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Hardy TA, Chadwick MR, Ferguson C, Cross TJ, Taylor BJ. Differential effects of exercise intensity and tolerable duration on exercise-induced diaphragm and expiratory muscle fatigue. J Appl Physiol (1985) 2024; 136:1591-1603. [PMID: 38695354 DOI: 10.1152/japplphysiol.00007.2024] [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: 01/04/2024] [Revised: 04/26/2024] [Accepted: 04/26/2024] [Indexed: 06/16/2024] Open
Abstract
We investigated the effect of exercise intensity and tolerable duration on the development of exercise-induced diaphragm and expiratory muscle fatigue. Ten healthy adults (25 ± 5 yr; 2 females) cycled to intolerance on three separate occasions: 1) 5% below critical power ( 0.05). In conclusion, the magnitude of exercise-induced diaphragm fatigue was greater after longer-duration severe exercise than after shorter-duration severe and heavy exercise. By contrast, the magnitude of exercise-induced expiratory muscle fatigue was unaffected by exercise intensity and tolerable duration.NEW & NOTEWORTHY Exercise-induced respiratory muscle fatigue contributes to limiting exercise tolerance. Accordingly, better understanding the exercise conditions under which respiratory muscle fatigue occurs is warranted. Although heavy-intensity as well as short- and long-duration severe-intensity exercise performed to intolerance elicit diaphragm and expiratory muscle fatigue, we find, for the first time, that the relationship between exercise intensity, exercise duration, and the magnitude of exercise-induced fatigue is different for the diaphragm compared with the expiratory muscles.
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Affiliation(s)
- Tim A Hardy
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
- Faculty of Medicine & Health, Leeds Institute of Rheumatic & Musculoskeletal Medicine, University of Leeds, Leeds, United Kingdom
| | - Matt R Chadwick
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Carrie Ferguson
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
- Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, United States
| | - Troy J Cross
- School of Health Sciences, The University of Sydney, Sydney, New South Wales, Australia
| | - Bryan J Taylor
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
- Cardiovascular Diseases, Department of Cardiovascular Medicine, Mayo Clinic Florida, Jacksonville, Florida, United States
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MacAskill W, Hoffman B, Johnson MA, Sharpe GR, Rands J, Wotherspoon SE, Gevorkov Y, Kolbe‐Alexander TL, Mills DE. The effects of age on dyspnea and respiratory mechanical and neural responses to exercise in healthy men. Physiol Rep 2023; 11:e15794. [PMID: 37604647 PMCID: PMC10442526 DOI: 10.14814/phy2.15794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 08/02/2023] [Accepted: 08/02/2023] [Indexed: 08/23/2023] Open
Abstract
The respiratory muscle pressure generation and inspiratory and expiratory neuromuscular recruitment patterns in younger and older men were compared during exercise, alongside descriptors of dyspnea. Healthy younger (n = 8, 28 ± 5 years) and older (n = 8, 68 ± 4 years) men completed a maximal incremental cycling test. Esophageal, gastric (Pga ) and transdiaphragmatic pressures, and electromyography (EMG) of the crural diaphragm were measured using a micro-transducer and EMG catheter. EMG of the parasternal intercostals, sternocleidomastoids, and rectus abdominis were measured using skin surface electrodes. After the exercise test, participants completed a questionnaire to evaluate descriptors of dyspnea. Pga at end-expiration, Pga expiratory tidal swings, and the gastric pressure-time product (PTPga ) at absolute and relative minute ventilation were higher (p < 0.05) for older compared to younger men. There were no differences in EMG responses between older and younger men. Younger men were more likely to report shallow breathing (p = 0.005) than older men. Our findings showed younger and older men had similar respiratory neuromuscular activation patterns and reported different dyspnea descriptors, and that older men had greater expiratory muscle pressure generation during exercise. Greater expiratory muscle pressures in older men may be due to compensatory mechanisms designed to offset increasing airway resistance due to aging. These results may have implications for exercise-induced expiratory muscle fatigue in older men.
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Affiliation(s)
- William MacAskill
- School of Health and Medical SciencesUniversity of Southern QueenslandIpswichQueenslandAustralia
- Respiratory and Exercise Physiology Research Group, School of Health and WellbeingUniversity of Southern QueenslandIpswichQueenslandAustralia
- Centre for Health ResearchInstitute for Resilient Regions, University of Southern QueenslandIpswichQueenslandAustralia
- Rural Clinical SchoolGriffith UniversityToowoombaQueenslandAustralia
| | - Ben Hoffman
- School of Health and Medical SciencesUniversity of Southern QueenslandIpswichQueenslandAustralia
- Centre for Health ResearchInstitute for Resilient Regions, University of Southern QueenslandIpswichQueenslandAustralia
| | - Michael A. Johnson
- Exercise and Health Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and TechnologyNottingham Trent UniversityNottinghamshireUK
| | - Graham R. Sharpe
- Exercise and Health Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and TechnologyNottingham Trent UniversityNottinghamshireUK
| | - Joshua Rands
- School of Health and Medical SciencesUniversity of Southern QueenslandIpswichQueenslandAustralia
- Respiratory and Exercise Physiology Research Group, School of Health and WellbeingUniversity of Southern QueenslandIpswichQueenslandAustralia
| | | | - Yaroslav Gevorkov
- Institute of Vision Systems, Hamburg University of TechnologyHamburgGermany
| | - Tracy L. Kolbe‐Alexander
- School of Health and Medical SciencesUniversity of Southern QueenslandIpswichQueenslandAustralia
- Centre for Health ResearchInstitute for Resilient Regions, University of Southern QueenslandIpswichQueenslandAustralia
- UCT Research Centre for Health through Physical Activity, Lifestyle and Sport (HPALS), Division of Research Unit for Exercise Science and Sports Medicine, Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
| | - Dean E. Mills
- School of Health and Medical SciencesUniversity of Southern QueenslandIpswichQueenslandAustralia
- Respiratory and Exercise Physiology Research Group, School of Health and WellbeingUniversity of Southern QueenslandIpswichQueenslandAustralia
- Centre for Health ResearchInstitute for Resilient Regions, University of Southern QueenslandIpswichQueenslandAustralia
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Hardy TA, Paula-Ribeiro M, Silva BM, Lyall GK, Birch KM, Ferguson C, Taylor BJ. The cardiovascular consequences of fatiguing expiratory muscle work in otherwise resting healthy humans. J Appl Physiol (1985) 2021; 130:421-434. [PMID: 33356985 DOI: 10.1152/japplphysiol.00116.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In 11 healthy adults (25 ± 4 yr; 2 female, 9 male subjects), we investigated the effect of expiratory resistive loaded breathing [65% maximal expiratory mouth pressure (MEP), 15 breaths·min-1, duty cycle 0.5; ERLPm] on mean arterial pressure (MAP), leg vascular resistance (LVR), and leg blood flow ([Formula: see text]). On a separate day, a subset of five male subjects performed ERL targeting 65% of maximal expiratory gastric pressure (ERLPga). ERL-induced expiratory muscle fatigue was confirmed by a 17 ± 5% reduction in MEP (P < 0.05) and a 16 ± 12% reduction in the gastric twitch pressure response to magnetic nerve stimulation (P = 0.09) from before to after ERLPm and ERLPga, respectively. From rest to task failure in ERLPm and ERLPga, MAP increased (ERLPm = 31 ± 10 mmHg, ERLPga = 18 ± 9 mmHg, both P < 0.05), but group mean LVR and [Formula: see text] were unchanged (ERLPm: LVR = 0.78 ± 0.21 vs. 0.97 ± 0.36 mmHg·mL-1·min, [Formula: see text] = 133 ± 34 vs. 152 ± 74 mL·min-1; ERLPga: LVR = 0.70 ± 0.21 vs. 0.84 ± 0.33 mmHg·mL-1·min, [Formula: see text] = 160 ± 48 vs. 179 ± 110 mL·min-1) (all P ≥ 0.05). Interestingly, [Formula: see text] during ERLPga oscillated within each breath, increasing (∼66%) and decreasing (∼50%) relative to resting values during resisted expirations and unresisted inspirations, respectively. In conclusion, fatiguing expiratory muscle work did not affect group mean LVR or [Formula: see text] in otherwise resting humans. We speculate that any sympathetically mediated peripheral vasoconstriction was counteracted by transient mechanical effects of high intra-abdominal pressures during ERL.NEW & NOTEWORTHY Fatiguing expiratory muscle work in otherwise resting humans elicits an increase in sympathetic motor outflow; whether limb blood flow ([Formula: see text]) and leg vascular resistance (LVR) are affected remains unknown. We found that fatiguing expiratory resistive loaded breathing (ERL) did not affect group mean [Formula: see text] or LVR. However, within-breath oscillations in [Formula: see text] may reflect a sympathetically mediated vasoconstriction that was counteracted by transient increases in [Formula: see text] due to the mechanical effects of high intra-abdominal pressure during ERL.
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Affiliation(s)
- Tim A Hardy
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Marcelle Paula-Ribeiro
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.,Department of Physiology, Federal University of São Paulo, São Paulo, Brazil
| | - Bruno M Silva
- Department of Physiology, Federal University of São Paulo, São Paulo, Brazil
| | - Gemma K Lyall
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Karen M Birch
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Carrie Ferguson
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Bryan J Taylor
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.,Department of Cardiovascular Diseases, Mayo Clinic, Jacksonville, Florida
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Hardy TA, How SC, Taylor BJ. The Effect of Preexercise Expiratory Muscle Loading on Exercise Tolerance in Healthy Men. Med Sci Sports Exerc 2021; 53:421-430. [PMID: 32735113 DOI: 10.1249/mss.0000000000002468] [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: 11/21/2022]
Abstract
PURPOSE Acute nonfatiguing inspiratory muscle loading transiently increases diaphragm excitability and global inspiratory muscle strength and may improve subsequent exercise performance. We investigated the effect of acute expiratory muscle loading on expiratory muscle function and exercise tolerance in healthy men. METHODS Ten males cycled at 90% of peak power output to the limit of tolerance (TLIM) after 1) 2 × 30 expiratory efforts against a pressure-threshold load of 40% maximal expiratory gastric pressure (PgaMAX) (EML-EX) and 2) 2 × 30 expiratory efforts against a pressure-threshold load of 10% PgaMAX (SHAM-EX). Changes in expiratory muscle function were assessed by measuring the mouth pressure (PEMAX) and PgaMAX responses to maximal expulsive efforts and magnetically evoked (1 Hz) gastric twitch pressure (Pgatw). RESULTS Expiratory loading at 40% of PgaMAX increased PEMAX (10% ± 5%, P = 0.001) and PgaMAX (9% ± 5%, P = 0.004). Conversely, there was no change in PEMAX (166 ± 40 vs 165 ± 35 cm H2O, P = 1.000) or PgaMAX (196 ± 38 vs 192 ± 39 cm H2O, P = 0.215) from before to after expiratory loading at 10% of PgaMAX. Exercise time was not different in EML-EX versus SHAM-EX (7.91 ± 1.96 vs 8.09 ± 1.77 min, 95% CI = -1.02 to 0.67, P = 0.651). Similarly, exercise-induced expiratory muscle fatigue was not different in EML-EX versus SHAM-EX (-28% ± 12% vs -26% ± 7% reduction in Pgatw amplitude, P = 0.280). Perceptual ratings of dyspnea and leg discomfort were not different during EML-EX versus SHAM-EX. CONCLUSION Acute expiratory muscle loading enhances expiratory muscle function but does not improve subsequent severe-intensity exercise tolerance in healthy men.
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Affiliation(s)
- Tim A Hardy
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UNITED KINGDOM
| | - Stephen C How
- School of Sport and Exercise, University of Gloucestershire, Gloucester, UNITED KINGDOM
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Davidson J, Tsopanoglou SP, Dourado VZ, Nunes Dos Santos AM, Goulart AL, Amorim CF, Solé D. Pattern of respiratory muscle activity during exercise tests in children born prematurely. J Bodyw Mov Ther 2020; 24:78-83. [PMID: 32826012 DOI: 10.1016/j.jbmt.2020.02.003] [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] [Indexed: 11/17/2022]
Abstract
INTRODUCTION Preterm children display only slightly lower exercise capacity than term children do during their development, despite their previous cardiopulmonary impairments. This raises doubts about the role of the respiratory muscles' influence on exercise capacity. This study aimed to compare respiratory muscle activity in preterm and term children using an exercise test. METHODS This cross-sectional study involved comparison of 35 term children and 39 matched preterm children aged 6-9 years, who were born prematurely with a birth weight <1500 g. An adapted treadmill incremental test was utilized and surface electromyography of the sternocleidomastoid (SCM), upper trapezius (UT), and rectus abdominis (RA) muscles was performed. The root mean square was calculated every minute and compared between and within groups. A Monte Carlo simulation was also applied, and the area under the curve was calculated to evaluate the differences between groups. RESULTS During the entire exercise, the SCM muscle activity was higher in preterm children with a larger area under the curve than in the term children. There was no difference in the RA and UT muscle activity between groups throughout the test. CONCLUSION The results suggest a greater contribution of the SCM muscle sin preterm children's performance than in term children's performance during high-intensity exercises. TRIAL REGISTRATION Brazilian Clinical Trial Registry (ReBec) - RBR-89hr2h.
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Affiliation(s)
- Josy Davidson
- Neonatal Division, Department of Pediatrics, Federal University of São Paulo, São Paulo, SP, Brazil.
| | | | - Victor Zuniga Dourado
- Department of Human Movement Sciences, Laboratory of Human Motricity, Federal University of São Paulo, Santos, SP, Brazil
| | | | - Ana Lucia Goulart
- Neonatal Division, Department of Pediatrics, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Cesar Ferreira Amorim
- Physical Therapy Master Program, University of the City of Sao Paulo (UNICID), São Paulo, Brazil
| | - Dirceu Solé
- Allergy, Clinical Immunology and Rheumatology Division, Department of Pediatrics, Federal University of São Paulo, São Paulo, SP, Brazil
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Larribaut J, Gruet M, McNarry MA, Mackintosh KA, Verges S. Methodology and reliability of respiratory muscle assessment. Respir Physiol Neurobiol 2019; 273:103321. [PMID: 31629881 DOI: 10.1016/j.resp.2019.103321] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 10/11/2019] [Accepted: 10/14/2019] [Indexed: 11/26/2022]
Abstract
The optimal method for respiratory muscle endurance (RME) assessment remains unclear. This study assessed the test-retest reliability of two RME-test methodologies. Fifteen healthy adults attended the laboratory on four occasions, separated by 5 ± 2 days, and completed each test in a random, "one on two" order. They performed spirometry testing, maximal respiratory pressure assessment and two different RME tests: an inspiratory resistive breathing (IRB) and an isocapnic hyperpnea endurance (IHE) test. Typical error, expressed as coefficient of variation, for IRB maximal inspiratory pressure (MIP) and IHE maximal ventilation were 12.21 (8.85-19.67) % and 10.73 (7.78-17.29) %, respectively. Intraclass correlation coefficients for the same parameters were 0.83 (0.46-0.94) and 0.80 (0.41-0.93), respectively. No correlations were found between RME parameters derived from the IHE and IRB tests (all p > 0.05). Significant positive correlations were found between both IRB and IHE outcomes and spirometry parameters, MIP and maximal expiratory pressure (p < 0.05). Given these results, IRB and IHE appear to be suitable for RME testing in healthy people, although they may reflect different physiological mechanisms (respiratory mechanics and respiratory muscle capacity for IHE test vs. inspiratory muscle capacity for IRB test). Future studies are therefore warranted that compare IRB and IHE tests in clinical settings.
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Affiliation(s)
- J Larribaut
- HP2 Laboratory, INSERM, Grenoble Alpes University, Grenoble, France
| | - M Gruet
- LAMHESS, Université de Toulon, France; Unité de Recherche Impact de l'Activité Physique sur la Santé, UR IAPS n°201723207F, France.
| | - M A McNarry
- A-STEM, Swansea University, Swansea, Wales, UK
| | | | - S Verges
- HP2 Laboratory, INSERM, Grenoble Alpes University, Grenoble, France
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7
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Welch JF, Kipp S, Sheel AW. Respiratory muscles during exercise: mechanics, energetics, and fatigue. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.04.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Abstract
This short review offers a general summary of the consequences of whole body exercise on neuromuscular fatigue pertaining to the locomotor musculature. Research from the past two decades have shown that whole body exercise causes considerable peripheral and central fatigue. Three determinants characteristic for locomotor exercise are discussed, namely, pulmonary system limitations, neural feedback mechanisms, and mental/psychological influences. We also discuss existing data suggesting that the impact of whole body exercise is not limited to locomotor muscles, but can also impair non-locomotor muscles, such as respiratory and cardiac muscles, and other limb muscles not directly contributing to the task.
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Affiliation(s)
- Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT
| | - Markus Amann
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT.,Department of Anesthesiology, University of Utah, Salt Lake City, UT
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9
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Tiller NB, Campbell IG, Romer LM. Influence of Upper-Body Exercise on the Fatigability of Human Respiratory Muscles. Med Sci Sports Exerc 2017; 49:1461-1472. [PMID: 28288012 PMCID: PMC5473371 DOI: 10.1249/mss.0000000000001251] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Purpose Diaphragm and abdominal muscles are susceptible to contractile fatigue in response to high-intensity, whole-body exercise. This study assessed whether the ventilatory and mechanical loads imposed by high-intensity, upper-body exercise would be sufficient to elicit respiratory muscle fatigue. Methods Seven healthy men (mean ± SD; age = 24 ± 4 yr, peak O2 uptake [V˙O2peak] = 31.9 ± 5.3 mL·kg−1·min−1) performed asynchronous arm-crank exercise to exhaustion at work rates equivalent to 30% (heavy) and 60% (severe) of the difference between gas exchange threshold and V˙O2peak. Contractile fatigue of the diaphragm and abdominal muscles was assessed by measuring pre- to postexercise changes in potentiated transdiaphragmatic and gastric twitch pressures (Pdi,tw and Pga,tw) evoked by supramaximal magnetic stimulation of the cervical and thoracic nerves, respectively. Results Exercise time was 24.5 ± 5.8 min for heavy exercise and 9.8 ± 1.8 min for severe exercise. Ventilation over the final minute of heavy exercise was 73 ± 20 L·min−1 (39% ± 11% maximum voluntary ventilation) and 99 ± 19 L·min−1 (53% ± 11% maximum voluntary ventilation) for severe exercise. Mean Pdi,tw did not differ pre- to postexercise at either intensity (P > 0.05). Immediately (5–15 min) after severe exercise, mean Pga,tw was significantly lower than pre-exercise values (41 ± 13 vs 53 ± 15 cm H2O, P < 0.05), with the difference no longer significant after 25–35 min. Abdominal muscle fatigue (defined as ≥15% reduction in Pga,tw) occurred in 1/7 subjects after heavy exercise and 5/7 subjects after severe exercise. Conclusions High-intensity, upper-body exercise elicits significant abdominal, but not diaphragm, muscle fatigue in healthy men. The increased magnitude and prevalence of fatigue during severe-intensity exercise is likely due to additional (nonrespiratory) loading of the thorax.
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Affiliation(s)
- Nicholas B Tiller
- 1Academy of Sport and Physical Activity, Sheffield Hallam University, Sheffield, UNITED KINGDOM; 2Division of Sport, Health and Exercise Sciences, Brunel University London, London, UNITED KINGDOM; and 3School of Life and Medical Sciences, University of Hertfordshire, Hertfordshire, UNITED KINGDOM
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10
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Wüthrich TU, Marty J, Kerherve H, Millet GY, Verges S, Spengler CM. Aspects of respiratory muscle fatigue in a mountain ultramarathon race. Med Sci Sports Exerc 2015; 47:519-27. [PMID: 25033264 DOI: 10.1249/mss.0000000000000449] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Ultramarathon running offers a unique possibility to investigate the mechanisms contributing to the limitation of endurance performance. Investigations of locomotor muscle fatigue show that central fatigue is a major contributor to the loss of strength in the lower limbs after an ultramarathon. In addition, respiratory muscle fatigue is known to limit exercise performance, but only limited data are available on changes in respiratory muscle function after ultramarathon running and it is not known whether the observed impairment is caused by peripheral and/or central fatigue. METHODS In 22 experienced ultra-trail runners, we assessed respiratory muscle strength, i.e., maximal voluntary inspiratory and expiratory pressures, mouth twitch pressure (n = 16), and voluntary activation (n = 16) using cervical magnetic stimulation, lung function, and maximal voluntary ventilation before and after a 110-km mountain ultramarathon with 5862 m of positive elevation gain. RESULTS Both maximal voluntary inspiratory (-16% ± 13%) and expiratory pressures (-21% ± 14%) were significantly reduced after the race. Fatigue of inspiratory muscles likely resulted from substantial peripheral fatigue (reduction in mouth twitch pressure, -19% ± 15%; P < 0.01), as voluntary activation (-3% ± 6%, P = 0.09) only tended to be decreased, suggesting negligible or only mild levels of central fatigue. Forced vital capacity remained unchanged, whereas forced expiratory volume in 1 s, peak inspiratory and expiratory flow rates, and maximal voluntary ventilation were significantly reduced (P < 0.05). CONCLUSIONS Ultraendurance running reduces respiratory muscle strength for inspiratory muscles shown to result from significant peripheral muscle fatigue with only little contribution of central fatigue. This is in contrast to findings in locomotor muscles. Whether this difference between muscle groups results from inherent neuromuscular differences, their specific pattern of loading or other reasons remain to be clarified.
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Affiliation(s)
- Thomas U Wüthrich
- 1Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, ETH Zurich, SWITZERLAND; 2School of Health and Exercise Science, University of the Sunshine Coast, Queensland, AUSTRALIA; 3Exercise Physiology Laboratory, University of Lyon, Saint-Étienne, FRANCE; 4Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, CANADA; 5HP2 Laboratory, University Grenoble Alpes, Grenoble, FRANCE; 6U1042, INSERM, Grenoble, FRANCE; and 7Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, SWITZERLAND
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11
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Wüthrich TU, Eberle EC, Spengler CM. Locomotor and diaphragm muscle fatigue in endurance athletes performing time-trials of different durations. Eur J Appl Physiol 2014; 114:1619-33. [DOI: 10.1007/s00421-014-2889-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 04/06/2014] [Indexed: 01/19/2023]
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Sugiura H, Sako S, Oshida Y. Effect of Expiratory Muscle Fatigue on the Respiratory Response during Exercise. J Phys Ther Sci 2013; 25:1491-5. [PMID: 24396218 PMCID: PMC3881485 DOI: 10.1589/jpts.25.1491] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 06/24/2013] [Indexed: 11/24/2022] Open
Abstract
[Purpose] The aim of this study was to reveal the effect of expiratory muscle fatigue
(EMF) on respiratory response under two different exercise conditions: exercise (EX) with
EMF (EMF-EX) and control EX without EMF (CON-EX). [Methods] Nine healthy adult men
performed cycle exercise with a ramp load, and a spirometer was used to measure forced
vital capacity (FVC), forced expiratory volume in one second, percent of forced expiratory
volume, maximal expiratory mouth pressure, and maximal inspiratory mouth pressure
(PImax) to evaluate respiratory functions immediately and at 15 and 30 min
after exercise. To assess the respiratory response during exercise, an exhaled gas
analyzer was used to measure minute ventilation (VE), respiratory frequency
(f), tidal volume (VT), oxygen uptake, and carbon dioxide output. In addition,
the Borg Scale was used to evaluate dyspnea, while electrocardiography was used to measure
heart rate. [Results] The results showed that compared with the CON-EX condition, no
change in VE, an increase in f, or a decrease in VT was observed
under the medium-intensity EMF-EX condition, while high-intensity exercise reduced
VE and f without changing VT. [Conclusion] These results suggest
that during medium-intensity exercise, EMF modulates the respiratory response by inducing
shallow and fast breathing to increase ventilation volume.
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Affiliation(s)
- Hiromichi Sugiura
- Department of Physical Therapy, Nagoya Isen, Japan ; Graduate School of Medicine, Nagoya University, Japan
| | - Shunji Sako
- Department of Physical Therapy, Nagoya Isen, Japan
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Bachasson D, Wuyam B, Pepin JL, Tamisier R, Levy P, Verges S. Quadriceps and respiratory muscle fatigue following high-intensity cycling in COPD patients. PLoS One 2013; 8:e83432. [PMID: 24324843 PMCID: PMC3855800 DOI: 10.1371/journal.pone.0083432] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 11/05/2013] [Indexed: 11/24/2022] Open
Abstract
Exercise intolerance in COPD seems to combine abnormal ventilatory mechanics, impaired O2 transport and skeletal muscle dysfunction. However their relative contribution and their influence on symptoms reported by patients remain to be clarified. In order to clarify the complex interaction between ventilatory and neuromuscular exercise limiting factors and symptoms, we evaluated respiratory muscles and quadriceps contractile fatigue, dynamic hyperinflation and symptoms induced by exhaustive high-intensity cycling in COPD patients. Fifteen gold II-III COPD patients (age = 67 ± 6 yr; BMI = 26.6 ± 4.2 kg.m(-2)) performed constant-load cycling test at 80% of their peak workload until exhaustion (9.3 ± 2.4 min). Before exercise and at exhaustion, potentiated twitch quadriceps strength (Q(tw)), transdiaphragmatic (P(di,tw)) and gastric (P(ga,tw)) pressures were evoked by femoral nerve, cervical and thoracic magnetic stimulation, respectively. Changes in operational lung volumes during exercise were assessed via repetitive inspiratory capacity (IC) measurements. Dyspnoea and leg discomfort were measured on visual analog scale. At exhaustion, Q(tw) (-33 ± 15%, >15% reduction observed in all patients but two) and Pdi,tw (-20 ± 15%, >15% reduction in 6 patients) were significantly reduced (P<0.05) but not Pga,tw (-6 ± 10%, >15% reduction in 3 patients). Percentage reduction in Q(tw) correlated with the percentage reduction in P(di,tw) (r = 0.66; P<0.05). Percentage reductions in P(di,tw) and P(ga,tw) negatively correlated with the reduction in IC at exhaustion (r = -0.56 and r = -0.62, respectively; P<0.05). Neither dyspnea nor leg discomfort correlated with the amount of muscle fatigue. In conclusion, high-intensity exercise induces quadriceps, diaphragm and less frequently abdominal contractile fatigue in this group of COPD patients. In addition, the rise in end-expiratory lung volume and diaphragm flattening associated with dynamic hyperinflation in COPD might limit the development of abdominal and diaphragm muscle fatigue. This study underlines that both respiratory and quadriceps fatigue should be considered to understand the complex interplay of factors leading to exercise intolerance in COPD patients.
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Affiliation(s)
- Damien Bachasson
- Grenoble Alpes University, HP2 Laboratory, Grenoble, France
- INSERM, U1042, Grenoble, France
- CHU, Grenoble Locomotor Unit, Reeducation & Physiology, Clinical Physiology, Sleep and Exercise, Grenoble, France
| | - Bernard Wuyam
- Grenoble Alpes University, HP2 Laboratory, Grenoble, France
- INSERM, U1042, Grenoble, France
- CHU, Grenoble Locomotor Unit, Reeducation & Physiology, Clinical Physiology, Sleep and Exercise, Grenoble, France
| | - Jean-Louis Pepin
- Grenoble Alpes University, HP2 Laboratory, Grenoble, France
- INSERM, U1042, Grenoble, France
- CHU, Grenoble Locomotor Unit, Reeducation & Physiology, Clinical Physiology, Sleep and Exercise, Grenoble, France
| | - Renaud Tamisier
- Grenoble Alpes University, HP2 Laboratory, Grenoble, France
- INSERM, U1042, Grenoble, France
- CHU, Grenoble Locomotor Unit, Reeducation & Physiology, Clinical Physiology, Sleep and Exercise, Grenoble, France
| | - Patrick Levy
- Grenoble Alpes University, HP2 Laboratory, Grenoble, France
- INSERM, U1042, Grenoble, France
- CHU, Grenoble Locomotor Unit, Reeducation & Physiology, Clinical Physiology, Sleep and Exercise, Grenoble, France
| | - Samuel Verges
- Grenoble Alpes University, HP2 Laboratory, Grenoble, France
- INSERM, U1042, Grenoble, France
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14
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Abstract
During dynamic exercise, the healthy pulmonary system faces several major challenges, including decreases in mixed venous oxygen content and increases in mixed venous carbon dioxide. As such, the ventilatory demand is increased, while the rising cardiac output means that blood will have considerably less time in the pulmonary capillaries to accomplish gas exchange. Blood gas homeostasis must be accomplished by precise regulation of alveolar ventilation via medullary neural networks and sensory reflex mechanisms. It is equally important that cardiovascular and pulmonary system responses to exercise be precisely matched to the increase in metabolic requirements, and that the substantial gas transport needs of both respiratory and locomotor muscles be considered. Our article addresses each of these topics with emphasis on the healthy, young adult exercising in normoxia. We review recent evidence concerning how exercise hyperpnea influences sympathetic vasoconstrictor outflow and the effect this might have on the ability to perform muscular work. We also review sex-based differences in lung mechanics.
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Affiliation(s)
- Andrew William Sheel
- The School of Kinesiology, The University of British Columbia, Vancouver, Canada.
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15
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Taylor BJ, How SC, Romer LM. Expiratory muscle fatigue does not regulate operating lung volumes during high-intensity exercise in healthy humans. J Appl Physiol (1985) 2013; 114:1569-76. [DOI: 10.1152/japplphysiol.00066.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To determine whether expiratory muscle fatigue (EMF) is involved in regulating operating lung volumes during exercise, nine recreationally active subjects cycled at 90% of peak work rate to the limit of tolerance with prior induction of EMF (EMF-ex) and for a time equal to that achieved in EMF-ex without prior induction of EMF (ISO-ex). EMF was assessed by measuring changes in magnetically evoked gastric twitch pressure. Changes in end-expiratory and end-inspiratory lung volume (EELV and EILV) and the degree of expiratory flow limitation (EFL) were quantified using maximal expiratory flow-volume curves and inspiratory capacity maneuvers. Resistive breathing reduced gastric twitch pressure (−24 ± 14%, P = 0.004). During EMF-ex, EELV decreased from rest to the 3rd min of exercise [39 ± 8 vs. 27 ± 7% of forced vital capacity (FVC), P = 0.001] before increasing toward baseline (34 ± 8% of FVC end exercise, P = 0.073 vs. rest). EILV increased from rest to the 3rd min of exercise (54 ± 8 vs. 84 ± 9% of FVC, P = 0.006) and remained elevated to end exercise (88 ± 9% of FVC). Neither EELV ( P = 0.18) nor EILV ( P = 0.26) was different at any time point during EMF-ex vs. ISO-ex. Four subjects became expiratory flow limited during the final minute of EMF-ex and ISO-ex; the degree of EFL was not different between trials (37 ± 18 vs. 35 ± 16% of tidal volume, P = 0.38). At end exercise in both trials, EELV was greater in subjects without vs. subjects with EFL. These findings suggest that 1) contractile fatigue of the expiratory muscles in healthy humans does not regulate operating lung volumes during high-intensity sustained cycle exercise; and 2) factors other than “frank” EFL cause the terminal increase in EELV.
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Affiliation(s)
- Bryan J. Taylor
- Centre for Sports Medicine and Human Performance, Brunel University, London, United Kingdom
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, New York; and
| | - Stephen C. How
- Exercise and Sport Research Centre, University of Gloucestershire, Gloucester, United Kingdom
| | - Lee M. Romer
- Centre for Sports Medicine and Human Performance, Brunel University, London, United Kingdom
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16
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Illi SK, Held U, Frank I, Spengler CM. Effect of Respiratory Muscle Training on Exercise Performance in Healthy Individuals. Sports Med 2012; 42:707-24. [DOI: 10.1007/bf03262290] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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17
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Illi SK, Held U, Frank I, Spengler CM. Effect of Respiratory Muscle Training on Exercise Performance in Healthy Individuals. Sports Med 2012. [DOI: 10.2165/11631670-000000000-00000] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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18
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Verges S, Bachasson D, Wuyam B. Effect of acute hypoxia on respiratory muscle fatigue in healthy humans. Respir Res 2010; 11:109. [PMID: 20701769 PMCID: PMC2929221 DOI: 10.1186/1465-9921-11-109] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 08/11/2010] [Indexed: 11/14/2022] Open
Abstract
Background Greater diaphragm fatigue has been reported after hypoxic versus normoxic exercise, but whether this is due to increased ventilation and therefore work of breathing or reduced blood oxygenation per se remains unclear. Hence, we assessed the effect of different blood oxygenation level on isolated hyperpnoea-induced inspiratory and expiratory muscle fatigue. Methods Twelve healthy males performed three 15-min isocapnic hyperpnoea tests (85% of maximum voluntary ventilation with controlled breathing pattern) in normoxic, hypoxic (SpO2 = 80%) and hyperoxic (FiO2 = 0.60) conditions, in a random order. Before, immediately after and 30 min after hyperpnoea, transdiaphragmatic pressure (Pdi,tw ) was measured during cervical magnetic stimulation to assess diaphragm contractility, and gastric pressure (Pga,tw ) was measured during thoracic magnetic stimulation to assess abdominal muscle contractility. Two-way analysis of variance (time x condition) was used to compare hyperpnoea-induced respiratory muscle fatigue between conditions. Results Hypoxia enhanced hyperpnoea-induced Pdi,tw and Pga,tw reductions both immediately after hyperpnoea (Pdi,tw : normoxia -22 ± 7% vs hypoxia -34 ± 8% vs hyperoxia -21 ± 8%; Pga,tw : normoxia -17 ± 7% vs hypoxia -26 ± 10% vs hyperoxia -16 ± 11%; all P < 0.05) and after 30 min of recovery (Pdi,tw : normoxia -10 ± 7% vs hypoxia -16 ± 8% vs hyperoxia -8 ± 7%; Pga,tw : normoxia -13 ± 6% vs hypoxia -21 ± 9% vs hyperoxia -12 ± 12%; all P < 0.05). No significant difference in Pdi,tw or Pga,tw reductions was observed between normoxic and hyperoxic conditions. Also, heart rate and blood lactate concentration during hyperpnoea were higher in hypoxia compared to normoxia and hyperoxia. Conclusions These results demonstrate that hypoxia exacerbates both diaphragm and abdominal muscle fatigability. These results emphasize the potential role of respiratory muscle fatigue in exercise performance limitation under conditions coupling increased work of breathing and reduced O2 transport as during exercise in altitude or in hypoxemic patients.
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Affiliation(s)
- Samuel Verges
- HP2 laboratory (INSERM ERI17), Joseph Fourier University, Grenoble University Hospital, Grenoble, France.
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19
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Athanasopoulos D, Louvaris Z, Cherouveim E, Andrianopoulos V, Roussos C, Zakynthinos S, Vogiatzis I. Expiratory muscle loading increases intercostal muscle blood flow during leg exercise in healthy humans. J Appl Physiol (1985) 2010; 109:388-95. [PMID: 20507965 DOI: 10.1152/japplphysiol.01290.2009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated whether expiratory muscle loading induced by the application of expiratory flow limitation (EFL) during exercise in healthy subjects causes a reduction in quadriceps muscle blood flow in favor of the blood flow to the intercostal muscles. We hypothesized that, during exercise with EFL quadriceps muscle blood flow would be reduced, whereas intercostal muscle blood flow would be increased compared with exercise without EFL. We initially performed an incremental exercise test on eight healthy male subjects with a Starling resistor in the expiratory line limiting expiratory flow to approximately 1 l/s to determine peak EFL exercise workload. On a different day, two constant-load exercise trials were performed in a balanced ordering sequence, during which subjects exercised with or without EFL at peak EFL exercise workload for 6 min. Intercostal (probe over the 7th intercostal space) and vastus lateralis muscle blood flow index (BFI) was calculated by near-infrared spectroscopy using indocyanine green, whereas cardiac output (CO) was measured by an impedance cardiography technique. At exercise termination, CO and stroke volume were not significantly different during exercise, with or without EFL (CO: 16.5 vs. 15.2 l/min, stroke volume: 104 vs. 107 ml/beat). Quadriceps muscle BFI during exercise with EFL (5.4 nM/s) was significantly (P = 0.043) lower compared with exercise without EFL (7.6 nM/s), whereas intercostal muscle BFI during exercise with EFL (3.5 nM/s) was significantly (P = 0.021) greater compared with that recorded during control exercise (0.4 nM/s). In conclusion, increased respiratory muscle loading during exercise in healthy humans causes an increase in blood flow to the intercostal muscles and a concomitant decrease in quadriceps muscle blood flow.
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Affiliation(s)
- Dimitris Athanasopoulos
- Department of Critical Care Medicine and Pulmonary Services, Evangelismos Hospital, M. Simou, and G. P. Livanos Laboratories, Athens, Greece
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20
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Hopkinson NS, Dayer MJ, Moxham J, Polkey MI. Abdominal muscle fatigue following exercise in chronic obstructive pulmonary disease. Respir Res 2010; 11:15. [PMID: 20132549 PMCID: PMC2824704 DOI: 10.1186/1465-9921-11-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Accepted: 02/04/2010] [Indexed: 11/16/2022] Open
Abstract
Background In patients with chronic obstructive pulmonary disease, a restriction on maximum ventilatory capacity contributes to exercise limitation. It has been demonstrated that the diaphragm in COPD is relatively protected from fatigue during exercise. Because of expiratory flow limitation the abdominal muscles are activated early during exercise in COPD. This adds significantly to the work of breathing and may therefore contribute to exercise limitation. In healthy subjects, prior expiratory muscle fatigue has been shown itself to contribute to the development of quadriceps fatigue. It is not known whether fatigue of the abdominal muscles occurs during exercise in COPD. Methods Twitch gastric pressure (TwT10Pga), elicited by magnetic stimulation over the 10th thoracic vertebra and twitch transdiaphragmatic pressure (TwPdi), elicited by bilateral anterolateral magnetic phrenic nerve stimulation were measured before and after symptom-limited, incremental cycle ergometry in patients with COPD. Results Twenty-three COPD patients, with a mean (SD) FEV1 40.8(23.1)% predicted, achieved a mean peak workload of 53.5(15.9) W. Following exercise, TwT10Pga fell from 51.3(27.1) cmH2O to 47.4(25.2) cmH2O (p = 0.011). TwPdi did not change significantly; pre 17.0(6.4) cmH2O post 17.5(5.9) cmH2O (p = 0.7). Fatiguers, defined as having a fall TwT10Pga ≥ 10% had significantly worse lung gas transfer, but did not differ in other exercise parameters. Conclusions In patients with COPD, abdominal muscle but not diaphragm fatigue develops following symptom limited incremental cycle ergometry. Further work is needed to establish whether abdominal muscle fatigue is relevant to exercise limitation in COPD, perhaps indirectly through an effect on quadriceps fatigability.
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Affiliation(s)
- Nicholas S Hopkinson
- National Heart and Lung Institute, Imperial College, Royal Brompton Hospital, Fulham Rd, London SW3 6NP, UK.
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21
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22
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Sugiura H, Ohta K, Minatani S, Tanoue H, Kokubo A, Kanada Y, Sako S. Relationship between Respiratory Muscle Strength and Exercise Tolerance. J Phys Ther Sci 2009. [DOI: 10.1589/jpts.21.393] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Hiromichi Sugiura
- Department of Physical Therapy, Faculty of Health Science, Suzuka University of Medical Science
| | - Kiyohito Ohta
- Department of Rehabilitation, Major in Physical Therapy, Gifu Junior College of Health Science
| | - Satsuki Minatani
- Department of Rehabilitation, Major in Physical Therapy, Gifu Junior College of Health Science
| | - Hironori Tanoue
- Department of Rehabilitation, Major in Physical Therapy, Gifu Junior College of Health Science
| | - Akira Kokubo
- Department of Physical Therapy, Nagoya Collage of Rehabilitation Medicine and Social Welfare
| | - Yoshikiyo Kanada
- Faculty of Rehabilitation, School of Health Sciences, Fujita Health University
| | - Shunji Sako
- Department of Rehabilitation, Major in Physical Therapy, Gifu Junior College of Health Science
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23
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Renggli AS, Verges S, Notter DA, Spengler CM. Development of respiratory muscle contractile fatigue in the course of hyperpnoea. Respir Physiol Neurobiol 2008; 164:366-72. [DOI: 10.1016/j.resp.2008.08.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 08/18/2008] [Accepted: 08/22/2008] [Indexed: 11/29/2022]
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24
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Ross E, Middleton N, Shave R, George K, McConnell A. Changes in respiratory muscle and lung function following marathon running in man. J Sports Sci 2008; 26:1295-301. [DOI: 10.1080/02640410802104904] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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25
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Taylor BJ, Romer LM. Effect of expiratory muscle fatigue on exercise tolerance and locomotor muscle fatigue in healthy humans. J Appl Physiol (1985) 2008; 104:1442-51. [DOI: 10.1152/japplphysiol.00428.2007] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
High-intensity exercise (≥90% of maximal O2 uptake) sustained to the limit of tolerance elicits expiratory muscle fatigue (EMF). We asked whether prior EMF affects subsequent exercise tolerance. Eight male subjects (means ± SD; maximal O2 uptake = 53.5 ± 5.2 ml·kg−1·min−1) cycled at 90% of peak power output to the limit of tolerance with (EMF-EX) and without (CON-EX) prior induction of EMF and for a time equal to that achieved in EMF-EX but without prior induction of EMF (ISO-EX). To induce EMF, subjects breathed against an expiratory flow resistor until task failure (15 breaths/min, 0.7 expiratory duty cycle, 40% of maximal expiratory gastric pressure). Fatigue of abdominal and quadriceps muscles was assessed by measuring the reduction relative to prior baseline values in magnetically evoked gastric twitch pressure (Pgatw) and quadriceps twitch force (Qtw), respectively. The reduction in Pgatw was not different after resistive breathing vs. after CON-EX (−27 ± 5 vs. −26 ± 6%; P = 0.127). Exercise time was reduced by 33 ± 10% in EMF-EX vs. CON-EX (6.85 ± 2.88 vs. 9.90 ± 2.94 min; P < 0.001). Exercise-induced abdominal and quadriceps muscle fatigue was greater after EMF-EX than after ISO-EX (−28 ± 9 vs. −12 ± 5% for Pgatw, P = 0.001; −28 ± 7 vs. −14 ± 6% for Qtw, P = 0.015). Perceptual ratings of dyspnea and leg discomfort (Borg CR10) were higher at 1 and 3 min and at end exercise during EMF-EX vs. during ISO-EX ( P < 0.05). Percent changes in limb fatigue and leg discomfort (EMF-EX vs. ISO-EX) correlated significantly with the change in exercise time. We propose that EMF impaired subsequent exercise tolerance primarily through an increased severity of limb locomotor muscle fatigue and a heightened perception of leg discomfort.
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26
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Romer LM, Polkey MI. Exercise-induced respiratory muscle fatigue: implications for performance. J Appl Physiol (1985) 2008; 104:879-88. [DOI: 10.1152/japplphysiol.01157.2007] [Citation(s) in RCA: 173] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is commonly held that the respiratory system has ample capacity relative to the demand for maximal O2and CO2transport in healthy humans exercising near sea level. However, this situation may not apply during heavy-intensity, sustained exercise where exercise may encroach on the capacity of the respiratory system. Nerve stimulation techniques have provided objective evidence that the diaphragm and abdominal muscles are susceptible to fatigue with heavy, sustained exercise. The fatigue appears to be due to elevated levels of respiratory muscle work combined with an increased competition for blood flow with limb locomotor muscles. When respiratory muscles are prefatigued using voluntary respiratory maneuvers, time to exhaustion during subsequent exercise is decreased. Partially unloading the respiratory muscles during heavy exercise using low-density gas mixtures or mechanical ventilation can prevent exercise-induced diaphragm fatigue and increase exercise time to exhaustion. Collectively, these findings suggest that respiratory muscle fatigue may be involved in limiting exercise tolerance or that other factors, including alterations in the sensation of dyspnea or mechanical load, may be important. The major consequence of respiratory muscle fatigue is an increased sympathetic vasoconstrictor outflow to working skeletal muscle through a respiratory muscle metaboreflex, thereby reducing limb blood flow and increasing the severity of exercise-induced locomotor muscle fatigue. An increase in limb locomotor muscle fatigue may play a pivotal role in determining exercise tolerance through a direct effect on muscle force output and a feedback effect on effort perception, causing reduced motor output to the working limb muscles.
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27
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Verges S, Sager Y, Erni C, Spengler CM. Expiratory muscle fatigue impairs exercise performance. Eur J Appl Physiol 2007; 101:225-32. [PMID: 17546459 DOI: 10.1007/s00421-007-0491-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2007] [Indexed: 11/24/2022]
Abstract
High-intensity, exhaustive exercise may lead to inspiratory as well as expiratory muscle fatigue (EMF). Induction of inspiratory muscle fatigue (IMF) before exercise has been shown to impair subsequent exercise performance. The purpose of the present study was to determine whether induction of EMF also affects subsequent exercise performance. Twelve healthy young men performed five 12-min running tests on a 400-m track on separate days: a preliminary trial, two trials after induction of EMF, and two trials without prior muscle fatigue. Tests with and without prior EMF were performed in an alternate order, randomly starting with either type. EMF was defined as a >or=20% drop in maximal expiratory mouth pressure achieved during expiratory resistive breathing against 50% maximal expiratory mouth pressure. The average distance covered in 12 min was significantly smaller during exercise with prior EMF compared to control exercise (2872+/-256 vs. 2957+/-325 m; P=0.002). Running speed was consistently lower (0.13 m s(-1)) throughout the entire 12 min of exercise with prior EMF. A significant correlation was observed between the level of EMF (decrement in maximal expiratory mouth pressure after resistive breathing) and the reduction in running distance (r2=0.528, P=0.007). Perceived respiratory exertion was higher during the first 800 m and heart rate was lower throughout the entire test of running with prior EMF compared to control exercise (5.3+/-1.6 vs. 4.5+/-1.7 points, P=0.002; 173+/-10 vs. 178+/-7 beats min(-1), P=0.005). We conclude that EMF impairs exercise performance as previously reported for IMF.
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Affiliation(s)
- S Verges
- Institute of Physiology and Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
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28
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Verges S, Lenherr O, Haner AC, Schulz C, Spengler CM. Increased fatigue resistance of respiratory muscles during exercise after respiratory muscle endurance training. Am J Physiol Regul Integr Comp Physiol 2007; 292:R1246-53. [PMID: 17068160 DOI: 10.1152/ajpregu.00409.2006] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Respiratory muscle fatigue develops during exhaustive exercise and can limit exercise performance. Respiratory muscle training, in turn, can increase exercise performance. We investigated whether respiratory muscle endurance training (RMT) reduces exercise-induced inspiratory and expiratory muscle fatigue. Twenty-one healthy, male volunteers performed twenty 30-min sessions of either normocapnic hyperpnoea ( n = 13) or sham training (CON, n = 8) over 4–5 wk. Before and after training, subjects performed a constant-load cycling test at 85% maximal power output to exhaustion (PREEXH, POSTEXH). A further posttraining test was stopped at the pretraining duration (POSTISO) i.e., isotime. Before and after cycling, transdiaphragmatic pressure was measured during cervical magnetic stimulation to assess diaphragm contractility, and gastric pressure was measured during thoracic magnetic stimulation to assess abdominal muscle contractility. Overall, RMT did not reduce respiratory muscle fatigue. However, in subjects who developed >10% of diaphragm or abdominal muscle fatigue in PREEXH, fatigue was significantly reduced after RMT in POSTISO(inspiratory: −17 ± 6% vs. −9 ± 10%, P = 0.038, n = 9; abdominal: −19 ± 10% vs. −11 ± 11%, P = 0.038, n = 9), while sham training had no significant effect. Similarly, cycling endurance in POSTEXHdid not improve after RMT ( P = 0.071), while a significant improvement was seen in the subgroup with >10% of diaphragm fatigue after PREEXH( P = 0.017), but not in the sham training group ( P = 0.674). However, changes in cycling endurance did not correlate with changes in respiratory muscle fatigue. In conclusion, RMT decreased the development of respiratory muscle fatigue during intensive exercise, but this change did not seem to improve cycling endurance.
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Affiliation(s)
- Samuel Verges
- Exercise Physiology, Institute for Human Movement Sciences, ETH Zurich, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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