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Boda MR, Otieno LA, Smith AE, Goldsworthy MR, Sidhu SK. Metaplastic neuromodulation via transcranial direct current stimulation has no effect on corticospinal excitability and neuromuscular fatigue. Exp Brain Res 2024; 242:1999-2012. [PMID: 38940961 PMCID: PMC11252223 DOI: 10.1007/s00221-024-06874-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Accepted: 06/13/2024] [Indexed: 06/29/2024]
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation tool with potential for managing neuromuscular fatigue, possibly due to alterations in corticospinal excitability. However, inconsistencies in intra- and inter- individual variability responsiveness to tDCS limit its clinical use. Emerging evidence suggests harnessing homeostatic metaplasticity induced via tDCS may reduce variability and boost its outcomes, yet little is known regarding its influence on neuromuscular fatigue in healthy adults. We explored whether cathodal tDCS (ctDCS) prior to exercise combined with anodal tDCS (atDCS) could augment corticospinal excitability and attenuate neuromuscular fatigue. 15 young healthy adults (6 males, 22 ± 4 years) participated in four pseudo-randomised neuromodulation sessions: sham stimulation prior and during exercise, sham stimulation prior and atDCS during exercise, ctDCS prior and atDCS during exercise, ctDCS prior and sham stimulation during exercise. The exercise constituted an intermittent maximal voluntary contraction (MVC) of the right first dorsal interosseous (FDI) for 10 min. Neuromuscular fatigue was quantified as an attenuation in MVC force, while motor evoked potential (MEP) amplitude provided an assessment of corticospinal excitability. MEP amplitude increased during the fatiguing exercise, whilst across time, force decreased. There were no differences in MEP amplitudes or force between neuromodulation sessions. These outcomes highlight the ambiguity of harnessing metaplasticity to ameliorate neuromuscular fatigue in young healthy individuals.
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Affiliation(s)
- Madison R Boda
- School of Biomedicine, The University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Lavender A Otieno
- School of Biomedicine, The University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Ashleigh E Smith
- Alliance for Research in Exercise, Nutrition and Activity (ARENA), Allied Health and Human Performance, University of South Australia, Adelaide, South Australia, Australia
| | - Mitchell R Goldsworthy
- School of Biomedicine, The University of Adelaide, Adelaide, South Australia, 5005, Australia
- Behaviour-Brain-Body Research Centre, Justice and Society, University of South Australia, Adelaide, South Australia, Australia
- Hopwood Centre for Neurobiology, Lifelong Health Theme, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
| | - Simranjit K Sidhu
- School of Biomedicine, The University of Adelaide, Adelaide, South Australia, 5005, Australia.
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Otieno LA, Semmler JG, Smith AE, Sidhu SK. Submaximal isometric fatiguing exercise of the elbow flexors has no age-related effect on GABA B mediated inhibition. J Appl Physiol (1985) 2021; 132:167-177. [PMID: 34855523 DOI: 10.1152/japplphysiol.00288.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Age-related changes in the neuromuscular system can result in differences in fatigability between young and older adults. Previous research has shown that single joint isometric fatiguing exercise of small muscle results in an age-related compensatory decrease in GABAB mediated inhibition. However, this has yet to be established in a larger muscle group. In 15 young (22 ± 4 years) and 15 older (65 ± 5 years) adults, long interval cortical inhibition (LICI; 100 ms ISI) and corticospinal silent period (SP) were measured in the biceps brachii during a 5% EMG contraction using transcranial magnetic stimulation (TMS) before, during and after a submaximal contraction (30% MVC force) held intermittently to task failure. Both age groups developed similar magnitude of fatigue (~24% decline in MVC; P = 0.001) and ~28% decline in LICI (P = 0.001) post fatiguing exercise. No change in SP duration was observed during and immediately following fatigue (P = 0.909) but ~ 6% decrease was seen at recovery in both age groups (P<0.001)." Contrary to previous work in a small muscle, these findings suggest no age-related differences in GABAB mediated inhibition following single joint isometric fatiguing exercise of the elbow flexors, indicating that GABAB modulation with ageing may be muscle group dependent. Furthermore, variations in SP duration and LICI modulation during and post fatigue in both groups suggest that these measures are likely mediated by divergent mechanisms.
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Affiliation(s)
- Lavender A Otieno
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
| | - John G Semmler
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
| | - Ashleigh Elizabeth Smith
- Alliance for Research in Exercise, Nutrition and Activity (ARENA), Allied Health and Human Performance, University of South Australia, City East Campus, Australia
| | - Simranjit K Sidhu
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
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Sidhu SK. Remote muscle priming anodal transcranial direct current stimulation attenuates short interval intracortical inhibition and increases time to task failure of a constant workload cycling exercise. Exp Brain Res 2021; 239:1975-1985. [PMID: 33891144 DOI: 10.1007/s00221-021-06103-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 03/31/2021] [Indexed: 10/21/2022]
Abstract
Anodal transcranial direct current stimulation (atDCS), a non-invasive neuromodulatory technique has been shown to increase the excitability of targeted brain area and influence endurance exercise performance. However, the effect of atDCS applied on an unexercised muscle motor cortex (M1) representation on GABAA-mediated intracortical inhibition and endurance exercise performance remains unknown. In two separate sessions, twelve subjects performed fatigue cycling exercise (80% peak power output) sustained to task failure in a double-blinded design, following either ten minutes of bicephalic anodal tDCS (atDCS) or sham applied on a non-exercised hand muscle M1 representation. Short interval intracortical inhibition (SICI) was measured at baseline, post neuromodulation and post-exercise using paired-pulse transcranial magnetic stimulation (TMS) in a resting hand muscle. There was a greater decrease in SICI (P < 0.05) post fatigue cycling with atDCS priming compared to sham. Time to task failure (TTF) was significantly increased following atDCS compared to sham (P < 0.05). These findings suggest that atDCS applied over the non-exercised muscle M1 representation can augment cycling exercise performance; and although this outcome may be mediated via a multitude of mechanisms, a decrease in the global excitability of GABAA inhibitory interneurons may be a possible contributing factor.
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Affiliation(s)
- Simranjit K Sidhu
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, S433, Helen Mayo South, Frome Rd, Adelaide, SA, 5005, Australia.
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Dempsey LM, Kavanagh JJ. Muscarinic receptor blockade causes postcontraction enhancement in corticospinal excitability following maximal contractions. J Neurophysiol 2021; 125:1269-1278. [PMID: 33625939 DOI: 10.1152/jn.00673.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although synaptic transmission in motor pathways can be regulated by neuromodulators, such as acetylcholine, few studies have examined how cholinergic activity affects cortical and spinal motor circuits following muscle contractions of varying intensities. This was a human, double-blinded, placebo-controlled, crossover study. Participants attended two sessions where they were administered either a placebo or 25 mg of promethazine. Electromyography of the abductor digiti minimi (ADM) was measured for all conditions. Motor evoked potentials (MEPs) were obtained via motor cortical transcranial magnetic stimulation (TMS), and F waves were obtained via ulnar nerve electrical stimulation. MEPs and F waves were examined: 1) when the muscle was at rest; 2) after the muscle had been active; and 3) after the muscle had been fatigued. MEPs were unaffected by muscarinic receptor blockade when measurements were recorded from resting muscle or following a 50% isometric maximal voluntary contraction (MVC). However, muscarinic receptor blockade increased MEP area following a 10-s MVC (P = 0.019) and following a fatiguing 60-s MVC (P = 0.040). F wave area and persistence were not affected by promethazine for any muscle contraction condition. Corticospinal excitability was influenced by cholinergic effects when voluntary drive to the muscle was high. Given that spinal motoneurone excitability remained unaffected, it is likely that cholinergic effects are influential within the motor cortex during strong muscle contractions. Future research should evaluate how cholinergic effects alter the relationship between subcortical structures and the motor cortex, as well as brainstem neuromodulatory pathways and spinal motoneurons.NEW & NOTEWORTHY The relationship between motor function and cholinergic circuitry in the central nervous system is complex. Although many studies have approached this issue at the cellular level, few studies have examined cholinergic mechanisms in humans performing muscle contractions. This study demonstrates that blockade of muscarinic acetylcholine receptors enhances motor evoked potentials (elicited with transcranial magnetic stimulation) following strong muscle contractions, but not weak muscle contractions.
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Affiliation(s)
- Lisa M Dempsey
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
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Otieno LA, Semmler JG, Sidhu SK. Single joint fatiguing exercise decreases long but not short-interval intracortical inhibition in older adults. Exp Brain Res 2020; 239:47-58. [PMID: 33098654 DOI: 10.1007/s00221-020-05958-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 10/13/2020] [Indexed: 12/18/2022]
Abstract
Ageing is accompanied by neuromuscular changes which may alter fatigue in older adults. These changes may include changes in corticospinal excitatory and inhibitory processes. Previous research has suggested that single joint fatiguing exercise decreases short-(SICI) and long-(LICI) interval intracortical inhibition in young adults. However, this is yet to be established in older adults. In 19 young (23 ± 4 years) and 18 older (69 ± 5 years) adults, SICI (2 ms interstimulus interval; ISI) and LICI (100 ms ISI) were measured in a resting first dorsal interosseous (FDI) muscle using transcranial magnetic stimulation (TMS) before and after a 15 min sustained submaximal contraction at 25% of their maximum EMG. Subsequent ten 2-min contractions held at 25% EMG were also performed to sustain fatigue for a total of 30 min, while SICI and LICI were taken immediately after each contraction. There was no change in SICI post-fatiguing exercise compared to baseline in both young and older adults (P = 0.4). Although there was no change in LICI post-fatiguing exercise in younger adults (P = 1.0), LICI was attenuated in older adults immediately post-fatiguing exercise and remained attenuated post-fatigue (PF)1 and PF2 (P < 0.05). Contrary to previous studies, the lack of change in SICI and LICI in young adults following a sustained submaximal EMG contraction suggests that GABA modulation may be dependent on the type of fatiguing task performed. The reduction in LICI in older adults post-fatiguing exercise suggests an age-related decrease in GABAB-mediated activity with sustained submaximal fatiguing exercise.
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Affiliation(s)
- Lavender A Otieno
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, S433, Helen Mayo South, Frome Rd, Adelaide, South Australia, 5005, Australia
| | - John G Semmler
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, S433, Helen Mayo South, Frome Rd, Adelaide, South Australia, 5005, Australia
| | - Simranjit K Sidhu
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, S433, Helen Mayo South, Frome Rd, Adelaide, South Australia, 5005, Australia.
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Flanagan SD, Proessl F, Dunn-Lewis C, Canino MC, Sterczala AJ, Connaboy C, DuPont WH, Caldwell LK, Kraemer WJ. Constitutive and Stress-Induced Psychomotor Cortical Responses to Compound K Supplementation. Front Neurosci 2020; 14:315. [PMID: 32322188 PMCID: PMC7158875 DOI: 10.3389/fnins.2020.00315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/17/2020] [Indexed: 12/14/2022] Open
Abstract
Isolated ginsenoside metabolites such as Compound K (CK) are of increasing interest to consumer and clinical populations as safe and non-pharmacological means to enhance psychomotor performance constitutively and in response to physical or cognitive stress. Nevertheless, the influence of CK on behavioral performance and EEG measures of cortical activity in humans is undetermined. In this double-blinded, placebo-controlled, counterbalanced within-group study, dose-dependent responses to CK (placebo, 160 and 960 mg) were assessed after 2 weeks of supplementation in nineteen healthy men and women (age: 39.9 ± 7.9 year, height 170.2 ± 8.6 cm, weight 79.7 ± 11.9 kg). Performance on upper- and lower-body choice reaction tests (CRTs) was tested before and after intense lower-body anaerobic exercise. Treatment- and stress-related changes in brain activity were measured with high-density EEG based on event-related potentials, oscillations, and source activity. Upper- (−12.3 ± 3.5 ms, p = 0.002) and lower-body (−12.3 ± 4.9 ms, p = 0.021) response times improved after exercise, with no difference between treatments (upper: p = 0.354; lower: p = 0.926). Analysis of cortical activity in sensor and source space revealed global increases in cortical arousal after exercise. CK increased activity in cortical regions responsible for sustained attention and mitigated exercise-induced increases in arousal. Responses to exercise varied depending on task, but CK appeared to reduce sensory interference from lower-body exercise during an upper-body CRT and improve the general maintenance of task-relevant sensory processes.
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Affiliation(s)
- Shawn D Flanagan
- Department of Human Sciences, The Ohio State University, Columbus, OH, United States.,Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
| | - Felix Proessl
- Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
| | - Courtenay Dunn-Lewis
- Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
| | - Maria C Canino
- Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
| | - Adam J Sterczala
- Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
| | - Chris Connaboy
- Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
| | - William H DuPont
- Department of Human Sciences, The Ohio State University, Columbus, OH, United States
| | - Lydia K Caldwell
- Department of Human Sciences, The Ohio State University, Columbus, OH, United States
| | - William J Kraemer
- Department of Human Sciences, The Ohio State University, Columbus, OH, United States
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Hautasaari P, McLellan S, Koskio M, Pesonen H, Tarkka IM. Acute Exercise Modulates Pain-induced Response on Sensorimotor Cortex ∼20 Hz Oscillation. Neuroscience 2020; 429:46-55. [DOI: 10.1016/j.neuroscience.2019.12.044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 12/13/2019] [Accepted: 12/28/2019] [Indexed: 01/29/2023]
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Madinabeitia-Mancebo E, Madrid A, Jácome A, Cudeiro J, Arias P. Temporal dynamics of muscle, spinal and cortical excitability and their association with kinematics during three minutes of maximal-rate finger tapping. Sci Rep 2020; 10:3166. [PMID: 32081862 PMCID: PMC7035251 DOI: 10.1038/s41598-020-60043-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 02/06/2020] [Indexed: 11/09/2022] Open
Abstract
We tested peripheral, spinal and cortical excitability during 3 minutes of unresisted finger tapping at the maximal possible rate, which induced fatigue. Subsequently, we studied the temporal dynamics of muscle fatigue, expressed in the tapping movement profile, and its relationship to neural systems using mixed model analyses. The tapping rate decreased by 40% over the duration of the task. The change in the amplitude of the range of motion was not significant. The excitability of the flexor and extensor muscles of the index finger was tested via evoked potentials obtained with various types of stimulation at various levels of the motor system. The change in spinal excitability with time was evaluated considering the simultaneous changes in muscle excitability; we also considered how spinal excitability changed over time to evaluate cortical excitability. Excitability in the flexor and extensor muscles at the different levels tested changed significantly, but similar excitability levels were observed at notably different tapping rates. Our results showed that only 33% of the decrease in the tapping rate was explained by changes in the excitability of the structures tested in the present work.
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Affiliation(s)
- Elena Madinabeitia-Mancebo
- Universidade da Coruña, Neuroscience and Motor Control Group (NEUROcom); Department of Sport and Physical Education; Department of Physiotherapy, Medicine and Biomedical Sciences; Institute of Biomedical Research of A Coruña, A Coruña, Spain
| | - Antonio Madrid
- Universidade da Coruña, Neuroscience and Motor Control Group (NEUROcom); Department of Sport and Physical Education; Department of Physiotherapy, Medicine and Biomedical Sciences; Institute of Biomedical Research of A Coruña, A Coruña, Spain
| | - Amalia Jácome
- Universidade da Coruña, MODES Research group, CITIC, Department of Mathematics, A Coruña, Spain
| | - Javier Cudeiro
- Universidade da Coruña, Neuroscience and Motor Control Group (NEUROcom); Department of Sport and Physical Education; Department of Physiotherapy, Medicine and Biomedical Sciences; Institute of Biomedical Research of A Coruña, A Coruña, Spain.,Centro de Estimulación Cerebral de Galicia, A Coruña, Spain
| | - Pablo Arias
- Universidade da Coruña, Neuroscience and Motor Control Group (NEUROcom); Department of Sport and Physical Education; Department of Physiotherapy, Medicine and Biomedical Sciences; Institute of Biomedical Research of A Coruña, A Coruña, Spain.
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Older Adults Differentially Modulate Transcranial Magnetic Stimulation-Electroencephalography Measures of Cortical Inhibition during Maximal Single-joint Exercise. Neuroscience 2019; 425:181-193. [PMID: 31809730 DOI: 10.1016/j.neuroscience.2019.11.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 11/11/2019] [Accepted: 11/12/2019] [Indexed: 12/22/2022]
Abstract
The effects of muscle fatigue are known to be altered in older adults, and age-related changes in the brain are likely to be a contributing factor. However, the neural mechanisms underlying these changes are not known. The aim of the current study was to use transcranial magnetic stimulation combined with electroencephalography (TMS-EEG) to investigate age-related changes in cortical excitability with muscle fatigue. In 23 young (mean age ± SD: 22 ± 2 years) and 17 older (mean age ± SD: 68.3 ± 5.6 years) adults, single-pulse TMS-EEG was applied before, during and after the performance of fatiguing, intermittent isometric abduction of the index finger. Motor-evoked potential (MEP) measures of cortical excitability were increased during (estimated mean difference, 123.3%; P < 0.0001) and after (estimated mean difference, 117.5%; P = 0.001) fatigue and this was not different between groups (P > 0.5). For TMS-EEG, the amplitude of the P30 and P180 potentials were unaffected by fatigue in older participants (P > 0.05). In contrast, the amplitude of the N45 potential in older adults was significantly reduced both during (positive cluster: mean voltage difference = 0.7 µV, P < 0.005; negative cluster: mean voltage difference = 0.9 µV, P < 0.0005) and after (mean voltage difference = 0.5 µV, P < 0.005) fatiguing exercise, whereas this response was absent in young participants. These results suggest that performance of maximal intermittent isometric exercise in old but not young adults is associated with modulation of cortical inhibition likely mediated by activation of gamma-aminobutyric acid type A receptors.
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Improving the measurement of TMS-assessed voluntary activation in the knee extensors. PLoS One 2019; 14:e0216981. [PMID: 31170180 PMCID: PMC6553714 DOI: 10.1371/journal.pone.0216981] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 05/02/2019] [Indexed: 01/25/2023] Open
Abstract
PURPOSE To test the accuracy, validity, reliability and sensitivity of an alternative method for the measure of TMS-assessed voluntary activation (VATMS) in the knee extensors. METHODS Ten healthy males (24 ± 5 years) completed a neuromuscular assessment protocol before and after a fatiguing isometric exercise: two sets of five contractions (50%, 62.5%, 75%, 87.5%, 100% Maximal Voluntary Contraction; MVC) with superimposed TMS-evoked twitches for calculation of VATMS using either the first 5 stimulations (1x5C) or all 10 (2x5C). This was performed on two separate occasions (between-day reliability). Accuracy and validity were compared with a routinely used protocol [i.e. 50%, 75%, and 100% of MVC (1x3C) performed three times (3x3C)]. RESULTS 95% confidence interval for estimated resting twitch, a key determinant of VATMS, was similar between 1x5C, 2x5C, and 3x3C but improved by six-fold when compared to 1x3C (P<0.05). In a fresh state, potentiated twitch force was unchanged following 1x5C but decreased following 2x5C (P<0.05). A recovery was found post-exercise but was smaller for 1x5C compared to 2x5C (P<0.05), with no difference between the latter two (P>0.05). Absolute reliability was strong enough for both 1x5C and 2x5C to depict a true detectable change in the sample's VATMS following the fatiguing exercise (TEM < 3% at rest, <9% post-exercise) but 2x5C was marginally more sensitive to individual's changes from baseline. CONCLUSION Both 1x5C and 2x5C provide reliable measures of VATMS. However, 1x5C may hold stronger internal validity. Both protocols allow detection of 'true' changes in sample's means but not individual scores following a fatiguing isometric exercise.
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