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Corticospinal and peripheral responses to heat-induced hypo-hydration: potential physiological mechanisms and implications for neuromuscular function. Eur J Appl Physiol 2022; 122:1797-1810. [PMID: 35362800 PMCID: PMC9287254 DOI: 10.1007/s00421-022-04937-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 03/16/2022] [Indexed: 12/05/2022]
Abstract
Heat-induced hypo-hydration (hyperosmotic hypovolemia) can reduce prolonged skeletal muscle performance; however, the mechanisms are less well understood and the reported effects on all aspects of neuromuscular function and brief maximal contractions are inconsistent. Historically, a 4–6% reduction of body mass has not been considered to impair muscle function in humans, as determined by muscle torque, membrane excitability and peak power production. With the development of magnetic resonance imaging and neurophysiological techniques, such as electromyography, peripheral nerve, and transcranial magnetic stimulation (TMS), the integrity of the brain-to-muscle pathway can be further investigated. The findings of this review demonstrate that heat-induced hypo-hydration impairs neuromuscular function, particularly during repeated and sustained contractions. Additionally, the mechanisms are separate to those of hyperthermia-induced fatigue and are likely a result of modulations to corticospinal inhibition, increased fibre conduction velocity, pain perception and impaired contractile function. This review also sheds light on the view that hypo-hydration has ‘no effect’ on neuromuscular function during brief maximal voluntary contractions. It is hypothesised that irrespective of unchanged force, compensatory reductions in cortical inhibition are likely to occur, in the attempt of achieving adequate force production. Studies using single-pulse TMS have shown that hypo-hydration can reduce maximal isometric and eccentric force, despite a reduction in cortical inhibition, but the cause of this is currently unclear. Future work should investigate the intracortical inhibitory and excitatory pathways within the brain, to elucidate the role of the central nervous system in force output, following heat-induced hypo-hydration.
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2
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Physiological Function during Exercise and Environmental Stress in Humans-An Integrative View of Body Systems and Homeostasis. Cells 2022; 11:cells11030383. [PMID: 35159193 PMCID: PMC8833916 DOI: 10.3390/cells11030383] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/26/2022] Open
Abstract
Claude Bernard’s milieu intérieur (internal environment) and the associated concept of homeostasis are fundamental to the understanding of the physiological responses to exercise and environmental stress. Maintenance of cellular homeostasis is thought to happen during exercise through the precise matching of cellular energetic demand and supply, and the production and clearance of metabolic by-products. The mind-boggling number of molecular and cellular pathways and the host of tissues and organ systems involved in the processes sustaining locomotion, however, necessitate an integrative examination of the body’s physiological systems. This integrative approach can be used to identify whether function and cellular homeostasis are maintained or compromised during exercise. In this review, we discuss the responses of the human brain, the lungs, the heart, and the skeletal muscles to the varying physiological demands of exercise and environmental stress. Multiple alterations in physiological function and differential homeostatic adjustments occur when people undertake strenuous exercise with and without thermal stress. These adjustments can include: hyperthermia; hyperventilation; cardiovascular strain with restrictions in brain, muscle, skin and visceral organs blood flow; greater reliance on muscle glycogen and cellular metabolism; alterations in neural activity; and, in some conditions, compromised muscle metabolism and aerobic capacity. Oxygen supply to the human brain is also blunted during intense exercise, but global cerebral metabolism and central neural drive are preserved or enhanced. In contrast to the strain seen during severe exercise and environmental stress, a steady state is maintained when humans exercise at intensities and in environmental conditions that require a small fraction of the functional capacity. The impact of exercise and environmental stress upon whole-body functions and homeostasis therefore depends on the functional needs and differs across organ systems.
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3
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Malcolm R, Cooper S, Folland J, Tyler C, Hannah R, Sunderland C. Reliability of transcranial magnetic stimulation measurements of maximum activation of the knee extensors in young adult males. Hum Mov Sci 2021; 78:102828. [PMID: 34091190 DOI: 10.1016/j.humov.2021.102828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 12/10/2020] [Accepted: 05/31/2021] [Indexed: 11/19/2022]
Abstract
PURPOSE METHODS: RESULTS: CONCLUSION.
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Affiliation(s)
- Rachel Malcolm
- Sport, Health and Performance Enhancement (SHAPE) Research Centre, Department of Sport Sciences, Nottingham Trent University, UK.
| | - Simon Cooper
- Sport, Health and Performance Enhancement (SHAPE) Research Centre, Department of Sport Sciences, Nottingham Trent University, UK
| | - Jonathan Folland
- School of Sport, Exercise and Health Sciences, Loughborough University, UK
| | | | - Ricci Hannah
- Department of Psychology, University of California, San Diego, USA
| | - Caroline Sunderland
- Sport, Health and Performance Enhancement (SHAPE) Research Centre, Department of Sport Sciences, Nottingham Trent University, UK
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4
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Brownstein CG, Millet GY, Thomas K. Neuromuscular responses to fatiguing locomotor exercise. Acta Physiol (Oxf) 2021; 231:e13533. [PMID: 32627930 DOI: 10.1111/apha.13533] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/26/2020] [Accepted: 06/29/2020] [Indexed: 12/26/2022]
Abstract
Over the last two decades, an abundance of research has explored the impact of fatiguing locomotor exercise on the neuromuscular system. Neurostimulation techniques have been implemented prior to and following locomotor exercise tasks of a wide variety of intensities, durations, and modes. These techniques have allowed for the assessment of alterations occurring within the central nervous system and the muscle, while techniques such as transcranial magnetic stimulation and spinal electrical stimulation have permitted further segmentalization of locomotor exercise-induced changes along the motor pathway. To this end, the present review provides a comprehensive synopsis of the literature pertaining to neuromuscular responses to locomotor exercise. Sections of the review were divided to discuss neuromuscular responses to maximal, severe, heavy and moderate intensity, high-intensity intermittent exercise, and differences in neuromuscular responses between exercise modalities. During maximal and severe intensity exercise, alterations in neuromuscular function reside primarily within the muscle. Although post-exercise reductions in voluntary activation following maximal and severe intensity exercise are generally modest, several studies have observed alterations occurring at the cortical and/or spinal level. During prolonged heavy and moderate intensity exercise, impairments in contractile function are attenuated with respect to severe intensity exercise, but are still widely observed. While reductions in voluntary activation are greater during heavy and moderate intensity exercise, the specific alterations occurring within the central nervous system remain unclear. Further work utilizing stimulation techniques during exercise and integrating new and emerging techniques such as high-density electromyography is warranted to provide further insight into neuromuscular responses to locomotor exercise.
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Affiliation(s)
- Callum G. Brownstein
- Inter‐University Laboratory of Human Movement Biology Université LyonUJM‐Saint‐Etienne Saint‐Etienne France
| | - Guillaume Y. Millet
- Inter‐University Laboratory of Human Movement Biology Université LyonUJM‐Saint‐Etienne Saint‐Etienne France
- Institut Universitaire de France (IUF) France
| | - Kevin Thomas
- Faculty of Health and Life Sciences Northumbria University Newcastle upon Tyne United Kingdom
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5
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de Poli RAB, Boullosa DA, Malta ES, Behm D, Lopes VHF, Barbieri FA, Zagatto AM. Cycling Performance Enhancement After Drop Jumps May Be Attributed to Postactivation Potentiation and Increased Anaerobic Capacity. J Strength Cond Res 2020; 34:2465-2475. [PMID: 32205815 DOI: 10.1519/jsc.0000000000003399] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
de Poli, RAB, Boullosa, DA, Malta, ES, Behm, D, Lopes, VHF, Barbieri, FA, and Zagatto, AM. Cycling performance enhancement after drop jumps may be attributed to postactivation potentiation and increased anaerobic capacity. J Strength Cond Res 34(9): 2465-2475, 2020-The study aimed to investigate the effects of drop jumps (DJs) on supramaximal cycling performance, anaerobic capacity (AC), electromyography, and fatigue. Thirty-eight recreational cyclists participated into 3 independent studies. In study 1 (n = 14), neuromuscular fatigue was assessed with the twitch interpolation technique. In study 2 (n = 16), the AC and metabolic contributions were measured with the maximal accumulated oxygen deficit method and the sum of the glycolytic and phosphagen pathways. In study 3 (n = 8), postactivation potentiation (PAP) induced by repeated DJs was evaluated. The DJ protocol was effective for significantly improving cycling performance by +9.8 and +7.4% in studies 1 and 2, respectively (p ≤ 0.05). No differences were observed in electromyography between conditions (p = 0.70); however, the force evoked by a doublet at low (10 Hz) and high frequencies (100 Hz) declined for control (-16.4 and -23.9%) and DJ protocols (-18.6 and -26.9%) (p < 0.01). Force decline was greater in the DJ condition (p < 0.03). Anaerobic capacity and glycolytic pathway contributions were +7.7 and +9.1% higher after DJ protocol (p = 0.01). Peak force during maximal voluntary contraction (+5.6%) and doublet evoked force at 100 Hz (+5.0%) were higher after DJs. The DJ protocol induced PAP, improved supramaximal cycling performance, and increased AC despite higher peripheral fatigue.
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Affiliation(s)
- Rodrigo A B de Poli
- Laboratory of Physiology and Sport Performance (LAFIDE), São Paulo State University (UNESP), Bauru, SP, Brazil.,Post-Graduate Program in Movement Sciences, São Paulo State University (UNESP), School of Science, Bauru, SP, Brazil
| | - Daniel A Boullosa
- College of Healthcare Sciences, James Cook University, Townsville, Australia; and
| | - Elvis S Malta
- Laboratory of Physiology and Sport Performance (LAFIDE), São Paulo State University (UNESP), Bauru, SP, Brazil.,Post-Graduate Program in Movement Sciences, São Paulo State University (UNESP), School of Science, Bauru, SP, Brazil
| | - David Behm
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, Newfoundland, Canada
| | - Vithor H F Lopes
- Laboratory of Physiology and Sport Performance (LAFIDE), São Paulo State University (UNESP), Bauru, SP, Brazil.,Post-Graduate Program in Movement Sciences, São Paulo State University (UNESP), School of Science, Bauru, SP, Brazil
| | - Fabio A Barbieri
- Post-Graduate Program in Movement Sciences, São Paulo State University (UNESP), School of Science, Bauru, SP, Brazil
| | - Alessandro M Zagatto
- Laboratory of Physiology and Sport Performance (LAFIDE), São Paulo State University (UNESP), Bauru, SP, Brazil.,Post-Graduate Program in Movement Sciences, São Paulo State University (UNESP), School of Science, Bauru, SP, Brazil
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6
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Hurrie DMG, Giesbrecht GG. Is active recovery during cold water immersion better than active or passive recovery in thermoneutral water for postrecovery high-intensity sprint interval performance? Appl Physiol Nutr Metab 2019; 45:251-257. [PMID: 31314993 DOI: 10.1139/apnm-2019-0189] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High-intensity exercise is impaired by increased esophageal temperature (Tes) above 38 °C and/or decreased muscle temperature. We compared the effects of three 30-min recovery strategies following a first set of three 30-s Wingate tests (set 1), on a similar postrecovery set of Wingate tests (set 2). Recovery conditions were passive recovery in thermoneutral (34 °C) water (Passive-TN) and active recovery (underwater cycling; ∼33% maximum power) in thermoneutral (Active-TN) or cold (15 °C) water (Active-C). Tes rose for all conditions by the end of set 1 (∼1.0 °C). After recovery, Tes returned to baseline in both Active-C and Passive-TN but remained elevated in Active-TN (p < 0.05). At the end of set 2, Tes was lower in Active-C (37.2 °C) than both Passive-TN (38.1 °C) and Active-TN (38.8 °C) (p < 0.05). From set 1 to 2 mean power did not change with Passive-TN (+0.2%), increased with Active-TN (+2.4%; p < 0.05), and decreased with Active-C (-3.2%; p < 0.05). Heart rate was similar between conditions throughout, except at end-recovery; it was lower in Passive-TN (92 beats·min-1) than both exercise conditions (Active-TN, 126 beats·min-1; Active-C, 116 beats·min-1) (p < 0.05). Although Active-C significantly reduced Tes, the best postrecovery performance occurred with Active-TN. Novelty An initial set of 3 Wingates increased Tes to ∼38 °C. Thirty minutes of Active-C was well tolerated, and decreased Tes and blood lactate to baseline values, but decreased subsequent Wingate performance.
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Affiliation(s)
- Daryl M G Hurrie
- Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Gordon G Giesbrecht
- Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.,Department of Emergency Medicine, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
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7
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Schäfer LU, Hayes M, Dekerle J. The magnitude of neuromuscular fatigue is not intensity dependent when cycling above critical power but relates to aerobic and anaerobic capacities. Exp Physiol 2018; 104:209-219. [PMID: 30468691 DOI: 10.1113/ep087273] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 11/22/2018] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Is the magnitude of neuromuscular fatigue dependent upon exercise intensity above critical power (CP) when W' (the curvature constant of the power-duration relationship) is depleted? What is the main finding and its importance? The magnitude of neuromuscular fatigue is the same after two bouts of supra-CP cycling (3 versus 12 min) when controlling for W' depletion but is larger for individuals of greater anaerobic capacity after the shorter bout and smaller for individuals of greater aerobic capacity after the longer exercise bout. These findings provide new insight into the mechanisms underpinning exercise above CP. ABSTRACT The aim of the present study was to test whether the development of neuromuscular fatigue within the severe-intensity domain could be linked to the depletion of the curvature constant (W') of the power-duration relationship. Twelve recreationally active men completed tests to determine peak oxygen consumption, critical power (CP) and W', followed by two randomly assigned constant-load supra-CP trials set to deplete W' fully in 3 (P-3) and 12 min (P-12). Pre- to postexercise changes in maximal voluntary contraction, potentiated quadriceps twitch force evoked by single (Qpot ) and paired high- (PS100) and low-frequency (PS10) stimulations and voluntary activation were determined. Cycling above CP reduced maximal voluntary contraction (P-3, -20 ± 10% versus P-12, -15 ± 7%), measures associated with peripheral fatigue (Qpot , -35 ± 13 versus -31 ± 14%; PS10, -38 ± 13 versus -37 ± 17%; PS100, -18 ± 9 versus -13 ± 8% for P-3 and P-12, respectively) and voluntary activation (P-3, -12 ± 3% versus P-12, -13 ± 3%; P < 0.05), with no significant difference between trials (P > 0.05). Changes in maximal voluntary contraction and evoked twitch forces were inversely correlated with CP and peak oxygen consumption after P-12, whereas W' was significantly correlated with changes in Qpot and PS10 after P-3 (P < 0.05). Therefore, the magnitude of neuromuscular fatigue does not depend on exercise intensity when W' is fully exhausted during severe-intensity exercise; nonetheless, exploration of inter-individual variations suggests that mechanisms underpinning exercise tolerance within this domain differ between short- and long-duration exercise.
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Affiliation(s)
- Lisa U Schäfer
- Fatigue and Exercise Laboratory, School of Sport and Service Management, University of Brighton, Eastbourne, UK
| | - Mark Hayes
- Fatigue and Exercise Laboratory, School of Sport and Service Management, University of Brighton, Eastbourne, UK
| | - Jeanne Dekerle
- Fatigue and Exercise Laboratory, School of Sport and Service Management, University of Brighton, Eastbourne, UK
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8
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Barley OR, Chapman DW, Blazevich AJ, Abbiss CR. Acute Dehydration Impairs Endurance Without Modulating Neuromuscular Function. Front Physiol 2018; 9:1562. [PMID: 30450056 PMCID: PMC6224374 DOI: 10.3389/fphys.2018.01562] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 10/18/2018] [Indexed: 01/06/2023] Open
Abstract
Introduction/Purpose: This study examined the influence of acute dehydration on neuromuscular function. Methods: On separate days, combat sports athletes experienced in acute dehydration practices (n = 14) completed a 3 h passive heating intervention (40°C, 63% relative humidity) to induce dehydration (DHY) or a thermoneutral euhydration control (25°C, 50% relative humidity: CON). In the ensuing 3 h ad libitum fluid and food intake was allowed, after which participants performed fatiguing exercise consisting of repeated unilateral knee extensions at 85% of their maximal voluntary isometric contraction (MVIC) torque until task failure. Both before and after the fatiguing protocol participants performed six MVICs during which measures of central and peripheral neuromuscular function were made. Urine and whole blood samples to assess urine specific gravity, urine osmolality, haematocrit and serum osmolality were collected before, immediately and 3 h after intervention. Results: Body mass was reduced by 3.2 ± 1.1% immediately after DHY (P < 0.001) but recovered by 3 h. Urine and whole blood markers indicated dehydration immediately after DHY, although blood markers were not different to CON at 3 h. Participants completed 28% fewer knee extensions at 85% MVIC (P < 0.001, g = 0.775) and reported a greater perception of fatigue (P = 0.012) 3 h after DHY than CON despite peak torque results being unaffected. No between-condition differences were observed in central or peripheral indicators of neuromuscular function at any timepoint. Conclusion: Results indicate that acute dehydration of 3.2% body mass followed by 3 h of recovery impairs muscular strength-endurance and increases fatigue perception without changes in markers of central or peripheral function. These findings suggest that altered fatigue perception underpins muscular performance decrements in recovery from acute dehydration.
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Affiliation(s)
- Oliver R Barley
- Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Dale W Chapman
- Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Anthony J Blazevich
- Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Chris R Abbiss
- Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
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9
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O'Leary TJ, Collett J, Morris MG. High-intensity exhaustive exercise reduces long-interval intracortical inhibition. Exp Brain Res 2018; 236:3149-3158. [PMID: 30159591 DOI: 10.1007/s00221-018-5364-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 08/17/2018] [Indexed: 12/19/2022]
Abstract
The development of fatigue during single-joint isolated muscle contractions is accompanied by an increase in long-interval intracortical inhibition (LICI). However, the effect of whole-body locomotor endurance exercise on LICI is unknown. Eighteen healthy men completed three exercise trials on a cycle ergometer. The first trial was completed to determine the lactate threshold (LT) and maximal oxygen uptake ([Formula: see text]). The remaining two trials (familiarisation and experimental) involved cycling to volitional exhaustion at an intensity equivalent to halfway between the LT and [Formula: see text] (50%Δ). Responses to stimulation of the femoral nerve [motor nerve stimulation (MNS)] and motor cortex [transcranial magnetic stimulation (TMS)] were determined pre- and post-exercise to determine the level of peripheral fatigue [potentiated quadriceps twitch (Qtw,pot)] and central fatigue [voluntary activation measured by MNS and TMS (VAMNS and VATMS, respectively)]. Corticospinal excitability (motor evoked potentials) and intracortical inhibition [LICI and corticospinal silent period (SP)] were also measured from electromyography recordings on the vastus lateralis. There were exercise-induced reductions in maximal voluntary contraction torque (- 21 ± 10%), Qtw,pot (- 37 ± 18%), VAMNS (- 7 ± 7%) and VATMS (- 8 ± 10) (all P < 0.01). There were increases in the LICI ratio and reductions in SP duration from pre- to post-exercise (mean absolute change of 16 ± 14% and - 31 ± 28 s, respectively) (both P < 0.01). The pre- and post-exercise MEP amplitudes were not different (P = 0.86). The neural inhibitory circuits that mediate the LICI and SP became less excitable with fatigue following high-intensity exhaustive cycling, which could be important in the aetiology of central fatigue during whole-body locomotor endurance exercise.
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Affiliation(s)
- Thomas J O'Leary
- Department of Sport and Health Sciences, Oxford Brookes University, Oxford, UK.,Army Personnel Research Capability, HQ Army, Andover, UK
| | - Johnny Collett
- Department of Sport and Health Sciences, Oxford Brookes University, Oxford, UK
| | - Martyn G Morris
- Department of Sport and Health Sciences, Oxford Brookes University, Oxford, UK. .,School of Life Sciences, Coventry University, Whitefriars Street, Coventry, CV1 2DS, UK.
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10
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Interactions between perceived exertion and thermal perception in the heat in endurance athletes. J Therm Biol 2018; 76:68-76. [DOI: 10.1016/j.jtherbio.2018.07.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 06/21/2018] [Accepted: 07/10/2018] [Indexed: 11/22/2022]
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11
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Goodall S, Howatson G, Thomas K. Modulation of specific inhibitory networks in fatigued locomotor muscles of healthy males. Exp Brain Res 2017; 236:463-473. [PMID: 29214392 PMCID: PMC5809538 DOI: 10.1007/s00221-017-5142-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 12/01/2017] [Indexed: 12/12/2022]
Abstract
Reduced maximal force capability of skeletal muscle, as a consequence of exercise, can be due to peripheral or central fatigue mechanisms. In upper-limb muscles, neuromuscular fatigue is concurrent with reduced corticospinal excitability and increased inhibition (lengthened corticospinal silent period [CSP]; reduced short-interval intracortical inhibition [SICI] ratio). However, it is unclear whether these adjustments occur in response to fatiguing exercise of locomotor muscles. This study examined the effect of fatiguing, maximal, knee-extensor exercise on motor cortical excitability and inhibition. Thirteen males performed three 30-s maximal, isometric contractions with the dominant knee-extensors (MVC1, MVC2 and MVC3), separated by 60 s. At the end of, and between each MVC, neuromuscular fatigue, corticospinal excitability, CSP and SICI were assessed with supramaximal stimulation of the femoral nerve, and motor cortical stimulation, respectively. Repeated MVCs caused progressive reductions in MVC (- 10, - 24 and - 29%, respectively, P ≤ 0.01), along with significant peripheral (reductions in potentiated twitch of - 23, -53 and - 60%, respectively, P < 0.001) and central (reductions in VA of - 10% and - 13% post-MVC2 and 3, respectively, P ≤ 0.01) fatigue. Following MVC1 corticospinal excitability was reduced, and remained depressed thereafter. CSP increased in duration and remained longer throughout the protocol; whereas, no change in SICI was observed. Repeated, sustained, maximal contractions of the knee-extensors elicited substantial peripheral and central fatigue that was accompanied by a concomitant reduction in corticospinal excitability. However, divergent responses exist between inhibitory networks within the motor cortex, the activity of inhibitory networks mediated by GABAB are increased, whereas those mediated by GABAA are not.
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Affiliation(s)
- Stuart Goodall
- Department of Sport, Exercise, and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK.
| | - Glyn Howatson
- Department of Sport, Exercise, and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK
- Water Research Group, School of Environmental Sciences and Development, Northwest University, Potchefstroom, South Africa
| | - Kevin Thomas
- Department of Sport, Exercise, and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK
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Carroll TJ, Taylor JL, Gandevia SC. Recovery of central and peripheral neuromuscular fatigue after exercise. J Appl Physiol (1985) 2017; 122:1068-1076. [DOI: 10.1152/japplphysiol.00775.2016] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 12/02/2016] [Accepted: 12/02/2016] [Indexed: 12/29/2022] Open
Abstract
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.
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Affiliation(s)
- T. J. Carroll
- Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, University of Queensland; and
| | - J. L. Taylor
- Neuroscience Research Australia and University of New South Wales
| | - S. C. Gandevia
- Neuroscience Research Australia and University of New South Wales
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13
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O'Leary TJ, Collett J, Howells K, Morris MG. Endurance capacity and neuromuscular fatigue following high- vs moderate-intensity endurance training: A randomized trial. Scand J Med Sci Sports 2017; 27:1648-1661. [DOI: 10.1111/sms.12854] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2017] [Indexed: 12/16/2022]
Affiliation(s)
- T. J. O'Leary
- Department of Sport and Health Sciences; Oxford Brookes University; Oxford UK
| | - J. Collett
- Department of Sport and Health Sciences; Oxford Brookes University; Oxford UK
| | - K. Howells
- Department of Sport and Health Sciences; Oxford Brookes University; Oxford UK
| | - M. G. Morris
- Department of Sport and Health Sciences; Oxford Brookes University; Oxford UK
- School of Life Sciences; Coventry University; Coventry UK
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14
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The assessment of neuromuscular fatigue during 120 min of simulated soccer exercise. Eur J Appl Physiol 2017; 117:687-697. [DOI: 10.1007/s00421-017-3561-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 02/01/2017] [Indexed: 10/20/2022]
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15
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Affiliation(s)
- Julien D. Périard
- Athlete Health and Performance Research Centre; Aspetar Orthopaedic and Sports Medicine Hospital; Doha Qatar
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16
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O'Leary TJ, Morris MG, Collett J, Howells K. Central and peripheral fatigue following non-exhaustive and exhaustive exercise of disparate metabolic demands. Scand J Med Sci Sports 2015; 26:1287-1300. [DOI: 10.1111/sms.12582] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2015] [Indexed: 11/29/2022]
Affiliation(s)
- T. J. O'Leary
- Department of Sport and Health Sciences; Oxford Brookes University; Oxford UK
| | - M. G. Morris
- Department of Sport and Health Sciences; Oxford Brookes University; Oxford UK
| | - J. Collett
- Department of Sport and Health Sciences; Oxford Brookes University; Oxford UK
| | - K. Howells
- Department of Sport and Health Sciences; Oxford Brookes University; Oxford UK
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