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Amann M, Sidhu SK, McNeil CJ, Gandevia SC. Critical considerations of the contribution of the corticomotoneuronal pathway to central fatigue. J Physiol 2022; 600:5203-5214. [PMID: 36326193 PMCID: PMC9772161 DOI: 10.1113/jp282564] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022] Open
Abstract
Neural drive originating in higher brain areas reaches exercising limb muscles through the corticospinal-motoneuronal pathway, which links the motor cortex and spinal motoneurones. The properties of this pathway have frequently been observed to change during fatiguing exercise in ways that could influence the development of central fatigue (i.e. the progressive reduction in voluntary muscle activation). However, based on differences in motor cortical and motoneuronal excitability between exercise modalities (e.g. single-joint vs. locomotor exercise), there is no characteristic response that allows for a categorical conclusion about the effect of these changes on functional impairments and performance limitations. Despite the lack of uniformity in findings during fatigue, there is strong evidence for marked 'inhibition' of motoneurones as a direct result of voluntary drive. Endogenous forms of neuromodulation, such as via serotonin released from neurones, can directly affect motoneuronal output and central fatigue. Exogenous forms of neuromodulation, such as brain stimulation, may achieve a similar effect, although the evidence is weak. Non-invasive transcranial direct current stimulation can cause transient or long-lasting changes in cortical excitability; however, variable results across studies cast doubt on its claimed capacity to enhance performance. Furthermore, with these studies, it is difficult to establish a cause-and-effect relationship between brain responsiveness and exercise performance. This review briefly summarizes changes in the corticomotoneuronal pathway during various types of exercise, and considers the relevance of these changes for the development of central fatigue, as well as the potential of non-invasive brain stimulation to enhance motor cortical excitability, motoneuronal output and, ultimately, exercise performance.
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Affiliation(s)
- Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Simranjit K. Sidhu
- School of Biomedicine, The University of Adelaide, South Australia, Australia
| | - Chris J McNeil
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Simon C Gandevia
- Neuroscience Research Australia and University of New South Wales, Sydney, Australia
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Lattari E, Oliveira BRR, Monteiro Júnior RS, Marques Neto SR, Oliveira AJ, Maranhão Neto GA, Machado S, Budde H. Acute effects of single dose transcranial direct current stimulation on muscle strength: A systematic review and meta-analysis. PLoS One 2018; 13:e0209513. [PMID: 30586389 PMCID: PMC6306262 DOI: 10.1371/journal.pone.0209513] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/06/2018] [Indexed: 11/19/2022] Open
Abstract
Previous studies investigating the effects of transcranial direct current stimulation (tDCS) on muscle strength showed no consensus. Therefore, the purpose of this article was to systematically review the literature on the effects of single dose tDCS to improve muscle strength. A systematic literature search was conducted on PubMeb, ISI Web of Science, SciELO, and Scopus using search terms regarding tDCS and muscle strength. Studies were included in accordance with Population, Intervention, Comparison, Outcomes, and Setting (PICOS) including criteria. Healthy men and women, strength training practitioners or sedentary were selected. The acute effects of single dose anode stimulus of tDCS (a-tDCS) and the placebo stimulus of tDCS (sham) or no interventions were considered as an intervention and comparators, respectively. Measures related to muscle strength were analyzed. To conduct the analyses a weighted mean difference (WMD) and the standardized mean difference (SMD) were applied as appropriate. A total of 15 studies were included in this systematic review and 14 in meta-analysis. Regarding the maximal isometric voluntary contraction (MIVC), a small effect was seen between tDCS and Sham with significant difference between the conditions (SMD = 0.29; CI95% = 0.05 to 0.54; Z = 2.36; p = 0.02). The muscular endurance measured by the seconds sustaining a percentage of MIVC demonstrated a large effect between tDCS and Sham (WMD = 43.66; CI95% = 29.76 to 57.55; Z = 6.16; p < 0.001), showing an improvement in muscular endurance after exposure to tDCS. However, muscular endurance based on total work showed a trivial effect between tDCS and Sham with no significant difference (SMD = 0.22; CI95% = -0.11 to 0.54; Z = 1.32, p = 0.19). This study suggests that the use of tDCS may promote increase in maximal voluntary contraction and muscular endurance through isometric contractions.
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Affiliation(s)
- Eduardo Lattari
- Physical Activity Sciences Post-Graduate Program (PGCAF), Salgado de Oliveira University (UNIVERSO), Niterói, RJ, Brazil
| | | | - Renato Sobral Monteiro Júnior
- Physical Education and Sport Department, State University of Montes Claros, Montes Claros, Minas Gerais, Brazil
- Post-graduation Program of Health Sciences, State University of Montes Claros, Montes Claros, Minas Gerais, Brazil
| | - Silvio Rodrigues Marques Neto
- Physical Activity Sciences Post-Graduate Program (PGCAF), Salgado de Oliveira University (UNIVERSO), Niterói, RJ, Brazil
| | - Aldair J. Oliveira
- School of Physical Activity, Rural Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Geraldo A. Maranhão Neto
- Physical Activity Sciences Post-Graduate Program (PGCAF), Salgado de Oliveira University (UNIVERSO), Niterói, RJ, Brazil
| | - Sergio Machado
- Physical Activity Sciences Post-Graduate Program (PGCAF), Salgado de Oliveira University (UNIVERSO), Niterói, RJ, Brazil
- * E-mail:
| | - Henning Budde
- Faculty of Human Sciences, Medical School Hamburg, Hamburg, Germany
- Lithuanian Sports University, Kaunas, Lithuania
- Physical Activity, Physical Education, Health and Sport Research Centre (PAPESH), Sports Science Department, School of Science and Engineering, Reykjavik University, Reykjavik, Iceland
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Holmes MR, Gould JR, Peña-González I, Enoka RM. Force steadiness during a co-contraction task can be improved with practice, but only by young adults and not by middle-aged or old adults. Exp Physiol 2015; 100:182-92. [PMID: 25398707 DOI: 10.1113/expphysiol.2014.083741] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 11/04/2014] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does the capacity to modulate afferent input to spinal motor neurons during steady submaximal contractions change with advancing age? What is the main finding and its importance? After practising a co-contraction task involving lower leg muscles, young subjects improved force steadiness by reducing the amount of Ia presynaptic inhibition as indexed by D1 inhibition. Middle-aged and old adults both found the task challenging, and force steadiness even worsened for old adults after practising the co-contraction task. Despite similar muscle strength for young and middle-aged adults, the capacity to modulate a spinal reflex pathway was reduced in middle-aged adults. This study compared the changes in steadiness and the modulation of presynaptic inhibition of soleus Ia afferents in young, middle-aged and old adults before and after a single session of practising a task that involved concurrent contraction of dorsiflexor and plantarflexor muscles. The hypothesis was that young subjects would be able to improve steadiness with practice by modulating Ia afferent feedback as indicated by changes in a measure of presynaptic inhibition (D1 inhibition), but that middle-aged and older subjects would exhibit a lesser ability to augment steadiness. There were no differences in steadiness between groups during an initial co-contraction trial (P = 0.713). Maximal voluntary contraction force for the plantarflexors was not significantly different between young and middle-aged subjects (P > 0.05), but it was significantly less in old subjects (P < 0.05). The main finding of the study was that young adults were able to improve steadiness by ∼19% (P < 0.001) during a co-contraction task after 50 min of practice, whereas there was no change for the middle-aged adults, and old adults became less steady by ∼15% (P < 0.05). The improvement in steadiness by young adults was accompanied by a significant reduction in the amount of Ia presynaptic inhibition as indexed by D1 inhibition (P < 0.01). Conversely, neither of the other two groups exhibited any change in D1 inhibition after practising the co-contraction task. In contrast to young subjects, middle-aged and old adults found the co-contraction task challenging and were not able to improve steadiness after practising the low-force isometric contraction.
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Affiliation(s)
- Matthew R Holmes
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80309, USA
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Milanović S, Filipović S, Blesić S, Ilić T, Dhanasekaran S, Ljubisavljević M. Paired-associative stimulation can modulate muscle fatigue induced motor cortex excitability changes. Behav Brain Res 2011; 223:30-5. [DOI: 10.1016/j.bbr.2011.04.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Revised: 04/01/2011] [Accepted: 04/10/2011] [Indexed: 11/25/2022]
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Hilty L, Lutz K, Maurer K, Rodenkirch T, Spengler CM, Boutellier U, Jäncke L, Amann M. Spinal opioid receptor-sensitive muscle afferents contribute to the fatigue-induced increase in intracortical inhibition in healthy humans. Exp Physiol 2011; 96:505-17. [PMID: 21317218 DOI: 10.1113/expphysiol.2010.056226] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We investigated the influence of spinal opioid receptor-sensitive muscle afferents on cortical changes following fatiguing unilateral knee-extensor exercise. On separate days, seven subjects performed an identical five sets of intermittent isometric right-quadriceps contractions, each consisting of eight submaximal contractions [63 ± 7% maximal voluntary contraction (MVC)] and one MVC. The exercise was performed following either lumbar interspinous saline injection or lumbar intrathecal fentanyl injection blocking the central projection of spinal opioid receptor-sensitive lower limb muscle afferents. To quantify exercise-induced peripheral fatigue, quadriceps twitch force (Q(tw,pot)) was assessed via supramaximal magnetic femoral nerve stimulation before and after exercise. Motor evoked potentials and cortical silent periods (CSPs) were evaluated via transcranial magnetic stimulation of the motor cortex during a 3% MVC pre-activation period immediately following exercise. End-exercise quadriceps fatigue was significant and similar in both conditions (Q(tw,pot) -35 and -39% for placebo and fentanyl, respectively; P = 0.38). Immediately following exercise on both days, motor evoked potentials were similar to those obtained prior to exercise. Compared with pre-exercise baseline, CSP in the placebo trial was 21 ± 5% longer postexercise (P < 0.01). In contrast, CSP following the fentanyl trial was not significantly prolonged compared with the pre-exercise baseline (6 ± 4%). Our findings suggest that the central effects of spinal opioid receptor-sensitive muscle afferents might facilitate the fatigue-induced increase in CSP. Furthermore, since the CSP is thought to reflect inhibitory intracortical interneuron activity, which may contribute to central fatigue, our findings imply that spinal opioid receptor-sensitive muscle afferents might influence central fatigue by facilitating intracortical inhibition.
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Affiliation(s)
- Lea Hilty
- Exercise Physiology, ETH Zurich and Institute of Physiology, University of Zurich, Switzerland
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Recovery of motor performance deterioration induced by a demanding finger motor task does not follow cortical excitability dynamics. Neuroscience 2011; 174:84-90. [DOI: 10.1016/j.neuroscience.2010.11.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 11/06/2010] [Indexed: 11/22/2022]
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Antal A, Terney D, Poreisz C, Paulus W. Towards unravelling task-related modulations of neuroplastic changes induced in the human motor cortex. Eur J Neurosci 2007; 26:2687-91. [DOI: 10.1111/j.1460-9568.2007.05896.x] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Dayer MJ, Jonville S, Chatwin M, Swallow EB, Porcher R, Sharshar T, Ross ET, Hopkinson NS, Moxham J, Polkey MI. Exercise-induced depression of the diaphragm motor evoked potential is not affected by non-invasive ventilation. Respir Physiol Neurobiol 2007; 155:243-54. [PMID: 16914394 DOI: 10.1016/j.resp.2006.06.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2005] [Revised: 06/19/2006] [Accepted: 06/20/2006] [Indexed: 10/24/2022]
Abstract
Whole body exercise is followed by a depression of the diaphragm motor evoked potential (MEP). It is unknown whether the change is due to diaphragm activity or whole body exercise. To test the hypothesis that exercise-induced MEP depression was related to diaphragm activity, we performed two experiments. The first examined the effect of whole body exercise, performed with and without the use of non-invasive ventilation (NIV). NIV resulted in significant unloading of the diaphragm (pressure time product 101+/-68 cm H(2)O/s/min versus 278+/-95 cm H(2)O/s/min, p<0.001). Both conditions produced significant MEP depression compared to the control condition (% drop at 5 min, after exercise and exercise with NIV: 29 and 34%, p=0.77). Study 2 compared exercise with isocapnic hyperventilation. At 20 min the MEP had fallen by 29% in the exercise session versus 5% with hyperventilation (p=0.098). We conclude that the work of breathing during whole body exercise is not the primary driver of exercise-induced diaphragm MEP depression.
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Affiliation(s)
- Mark J Dayer
- Respiratory Muscle Laboratory, Royal Brompton Hospital, London SW3 6NP, United Kingdom
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Kalmar JM, Cafarelli E. Central excitability does not limit postfatigue voluntary activation of quadriceps femoris. J Appl Physiol (1985) 2006; 100:1757-64. [PMID: 16424071 DOI: 10.1152/japplphysiol.01347.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
After fatigue, motor evoked potentials (MEP) elicited by transcranial magnetic stimulation and cervicomedullary evoked potentials elicited by stimulation of the corticospinal tract are depressed. These reductions in corticomotor excitability and corticospinal transmission are accompanied by voluntary activation failure, but this may not reflect a causal relationship. Our purpose was to determine whether a decline in central excitability contributes to central fatigue. We hypothesized that, if central excitability limits voluntary activation, then a caffeine-induced increase in central excitability should offset voluntary activation failure. In this repeated-measures study, eight men each attended two sessions. Baseline measures of knee extension torque, maximal voluntary activation, peripheral transmission, contractile properties, and central excitability were made before administration of caffeine (6 mg/kg) or placebo. The amplitude of vastus lateralis MEPs elicited during minimal muscle activation provided a measure of central excitability. After a 1-h rest, baseline measures were repeated before, during, and after a fatigue protocol that ended when maximal voluntary torque declined by 35% (Tlim). Increased prefatigue MEP amplitude ( P = 0.055) and cortically evoked twitch ( P < 0.05) in the caffeine trial indicate that the drug increased central excitability. In the caffeine trial, increased MEP amplitude was correlated with time to task failure ( r = 0.74, P < 0.05). Caffeine potentiated the MEP early in the fatigue protocol ( P < 0.05) and offset the 40% decline in placebo MEP ( P < 0.05) at Tlim. However, this was not associated with enhanced maximal voluntary activation during fatigue or recovery, demonstrating that voluntary activation is not limited by central excitability.
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Affiliation(s)
- J M Kalmar
- Department of Biology, Rm. 346, Bethune College, York University, 4700 Keele St., Toronto, ON, Canada M3J 1P3
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Boroojerdi B, Ziemann U, Chen R, Bütefisch CM, Cohen LG. Mechanisms underlying human motor system plasticity. Muscle Nerve 2001; 24:602-13. [PMID: 11317269 DOI: 10.1002/mus.1045] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There has been increased interest in the ability of the adult human nervous system to reorganize and adapt to environmental changes throughout life. This ability has been termed "plasticity." Plastic changes in the cerebral cortex have been studied: (a) as modifications of sensory or motor cortical representation of specific body parts (cortical maps, body representation level); and (b) as changes in the efficacy of existing synapses or generation of new synapses (neuronal or synaptic level). In this review, we describe paradigms used to study mechanisms of plasticity in the intact human motor system, the functional relevance of such plasticity, and possible ways to modulate it.
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Affiliation(s)
- B Boroojerdi
- Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, Room 5N 234, 10 Center Drive, MSC 1428, Bethesda, Maryland 20892-1428, USA
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Tergau F, Geese R, Bauer A, Baur S, Paulus W, Reimers CD. Motor cortex fatigue in sports measured by transcranial magnetic double stimulation. Med Sci Sports Exerc 2000; 32:1942-8. [PMID: 11079526 DOI: 10.1097/00005768-200011000-00019] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Besides peripheral mechanisms, central fatigue is an important factor limiting the performance of exhausting exercise in sport. The mechanisms responsible are still in discussion. Using noninvasive transcranial magnetic stimulation (TMS) in a double-pulse technique, we sought to assess fatigue of the motor cortex after exhaustive anaerobic strain. METHODS 23 male subjects (22-52 yr) taking part in the study were requested to accomplish as many pull-ups as possible until exhaustion. The amount of physical lifting work was recorded. Before and immediately after the task, intracortical inhibition (ICI) and facilitation (ICF) were measured by a conditioned-test double-pulse TMS method for the right brachioradialis (BR) and abductor pollicis brevis muscle (APB). RESULTS After exercise, ICF was significantly reduced in the BR but not in the APB. ICI was not altered. Changes tended to normalize within 8 min after the task. The amount of lifting work accomplished showed significant correlation to the values of ICF reduction (r = 0.73). Moreover, the baseline values of ICF before exercise were also significantly correlated to the lifting work (r = 0.63). CONCLUSIONS Because double-pulse TMS gives access to the motor cortex independently of spinal or peripheral mechanisms, reduced ICF reflects decreased excitability of interneuronal circuits within the motor cortex. We suggest that ICF measures motor cortex fatigue after exhausting strain specifically for the muscles performing the task. Gamma-aminobutyric acid (GABA)-ergic neurotransmission is possibly involved in the mechanisms mediating central fatigue. Double-pulse TMS may be a useful tool in the control of training in sports as well as in the detection of pathological central fatigue in overreaching and in the prevention of overtraining.
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Affiliation(s)
- F Tergau
- Department of Clinical Neurophysiology, University of Göttingen, Germany.
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Cohen LG, Ziemann U, Chen R, Classen J, Hallett M, Gerloff C, Butefisch C. Studies of neuroplasticity with transcranial magnetic stimulation. J Clin Neurophysiol 1998; 15:305-24. [PMID: 9736465 DOI: 10.1097/00004691-199807000-00003] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
In recent years, there has been increasing interest in studies of brain plasticity. Although still loosely defined, this term describes the ability of the brain to change. Cortical plasticity encompasses a wide variety of phenomena and mechanisms, including modifications in cortical properties such as strength of internal connections, representational patterns, or neuronal modifications, either morphological or functional (Donoghue et al., 1996). We focus on the description of different ways in which transcranial magnetic stimulation (TMS) can be used to study patterns of reorganization and some of the mechanisms involved in these changes. Correlation between TMS and neuroimaging studies in humans and animal studies addressing similar questions is discussed. It is important to identify in each situation whether plasticity plays a beneficial role or is maladaptive in terms of functional compensation. The understanding of patterns, mechanisms, and functional relevance of cortical plasticity will hopefully lead to the design of effective strategies to enhance plasticity when it is beneficial and to down-regulate it when it is maladaptive. An example of a possible strategy, using TMS, is discussed.
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Affiliation(s)
- L G Cohen
- Human Cortical Physiology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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