twitch force (ΔQtw,pot; peripheral-fatigue), and voluntary muscle activation (ΔVA; central-fatigue). As reflected by the 57±11% reduction in electrically-evoked pulse force, the electrically-induced fatigue protocol caused significant knee-extensors fatigue. KE endurance time to exhaustion was shorter during PreF compared to No-PreF (4.6±1.2 vs 7.7±2.4 min; p<0.01). While ΔQtw,pot was significantly larger in No-PreF compared to PreF (-60% vs -52%, p<0.05), ΔVA was greater in PreF (-14% vs -10%, p<0.05). Taken together, electrically-induced quadriceps fatigue in the contralateral leg limits KE endurance performance and the development of peripheral fatigue in the ipsilateral leg. These findings support the hypothesis that the crossover-effect of central fatigue is mainly mediated by group III/IV muscle afferent feedback and suggest that impairments associated with central motor drive may only play a minor role in this phenomenon.

Fatigue of intermittent submaximal voluntary contractions: central and peripheral factors

1986 ◽  
Vol 61 (2) ◽  
pp. 421-429 ◽  
Author(s):  
B. Bigland-Ritchie ◽  
F. Furbush ◽  
J. J. Woods
Keyword(s):  
No Reduction ◽  
Rest Period ◽  
Central Fatigue ◽  
Voluntary Contraction ◽  
Adductor Pollicis ◽  
M Wave ◽  
Generating Capacity ◽  
Target Force ◽  
Voluntary Contractions ◽  
Muscle Contractile

Central and peripheral factors were studied in fatigue of submaximal intermittent isometric contractions of the human quadriceps and soleus muscles. Subjects made repeated 6 s, 50% maximal voluntary contractions (MVC) followed by 4 s rest until the limit of endurance (Tlim). Periodically, a fatigue test was performed. This included a brief MVC, either a single shock or 8 pulses at 50 Hz during a rest period and a shock superimposed on a target force voluntary contraction. At Tlim, the MVC force had declined by 50%, usually in parallel with the force from stimulation at 50 Hz. The twitches superimposed on the target forces declined more rapidly, disappearing entirely at Tlim. In similar experiments on adductor pollicis, no reduction of the evoked M wave was seen. The results suggest that, during fatigue of quadriceps and adductor pollicis induced by this protocol, no central fatigue was apparent, but some was seen in soleus. Thus the reduced force-generating capacity could result mainly or entirely from failure of the muscle contractile apparatus.

In vivo contractile properties of fatigued diaphragm

1987 ◽  
Vol 63 (2) ◽  
pp. 471-478 ◽  
Author(s):  
J. Road ◽  
R. Vahi ◽  
P. del Rio ◽  
A. Grassino
Keyword(s):  
Spontaneous Breathing ◽  
Central Fatigue ◽  
Contractile Properties ◽  
Peripheral Fatigue ◽  
Electromyographic Activity ◽  
Force Frequency ◽  
Shortening Velocity ◽  
Velocity Of Shortening ◽  
The Right

The effects of fatigue on diaphragmatic contractility in vivo are unknown. In this study we used sonomicrometry to examine the velocity of shortening and lengthening and the amount of shortening in the fresh and fatigued canine hemidiaphragm (8 dogs) including the force generated. Fatigue was produced by epiphrenic stimulation of the left phrenic nerve; the right hemidiaphragm acted as the control. We found that 1) hemidiaphragmatic fatigue caused an increase in frequency with reduced tidal volume; 2) fatigue resulted in a near complete cessation of tidal shortening during spontaneous breathing; 3) there was an initial decrease in central activation (electromyogram) to the fatigued hemidiaphragm, an indication of central fatigue; 4) force-frequency curves showed a considerable and prolonged loss of the amount of shortening, velocity, and force generated by the fatigued hemidiaphragm during supramaximal stimulation, an indication of peripheral fatigue; and 5) during spontaneous breathing in the fatigued hemidiaphragm, tidal shortening remained reduced for up to 3 h, whereas in the right right hemidiaphragm tidal shortening and electromyographic activity did not change. We conclude that fatigue of a hemidiaphragm alters the spontaneous breathing pattern and produces profound modifications in its contractile properties without altering contralateral hemidiaphragmatic performance.

scholarly journals Child-adult differences in neuromuscular fatigue are muscle dependent

2018 ◽  
Vol 125 (4) ◽  
pp. 1246-1256 ◽  
Author(s):  
Enzo Piponnier ◽  
Vincent Martin ◽  
Bastien Bontemps ◽  
Emeric Chalchat ◽  
Valérie Julian ◽  
...  
Keyword(s):  
Near Infrared ◽  
Knee Extensor ◽  
Central Fatigue ◽  
Neuromuscular Fatigue ◽  
Muscle Group ◽  
Voluntary Activation ◽  
Peripheral Fatigue ◽  
Plantar Flexor ◽  
Significant Difference ◽  
Lower Extent

The aim of the present study was to compare the development and etiology of neuromuscular fatigue of the knee extensor (KE) and plantar flexor (PF) muscles during repeated maximal voluntary isometric contractions (MVICs) between children and adults. Prepubertal boys ( n = 21; 9–11 yr) and men ( n = 24; 18–30 yr) performed two fatigue protocols consisting of a repetition of 5-s isometric MVIC of the KE or PF muscles interspersed with 5-s passive recovery periods until MVIC reached 60% of its initial value. The etiology of neuromuscular fatigue of the KE and PF muscles was investigated by means of noninvasive methods, such as the surface electromyography, single and doublet magnetic stimulation, twitch interpolation technique, and near-infrared spectroscopy. The number of repetitions performed was significantly lower in men (15.4 ± 3.8) than boys (38.7 ± 18.8) for the KE fatigue test. In contrast, no significant difference was found for the PF muscles between boys and men (12.1 ± 4.9 and 13.8 ± 4.9 repetitions, respectively). Boys displayed a lower reduction in potentiated twitch torque, low-frequency fatigue, and muscle oxygenation than men whatever the muscle group considered. In contrast, voluntary activation level and normalized electromyography data decreased to a greater extent in boys than men for both muscle groups. To conclude, boys experienced less peripheral and more central fatigue during repeated MVICs than men whatever the muscle group considered. However, child-adult differences in neuromuscular fatigue were muscle-dependent since boys fatigued similarly to men with the PF muscles and to a lower extent with the KE muscles. NEW & NOTEWORTHY Child-adult differences in neuromuscular fatigue during repeated maximal voluntary contractions are specific to the muscle group since children fatigue similarly to adults with the plantar flexor muscles and to a lower extent with the knee extensor muscles. Children experience less peripheral fatigue and more central fatigue than adults, regardless of the muscle group considered.

scholarly journals Contralateral fatigue during severe-intensity single-leg exercise: influence of acute acetaminophen ingestion

2019 ◽  
Vol 317 (2) ◽  
pp. R346-R354 ◽  
Author(s):  
Paul T. Morgan ◽  
Stephen J. Bailey ◽  
Rhys A. Banks ◽  
Jonathan Fulford ◽  
Anni Vanhatalo ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Knee Extensor ◽  
Central Fatigue ◽  
Metabolic Perturbation ◽  
Fatigue Development ◽  
Severe Intensity ◽  
Phosphorus Containing ◽  
Leg Exercise ◽  
Neuromuscular Responses ◽  
Fatiguing Exercise

Exhaustive single-leg exercise has been suggested to reduce time to task failure (Tlim) during subsequent exercise in the contralateral leg by exacerbating central fatigue development. We investigated the influence of acetaminophen (ACT), an analgesic that may blunt central fatigue development, on Tlim during single-leg exercise completed with and without prior fatiguing exercise of the contralateral leg. Fourteen recreationally active men performed single-leg severe-intensity knee-extensor exercise to Tlim on the left (Leg1) and right (Leg2) legs without prior contralateral fatigue and on Leg2 immediately following Leg1 (Leg2-CONTRA). The tests were completed following ingestion of 1-g ACT or maltodextrin [placebo (PL)] capsules. Intramuscular phosphorus-containing metabolites and substrates and muscle activation were assessed using 31P-MRS and electromyography, respectively. Tlim was not different between Leg1ACT and Leg1PL conditions (402 ± 101 vs. 390 ± 106 s, P = 0.11). There was also no difference in Tlim between Leg2ACT-CONTRA and Leg2PL-CONTRA (324 ± 85 vs. 311 ± 92 s, P = 0.10), but Tlim was shorter in Leg2ACT-CONTRA and Leg2PL-CONTRA than in Leg2CON (385 ± 104 s, both P < 0.05). There were no differences in intramuscular phosphorus-containing metabolites and substrates or muscle activation between Leg1ACT and Leg1PL and between Leg2ACT-CONTRA and Leg2PL-CONTRA (all P > 0.05). These findings suggest that levels of metabolic perturbation and muscle activation at Tlim are not different during single-leg severe-intensity knee-extensor exercise completed with or without prior fatiguing exercise of the contralateral leg. Despite contralateral fatigue, ACT ingestion did not alter neuromuscular responses, muscle metabolites, or exercise performance.

Study on Efficient Central Fatigue Detection Scheme

2013 ◽  
Vol 312 ◽  
pp. 615-619
Author(s):  
Yi Xiong ◽  
Wen Tao Su
Keyword(s):  
Athletic Performance ◽  
Research Work ◽  
Central Fatigue ◽  
Focus Of Attention ◽  
Training Load ◽  
Generation Mechanism ◽  
Detection Scheme ◽  
Exercise Fatigue ◽  
Fatigue Detection ◽  
Fatigue Recovery

The growing sports training load and the more prone to fatigue will directly affect the athletes fatigue recovery, and improvement of athletic performance, so the research of the generation mechanism of fatigue and effective way to eliminate fatigue is increasingly important. Scientists gradually put the fatigue prevention and recovery promotion on a day-to-day research work. As a kind of exercise fatigue, central fatigue during exercise has increasingly become the focus of attention. This paper mainly explains the central fatigue mechanisms and detection.

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