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Horner D, Jeffries O, Brownstein CG. Eccentric Exercise-Induced Muscle Damage Reduces Gross Efficiency. Med Sci Sports Exerc 2024; 56:1816-1829. [PMID: 38768026 DOI: 10.1249/mss.0000000000003467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
INTRODUCTION The effect of eccentric exercise-induced muscle damage (EIMD) on cycling efficiency is unknown. The aim of the present study was to assess the effect of EIMD on gross and delta efficiency and the cardiopulmonary responses to cycle ergometry. METHODS Twenty-one recreational athletes performed cycling at 70%, 90%, and 110% of the gas exchange threshold (GET) under control conditions (Control) and 24 h following an eccentric damaging protocol (Damage). Knee extensor isometric maximal voluntary contraction, potentiated twitch ( Qtw,pot ), and voluntary activation were assessed before Control and Damage. Gross and delta efficiency were assessed using indirect calorimetry, and cardiopulmonary responses were measured at each power output. Electromyography root-mean-square (EMG RMS ) during cycling was also determined. RESULTS Maximal voluntary contraction was 25% ± 18% lower for Damage than Control ( P < 0.001). Gross efficiency was lower for Damage than Control ( P < 0.001) by 0.55% ± 0.79%, 0.59% ± 0.73%, and 0.60% ± 0.87% for 70%, 90%, and 110% GET, respectively. Delta efficiency was unchanged between conditions ( P = 0.513). Concurrently, cycling EMG RMS was higher for Damage than Control ( P = 0.004). An intensity-dependent increase in breath frequency and V̇ E /V̇CO 2 was found, which were higher for Damage only at 110% GET ( P ≤ 0.019). CONCLUSIONS Thus, gross efficiency is reduced following EIMD. The concurrently higher EMG RMS suggests that increases in muscle activation in the presence of EIMD might have contributed to reduced gross efficiency. The lack of change in delta efficiency might relate to its poor reliability hindering the ability to detect change. The findings also show that EIMD-associated hyperventilation is dependent on exercise intensity, which might relate to increases in central command with EIMD.
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Affiliation(s)
- Daniel Horner
- School of Biomedical, Nutritional, and Sport Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UNITED KINGDOM
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2
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Araujo Bonetti DE Poli R, Murias JM, Antunes BM, Marinari G, Dutra YM, Milioni F, Zagatto AM. Five Weeks of Sprint Interval Training Improve Muscle Glycolytic Content and Activity But Not Time to Task Failure in Severe-Intensity Exercise. Med Sci Sports Exerc 2024; 56:1355-1367. [PMID: 38537252 DOI: 10.1249/mss.0000000000003425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
PURPOSE This study examined the impact of a 5-wk sprint interval training (SIT) intervention on time to task failure (TTF) during severe-intensity constant work rate (CWR) exercise, as well as in glycolytic enzymatic content and activity, and glycogen content. METHODS Fourteen active males were randomized into either a SIT group ( n = 8) composed of 15 SIT sessions over 5 wk, or a control group ( n = 6). At pretraining period, participants performed i) ramp incremental test to measure the cardiorespiratory function; ii) CWR cycling TTF at 150% of the power output (PO) at the respiratory compensation point (RCP-PO) with muscle biopsies at rest and immediately following task failure. After 5 wk, the same evaluations were repeated (i.e., exercise intensities matched to current training status), and an additional cycling CWR matched to pretraining 150% RCP-PO was performed only for TTF evaluation. The content and enzymatic activity of glycogen phosphorylase (GPhos), hexokinase (HK), phosphofructokinase (PFK), and lactate dehydrogenase (LDH), as well as the glycogen content, were analyzed. Content of monocarboxylate transporter isoform 4 (MCT4) and muscle buffering capacity were also measured. RESULTS Despite improvements in total work performed at CWR posttraining, no differences were observed for TTF. The GPhos, HK, PFK, and LDH content and activity, and glycogen content also improved after training only in the SIT group. Furthermore, the MCT4 concentrations and muscle buffering capacity were also improved only for the SIT group. However, no difference in glycogen depletion was observed between groups and time. CONCLUSIONS Five weeks of SIT improved the glycolytic pathway parameters and total work performed; however, glycogen depletion was not altered during CWR severe-intensity exercise, and TTF remained similar.
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Affiliation(s)
- Rodrigo Araujo Bonetti DE Poli
- Laboratory of Physiology and Sport Performance (LAFIDE), Graduate Program in Movement Sciences, São Paulo State University (UNESP), School of Sciences. Bauru, BRAZIL
| | - Juan Manuel Murias
- College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, QATAR
| | - Barbara Moura Antunes
- Laboratory of Physiology and Sport Performance (LAFIDE), Graduate Program in Movement Sciences, São Paulo State University (UNESP), School of Sciences. Bauru, BRAZIL
| | - Gabriele Marinari
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, CANADA
| | - Yago Medeiros Dutra
- Laboratory of Physiology and Sport Performance (LAFIDE), Graduate Program in Movement Sciences, São Paulo State University (UNESP), School of Sciences. Bauru, BRAZIL
| | - Fabio Milioni
- Centro Universitário Nossa Senhora do Patrocínio, Itu, BRAZIL
| | - Alessandro Moura Zagatto
- Laboratory of Physiology and Sport Performance (LAFIDE), Graduate Program in Movement Sciences, São Paulo State University (UNESP), School of Sciences. Bauru, BRAZIL
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3
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Otaif A, Alshammari M, Gerin CG. Can alternative medical methods evoke somatosensory responses and functional improvement? Heliyon 2024; 10:e30010. [PMID: 38726182 PMCID: PMC11078864 DOI: 10.1016/j.heliyon.2024.e30010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 04/09/2024] [Accepted: 04/18/2024] [Indexed: 05/12/2024] Open
Abstract
Background Evidence-based scientific studies focusing on complementary alternative medicine (CAM) and potential functional improvement after an insult of the central nervous system are lacking. Aims We aim to demonstrate that functional recovery after stimulation applied as a CAM treatment through cauterization might trigger neural repair and regenerative paths similarly as acupuncture, cupping, electrical or magnetic stimulations. Those paths are important in recovery of function. Procedures Medical records and information of ten patients, with initial presentations of cerebral trauma or spinal cord insult inducing paralysis, were studied. Patients ages ranged from 17 to 95-year-old. Patients consulted for alternative medical treatment one year or more after initial diagnosis.CAM treatment consisted in 10-point stimulation on the skull and 4-point stimulation located at the right and left calves and forearms. Stimulations consisted of a heated steel rod application (cautery) in a one-time session. The duration of each stimulation was about 0.5 s. Results Most studies using CAM stimulations (acupuncture, cautery, cupping, moxibustion, electrical and magnetic stimulations) describe improvement. In all 10 medical records and information from our practitioner, patients had improvement in their motor skills, including gain of weight support, unassisted small walks, independent and voluntary movements of limbs. Improvement was steady over a period of one to several years. Conclusion We compared our findings to acupuncture, electrical, magnetic field effects to highlight common paths and to provide scientific evidence for recovery of the function. We believe that CAM treatments triggered existing or new neuronal networks as well as synaptic efficiency or reactivation, through highly increased, sensory nociceptive coupled to proprioceptive, afferences. Those results also highlight the need to further investigate neural function of cortical and subcortical areas through indirect pathways stimulations.
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Affiliation(s)
| | - Mashan Alshammari
- Texas A&M, Corpus Christi, TX, USA
- King Khalid Military Academy, Riyadh, Saudi Arabia
| | - Christine G. Gerin
- Texas A&M, Corpus Christi, TX, USA
- Institute of Neuroscience, Department of Neuro and Behavioral Health, UTRGV-SOM, TX, USA
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4
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Stavres J, Aultman RS, Newsome TA. Exercise pressor responses are exaggerated relative to force production during, but not following, thirty-minutes of rhythmic handgrip exercise. Eur J Appl Physiol 2024; 124:1547-1559. [PMID: 38155209 DOI: 10.1007/s00421-023-05390-2] [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: 08/03/2023] [Accepted: 11/29/2023] [Indexed: 12/30/2023]
Abstract
PURPOSE This study tested the hypothesis that blood pressure responses would increase relative to force production in response to prolonged bouts of muscular work. METHODS Fifteen individuals performed two minutes of static handgrip (SHG; 35% MVC), followed by three minutes of post-exercise-cuff-occlusion (PECO), before and after thirty minutes of rest (control), or rhythmic handgrip exercise (RHG) of the contralateral and ipsilateral forearms. Beat-by-beat recordings of mean arterial pressure (MAP), heart rate (HR), and handgrip force (kg) were averaged across one-minute periods at baseline, and minutes 5, 10, 15, 20, 25, and 30 of RHG. MAP was also normalized to handgrip force, providing a relative measure of exercise pressor responses (mmHg/kg). Hemodynamic responses to SHG and PECO were also compared before and after contralateral RHG, ipsilateral RHG, and control, respectively. Similar to the RHG trial, areas under the curve were calculated for MAP (blood pressure index; BPI) and normalized to the time tension index (BPInorm). RESULTS HR and MAP significantly increased during RHG (15.3 ± 1.4% and 20.4 ± 3.2%, respectively, both p < 0.01), while force output decreased by up to 36.6 ± 8.0% (p < 0.01). This resulted in a 51.6 ± 9.4% increase in BPInorm during 30 min of RHG (p < 0.01). In contrast, blood pressure responses to SHG and PECO were unchanged following RHG (all p ≥ 0.07), and only the mean HR (4.2 ± 1.5%, p = 0.01) and ΔHR (67.2 ± 18.1%, p < 0.01) response to SHG were exaggerated following ipsilateral RHG. CONCLUSIONS The magnitude of exercise pressor responses relative to force production progressively increases during, but not following, prolonged bouts of muscular work.
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Affiliation(s)
- Jon Stavres
- School of Kinesiology and Nutrition, University of Southern Mississippi, 118 College Drive, Hattiesburg, MS, USA.
| | - Ryan S Aultman
- School of Kinesiology and Nutrition, University of Southern Mississippi, 118 College Drive, Hattiesburg, MS, USA
| | - Ta'Quoris A Newsome
- School of Kinesiology and Nutrition, University of Southern Mississippi, 118 College Drive, Hattiesburg, MS, USA
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Coovadia Y, Schwende BK, Taylor CE, Usselman CW. Limb-specific muscle sympathetic nerve activity responses to the cold pressor test. Auton Neurosci 2024; 251:103146. [PMID: 38181550 DOI: 10.1016/j.autneu.2023.103146] [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: 09/29/2023] [Revised: 12/22/2023] [Accepted: 12/26/2023] [Indexed: 01/07/2024]
Abstract
Recent studies have demonstrated that muscle sympathetic nerve activity (MSNA) responses to isometric exercise differs between active and inactive limbs. Whether limb-dependent responses are characteristic of responses to the cold pressor test (CPT) remains to be established. Therefore, we tested the hypothesis that CPT-induced MSNA responses differ between affected and unaffected limbs such that MSNA in the affected lower limb is greater than MSNA responses in the contralateral lower limb and the upper limb. Integrated peroneal MSNA (microneurography) was measured in young healthy individuals (n = 10) at rest and during three separate 3-min CPTs: the microneurography foot, opposite foot, and opposite hand. Peak MSNA responses were extracted for further analysis, as well as corresponding hemodynamic outcomes including mean arterial pressure (MAP; Finometer). MSNA responses were greater when the microneurography foot was immersed in ice water than when the opposite foot was immersed (38 ± 18 vs 28 ± 16 bursts/100hb: P < 0.01). MSNA responses when the opposite hand was immersed were greater than both the microneurography foot (46 ± 22 vs 38 ± 18 bursts/100hb: P < 0.01) and opposite foot (46 ± 22 vs 28 ± 16 bursts/100hb: P ≤0.01). Likewise, MAP responses were greater during the hand CPT than the microneurography foot (99 ± 9 vs 96 ± 8 mmHg: P < 0.01) and opposite foot CPT (99 ± 9 vs 96 ± 9 mmHg: P < 0.01). These data indicate that (a) upper limbs and (b) immersed limbs elicit greater MSNA responses to the CPT than lower and/or non-immersed limbs.
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Affiliation(s)
- Yasmine Coovadia
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, Quebec, Canada
| | - Brittany K Schwende
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, Quebec, Canada
| | - Chloe E Taylor
- School of Health Sciences, Western Sydney University, Sydney, New South Wales, Australia
| | - Charlotte W Usselman
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, Quebec, Canada.
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Farra SD, Jacobs I. Arterial desaturation rate does not influence self-selected knee extension force but alters ventilatory response to progressive hypoxia: A pilot study. Physiol Rep 2024; 12:e15892. [PMID: 38172088 PMCID: PMC10764295 DOI: 10.14814/phy2.15892] [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: 11/15/2023] [Revised: 12/04/2023] [Accepted: 12/04/2023] [Indexed: 01/05/2024] Open
Abstract
The absolute magnitude and rate of arterial desaturation each independently impair whole-body aerobic exercise. This study examined potential mechanisms underlying the rate-dependent relationship. Utilizing an exercise protocol involving unilateral, intermittent, isometric knee extensions (UIIKE), we provided sufficient reperfusion time between contractions to reduce the accumulation of intramuscular metabolic by-products that typically stimulate muscle afferents. The objective was to create a milieu conducive to accentuating any influence of arterial desaturation rate on muscular fatigue. Eight participants completed four UIIKE sessions, performing one 3 s contraction every 30s at a perceived intensity of 50% MVC for 25 min. Participants voluntarily adjusted their force generation to maintain perceptual effort at 50% MVC without feedback. Reductions in inspired oxygen fraction (FI O2 ) decreased arterial saturation from >98% to 70% with varying rates in three trials: FAST (5.3 ± 1.3 min), MED (11.8 ± 2.7 min), and SLOW (19.9 ± 3.7 min). FI O2 remained at 0.21 during the control trial. Force generation and muscle activation remained at baseline levels throughout UIIKE trials, unaffected by the magnitude or rate of desaturation. Minute ventilation increased with hypoxia (p < 0.05), and faster desaturation rates magnified this response. These findings demonstrate that arterial desaturation magnitude and rate independently affect ventilation, but do not influence fatigue development during UIIKE.
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Affiliation(s)
- Saro D. Farra
- Faculty of Kinesiology & Physical EducationUniversity of TorontoTorontoOntarioCanada
| | - Ira Jacobs
- Faculty of Kinesiology & Physical EducationUniversity of TorontoTorontoOntarioCanada
- Tanenbaum Institute for Science in Sport, University of TorontoTorontoOntarioCanada
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Wan HY, Bunsawat K, Amann M. Autonomic cardiovascular control during exercise. Am J Physiol Heart Circ Physiol 2023; 325:H675-H686. [PMID: 37505474 PMCID: PMC10659323 DOI: 10.1152/ajpheart.00303.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/11/2023] [Accepted: 07/23/2023] [Indexed: 07/29/2023]
Abstract
The cardiovascular response to exercise is largely determined by neurocirculatory control mechanisms that help to raise blood pressure and modulate vascular resistance which, in concert with regional vasodilatory mechanisms, promote blood flow to active muscle and organs. These neurocirculatory control mechanisms include a feedforward mechanism, known as central command, and three feedback mechanisms, namely, 1) the baroreflex, 2) the exercise pressor reflex, and 3) the arterial chemoreflex. The hemodynamic consequences of these control mechanisms result from their influence on the autonomic nervous system and subsequent alterations in cardiac output and vascular resistance. Although stimulation of the baroreflex inhibits sympathetic outflow and facilitates parasympathetic activity, central command, the exercise pressor reflex, and the arterial chemoreflex facilitate sympathetic activation and inhibit parasympathetic drive. Despite considerable understanding of the cardiovascular consequences of each of these mechanisms in isolation, the circulatory impact of their interaction, which occurs when various control systems are simultaneously activated (e.g., during exercise at altitude), has only recently been recognized. Although aging and cardiovascular disease (e.g., heart failure, hypertension) have both been recognized to alter the hemodynamic consequences of these regulatory systems, this review is limited to provide a brief overview on the action and interaction of neurocirculatory control mechanisms in health.
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Affiliation(s)
- Hsuan-Yu Wan
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, United States
| | - Kanokwan Bunsawat
- Geriatric Research, Education, and Clinical Center, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah, United States
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States
| | - Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, United States
- Geriatric Research, Education, and Clinical Center, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah, United States
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States
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8
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Dempsey JA, Welch JF. Control of Breathing. Semin Respir Crit Care Med 2023; 44:627-649. [PMID: 37494141 DOI: 10.1055/s-0043-1770342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Substantial advances have been made recently into the discovery of fundamental mechanisms underlying the neural control of breathing and even some inroads into translating these findings to treating breathing disorders. Here, we review several of these advances, starting with an appreciation of the importance of V̇A:V̇CO2:PaCO2 relationships, then summarizing our current understanding of the mechanisms and neural pathways for central rhythm generation, chemoreception, exercise hyperpnea, plasticity, and sleep-state effects on ventilatory control. We apply these fundamental principles to consider the pathophysiology of ventilatory control attending hypersensitized chemoreception in select cardiorespiratory diseases, the pathogenesis of sleep-disordered breathing, and the exertional hyperventilation and dyspnea associated with aging and chronic diseases. These examples underscore the critical importance that many ventilatory control issues play in disease pathogenesis, diagnosis, and treatment.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin, Madison, Wisconsin
| | - Joseph F Welch
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
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Marzouk M, McKeown DJ, Borg DN, Headrick J, Kavanagh JJ. Perceptions of fatigue and neuromuscular measures of performance fatigability during prolonged low-intensity elbow flexions. Exp Physiol 2023; 108:465-479. [PMID: 36763088 PMCID: PMC10103868 DOI: 10.1113/ep090981] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/24/2023] [Indexed: 02/11/2023]
Abstract
NEW FINDINGS What is the central question of this study? What is the predictive relationship between self-reported scales to quantify perceptions of fatigue during exercise and gold standard measures used to quantify the development of neuromuscular fatigue? What is the main finding and its importance? No scale was determined to be substantively more effective than another. However, the number of ongoing contractions performed was shown to be a better predictor of fatigue in the motor system than any of the subjective scales. ABSTRACT The purpose of this study was to determine the relationship between transcranial magnetic stimulation (TMS) measures of performance fatigability and commonly used scales that quantify perceptions of fatigue during exercise. Twenty healthy participants (age 23 ± 3 years, 10 female) performed 10 submaximal isometric elbow flexions at 20% maximal voluntary contraction (MVC) for 2 min, separated by 45 s of rest. Biceps brachii muscle electromyography and elbow flexion torque responses to single-pulse TMS were obtained at the end of each contraction to assess central factors of performance fatigability. A rating of perceived exertion (RPE) scale, Omnibus Resistance scale, Likert scale, Rating of Fatigue scale and a visual analogue scale (VAS) were used to assess perceptions of fatigue at the end of each contraction. The RPE (root mean square error (RMSE) = 0.144) and Rating of Fatigue (RMSE = 0.145) scales were the best predictors of decline in MVC torque, whereas the Likert (RMSE= 0.266) and RPE (RMSE= 0.268) scales were the best predictors of electromyographic amplitude. Although the Likert (RMSE = 7.6) and Rating of Fatigue (RMSE = 7.6) scales were the best predictors of voluntary muscle activation of any scale, the number of contractions performed during the protocol was a better predictor (RMSE = 7.3). The ability of the scales to predict TMS measures of performance fatigability were in general similar. Interestingly, the number of contractions performed was a better predictor of TMS measures than the scales themselves.
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Affiliation(s)
- Monica Marzouk
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
| | - Daniel J. McKeown
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
| | - David N. Borg
- The Australian Centre for Health Services Innovation and Centre for Healthcare Transformation, School of Public Health and Social WorkQueensland University of TechnologyBrisbaneQueenslandAustralia
| | - Jonathon Headrick
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
| | - Justin J. Kavanagh
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
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10
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Nicolò A, Sacchetti M. Differential control of respiratory frequency and tidal volume during exercise. Eur J Appl Physiol 2023; 123:215-242. [PMID: 36326866 DOI: 10.1007/s00421-022-05077-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 10/18/2022] [Indexed: 11/06/2022]
Abstract
The lack of a testable model explaining how ventilation is regulated in different exercise conditions has been repeatedly acknowledged in the field of exercise physiology. Yet, this issue contrasts with the abundance of insightful findings produced over the last century and calls for the adoption of new integrative perspectives. In this review, we provide a methodological approach supporting the importance of producing a set of evidence by evaluating different studies together-especially those conducted in 'real' exercise conditions-instead of single studies separately. We show how the collective assessment of findings from three domains and three levels of observation support the development of a simple model of ventilatory control which proves to be effective in different exercise protocols, populations and experimental interventions. The main feature of the model is the differential control of respiratory frequency (fR) and tidal volume (VT); fR is primarily modulated by central command (especially during high-intensity exercise) and muscle afferent feedback (especially during moderate exercise) whereas VT by metabolic inputs. Furthermore, VT appears to be fine-tuned based on fR levels to match alveolar ventilation with metabolic requirements in different intensity domains, and even at a breath-by-breath level. This model reconciles the classical neuro-humoral theory with apparently contrasting findings by leveraging on the emerging control properties of the behavioural (i.e. fR) and metabolic (i.e. VT) components of minute ventilation. The integrative approach presented is expected to help in the design and interpretation of future studies on the control of fR and VT during exercise.
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Affiliation(s)
- Andrea Nicolò
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro De Bosis 6, 00135, Rome, Italy.
| | - Massimo Sacchetti
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro De Bosis 6, 00135, Rome, Italy
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11
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Bergevin M, Steele J, Payen de la Garanderie M, Feral-Basin C, Marcora SM, Rainville P, Caron JG, Pageaux B. Pharmacological Blockade of Muscle Afferents and Perception of Effort: A Systematic Review with Meta-analysis. Sports Med 2023; 53:415-435. [PMID: 36318384 DOI: 10.1007/s40279-022-01762-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2022] [Indexed: 01/27/2023]
Abstract
BACKGROUND The perception of effort provides information on task difficulty and influences physical exercise regulation and human behavior. This perception differs from other-exercise related perceptions such as pain. There is no consensus on the role of group III/IV muscle afferents as a signal processed by the brain to generate the perception of effort. OBJECTIVE The aim of this meta-analysis was to investigate the effect of pharmacologically blocking muscle afferents on the perception of effort. METHODS Six databases were searched to identify studies measuring the ratings of perceived effort during physical exercise, with and without pharmacological blockade of muscle afferents. Articles were coded based on the operational measurement used to distinguish studies in which perception of effort was assessed specifically (effort dissociated) or as a composite experience including other exercise-related perceptions (effort not dissociated). Articles that did not provide enough information for coding were assigned to the unclear group. RESULTS The effort dissociated group (n = 6) demonstrated a slight increase in ratings of perceived effort with reduced muscle afferent feedback (standard mean change raw, 0.39; 95% confidence interval 0.13-0.64). The group effort not dissociated (n = 2) did not reveal conclusive results (standard mean change raw, - 0.29; 95% confidence interval - 2.39 to 1.8). The group unclear (n = 8) revealed a slight ratings of perceived effort decrease with reduced muscle afferent feedback (standard mean change raw, - 0.27; 95% confidence interval - 0.50 to - 0.04). CONCLUSIONS The heterogeneity in results between groups reveals that the inclusion of perceptions other than effort in its rating influences the ratings of perceived effort reported by the participants. The absence of decreased ratings of perceived effort in the effort dissociated group suggests that muscle afferent feedback is not a sensory signal for the perception of effort.
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Affiliation(s)
- Maxime Bergevin
- École de kinésiologie et des sciences de l'activite physique (EKSAP), Faculté de médecine, Université́ de Montréal, Montreal, QC, Canada.,Centre de recherche de l'Institut universitaire de gériatrie de Montréal (CRIUGM), Montreal, Canada
| | - James Steele
- School of Sport, Health and Social Sciences, Southampton, UK
| | - Marie Payen de la Garanderie
- École de kinésiologie et des sciences de l'activite physique (EKSAP), Faculté de médecine, Université́ de Montréal, Montreal, QC, Canada.,Centre de recherche de l'Institut universitaire de gériatrie de Montréal (CRIUGM), Montreal, Canada
| | - Camille Feral-Basin
- École de kinésiologie et des sciences de l'activite physique (EKSAP), Faculté de médecine, Université́ de Montréal, Montreal, QC, Canada.,Centre de recherche de l'Institut universitaire de gériatrie de Montréal (CRIUGM), Montreal, Canada
| | - Samuele M Marcora
- Department of Biomedical and Neuromotor Sciences (DiBiNeM), University of Bologna, Bologna, Italy
| | - Pierre Rainville
- Centre de recherche de l'Institut universitaire de gériatrie de Montréal (CRIUGM), Montreal, Canada.,Département de stomatologie, Faculté de médecine dentaire, Université de Montréal, Montreal, QC, Canada
| | - Jeffrey G Caron
- École de kinésiologie et des sciences de l'activite physique (EKSAP), Faculté de médecine, Université́ de Montréal, Montreal, QC, Canada.,Centre de recherche interdisciplinaire en réadaptation du Montréal métropolitain, Montreal, QC, Canada
| | - Benjamin Pageaux
- École de kinésiologie et des sciences de l'activite physique (EKSAP), Faculté de médecine, Université́ de Montréal, Montreal, QC, Canada. .,Centre de recherche de l'Institut universitaire de gériatrie de Montréal (CRIUGM), Montreal, Canada. .,Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage (CIRCA), Montreal, QC, Canada.
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12
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The effect of constant load cycling at extreme- and severe-intensity domains on performance fatigability and its determinants in young female. Sci Sports 2023. [DOI: 10.1016/j.scispo.2022.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Stavres J, Luck JC, Hamaoka T, Blaha C, Cauffman A, Dalton PC, Herr MD, Ruiz-Velasco V, Carr ZJ, Janicki P, Cui J. A 10-mg dose of amiloride increases time to failure during blood-flow-restricted plantar flexion in healthy adults without influencing blood pressure. Am J Physiol Regul Integr Comp Physiol 2022; 323:R875-R888. [PMID: 36222880 PMCID: PMC9678418 DOI: 10.1152/ajpregu.00190.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/22/2022] [Accepted: 10/05/2022] [Indexed: 11/22/2022]
Abstract
Amiloride has been shown to inhibit acid-sensing ion channels (ASICs), which contribute to ischemia-related muscle pain during exercise. The purpose of this study was to determine if a single oral dose of amiloride would improve exercise tolerance and attenuate blood pressure during blood-flow-restricted (BFR) exercise in healthy adults. Ten subjects (4 females) performed isometric plantar flexion exercise with BFR (30% maximal voluntary contraction) after ingesting either a 10-mg dose of amiloride or a volume-matched placebo (random order). Time to failure, time-tension index (TTI), and perceived pain (visual analog scale) were compared between the amiloride and placebo trials. Mean blood pressure, heart rate, blood pressure index (BPI), and BPI normalized to TTI (BPInorm) were also compared between trials using both time-matched (TM50 and TM100) and effort-matched (T50 and T100) comparisons. Time to failure (+69.4 ± 63.2 s, P < 0.01) and TTI (+1,441 ± 633 kg·s, P = 0.02) were both significantly increased in the amiloride trial compared with placebo, despite no increase in pain (+0.4 ± 1.7 cm, P = 0.46). In contrast, amiloride had no significant influence on the mean blood pressure or heart rate responses, nor were there any significant differences in BPI or BPInorm between trials when matched for time (all P ≥ 0.13). When matched for effort, BPI was significantly greater in the amiloride trial (+5,300 ± 1,798 mmHg·s, P = 0.01), likely owing to an increase in total exercise duration. In conclusion, a 10-mg oral dose of amiloride appears to significantly improve the tolerance to BFR exercise in healthy adults without influencing blood pressure responses.
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Affiliation(s)
- Jon Stavres
- School of Kinesiology and Nutrition, University of Southern Mississippi, Hattiesburg, Mississippi
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - J Carter Luck
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Takuto Hamaoka
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Cheryl Blaha
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Aimee Cauffman
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Paul C Dalton
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Michael D Herr
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Victor Ruiz-Velasco
- Department of Anesthesiology and Perioperative Medicine, Penn State University College of Medicine, Penn State Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Zyad J Carr
- Department of Anesthesiology, Yale School of Medicine, Yale New Haven Hospital, New Haven, Connecticut
| | - Piotr Janicki
- Department of Anesthesiology and Perioperative Medicine, Penn State University College of Medicine, Penn State Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Jian Cui
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania
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Zambolin F, Duro-Ocana P, Faisal A, Bagley L, Gregory WJ, Jones AW, McPhee JS. Fibromyalgia and Chronic Fatigue Syndromes: A systematic review and meta-analysis of cardiorespiratory fitness and neuromuscular function compared with healthy individuals. PLoS One 2022; 17:e0276009. [PMID: 36264901 PMCID: PMC9584387 DOI: 10.1371/journal.pone.0276009] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 09/27/2022] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE To determine cardiorespiratory fitness and neuromuscular function of people with CFS and FMS compared to healthy individuals. DESIGN Systematic review and meta-analysis. DATA SOURCES PubMed, Medline, CINAHL, AMED, Cochrane Central Register of Controlled Trials (CENTRAL), and PEDro from inception to June 2022. ELIGIBLE CRITERIA FOR SELECTING STUDIES Studies were included if presenting baseline data on cardiorespiratory fitness and/or neuromuscular function from observational or interventional studies of patients diagnosed with FMS or CFS. Participants were aged 18 years or older, with results also provided for healthy controls. Risk of bias assessment was conducted using the Quality Assessment Tool for Quantitative Studies (EPHPP). RESULTS 99 studies including 9853 participants (5808 patients; 4405 healthy controls) met our eligibility criteria. Random effects meta-analysis showed lower cardiorespiratory fitness (VO2max, anaerobic threshold, peak lactate) and neuromuscular function (MVC, fatigability, voluntary activation, muscle volume, muscle mass, rate of perceived exertion) in CFS and FMS compared to controls: all with moderate to high effect sizes. DISCUSSION Our results demonstrate lower cardiorespiratory fitness and muscle function in those living with FMS or CFS when compared to controls. There were indications of dysregulated neuro-muscular interactions including heightened perceptions of effort, reduced ability to activate the available musculature during exercise and reduced tolerance of exercise. TRAIL REGISTRATION PROSPERO registration number: (CRD42020184108).
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Affiliation(s)
- Fabio Zambolin
- Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Manchester Metropolitan University Institute of Sport, Manchester, United Kingdom
- * E-mail:
| | - Pablo Duro-Ocana
- Manchester Metropolitan University Institute of Sport, Manchester, United Kingdom
- Department of Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Department of Anaesthesia, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - Azmy Faisal
- Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Manchester Metropolitan University Institute of Sport, Manchester, United Kingdom
- Faculty of Physical Education for Men, Alexandria University, Alexandria, Egypt
| | - Liam Bagley
- Manchester Metropolitan University Institute of Sport, Manchester, United Kingdom
- Department of Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Department of Anaesthesia, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - William J. Gregory
- Rheumatology Department, Salford Care Organisation, Northern Care Alliance NHS Foundation Trust, Salford, United Kingdom
- Faculty of Health, Psychology and Social Care, Manchester Metropolitan University, Manchester, United Kingdom
| | - Arwel W. Jones
- Respiratory Research@Alfred, Monash University, Melbourne, Australia
| | - Jamie S. McPhee
- Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Manchester Metropolitan University Institute of Sport, Manchester, United Kingdom
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15
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Zambolin F, Giuriato G, Laginestra FG, Ottaviani MM, Favaretto T, Calabria E, Duro-Ocana P, Bagley L, Faisal A, Peçanha T, McPhee JS, Venturelli M. Effects of nociceptive and mechanosensitive afferents sensitization on central and peripheral hemodynamics following exercise-induced muscle damage. J Appl Physiol (1985) 2022; 133:945-958. [PMID: 35981730 DOI: 10.1152/japplphysiol.00302.2022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 08/04/2022] [Accepted: 08/16/2022] [Indexed: 11/22/2022] Open
Abstract
This study aims to test the separated and combined effects of mechanoreflex activation and nociception through exercise-induced muscle damage (EIMD) on central and peripheral hemodynamics before and during single passive leg movement (sPLM). Eight healthy young males undertook four experimental sessions, in which a sPLM was performed on the dominant limb while in each specific session the contralateral was: 1) in a resting condition (CTRL), 2) stretched (ST), 3) resting after EIMD called delayed onset muscle soreness (DOMS) condition, or 4) stretched after EIMD (DOMS + ST). EIMD was used to induce DOMS in the following 24-48 h. Femoral blood flow (FBF) was assessed using Doppler ultrasound whereas central hemodynamics were assessed via finger photoplethysmography. Leg vascular conductance (LVC) was calculated as FBF/mean arterial pressure (MAP). RR-intervals were analyzed in the time (root mean squared of successive intervals; RMSSD) and frequency domain [low frequency (LF)/high frequency (HF)]. Blood samples were collected before each condition and gene expression analysis showed increased fold changes for P2X4 and IL1β in DOMS and DOMS + ST compared with baseline. Resting FBF and LVC were decreased only in the DOMS + ST condition (-26 mL/min and -50 mL/mmHg/min respectively) with decreased RMSSD and increased LF/HF ratio. MAP, HR, CO, and SV were increased in ST and DOMS + ST compared with CTRL. Marked decreases of Δpeaks and AUC were observed for FBF (Δ: -146 mL/min and -265 mL respectively) and LVC (Δ: -8.66 mL/mmHg/min and ±1.7 mL/mmHg/min respectively) all P < 0.05. These results suggest that the combination of mechanoreflex and nociception resulted in decreased vagal tone and concomitant rise in sympathetic drive that led to increases in resting central hemodynamics with reduced limb blood flow before and during sPLM.NEW & NOTEWORTHY Exercise-induced muscle damage (EIMD) is a well-known model to study mechanical hyperalgesia and muscle peripheral nerve sensitizations. The combination of static stretching protocol on the damaged limb extensively increases resting central hemodynamics with reduction in resting limb blood flow and passive leg movement-induced hyperemia. The mechanism underlining these results may be linked to reduction of vagal tone with concomitant increase in sympathetic activity following mechano- and nociceptive activation.
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Affiliation(s)
- Fabio Zambolin
- Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Manchester Metropolitan University Institute of Sport, Manchester Metropolitan University, Manchester, United Kingdom
| | - Gaia Giuriato
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Fabio Giuseppe Laginestra
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Matteo Maria Ottaviani
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
- Department Medicine, University of Udine, Udine, Italy
| | - Thomas Favaretto
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
- Department of Neurosurgery, University Politecnica delle Marche, Ancona, Italy
| | - Elisa Calabria
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Pablo Duro-Ocana
- Department of Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Department of Anesthesia, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - Liam Bagley
- Manchester Metropolitan University Institute of Sport, Manchester Metropolitan University, Manchester, United Kingdom
- Department of Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Department of Anesthesia, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - Azmy Faisal
- Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Manchester Metropolitan University Institute of Sport, Manchester Metropolitan University, Manchester, United Kingdom
- Faculty of Physical Education for Men, Alexandria University, Alexandria, Egypt
| | - Tiago Peçanha
- Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Manchester Metropolitan University Institute of Sport, Manchester Metropolitan University, Manchester, United Kingdom
| | - Jamie Stewart McPhee
- Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Manchester Metropolitan University Institute of Sport, Manchester Metropolitan University, Manchester, United Kingdom
| | - Massimo Venturelli
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
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16
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Dempsey JA, Neder JA, Phillips DB, O'Donnell DE. The physiology and pathophysiology of exercise hyperpnea. HANDBOOK OF CLINICAL NEUROLOGY 2022; 188:201-232. [PMID: 35965027 DOI: 10.1016/b978-0-323-91534-2.00001-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In health, the near-eucapnic, highly efficient hyperpnea during mild-to-moderate intensity exercise is driven by three obligatory contributions, namely, feedforward central command from supra-medullary locomotor centers, feedback from limb muscle afferents, and respiratory CO2 exchange (V̇CO2). Inhibiting each of these stimuli during exercise elicits a reduction in hyperpnea even in the continuing presence of the other major stimuli. However, the relative contribution of each stimulus to the hyperpnea remains unknown as does the means by which V̇CO2 is sensed. Mediation of the hyperventilatory response to exercise in health is attributed to the multiple feedback and feedforward stimuli resulting from muscle fatigue. In patients with COPD, diaphragm EMG amplitude and its relation to ventilatory output are used to decipher mechanisms underlying the patients' abnormal ventilatory responses, dynamic lung hyperinflation and dyspnea during exercise. Key contributions to these exercise-limiting responses across the spectrum of COPD severity include high dead space ventilation, an excessive neural drive to breathe and highly fatigable limb muscles, together with mechanical constraints on ventilation. Major controversies concerning control of exercise hyperpnea are discussed along with the need for innovative research to uncover the link of metabolism to breathing in health and disease.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI, United States.
| | - J Alberto Neder
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
| | - Devin B Phillips
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
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17
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Zero AM, Kirk EA, Rice CL. Firing rate trajectories of human motor units during activity-dependent muscle potentiation. J Appl Physiol (1985) 2021; 132:402-412. [PMID: 34913736 DOI: 10.1152/japplphysiol.00672.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During activity-dependent potentiation (ADP) motor unit firing rates (MUFRs) are lower, however, the mechanism for this response is not known. During increasing torque isometric contractions at low contraction intensities, MUFR trajectories initially accelerate and saturate demonstrating a non-linear response due to the activation of persistent inward currents (PICs) at the motoneuron. The purpose was to assess whether PICs are a factor in the reduction of MUFRs during ADP. To assess this, MUFR trajectories were fit with competing functions of linear regression and a rising exponential (i.e., acceleration and saturation). Using fine-wire electrodes, discrete MU potential trains were recorded in the tibialis anterior during slowly increasing dorsiflexion contractions to 10% of maximal voluntary contraction following both voluntary (post-activation potentiation; PAP) and evoked (post-tetanic potentiation; PTP) contractions. In 8 participants, 25 MUs were recorded across both ADP conditions and compared to the control with no ADP effect. During PAP and PTP, the average MUFRs were 16.4% and 9.2% lower (both P≤ 0.001), respectively. More MUFR trajectories were better fit to the rising exponential during control (16/25) compared to PAP (4/25, P<0.001) and PTP (8/25, P=0.03). The MU samples that had a rising exponential MUFR trajectory during PAP and PTP displayed an ~11% lower initial acceleration compared to control (P<0.05). Thus, synaptic amplification and MUFR saturation due to PIC properties are attenuated during ADP regardless of the type of conditioning contraction. This response may contribute to lower MUFRs and likely occurred because synaptic input is reduced when contractile function is enhanced.
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Affiliation(s)
- Alexander M Zero
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada
| | - Eric A Kirk
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
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18
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Germano Maciel D, Santos Cerqueira M, Gabbett TJ, Elsangedy HM, de Brito Vieira WH. Should We Trust Perceived Effort for Loading Control and Resistance Exercise Prescription After ACL Reconstruction? Sports Health 2021; 14:764-769. [PMID: 34486455 DOI: 10.1177/19417381211041289] [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: 11/15/2022] Open
Abstract
CONTEXT The rating of perceived effort (RPE) is a common method used in clinical practice for monitoring, loading control, and resistance training prescription during rehabilitation after rupture and anterior cruciate ligament reconstruction (ACLR). It is suggested that the RPE results from the integration of the afferent feedback and corollary discharge in the motor and somatosensory cortex, and from the activation of brain areas related to emotions, affect, memory, and pain (eg, posterior cingulate cortex, precuneus, and prefrontal cortex). Recent studies have shown that rupture and ACLR induce neural adaptations in the brain commonly associated with the RPE. Therefore, we hypothesize that RPE could be affected because of neural adaptations induced by rupture and ACLR. STUDY DESIGN Clinical review. LEVEL OF EVIDENCE Level 5. RESULTS RPE could be directly altered by changes in the activation of motor cortex, posterior cingulate cortex, and prefrontal cortex. These neural adaptations may be induced by indirect mechanisms, such as the afferent feedback deficit, pain, and fear of movement (kinesiophobia) that patients may feel after rupture and ACLR. CONCLUSION Using only RPE for monitoring, loading control, and resistance training prescription in patients who had undergone ACLR could lead to under- or overdosing resistance exercise, and therefore, impair the rehabilitation process. STRENGTH-OF-RECOMMENDATION TAXONOMY 3C.
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Affiliation(s)
- Daniel Germano Maciel
- Department of Physical Therapy, Laboratory of Neuromuscular Performance, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Mikhail Santos Cerqueira
- Department of Physical Therapy, Laboratory of Neuromuscular Performance, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Tim J Gabbett
- Gabbett Performance Solutions, Brisbane, Queensland, Australia.,University of Southern Queensland, Institute for Resilient Regions, Ipswich, Queensland, Australia
| | - Hassan Mohamed Elsangedy
- Department of Physical Education, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Wouber Hérickson de Brito Vieira
- Department of Physical Therapy, Laboratory of Neuromuscular Performance, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
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19
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da Silva Machado DG, Bikson M, Datta A, Caparelli-Dáquer E, Unal G, Baptista AF, Cyrino ES, Li LM, Morya E, Moreira A, Okano AH. Acute effect of high-definition and conventional tDCS on exercise performance and psychophysiological responses in endurance athletes: a randomized controlled trial. Sci Rep 2021; 11:13911. [PMID: 34230503 PMCID: PMC8260713 DOI: 10.1038/s41598-021-92670-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 06/03/2021] [Indexed: 02/06/2023] Open
Abstract
Transcranial direct current stimulation (tDCS) has been used aiming to boost exercise performance and inconsistent findings have been reported. One possible explanation is related to the limitations of the so-called "conventional" tDCS, which uses large rectangular electrodes, resulting in a diffuse electric field. A new tDCS technique called high-definition tDCS (HD-tDCS) has been recently developed. HD-tDCS uses small ring electrodes and produces improved focality and greater magnitude of its aftereffects. This study tested whether HD-tDCS would improve exercise performance to a greater extent than conventional tDCS. Twelve endurance athletes (29.4 ± 7.3 years; 60.15 ± 5.09 ml kg-1 min-1) were enrolled in this single-center, randomized, crossover, and sham-controlled trial. To test reliability, participants performed two time to exhaustion (TTE) tests (control conditions) on a cycle simulator with 80% of peak power until volitional exhaustion. Next, they randomly received HD-tDCS (2.4 mA), conventional (2.0 mA), or active sham tDCS (2.0 mA) over the motor cortex for 20-min before performing the TTE test. TTE, heart rate (HR), associative thoughts, peripheral (lower limbs), and whole-body ratings of perceived exertion (RPE) were recorded every minute. Outcome measures were reliable. There was no difference in TTE between HD-tDCS (853.1 ± 288.6 s), simulated conventional (827.8 ± 278.7 s), sham (794.3 ± 271.2 s), or control conditions (TTE1 = 751.1 ± 261.6 s or TTE2 = 770.8 ± 250.6 s) [F(1.95; 21.4) = 1.537; P = 0.24; η2p = 0.123]. There was no effect on peripheral or whole-body RPE and associative thoughts (P > 0.05). No serious adverse effect was reported. A single session of neither HD-tDCS nor conventional tDCS changed exercise performance and psychophysiological responses in athletes, suggesting that a ceiling effect may exist.
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Affiliation(s)
- Daniel Gomes da Silva Machado
- Associate Graduate Program in Physical Education - UEM/UEL, State University of Londrina, Londrina, PR, Brazil
- Department of Physical Education, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York of CUNY, New York, NY, USA
| | - Abhishek Datta
- Department of Biomedical Engineering, The City College of New York of CUNY, New York, NY, USA
| | - Egas Caparelli-Dáquer
- Nervous System Electric Stimulation Lab (LabEEL), Rio de Janeiro State University (UERJ), Rio de Janeiro, RJ, Brazil
| | - Gozde Unal
- Department of Biomedical Engineering, The City College of New York of CUNY, New York, NY, USA
| | - Abrahão F Baptista
- Nervous System Electric Stimulation Lab (LabEEL), Rio de Janeiro State University (UERJ), Rio de Janeiro, RJ, Brazil
- Center of Mathematics, Computation, and Cognition, Universidade Federal do ABC, São Bernardo do Campo, SP, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN/CEPID-FAPESP), Faculty of Medical Sciences, Department of Neurology, University of Campinas, Campinas, São Paulo, Brazil
| | - Edilson Serpeloni Cyrino
- Associate Graduate Program in Physical Education - UEM/UEL, State University of Londrina, Londrina, PR, Brazil
| | - Li Min Li
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN/CEPID-FAPESP), Faculty of Medical Sciences, Department of Neurology, University of Campinas, Campinas, São Paulo, Brazil
| | - Edgard Morya
- Edmond and Lily Safra International Institute of Neuroscience, Santos Dumont Institute, Macaíba, RN, Brazil
| | - Alexandre Moreira
- Department of Sport, School of Physical Education and Sport, University of São Paulo, São Paulo, SP, Brazil
| | - Alexandre Hideki Okano
- Associate Graduate Program in Physical Education - UEM/UEL, State University of Londrina, Londrina, PR, Brazil.
- Center of Mathematics, Computation, and Cognition, Universidade Federal do ABC, São Bernardo do Campo, SP, Brazil.
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN/CEPID-FAPESP), Faculty of Medical Sciences, Department of Neurology, University of Campinas, Campinas, São Paulo, Brazil.
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20
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Grotle AK, Kaur J, Stone AJ, Fadel PJ. Neurovascular Dysregulation During Exercise in Type 2 Diabetes. Front Physiol 2021; 12:628840. [PMID: 33927637 PMCID: PMC8076798 DOI: 10.3389/fphys.2021.628840] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 03/05/2021] [Indexed: 12/12/2022] Open
Abstract
Emerging evidence suggests that type 2 diabetes (T2D) may impair the ability to properly adjust the circulation during exercise with augmented blood pressure (BP) and an attenuated contracting skeletal muscle blood flow (BF) response being reported. This review provides a brief overview of the current understanding of these altered exercise responses in T2D and the potential underlying mechanisms, with an emphasis on the sympathetic nervous system and its regulation during exercise. The research presented support augmented sympathetic activation, heightened BP, reduced skeletal muscle BF, and impairment in the ability to attenuate sympathetically mediated vasoconstriction (i.e., functional sympatholysis) as potential drivers of neurovascular dysregulation during exercise in T2D. Furthermore, emerging evidence supporting a contribution of the exercise pressor reflex and central command is discussed along with proposed future directions for studies in this important area of research.
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Affiliation(s)
- Ann-Katrin Grotle
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, United States
| | - Jasdeep Kaur
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States
| | - Audrey J Stone
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States
| | - Paul J Fadel
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, United States
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21
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Amann M, Wan HY, Thurston TS, Georgescu VP, Weavil JC. On the Influence of Group III/IV Muscle Afferent Feedback on Endurance Exercise Performance. Exerc Sport Sci Rev 2020; 48:209-216. [PMID: 32658041 DOI: 10.1249/jes.0000000000000233] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review discusses evidence suggesting that group III/IV muscle afferents affect locomotor performance by influencing neuromuscular fatigue. These neurons regulate the hemodynamic and ventilatory response to exercise and, thus, assure appropriate locomotor muscle O2 delivery, which optimizes peripheral fatigue development and facilitates endurance performance. In terms of central fatigue, group III/IV muscle afferents inhibit motoneuronal output and thereby limit exercise performance.
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Affiliation(s)
| | - Hsuan-Yu Wan
- Department of Anesthesiology, University of Utah
| | - Taylor S Thurston
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT
| | - Vincent P Georgescu
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT
| | - Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT
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22
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Iepsen UW, Ryrsø CK, Rugbjerg M, Secher NH, Barbosa TC, Lange P, Thaning P, Pedersen BK, Mortensen SP, Fadel PJ. Cardiorespiratory responses to high-intensity skeletal muscle metaboreflex activation in chronic obstructive pulmonary disease. Clin Physiol Funct Imaging 2020; 41:146-155. [PMID: 33159389 DOI: 10.1111/cpf.12678] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/08/2020] [Accepted: 11/04/2020] [Indexed: 11/29/2022]
Abstract
BACKGROUND Augmented skeletal muscle metaboreflex activation may accompany chronic obstructive pulmonary disease (COPD). The maintained metaboreflex control of mean arterial pressure (MAP) that has been reported may reflect limited evaluation using only one moderate bout of static handgrip (HG) and following postexercise ischaemia (PEI). OBJECTIVE We tested the hypothesis that cardiovascular and respiratory responses to high-intensity static HG and isolated metaboreflex activation during PEI are augmented in COPD patients. METHODS Ten patients with moderate to severe COPD and eight healthy age- and BMI-matched controls performed two-minute static HG at moderate (30% maximal voluntary contraction; MVC) and high (40% MVC) intensity followed by PEI. RESULTS Despite similar ratings of perceived exertion, arm muscle mass and strength, COPD patients demonstrated lower MAP responses during both HG intensities compared with controls (time × group interaction, p < .05). Indeed, during high-intensity HG at 40% MVC, peak MAP responses were significantly lower in COPD patients (ΔMAP: COPD 41 ± 9 mmHg vs. controls 56 ± 14 mmHg, p < .05). Notably, no group differences in MAP were observed during PEI (e.g. 40% MVC PEI: ΔMAP COPD 33 ± 9 mmHg vs. controls 33 ± 6 mmHg, p > .05). We found no between-group differences in heart rate, respiratory rate, or estimated minute ventilation during HG or PEI. CONCLUSION These results suggest that the pressor response to high-intensity HG is blunted in COPD patients. Moreover, despite inducing a strong cardiovascular and respiratory stimulus, skeletal muscle metaboreflex activation evoked similar responses in COPD patients and controls.
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Affiliation(s)
- Ulrik Winning Iepsen
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Camilla Koch Ryrsø
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Mette Rugbjerg
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Niels H Secher
- Department of Anaesthesiology, Institute of Clinical Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | | | - Peter Lange
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Medical Department O, Respiratory Section, Herlev and Gentofte Hospital, Herlev, Denmark.,Department of Public Health, Section of Epidemiology, University of Copenhagen, Copenhagen, Denmark
| | - Pia Thaning
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Department of Respiratory Medicine, University Hospital Hvidovre, Hvidovre, Denmark
| | - Bente K Pedersen
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Sefan P Mortensen
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX, USA
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23
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Hsu MJ, Chan HL, Huang YZ, Lin JH, Hsu HH, Chang YJ. Mechanism of Fatigue Induced by Different Cycling Paradigms With Equivalent Dosage. Front Physiol 2020; 11:545. [PMID: 32547418 PMCID: PMC7273923 DOI: 10.3389/fphys.2020.00545] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/30/2020] [Indexed: 11/18/2022] Open
Abstract
Leg cycling is one of the most common modes of exercise used in athletics and rehabilitation. This study used a novel cycling setting to elucidate the mechanisms, central vs. peripheral fatigue induced by different resistance with equivalent works (watt∗min). Twelve male adults received low and relatively high resistance cycling fatigue tests until exhausted (RPE > 18) in 2 weeks. The maximal voluntary contraction, voluntary activation level, and twitch forces were measured immediately before and after cycling to calculate General (GFI), central (CFI), and peripheral (PFI) fatigue indices of knee extensors, respectively. The results showed that the CFI (high: 92.26 ± 8.67%, low: 78.32 ± 11.77%, p = 0.004) and PFI (high: 73.76 ± 17.32%, low: 89.63 ± 11.01%, p < 0.017) were specific to the resistance of fatigue protocol. The GFI is influenced by the resistance of cycling to support the equivalent dosage. This study concluded that the mechanism of fatigue would be influenced by the resistance of fatigue protocol although the total works had been controlled.
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Affiliation(s)
- Miao-Ju Hsu
- Department of Physical Therapy, College of Health Science, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Physical Medicine and Rehabilitation and Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Hsiao-Lung Chan
- Department of Electrical Engineering, College of Engineering, Chang Gung University, Taoyuan, Taiwan
- Neuroscience Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Ying-Zu Huang
- Neuroscience Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
- Department of Neurology, Chang Gung Memorial Hospital, Taoyuan, Taiwan
- School of Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Jau-Hong Lin
- Department of Physical Therapy, College of Health Science, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Physical Medicine and Rehabilitation and Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Heng-Hsiang Hsu
- School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, and Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Ya-Ju Chang
- Neuroscience Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
- School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, and Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan
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24
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Treadmill running using an RPE-clamp model: mediators of perception and implications for exercise prescription. Eur J Appl Physiol 2019; 119:2083-2094. [PMID: 31372804 DOI: 10.1007/s00421-019-04197-4] [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] [Received: 04/08/2019] [Accepted: 07/23/2019] [Indexed: 10/26/2022]
Abstract
PURPOSE The mediators of the perception of effort during exercise are still unclear. The aim of the present study was to examine physiological responses during runs using a rating of perceived exertion (RPE)-clamp model at the RPE corresponding to the gas exchange threshold (RPEGET) and 15% above GET (RPEGET+15%) to identify potential mediators and performance applications for RPE during treadmill running. METHODS Twenty-one runners ([Formula: see text]max = 51.7 ± 8.3 ml kg-1 min-1) performed a graded exercise test to determine maximal oxygen consumption and the RPE associated with GET and GET + 15% followed by randomized 60 min RPE-clamp runs at RPEGET and RPEGET+15%. Mean differences for [Formula: see text], heart rate (HR), minute ventilation ([Formula: see text]), respiratory frequency ([Formula: see text], respiratory exchange ratio (RER), and velocity were compared across each run. RESULTS After minute 14, [Formula: see text], RER and velocity did not differ across conditions, but decreased across time (p < 0.05). There was a significant (p < 0.05) condition × time interaction for [Formula: see text], where values were significantly higher during RPE-clamp runs at RPEGET+15% and decreased across time in both conditions. There were no differences across condition or time for HR, and only small difference between conditions for [Formula: see text]. CONCLUSIONS HR and [Formula: see text] may play a role in mediating the perception of effort, while [Formula: see text], RER, and [Formula: see text] may not. Although HR and [Formula: see text] may mediate the maintenance of a perceptual intensity, they may not be sensitive to differentiate perceptual intensities at GET and GET + 15%. Thus, prescribing exercise using an RPE-clamp model may only reflect a sustainable [Formula: see text] within the moderate intensity domain.
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25
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O’Donnell DE, James MD, Milne KM, Neder JA. The Pathophysiology of Dyspnea and Exercise Intolerance in Chronic Obstructive Pulmonary Disease. Clin Chest Med 2019; 40:343-366. [DOI: 10.1016/j.ccm.2019.02.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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26
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Murphy S, Durand M, Negro F, Farina D, Hunter S, Schmit B, Gutterman D, Hyngstrom A. The Relationship Between Blood Flow and Motor Unit Firing Rates in Response to Fatiguing Exercise Post-stroke. Front Physiol 2019; 10:545. [PMID: 31133877 PMCID: PMC6524339 DOI: 10.3389/fphys.2019.00545] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 04/17/2019] [Indexed: 11/22/2022] Open
Abstract
We quantified the relationship between the change in post-contraction blood flow with motor unit firing rates and metrics of fatigue during intermittent, sub-maximal fatiguing contractions of the knee extensor muscles after stroke. Ten chronic stroke survivors (>1-year post-stroke) and nine controls participated. Throughout fatiguing contractions, the discharge timings of individual motor units were identified by decomposition of high-density surface EMG signals. After five consecutive contractions, a blood flow measurement through the femoral artery was obtained using an ultrasound machine and probe designed for vascular measurements. There was a greater increase of motor unit firing rates from the beginning of the fatigue protocol to the end of the fatigue protocol for the control group compared to the stroke group (14.97 ± 3.78% vs. 1.99 ± 11.90%, p = 0.023). While blood flow increased with fatigue for both groups (p = 0.003), the magnitude of post-contraction blood flow was significantly greater for the control group compared to the stroke group (p = 0.004). We found that despite the lower magnitude of muscle perfusion through the femoral artery in the stroke group, blood flow has a greater impact on peripheral fatigue for the control group; however, we observed a significant correlation between change in blood flow and motor unit firing rate modulation (r2 = 0.654, p = 0.004) during fatigue in the stroke group and not the control group (r2 = 0.024, p < 0.768). Taken together, this data showed a disruption between motor unit firing rates and post-contraction blood flow in the stroke group, suggesting that there may be a disruption to common inputs to both the reticular system and the corticospinal tract. This study provides novel insights in the relationship between the hyperemic response to exercise and motor unit firing behavior for post-stroke force production and may provide new approaches for recovery by improving both blood flow and muscle activation simultaneously.
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Affiliation(s)
- Spencer Murphy
- Integrative Neural Engineering and Rehabilitation Laboratory, Department of Biomedical Engineering, Marquette University, Milwaukee, WI, United States
| | - Matthew Durand
- Department of Physical Medicine and Rehabilitation, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, Università degli studi di Brescia, Brescia, Italy
| | - Dario Farina
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Sandra Hunter
- Department of Physical Therapy, Marquette University, Milwaukee, WI, United States
| | - Brian Schmit
- Integrative Neural Engineering and Rehabilitation Laboratory, Department of Biomedical Engineering, Marquette University, Milwaukee, WI, United States
| | - David Gutterman
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Allison Hyngstrom
- Integrative Neural Engineering and Rehabilitation Laboratory, Department of Biomedical Engineering, Marquette University, Milwaukee, WI, United States.,Department of Physical Therapy, Marquette University, Milwaukee, WI, United States
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27
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Nicolò A, Girardi M, Bazzucchi I, Felici F, Sacchetti M. Respiratory frequency and tidal volume during exercise: differential control and unbalanced interdependence. Physiol Rep 2018; 6:e13908. [PMID: 30393984 PMCID: PMC6215760 DOI: 10.14814/phy2.13908] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 10/02/2018] [Accepted: 10/03/2018] [Indexed: 01/14/2023] Open
Abstract
Differentiating between respiratory frequency (fR ) and tidal volume (VT ) may improve our understanding of exercise hyperpnoea because fR and VT seem to be regulated by different inputs. We designed a series of exercise manipulations to improve our understanding of how fR and VT are regulated during exercise. Twelve cyclists performed an incremental test and three randomized experimental sessions in separate visits. In two of the three experimental visits, participants performed a moderate-intensity sinusoidal test followed, after recovery, by a moderate-to-severe-intensity sinusoidal test. These two visits differed in the period of the sinusoid (2 min vs. 8 min). In the third experimental visit, participants performed a trapezoidal test where the workload was self-paced in order to match a predefined trapezoidal template of rating of perceived exertion (RPE). The results collectively reveal that fR changes more with RPE than with workload, gas exchange, VT or the amount of muscle activation. However, fR dissociates from RPE during moderate exercise. Both VT and minute ventilation ( V ˙ E ) showed a similar time course and a large correlation with V ˙ CO 2 in all the tests. Nevertheless, V ˙ CO 2 was associated more with V ˙ E than with VT because VT seems to adjust continuously on the basis of fR levels to match V ˙ E with V ˙ CO 2 . The present findings provide novel insight into the differential control of fR and VT - and their unbalanced interdependence - during exercise. The emerging conceptual framework is expected to guide future research on the mechanisms underlying the long-debated issue of exercise hyperpnoea.
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Affiliation(s)
- Andrea Nicolò
- Department of Movement, Human and Health SciencesUniversity of Rome “Foro Italico”RomeItaly
| | - Michele Girardi
- Department of Movement, Human and Health SciencesUniversity of Rome “Foro Italico”RomeItaly
| | - Ilenia Bazzucchi
- Department of Movement, Human and Health SciencesUniversity of Rome “Foro Italico”RomeItaly
| | - Francesco Felici
- Department of Movement, Human and Health SciencesUniversity of Rome “Foro Italico”RomeItaly
| | - Massimo Sacchetti
- Department of Movement, Human and Health SciencesUniversity of Rome “Foro Italico”RomeItaly
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28
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Seed JD, St Peters B, Power GA, Millar PJ. Cardiovascular responses during isometric exercise following lengthening and shortening contractions. J Appl Physiol (1985) 2018; 126:278-285. [PMID: 30382808 DOI: 10.1152/japplphysiol.00601.2018] [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] [Indexed: 11/22/2022] Open
Abstract
The present study investigated the effects of prior lengthening or shortening contractions on cardiovascular responses during isometric exercise. We utilized the history dependence of skeletal muscle, where active 2-s lengthening or shortening before an isometric contraction can increase [residual force enhancement (RFE)] or decrease [force depression (FD)] force production. Matching torque output between RFE and FD conditions yields lower and higher electromyography (EMG) values, respectively. In study 1, heart rate and perceived exertion (PE; Borg10) were measured in 20 participants during 20-s isometric plantar flexion contractions at low (16 ± 4% MVC)-, moderate (50 ± 5% MVC)-, and high (88 ± 7% MVC)-intensity. In study 2, heart rate and blood pressure were measured in 14 participants during 2-min isometric plantar flexion contractions (40% MVC). In both studies, torque output was held constant between FD and RFE conditions resulting in differences in soleus EMG activity ( P < 0.05). In study 1, PE was lower during the RFE condition ( P < 0.01), while increases in heart rate were similar between FD and RFE at low (∆2 ± 8 vs. 3 ± 6 beats/min, P > 0.99) and moderate (∆14 ± 9 vs. 14 ± 9 beats/min, P > 0.99) intensity but smaller during RFE at high intensity (∆35 ± 13 vs. 29 ± 13 beats/min, P = 0.004). In study 2, heart rate responses were smaller in the RFE condition following the initial 20-s period; diastolic blood pressure responses were smaller during the last 80 s. A 2-s active change in muscle length before an isometric contraction can influence heart rate and blood pressure responses; however, these differences appear to be modulated by both intensity and duration of the contraction. NEW & NOTEWORTHY Using the history dependence of isometric force to alter maximal torque production and motor unit activation between residual force enhancement and force depression conditions, we observed that heart rate responses were different between conditions during a subsequent 20-s high-, but not low- or moderate-, intensity isometric contraction. A 2-min moderate-intensity contraction revealed time-dependent effects on heart rate and diastolic blood pressure. Active 2-s shortening and lengthening before an isometric contraction can influence the cardiovascular responses.
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Affiliation(s)
- Jeremy D Seed
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Benjamin St Peters
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Geoffrey A Power
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada.,Toronto General Research Institute, Toronto General Hospital , Toronto, Ontario , Canada
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29
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Collins BW, Pearcey GE, Buckle NC, Power KE, Button DC. Neuromuscular fatigue during repeated sprint exercise: underlying physiology and methodological considerations. Appl Physiol Nutr Metab 2018; 43:1166-1175. [DOI: 10.1139/apnm-2018-0080] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Neuromuscular fatigue occurs when an individual’s capacity to produce force or power is impaired. Repeated sprint exercise requires an individual to physically exert themselves at near-maximal to maximal capacity for multiple short-duration bouts, is extremely taxing on the neuromuscular system, and consequently leads to the rapid development of neuromuscular fatigue. During repeated sprint exercise the development of neuromuscular fatigue is underlined by a combination of central and peripheral fatigue. However, there are a number of methodological considerations that complicate the quantification of the development of neuromuscular fatigue. The main goal of this review is to synthesize the results from recent investigations on the development of neuromuscular fatigue during repeated sprint exercise. Hence, we summarize the overall development of neuromuscular fatigue, explain how recovery time may alter the development of neuromuscular fatigue, outline the contributions of peripheral and central fatigue to neuromuscular fatigue, and provide some methodological considerations for quantifying neuromuscular fatigue during repeated sprint exercise.
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Affiliation(s)
- Brandon W. Collins
- BioMedical Sciences, Faculty of Medicine, Memorial University, St. John’s, NL A1C 5S7, Canada
| | - Gregory E.P. Pearcey
- Rehabilitation Neuroscience Laboratory and Centre for Biomedical Research, University of Victoria, Victoria, BC V8W 2Y2, Canada
- Human Discovery Science, International Collaboration on Repair Discoveries (ICORD), Vancouver, BC V5Z 1M9, Canada
| | - Natasha C.M. Buckle
- School of Human Kinetics and Recreation and BioMedical Sciences, Faculty of Medicine, Memorial University, St. John’s, NL A1C 5S7, Canada
| | - Kevin E. Power
- School of Human Kinetics and Recreation and BioMedical Sciences, Faculty of Medicine, Memorial University, St. John’s, NL A1C 5S7, Canada
| | - Duane C. Button
- School of Human Kinetics and Recreation and BioMedical Sciences, Faculty of Medicine, Memorial University, St. John’s, NL A1C 5S7, Canada
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30
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Notay K, Klingel SL, Lee JB, Doherty CJ, Seed JD, Swiatczak M, Mutch DM, Millar PJ. TRPV1 and BDKRB2 receptor polymorphisms can influence the exercise pressor reflex. J Physiol 2018; 596:5135-5148. [PMID: 30206938 DOI: 10.1113/jp276526] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 08/02/2018] [Indexed: 01/23/2023] Open
Abstract
KEY POINTS The mechanisms responsible for the high inter-individual variability in blood pressure responses to exercise remain unclear. Common genetic variants of genes related to the vascular transduction of sympathetic outflow have been investigated, but variants influencing skeletal muscle afferent feedback during exercise have not been explored. Single nucleotide polymorphisms in TRPV1 rs222747 and BDKRB2 rs1799722 receptors present in skeletal muscle were associated with differences in the magnitude of the blood pressure response to static handgrip exercise but not mental stress. The combined effects of TRPV1 rs222747 and BDKRB2 rs1799722 on blood pressure and heart rate responses during exercise were additive, and primarily found in men. Genetic differences in skeletal muscle metaboreceptors may be a risk factor for exaggerated blood pressure responses to exercise. ABSTRACT Exercise blood pressure (BP) responses demonstrate high inter-individual variability, which could relate to differences in metabolically sensitive afferent feedback from the exercising muscle. We hypothesized that single-nucleotide polymorphisms (SNPs) in genes encoding metaboreceptors present in group III/IV skeletal muscle afferents can influence the exercise pressor response. Two hundred men and women underwent measurements of continuous BP and heart rate at baseline and during 2 min of static handgrip exercise (30% maximal volitional contraction), post-exercise circulatory occlusion and mental stress (serial subtraction; internal control). Participants were genotyped for SNPs in TRPV1 (rs222747; G/C), ASIC3 (rs2288645; G/A), BDKRB2 (rs1799722; C/T), PTGER2 (rs17197; A/G) and P2RX4 (rs25644; A/G). Exercise systolic BP (19 ± 10 vs. 22 ± 10 mmHg, P = 0.03) was lower in GG versus GC/CC minor allele carriers for TRPV1 rs222747, while exercise diastolic BP (14 ± 7 vs. 17 ± 7 mmHg, P = 0.007) and heart rate (12 ± 8 vs. 15 ± 9 beats min-1 , P = 0.03) were lower in CC versus CT/TT minor allele carriers for BDKRB2 rs1799722. Individuals carrying both minor alleles for TRPV1 rs222747 and BDKRB2 rs1799722 had greater systolic (22 ± 11 vs. 17 ± 10 mmHg, P = 0.04) and diastolic (18 ± 7 vs. 14 ± 7 mmHg, P = 0.01) BP responses than those with no minor alleles; these differences were larger in men. No differences in BP or heart rate responses were detected during static handgrip with ASIC3 rs2288645, PTGER2 rs17197 or P2RX4 rs25644. None of the selected SNPs were associated with differences during mental stress. These findings demonstrate that variants in TRPV1 and BDKRB2 receptors can contribute to BP differences during static exercise in an additive manner.
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Affiliation(s)
- Karambir Notay
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Shannon L Klingel
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jordan B Lee
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Connor J Doherty
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jeremy D Seed
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Michal Swiatczak
- Department of Kinesiology, University of Guelph-Humber, Toronto, Ontario, Canada
| | - David M Mutch
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.,Toronto General Research Institute , Toronto General Hospital, Toronto, Ontario, Canada
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31
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Hedayatpour N, Izanloo Z, Falla D. The effect of eccentric exercise and delayed onset muscle soreness on the homologous muscle of the contralateral limb. J Electromyogr Kinesiol 2018; 41:154-159. [PMID: 29902705 DOI: 10.1016/j.jelekin.2018.06.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 05/31/2018] [Accepted: 06/05/2018] [Indexed: 12/30/2022] Open
Abstract
High intensity eccentric exercise induces muscle fiber damage and associated delayed-onset muscle soreness (DOMS) resulting in an impaired ability of the muscle to generate voluntary force. This study investigates the extent to which DOMS, induced by high intensity eccentric exercise, can affect the activation and performance of the non-exercised homologous muscle of the contralateral limb. Healthy volunteers performed maximal voluntary contractions of knee extension and sustained isometric knee extension at 50% of maximal force until task failure on both the ipsilateral exercised limb and the contralateral limb. Surface electromyography (EMG) was recorded from the ipsilateral and contralateral knee extensor muscles (vastus medialis, rectus femoris, and vastus lateralis). Maximal isometric knee extension force (13.7% reduction) and time to task failure (38.1% reduction) of the contralateral non-exercised leg decreased immediately after eccentric exercise, and persisted 24 h and 48 h later (p < 0.05). Moreover, the amplitude of muscle activity recorded from the contralateral knee extensor muscles was significantly lower during the post exercise maximal and submaximal contractions following high intensity eccentric exercise of the opposite limb (p < 0.05). Unilateral high intensity eccentric exercise of the quadriceps can contribute to reduced neuromuscular activity and physical work capacity of the non-exercised homologous muscle in the contralateral limb.
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Affiliation(s)
- Nosratollah Hedayatpour
- Center for Biomechanics and Motor Control (BMC), Department of Physical Education and Sport Science, University of Bojnord, Bojnord, Iran
| | - Zahra Izanloo
- Center for Biomechanics and Motor Control (BMC), Department of Physical Education and Sport Science, University of Bojnord, Bojnord, Iran
| | - Deborah Falla
- Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, United Kingdom.
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32
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Hodgson MD, Keir DA, Copithorne DB, Rice CL, Kowalchuk JM. Power reserve following ramp-incremental cycling to exhaustion: implications for muscle fatigue and function. J Appl Physiol (1985) 2018; 125:304-312. [PMID: 29698107 DOI: 10.1152/japplphysiol.00722.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In ramp-incremental cycling exercise, some individuals are capable of producing power output (PO) in excess of that produced at their limit of tolerance (LoT) whereas others cannot. This study sought to describe the 1) prevalence of a "power reserve" within a group of young men ( n = 21; mean ± SD: age 25 ± 4 yr; V̇o2max 45 ± 8 ml·kg-1·min-1); and 2) muscle fatigue characteristics of those with and without a power reserve. "Power reserve" (ΔPReserve) was determined as the difference between peak PO achieved during a ramp-incremental test to exhaustion and maximal, single-leg isokinetic dynamometer power determined within 45 s of completing the ramp-incremental test. Between-group differences in pre- vs. postexercise changes in voluntary and electrically stimulated single-leg muscle force production measures (maximal voluntary contraction torque, voluntary activation, maximal isotonic velocity and isokinetic power; 1-, 10-, 50-Hz torque; and 10/50-Hz ratio), V̇o2max, and constant-PO cycling time-to-exhaustion also were assessed. Frequency distribution analysis revealed a dichotomy in the prevalence of a power reserve within the sample resulting in two groups: 1) "No Reserve" (NRES: power reserve <5%; n = 10) and 2) "Reserve" (RES: power reserve >15%; n = 11). At the LoT, all participants had achieved V̇o2max. Muscle fatigue was evident in both groups, although the NRES group had greater reductions ( P < 0.05) in 10-Hz peak torque (PT), 10/50 Hz ratio, and maximal velocity. Time to the LoT during the constant PO test was 22 ± 16% greater ( P < 0.05) in RES (116 ± 19 s; PO = 317 ± 52 W) than in NRES (90 ± 23 s; PO = 337 ± 71 W), despite similar ramp-incremental exercise durations and V̇o2max between groups. Compared with the RES group, the NRES group accrued greater peripheral muscle fatigue at the LoT, suggesting that the mechanisms contributing to exhaustion in a ramp-incremental protocol are not uniform. NEW & NOTEWORTHY This study demonstrates that the mechanisms associated with the limit of tolerance during ramp-incremental cycling exercise differ between those who are capable of generating power output in excess of that at exercise termination vs. those who are not. Those without a "power reserve" exhibit greater peripheral muscle fatigue and reduced muscle endurance, supporting the hypothesis that exhaustion occurs at a specific level of neuromuscular fatigue. In contrast, those with a power reserve likely are limited by other mechanisms.
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Affiliation(s)
- Michael D Hodgson
- Canadian Centre for Activity and Aging, The University of Western Ontario , London, Ontario , Canada.,School of Kinesiology, The University of Western Ontario , London, Ontario , Canada
| | - Daniel A Keir
- Canadian Centre for Activity and Aging, The University of Western Ontario , London, Ontario , Canada.,School of Kinesiology, The University of Western Ontario , London, Ontario , Canada
| | - David B Copithorne
- Canadian Centre for Activity and Aging, The University of Western Ontario , London, Ontario , Canada.,School of Kinesiology, The University of Western Ontario , London, Ontario , Canada
| | - Charles L Rice
- Canadian Centre for Activity and Aging, The University of Western Ontario , London, Ontario , Canada.,School of Kinesiology, The University of Western Ontario , London, Ontario , Canada.,Department of Anatomy and Cell Biology, The University of Western Ontario , London, Ontario , Canada
| | - John M Kowalchuk
- Canadian Centre for Activity and Aging, The University of Western Ontario , London, Ontario , Canada.,School of Kinesiology, The University of Western Ontario , London, Ontario , Canada.,Department of Physiology and Pharmacology, The University of Western Ontario , London, Ontario , Canada
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Abstract
Carriker, CR. Components of fatigue: mind and body. J Strength Cond Res 31(11): 3170-3176, 2017-Maximal intensity exercise requires significant energy demand. Subsequently, prolonged high-intensity effort eventually initiates volitional cessation of the event; often preceeded by a sensation of fatigue. Those examining the basis of fatigue tend to advocate either a peripheral or central model to explain such volitional failure. Practitioners and athletes who understand the tenants of fatigue can tailor their exercise regimens to target areas of potential physical or mental limitation. This review examines the rationale surrounding 2 separate models which postulate the origination of fatigue. Although the peripheral model suggests that fatigue occurs at the muscles, others have suggested a teloanticipatory cognitive component which plays a dominant role. Those familiar with both models may better integrate practice-based evidence into evidence-based practice. The highly individual nature of human performance further highlights the compulsion to comprehend the spectrum of fatigue, such that the identification of insufficiencies should mandate the development of a training purview for peak human performance.
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Affiliation(s)
- Colin R Carriker
- Department of Exercise Science, High Point University, High Point, North Carolina
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Abstract
The rating-of-perceived-exertion (RPE) template is thought to regulate pacing and has been shown to be very robust in different circumstances. PURPOSE The primary purpose was to investigate whether the RPE template can be manipulated by changing the race distance during the course of a time trial. The secondary purpose was to study how athletes cope with this manipulation, especially in terms of the RPE template. METHOD Trained male subjects (N = 10) performed 3 cycling time trials: a 10-km (TT10), a 15-km (TT15), and a manipulated 15-km (TTman). During the TTman, subjects started the time trial believing that they were going to perform a 10-km time trial. However, at 7.5 km they were told that it was a 15-km time trial. RESULTS A significant main effect of time-trial condition on RPE scores until kilometer 7.5 was found (P = .016). Post hoc comparisons showed that the RPE values of the TT15 were lower than the RPE values of the TT10 (difference 0.60; CI95% 0.11, 1.0) and TTman (difference 0.73; CI95% 0.004, 1.5). After the 7.5 km, a transition phase occurs, in which an interaction effect is present (P = .011). After this transition phase, the RPE values of TTman and TT15 did not statistically differ (P = 1.00). CONCLUSIONS This novel distance-endpoint manipulation demonstrates that it is possible to switch between RPE templates. A clear shift in RPE during the TTman is present between the RPE templates of the TT10 and TT15. The shift strongly supports suggestions that pacing is regulated using an RPE template.
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Hureau TJ, Weavil JC, Thurston TS, Broxterman RM, Nelson AD, Bledsoe AD, Jessop JE, Richardson RS, Wray DW, Amann M. Identifying the role of group III/IV muscle afferents in the carotid baroreflex control of mean arterial pressure and heart rate during exercise. J Physiol 2018; 596:1373-1384. [PMID: 29388218 DOI: 10.1113/jp275465] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 01/29/2018] [Indexed: 02/05/2023] Open
Abstract
KEY POINTS We investigated the contribution of group III/IV muscle afferents to carotid baroreflex resetting during electrically evoked (no central command) and voluntary (requiring central command) isometric knee extension exercise. Lumbar intrathecal fentanyl was used to attenuate the central projection of μ-opioid receptor-sensitive group III/IV leg muscle afferent feedback. Spontaneous carotid baroreflex control was assessed by loading and unloading the carotid baroreceptors with a variable pressure neck chamber. Group III/IV muscle afferents did not influence spontaneous carotid baroreflex responsiveness at rest or during exercise. Afferent feedback accounted for at least 50% of the exercise-induced increase in the carotid baroreflex blood pressure and heart rate operating points, adjustments that are critical for an appropriate cardiovascular response to exercise. These findings suggest that group III/IV muscle afferent feedback is, independent of central command, critical for the resetting of the carotid baroreflex blood pressure and heart rate operating points, but not for spontaneous baroreflex responsiveness. ABSTRACT This study sought to comprehensively investigate the role of metabolically and mechanically sensitive group III/IV muscle afferents in carotid baroreflex responsiveness and resetting during both electrically evoked (EVO, no central command) and voluntary (VOL, requiring central command) isometric single-leg knee-extension (15% of maximal voluntary contraction; MVC) exercise. Participants (n = 8) were studied under control conditions (CTRL) and following lumbar intrathecal fentanyl injection (FENT) to inhibit μ-opioid receptor-sensitive lower limb muscle afferents. Spontaneous carotid baroreflex control of mean arterial pressure (MAP) and heart rate (HR) were assessed following rapid 5 s pulses of neck pressure (NP, +40 mmHg) or suction (NS, -60 mmHg). Resting MAP (87 ± 10 mmHg) and HR (70 ± 8 bpm) were similar between CTRL and FENT conditions (P > 0.4). In terms of spontaneous carotid baroreflex responsiveness, FENT did not alter the change in MAP or HR responses to NP (+13 ± 5 mmHg, P = 0.85; +9 ± 3 bpm; P = 0.99) or NS (-13 ± 5 mmHg, P = 0.99; -24 ± 11 bpm; P = 0.49) at rest or during either exercise protocol, which were of a remarkably similar magnitude to rest. In contrast, FENT administration reduced the exercise-induced resetting of the operating point for MAP and HR during both EVO (116 ± 10 mmHg to 100 ± 15 mmHg and 93 ± 14 bpm to 82 ± 10 bpm) and VOL (107 ± 13 mmHg to 100 ± 17 mmHg and 89 ± 10 bpm to 72 ± 10 bpm) exercise bouts. Together, these findings document that group III/IV muscle afferent feedback is critical for the resetting of the carotid baroreflex MAP and HR operating points, independent of exercise-induced changes in central command, but not for spontaneous carotid baroreflex responsiveness.
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Affiliation(s)
- Thomas J Hureau
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Joshua C Weavil
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Taylor S Thurston
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Ryan M Broxterman
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Russell S Richardson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - D Walter Wray
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Markus Amann
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA.,Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
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36
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Finn HT, Rouffet DM, Kennedy DS, Green S, Taylor JL. Motoneuron excitability of the quadriceps decreases during a fatiguing submaximal isometric contraction. J Appl Physiol (1985) 2018; 124:970-979. [PMID: 29357479 DOI: 10.1152/japplphysiol.00739.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
During fatiguing voluntary contractions, the excitability of motoneurons innervating arm muscles decreases. However, the behavior of motoneurons innervating quadriceps muscles is unclear. Findings may be inconsistent because descending cortical input influences motoneuron excitability and confounds measures during exercise. To overcome this limitation, we examined effects of fatigue on quadriceps motoneuron excitability tested during brief pauses in descending cortical drive after transcranial magnetic stimulation (TMS). Participants ( n = 14) performed brief (~5-s) isometric knee extension contractions before and after a 10-min sustained contraction at ~25% maximal electromyogram (EMG) of vastus medialis (VM) on one ( n = 5) or two ( n = 9) days. Electrical stimulation over thoracic spine elicited thoracic motor evoked potentials (TMEP) in quadriceps muscles during ongoing voluntary drive and 100 ms into the silent period following TMS (TMS-TMEP). Femoral nerve stimulation elicited maximal M-waves (Mmax). On the 2 days, either large (~50% Mmax) or small (~15% Mmax) TMS-TMEPs were elicited. During the 10-min contraction, VM EMG was maintained ( P = 0.39), whereas force decreased by 52% (SD 13%) ( P < 0.001). TMEP area remained unchanged ( P = 0.9), whereas large TMS-TMEPs decreased by 49% (SD 28%) ( P = 0.001) and small TMS-TMEPs by 71% (SD 22%) ( P < 0.001). This decline was greater for small TMS-TMEPs ( P = 0.019; n = 9). Therefore, without the influence of descending drive, quadriceps TMS-TMEPs decreased during fatigue. The greater reduction for smaller responses, which tested motoneurons that were most active during the contraction, suggests a mechanism related to repetitive activity contributes to reduced quadriceps motoneuron excitability during fatigue. By contrast, the unchanged TMEP suggests that ongoing drive compensates for altered motoneuron excitability. NEW & NOTEWORTHY We provide evidence that the excitability of quadriceps motoneurons decreases with fatigue. Our results suggest that altered intrinsic properties brought about by repetitive activation of the motoneurons underlie their decreased excitability. Furthermore, we note that testing during voluntary contraction may not reflect the underlying depression of motoneuron excitability because of compensatory changes in ongoing voluntary drive. Thus, this study provides evidence that processes intrinsic to the motoneuron contribute to muscle fatigue of the knee extensors.
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Affiliation(s)
- Harrison T Finn
- Neuroscience Research Australia, Randwick, New South Wales , Australia.,University of New South Wales , Kensington, New South Wales , Australia
| | - David M Rouffet
- Victoria University , Melbourne, Victoria , Australia.,Australian Institute for Musculoskeletal Science, Victoria University , Melbourne , Australia.,Institute of Sport, Exercise, and Active Living, Victoria University , Melbourne , Australia
| | - David S Kennedy
- University of Sydney, Cumberland, New South Wales , Australia.,University of Technology , Ultimo, New South Wales , Australia
| | - Simon Green
- Western Sydney University, Campbelltown, New South Wales , Australia
| | - Janet L Taylor
- Neuroscience Research Australia, Randwick, New South Wales , Australia.,University of New South Wales , Kensington, New South Wales , Australia.,Edith Cowan University , Perth, Western Australia , Australia
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37
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Korsak A, Sheikhbahaei S, Machhada A, Gourine AV, Huckstepp RTR. The Role Of Parafacial Neurons In The Control Of Breathing During Exercise. Sci Rep 2018; 8:400. [PMID: 29321559 PMCID: PMC5762684 DOI: 10.1038/s41598-017-17412-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/24/2017] [Indexed: 02/07/2023] Open
Abstract
Neuronal cell groups residing within the retrotrapezoid nucleus (RTN) and C1 area of the rostral ventrolateral medulla oblongata contribute to the maintenance of resting respiratory activity and arterial blood pressure, and play an important role in the development of cardiorespiratory responses to metabolic challenges (such as hypercapnia and hypoxia). In rats, acute silencing of neurons within the parafacial region which includes the RTN and the rostral aspect of the C1 circuit (pFRTN/C1), transduced to express HM4D (Gi-coupled) receptors, was found to dramatically reduce exercise capacity (by 60%), determined by an intensity controlled treadmill running test. In a model of simulated exercise (electrical stimulation of the sciatic or femoral nerve in urethane anaesthetised spontaneously breathing rats) silencing of the pFRTN/C1 neurons had no effect on cardiovascular changes, but significantly reduced the respiratory response during steady state exercise. These results identify a neuronal cell group in the lower brainstem which is critically important for the development of the respiratory response to exercise and, determines exercise capacity.
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Affiliation(s)
- Alla Korsak
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Shahriar Sheikhbahaei
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Asif Machhada
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom.
| | - Robert T R Huckstepp
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom. .,School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom.
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Pearcey GEP, Noble SA, Munro B, Zehr EP. Spinal Cord Excitability and Sprint Performance Are Enhanced by Sensory Stimulation During Cycling. Front Hum Neurosci 2017; 11:612. [PMID: 29326570 PMCID: PMC5741677 DOI: 10.3389/fnhum.2017.00612] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 12/04/2017] [Indexed: 12/18/2022] Open
Abstract
Spinal cord excitability, as assessed by modulation of Hoffmann (H-) reflexes, is reduced with fatiguing isometric contractions. Furthermore, spinal cord excitability is reduced during non-fatiguing arm and leg cycling. Presynaptic inhibition of Ia terminals is believed to contribute to this suppression of spinal cord excitability. Electrical stimulation to cutaneous nerves reduces Ia presynaptic inhibition, which facilitates spinal cord excitability, and this facilitation is present during arm cycling. Although it has been suggested that reducing presynaptic inhibition may prolong fatiguing contractions, it is unknown whether sensory stimulation can alter the effects of fatiguing exercise on performance or spinal cord excitability. Thus, the aim of this experiment was to determine if sensory stimulation can interfere with fatigue-related suppression of spinal cord excitability, and alter fatigue rates during cycling sprints. Thirteen participants randomly performed three experimental sessions that included: unloaded cycling with sensory stimulation (CONTROL + STIM), sprints with sensory stimulation (SPRINT + STIM) and sprints without stimulation (SPRINT). Seven participants also performed a fourth session (CONTROL), which consisted of unloaded cycling. During SPRINT and SPRINT + STIM, participants performed seven, 10 s cycling sprints interleaved with 3 min rest. For CONTROL and CONTROL + STIM, participants performed unloaded cycling for ~30 min. During SPRINT + STIM and CONTROL + STIM, participants received patterned sensory stimulation to nerves of the right foot. H-reflexes and M-waves of the right soleus were evoked by stimulation of the tibial nerve at multiple time points throughout exercise. Sensory stimulation facilitated soleus H-reflexes during unloaded cycling, whereas sprints suppressed soleus H-reflexes. While receiving sensory stimulation, there was less suppression of soleus H-reflexes and slowed reduction in average power output, compared to sprints without stimulation. These results demonstrate that sensory stimulation can substantially mitigate the fatiguing effects of sprints.
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Affiliation(s)
- Gregory E P Pearcey
- Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC, Canada.,Human Discovery Science, International Collaboration on Repair Discoveries (ICORD), Vancouver, BC, Canada.,Centre for Biomedical Research, University of Victoria, Victoria, BC, Canada
| | - Steven A Noble
- Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC, Canada.,Human Discovery Science, International Collaboration on Repair Discoveries (ICORD), Vancouver, BC, Canada.,Centre for Biomedical Research, University of Victoria, Victoria, BC, Canada
| | - Bridget Munro
- Nike Exploration Team Sport Research Laboratory, Nike Inc., Beaverton, OR, United States
| | - E Paul Zehr
- Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC, Canada.,Human Discovery Science, International Collaboration on Repair Discoveries (ICORD), Vancouver, BC, Canada.,Centre for Biomedical Research, University of Victoria, Victoria, BC, Canada.,Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
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39
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Doherty CJ, Incognito AV, Notay K, Burns MJ, Slysz JT, Seed JD, Nardone M, Burr JF, Millar PJ. Muscle sympathetic nerve responses to passive and active one-legged cycling: insights into the contributions of central command. Am J Physiol Heart Circ Physiol 2017; 314:H3-H10. [PMID: 28939650 DOI: 10.1152/ajpheart.00494.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The contribution of central command to the peripheral vasoconstrictor response during exercise has been investigated using primarily handgrip exercise. The purpose of the present study was to compare muscle sympathetic nerve activity (MSNA) responses during passive (involuntary) and active (voluntary) zero-load cycling to gain insights into the effects of central command on sympathetic outflow during dynamic exercise. Hemodynamic measurements and contralateral leg MSNA (microneurography) data were collected in 18 young healthy participants at rest and during 2 min of passive and active zero-load one-legged cycling. Arterial baroreflex control of MSNA burst occurrence and burst area were calculated separately in the time domain. Blood pressure and stroke volume increased during exercise ( P < 0.0001) but were not different between passive and active cycling ( P > 0.05). In contrast, heart rate, cardiac output, and total vascular conductance were greater during the first and second minute of active cycling ( P < 0.001). MSNA burst frequency and incidence decreased during passive and active cycling ( P < 0.0001), but no differences were detected between exercise modes ( P > 0.05). Reductions in total MSNA were attenuated during the first ( P < 0.0001) and second ( P = 0.0004) minute of active compared with passive cycling, in concert with increased MSNA burst amplitude ( P = 0.02 and P = 0.005, respectively). The sensitivity of arterial baroreflex control of MSNA burst occurrence was lower during active than passive cycling ( P = 0.01), while control of MSNA burst strength was unchanged ( P > 0.05). These results suggest that central feedforward mechanisms are involved primarily in modulating the strength, but not the occurrence, of a sympathetic burst during low-intensity dynamic leg exercise. NEW & NOTEWORTHY Muscle sympathetic nerve activity burst frequency decreased equally during passive and active cycling, but reductions in total muscle sympathetic nerve activity were attenuated during active cycling. These results suggest that central command primarily regulates the strength, not the occurrence, of a muscle sympathetic burst during low-intensity dynamic leg exercise.
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Affiliation(s)
- Connor J Doherty
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Karambir Notay
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Matthew J Burns
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Joshua T Slysz
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Jeremy D Seed
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Massimo Nardone
- Department of Kinesiology, University of Guelph-Humber , Toronto, Ontario , Canada
| | - Jamie F Burr
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada.,Toronto General Research Institute, Toronto General Hospital , Toronto, Ontario , Canada
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40
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Nicolò A, Marcora SM, Bazzucchi I, Sacchetti M. Differential control of respiratory frequency and tidal volume during high-intensity interval training. Exp Physiol 2017; 102:934-949. [PMID: 28560751 DOI: 10.1113/ep086352] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 05/25/2017] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? By manipulating recovery intensity and exercise duration during high-intensity interval training (HIIT), we tested the hypothesis that fast inputs contribute more than metabolic stimuli to respiratory frequency (fR ) regulation. What is the main finding and its importance? Respiratory frequency, but not tidal volume, responded rapidly and in proportion to changes in workload during HIIT, and was dissociated from some markers of metabolic stimuli in response to both experimental manipulations, suggesting that fast inputs contribute more than metabolic stimuli to fR regulation. Differentiating between fR and tidal volume may help to unravel the mechanisms underlying exercise hyperpnoea. Given that respiratory frequency (fR ) has been proposed as a good marker of physical effort, furthering the understanding of how fR is regulated during exercise is of great importance. We manipulated recovery intensity and exercise duration during high-intensity interval training (HIIT) to test the hypothesis that fast inputs (including central command) contribute more than metabolic stimuli to fR regulation. Seven male cyclists performed an incremental test, a 10 and a 20 min continuous time trial (TT) as preliminary tests. Subsequently, recovery intensity and exercise duration were manipulated during HIIT (30 s work and 30 s active recovery) by performing four 10 min and one 20 min trial (recovery intensities of 85, 70, 55 and 30% of the 10 min TT mean workload; and 85% of the 20 min TT mean workload). The work intensity of the HIIT sessions was self-paced by participants to achieve the best performance possible. When manipulating recovery intensity, fR , but not tidal volume (VT ), showed a fast response to the alternation of the work and recovery phases, proportional to the extent of workload variations. No association between fR and gas exchange responses was observed. When manipulating exercise duration, fR and rating of perceived exertion were dissociated from VT , carbon dioxide output and oxygen uptake responses. Overall, the rating of perceived exertion was strongly correlated with fR (r = 0.87; P < 0.001) but not with VT . These findings may reveal a differential control of fR and VT during HIIT, with fast inputs appearing to contribute more than metabolic stimuli to fR regulation. Differentiating between fR and VT may help to unravel the mechanisms underlying exercise hyperpnoea.
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Affiliation(s)
- Andrea Nicolò
- Department of Movement, Human and Health Sciences, University of Rome 'Foro Italico', Rome, Italy
| | - Samuele M Marcora
- Endurance Research Group, School of Sport and Exercise Sciences, University of Kent, Chatham Maritime, Kent, UK
| | - Ilenia Bazzucchi
- Department of Movement, Human and Health Sciences, University of Rome 'Foro Italico', Rome, Italy
| | - Massimo Sacchetti
- Department of Movement, Human and Health Sciences, University of Rome 'Foro Italico', Rome, Italy
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41
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Fox R, Patterson SD, Waldron M. The relationship between heart rate recovery and temporary fatigue of kinematic and energetic indices among soccer players. SCI MED FOOTBALL 2017. [DOI: 10.1080/24733938.2017.1329590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Robert Fox
- School of Sport, Health and Applied Science, St Marys University, Twickenham, UK
- Academy Sports Science and Medical Department, Stoke City Football Club, UK
| | | | - Mark Waldron
- School of Sport, Health and Applied Science, St Marys University, Twickenham, UK
- School of Science and Technology, University of New England, Armidale, Australia
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42
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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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43
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Magnani S, Olla S, Pau M, Palazzolo G, Tocco F, Doneddu A, Marcelli M, Loi A, Corona F, Corona F, Coghe G, Marrosu MG, Concu A, Cocco E, Marongiu E, Crisafulli A. Effects of Six Months Training on Physical Capacity and Metaboreflex Activity in Patients with Multiple Sclerosis. Front Physiol 2016; 7:531. [PMID: 27895592 PMCID: PMC5108173 DOI: 10.3389/fphys.2016.00531] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 10/25/2016] [Indexed: 12/20/2022] Open
Abstract
Patients with multiple sclerosis (MS) have an increased systemic vascular resistance (SVR) response during the metaboreflex. It has been hypothesized that this is the consequence of a sedentary lifestyle secondary to MS. The purpose of this study was to discover whether a 6-month training program could reverse this hemodynamic dysregulation. Patients were randomly assigned to one of the following two groups: the intervention group (MSIT, n = 11), who followed an adapted training program; and the control group (MSCTL, n = 10), who continued with their sedentary lifestyle. Cardiovascular response during the metaboreflex was evaluated using the post-exercise muscle ischemia (PEMI) method and during a control exercise recovery (CER) test. The difference in hemodynamic variables such as stroke volume (SV), cardiac output (CO), and SVR between the PEMI and the CER tests was calculated to assess the metaboreflex response. Moreover, physical capacity was measured during a cardiopulmonary test till exhaustion. All tests were repeated after 3 and 6 months (T3 and T6, respectively) from the beginning of the study. The main result was that the MSIT group substantially improved parameters related to physical capacity (+5.31 ± 5.12 ml·min−1/kg in maximal oxygen uptake at T6) in comparison with the MSCTL group (−0.97 ± 4.89 ml·min−1/kg at T6; group effect: p = 0.0004). However, none of the hemodynamic variables changed in response to the metaboreflex activation. It was concluded that a 6-month period of adapted physical training was unable to reverse the hemodynamic dys-regulation in response to metaboreflex activation in these patients.
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Affiliation(s)
- Sara Magnani
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
| | - Sergio Olla
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
| | - Massimiliano Pau
- Department of Mechanical, Chemical and Materials Engineering, University of Cagliari Cagliari, Italy
| | - Girolamo Palazzolo
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
| | - Filippo Tocco
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
| | - Azzurra Doneddu
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
| | - Maura Marcelli
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
| | - Andrea Loi
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
| | - Federica Corona
- Department of Mechanical, Chemical and Materials Engineering, University of CagliariCagliari, Italy; Department of Public Health, Clinical and Molecular Medicine, University of CagliariCagliari, Italy
| | - Francesco Corona
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
| | - Giancarlo Coghe
- Department of Mechanical, Chemical and Materials Engineering, University of Cagliari Cagliari, Italy
| | - Maria G Marrosu
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
| | - Alberto Concu
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
| | - Eleonora Cocco
- Department of Mechanical, Chemical and Materials Engineering, University of Cagliari Cagliari, Italy
| | - Elisabetta Marongiu
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
| | - Antonio Crisafulli
- Sports Physiology Lab, Department of Medical Sciences, University of Cagliari Cagliari, Italy
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44
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Hureau TJ, Romer LM, Amann M. The 'sensory tolerance limit': A hypothetical construct determining exercise performance? Eur J Sport Sci 2016; 18:13-24. [PMID: 27821022 DOI: 10.1080/17461391.2016.1252428] [Citation(s) in RCA: 149] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Neuromuscular fatigue compromises exercise performance and is determined by central and peripheral mechanisms. Interactions between the two components of fatigue can occur via neural pathways, including feedback and feedforward processes. This brief review discusses the influence of feedback and feedforward mechanisms on exercise limitation. In terms of feedback mechanisms, particular attention is given to group III/IV sensory neurons which link limb muscle with the central nervous system. Central corollary discharge, a copy of the neural drive from the brain to the working muscles, provides a signal from the motor system to sensory systems and is considered a feedforward mechanism that might influence fatigue and consequently exercise performance. We highlight findings from studies supporting the existence of a 'critical threshold of peripheral fatigue', a previously proposed hypothesis based on the idea that a negative feedback loop operates to protect the exercising limb muscle from severe threats to homeostasis during whole-body exercise. While the threshold theory remains to be disproven within a given task, it is not generalisable across different exercise modalities. The 'sensory tolerance limit', a more theoretical concept, may address this issue and explain exercise tolerance in more global terms and across exercise modalities. The 'sensory tolerance limit' can be viewed as a negative feedback loop which accounts for the sum of all feedback (locomotor muscles, respiratory muscles, organs, and muscles not directly involved in exercise) and feedforward signals processed within the central nervous system with the purpose of regulating the intensity of exercise to ensure that voluntary activity remains tolerable.
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Affiliation(s)
- Thomas J Hureau
- a Department of Medicine , University of Utah , Salt Lake City , UT , USA
| | - Lee M Romer
- b Centre for Human Performance, Exercise and Rehabilitation, Department of Life Sciences , Brunel University London , UK
| | - Markus Amann
- a Department of Medicine , University of Utah , Salt Lake City , UT , USA
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Taylor JL, Amann M, Duchateau J, Meeusen R, Rice CL. Neural Contributions to Muscle Fatigue: From the Brain to the Muscle and Back Again. Med Sci Sports Exerc 2016; 48:2294-2306. [PMID: 27003703 PMCID: PMC5033663 DOI: 10.1249/mss.0000000000000923] [Citation(s) in RCA: 295] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
: During exercise, there is a progressive reduction in the ability to produce muscle force. Processes within the nervous system as well as within the muscles contribute to this fatigue. In addition to impaired function of the motor system, sensations associated with fatigue and impairment of homeostasis can contribute to the impairment of performance during exercise. This review discusses some of the neural changes that accompany exercise and the development of fatigue. The role of brain monoaminergic neurotransmitter systems in whole-body endurance performance is discussed, particularly with regard to exercise in hot environments. Next, fatigue-related alterations in the neuromuscular pathway are discussed in terms of changes in motor unit firing, motoneuron excitability, and motor cortical excitability. These changes have mostly been investigated during single-limb isometric contractions. Finally, the small-diameter muscle afferents that increase firing with exercise and fatigue are discussed. These afferents have roles in cardiovascular and respiratory responses to exercise, and in the impairment of exercise performance through interaction with the motor pathway, as well as in providing sensations of muscle discomfort. Thus, changes at all levels of the nervous system, including the brain, spinal cord, motor output, sensory input, and autonomic function, occur during exercise and fatigue. The mix of influences and the importance of their contribution vary with the type of exercise being performed.
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Affiliation(s)
- Janet L Taylor
- 1Neuroscience Research Australia, Sydney, AUSTRALIA; 2School of Medical Sciences, the University of New South Wales, Sydney, AUSTRALIA; 3Department of Medicine, University of Utah, Salt Lake City, UT; 4Laboratory of Applied Biology and Neurophysiology, ULB Neuroscience Institute, Université Libre de Bruxelles, Brussels, BELGIUM; 5Human Physiology Research Group Vrije Universiteit Brussel, Brussels, BELGIUM; 6School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Queensland, AUSTRALIA; and 7School of Kinesiology, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, CANADA
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46
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Role of Ratings of Perceived Exertion during Self-Paced Exercise: What are We Actually Measuring? Sports Med 2016; 45:1235-1243. [PMID: 26054383 DOI: 10.1007/s40279-015-0344-5] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Ratings of perceived exertion (RPE) and effort are considered extremely important in the regulation of intensity during self-paced physical activity. While effort and exertion are slightly different constructs, these terms are often used interchangeably within the literature. The development of perceptions of both effort and exertion is a complicated process involving numerous neural processes occurring in various regions within the brain. It is widely accepted that perceptions of effort are highly dependent on efferent copies of central drive which are sent from motor to sensory regions of the brain. Additionally, it has been suggested that perceptions of effort and exertion are integrated based on the balance between corollary discharge and actual afferent feedback; however, the involvement of peripheral afferent sensory feedback in the development of such perceptions has been debated. As such, this review examines the possible difference between effort and exertion, and the implications of such differences in understanding the role of such perceptions in the regulation of pace during exercise.
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Fan JL, Kayser B. Fatigue and Exhaustion in Hypoxia: The Role of Cerebral Oxygenation. High Alt Med Biol 2016; 17:72-84. [DOI: 10.1089/ham.2016.0034] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- Jui-Lin Fan
- Centre for Translational Physiology, University of Otago, Wellington, New Zealand
- Department of Surgery & Anaesthesia, University of Otago, Wellington, New Zealand
| | - Bengt Kayser
- Institute of Sports Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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Mulliri G, Sainas G, Magnani S, Palazzolo G, Milia N, Orrù A, Roberto S, Marongiu E, Milia R, Crisafulli A. Ischemic preconditioning reduces hemodynamic response during metaboreflex activation. Am J Physiol Regul Integr Comp Physiol 2016; 310:R777-87. [PMID: 26936782 DOI: 10.1152/ajpregu.00429.2015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 03/01/2016] [Indexed: 11/22/2022]
Abstract
Ischemic preconditioning (IP) has been shown to improve exercise performance and to delay fatigue. However, the precise mechanisms through which IP operates remain elusive. It has been hypothesized that IP lowers the sensation of fatigue by reducing the discharge of group III and IV nerve endings, which also regulate hemodynamics during the metaboreflex. We hypothesized that IP reduces the blood pressure response during the metaboreflex. Fourteen healthy males (age between 25 and 48 yr) participated in this study. They underwent the following randomly assigned protocol: postexercise muscle ischemia (PEMI) test, during which the metaboreflex was elicited after dynamic handgrip; control exercise recovery session (CER) test; and PEMI after IP (IP-PEMI) test. IP was obtained by occluding forearm circulation for three cycles of 5 min spaced by 5 min of reperfusion. Hemodynamics were evaluated by echocardiography and impedance cardiography. The main results were that after IP the mean arterial pressure response was reduced compared with the PEMI test (means ± SD +3.37 ± 6.41 vs. +9.16 ± 7.09 mmHg, respectively). This was the consequence of an impaired venous return that impaired the stroke volume during the IP-PEMI more than during the PEMI test (-1.43 ± 15.35 vs. +10.28 ± 10.479 ml, respectively). It was concluded that during the metaboreflex, IP affects hemodynamics mainly because it impairs the capacity to augment venous return and to recruit the cardiac preload reserve. It was hypothesized that this is the consequence of an increased nitric oxide production, which reduces the possibility to constrict venous capacity vessels.
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Affiliation(s)
- Gabriele Mulliri
- Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Gianmarco Sainas
- Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Sara Magnani
- Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Girolamo Palazzolo
- Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Nicola Milia
- Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Andrea Orrù
- Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Silvana Roberto
- Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Elisabetta Marongiu
- Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Raffaele Milia
- Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Antonio Crisafulli
- Department of Medical Sciences, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
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Pearcey GE, Bradbury-Squires DJ, Monks M, Philpott D, Power KE, Button DC. Arm-cycling sprints induce neuromuscular fatigue of the elbow flexors and alter corticospinal excitability of the biceps brachii. Appl Physiol Nutr Metab 2016; 41:199-209. [DOI: 10.1139/apnm-2015-0438] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We examined the effects of arm-cycling sprints on maximal voluntary elbow flexion and corticospinal excitability of the biceps brachii. Recreationally trained athletes performed ten 10-s arm-cycling sprints interspersed with 150 s of rest in 2 separate experiments. In experiment A (n = 12), maximal voluntary contraction (MVC) force of the elbow flexors was measured at pre-sprint 1, post-sprint 5, and post-sprint 10. Participants received electrical motor point stimulation during and following the elbow flexor MVCs to estimate voluntary activation (VA). In experiment B (n = 7 participants from experiment A), supraspinal and spinal excitability of the biceps brachii were measured via transcranial magnetic and transmastoid electrical stimulation that produced motor evoked potentials (MEPs) and cervicomedullary motor evoked potentials (CMEPs), respectively, during a 5% isometric MVC at pre-sprint 1, post-sprint 1, post-sprint 5, and post-sprint 10. In experiment A, mean power output, MVC force, potentiated twitch force, and VA decreased 13.1% (p < 0.001), 8.7% (p = 0.036), 27.6% (p = 0.003), and 5.6% (p = 0.037), respectively, from pre-sprint 1 to post-sprint 10. In experiment B, (i) MEPs decreased 42.1% (p = 0.002) from pre-sprint 1 to post-sprint 5 and increased 40.1% (p = 0.038) from post-sprint 5 to post-sprint 10 and (ii) CMEPs increased 28.5% (p = 0.045) from post-sprint 1 to post-sprint 10. Overall, arm-cycling sprints caused neuromuscular fatigue of the elbow flexors, which corresponded with decreased supraspinal and increased spinal excitability of the biceps brachii. The different post-sprint effects on supraspinal and spinal excitability may illustrate an inhibitory effect on supraspinal drive that reduces motor output and, therefore, decreases arm-cycling sprint performance.
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Affiliation(s)
- Gregory E.P. Pearcey
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | | | - Michael Monks
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | - Devin Philpott
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | - Kevin E. Power
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
- Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | - Duane C. Button
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
- Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
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Torres-Peralta R, Morales-Alamo D, González-Izal M, Losa-Reyna J, Pérez-Suárez I, Izquierdo M, Calbet JAL. Task Failure during Exercise to Exhaustion in Normoxia and Hypoxia Is Due to Reduced Muscle Activation Caused by Central Mechanisms While Muscle Metaboreflex Does Not Limit Performance. Front Physiol 2016; 6:414. [PMID: 26793117 PMCID: PMC4707284 DOI: 10.3389/fphys.2015.00414] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 12/17/2015] [Indexed: 11/26/2022] Open
Abstract
To determine whether task failure during incremental exercise to exhaustion (IE) is principally due to reduced neural drive and increased metaboreflex activation eleven men (22 ± 2 years) performed a 10 s control isokinetic sprint (IS; 80 rpm) after a short warm-up. This was immediately followed by an IE in normoxia (Nx, PIO2:143 mmHg) and hypoxia (Hyp, PIO2:73 mmHg) in random order, separated by a 120 min resting period. At exhaustion, the circulation of both legs was occluded instantaneously (300 mmHg) during 10 or 60 s to impede recovery and increase metaboreflex activation. This was immediately followed by an IS with open circulation. Electromyographic recordings were obtained from the vastus medialis and lateralis. Muscle biopsies and blood gases were obtained in separate experiments. During the last 10 s of the IE, pulmonary ventilation, VO2, power output and muscle activation were lower in hypoxia than in normoxia, while pedaling rate was similar. Compared to the control sprint, performance (IS-Wpeak) was reduced to a greater extent after the IE-Nx (11% lower P < 0.05) than IE-Hyp. The root mean square (EMGRMS) was reduced by 38 and 27% during IS performed after IE-Nx and IE-Hyp, respectively (Nx vs. Hyp: P < 0.05). Post-ischemia IS-EMGRMS values were higher than during the last 10 s of IE. Sprint exercise mean (IS-MPF) and median (IS-MdPF) power frequencies, and burst duration, were more reduced after IE-Nx than IE-Hyp (P < 0.05). Despite increased muscle lactate accumulation, acidification, and metaboreflex activation from 10 to 60 s of ischemia, IS-Wmean (+23%) and burst duration (+10%) increased, while IS-EMGRMS decreased (−24%, P < 0.05), with IS-MPF and IS-MdPF remaining unchanged. In conclusion, close to task failure, muscle activation is lower in hypoxia than in normoxia. Task failure is predominantly caused by central mechanisms, which recover to great extent within 1 min even when the legs remain ischemic. There is dissociation between the recovery of EMGRMS and performance. The reduction of surface electromyogram MPF, MdPF and burst duration due to fatigue is associated but not caused by muscle acidification and lactate accumulation. Despite metaboreflex stimulation, muscle activation and power output recovers partly in ischemia indicating that metaboreflex activation has a minor impact on sprint performance.
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Affiliation(s)
- Rafael Torres-Peralta
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas de Gran Canaria, Spain; Research Institute of Biomedical and Health Sciences (IUIBS)Las Palmas de Gran Canaria, Spain
| | - David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas de Gran Canaria, Spain; Research Institute of Biomedical and Health Sciences (IUIBS)Las Palmas de Gran Canaria, Spain
| | | | - José Losa-Reyna
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas de Gran Canaria, Spain; Research Institute of Biomedical and Health Sciences (IUIBS)Las Palmas de Gran Canaria, Spain
| | - Ismael Pérez-Suárez
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas de Gran Canaria, Spain; Research Institute of Biomedical and Health Sciences (IUIBS)Las Palmas de Gran Canaria, Spain
| | - Mikel Izquierdo
- Department of Health Sciences, Public University of Navarra Tudela, Spain
| | - José A L Calbet
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas de Gran Canaria, Spain; Research Institute of Biomedical and Health Sciences (IUIBS)Las Palmas de Gran Canaria, Spain
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