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Ugale CB, Salmon OF, Segovia MD, Smith CM. Impact of acute hypoxic exposure on neuromuscular and hemodynamic responses during step intensity dynamic constant external resistance leg extension exercise. J Electromyogr Kinesiol 2024; 77:102887. [PMID: 38761513 DOI: 10.1016/j.jelekin.2024.102887] [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: 02/29/2024] [Revised: 04/25/2024] [Accepted: 05/13/2024] [Indexed: 05/20/2024] Open
Abstract
OBJECTIVES This study examined the effects of acute normoxic and hypoxic exposure on neuromuscular and hemodynamic physiological responses performed during dynamic step muscle actions. METHODS Thirteen recreationally active men (mean ± SD age: 21.2 ± 2.9 yrs) performed dynamic leg extensions unilaterally under Normoxic (FiO2 = 21 %) and Hypoxic (FiO2 = 13 %) conditions in a randomized order at 20 %, 40 %, 60 %, 80 %, and 100 % of their maximal strength. Electromyographic (EMG) amplitude, EMG frequency, (Oxygenated and Deoxygenated hemoglobin; OxyHb, DeoxyHb), Total hemoglobin (TotalHb), and skeletal muscle tissue oxygenation status (StO2) were measured from the vastus lateralis during all contractions. RESULTS There were no detectable differences in the neuromuscular responses between normoxia and hypoxia for EMG amplitude (p = 0.37-0.74) and frequency (p = 0.17-0.83). For EMG amplitude there were general increases with intensity (p < 0.01-0.03). EMG frequency remained similar from 20% to 80% and then increased at 100 % effort (p = 0.02). There was no significant difference in patterns of responses for OxyHb (p = 0.870) and TotalHb (p = 0.200) between normoxia and hypoxia. StO2 (p = 0.028) decreased and DeoxyHb (p = 0.006) increased under hypoxia compared to normoxia during dynamic step muscle actions performed in a randomized order. CONCLUSION Unlike fatigue, acute hypoxemia in an unfatigued state does not impact the localized neuromuscular responses, but minimally impacts the hemodynamic responses.
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Affiliation(s)
- Cierra B Ugale
- Robbins College of Health and Human Sciences, Human & Environmental Physiology Laboratory, Baylor University, One Bear Place #97313, Waco, TX 76798, USA.
| | - Owen F Salmon
- Robbins College of Health and Human Sciences, Human & Environmental Physiology Laboratory, Baylor University, One Bear Place #97313, Waco, TX 76798, USA
| | - Matt D Segovia
- Robbins College of Health and Human Sciences, Human & Environmental Physiology Laboratory, Baylor University, One Bear Place #97313, Waco, TX 76798, USA
| | - Cory M Smith
- Robbins College of Health and Human Sciences, Human & Environmental Physiology Laboratory, Baylor University, One Bear Place #97313, Waco, TX 76798, USA.
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Šarabon N, Sašek M. Comments on: Electromyographic signature of isometric squat in the highest refuge in Europe. Eur J Transl Myol 2023; 33:11846. [PMID: 37753787 PMCID: PMC10583143 DOI: 10.4081/ejtm.2023.11846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 09/20/2023] [Indexed: 09/28/2023] Open
Abstract
We read with particular interest the study by Rua et al. (Eur J Transl Myol 33 (3) 11637, 2023 doi: 10.4081/ejtm.2023.11637) on the electromyographic (EMG) activity of the quadriceps muscle during squat at high-altitude. It offers interesting insights into how neural factors might alter muscle function during a multi-joint low-intensity motor task with sustained contraction after trekking under hypoxic conditions. However, the methodological processes and procedures used in the study could bias the interpretation of the outcomes. Therefore, we outline the procedural considerations that should be taken into account in further studies aimed at investigating the potential changes in quadriceps EMG activity during the squat as a result of trekking at high-altitude.
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Affiliation(s)
- Nejc Šarabon
- Faculty of Health Sciences, University of Primorska, Izola, Slovenia; InnoRenew CoE, Izola, Slovenia; Laboratory for Motor Control and Motor Behavior, S2P, Science To Practice, Ltd, Ljubljana, Slovenia; Ludwig Boltzmann Institute for Rehabilitation Research, Vienna.
| | - Matic Sašek
- Faculty of Health Sciences, University of Primorska, Izola, Slovenia; InnoRenew CoE, Izola.
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Rua R, Bondi D, Santangelo C, Pignatelli P, Pietrangelo T, Fulle S, Fanelli V, Verratti V. Electromyographic signature of isometric squat in the highest refuge in Europe. Eur J Transl Myol 2023; 33:11637. [PMID: 37700736 PMCID: PMC10583152 DOI: 10.4081/ejtm.2023.11637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 09/12/2023] [Indexed: 09/14/2023] Open
Abstract
Reports of electromyography during hypoxic exercise are contrasting, due to protocol and muscle diversity. This work aimed to investigate alterations in muscle activation and myoelectrical fatigue during exercise at high-altitude in those muscles primarily involved in trekking. Twelve young adults balanced by gender and age were tested at low (1,667 m) and high (4,554 m, "Capanna Margherita", Italy) altitude, during an isometric squat lasting 60 seconds. High-density surface electromyography was performed from the quadriceps of right limb. The root mean square (RMS), median frequency with its slope, and muscle fiber conduction velocity (MFCV) were computed. Neither males nor females showed changes in median frequency (Med: 36.13 vs 35.63 Hz) and its slope (Med: -9 vs -12 degree) in response to high-altitude trekking, despite a great inter-individual heterogeneity, nor differences were found for MFCV. RMS was not significantly equivalent, with greater values at low altitude (0.385 ± 0.104 mV) than high altitude (0.346 ± 0.090 mV). Unexpected results can be due either to a postural compensation of the whole body compensating for a relatively greater effort or to the inability to support muscle activation after repeated physical efforts. Interesting results may emerge by measuring simultaneously electromyography, muscle oxygenation and kinematics comparing trekking at normoxia vs hypoxia.
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Affiliation(s)
- Riccardo Rua
- Department of Surgical Science, Anaesthesia and Critical Care, University of Turin, Torino.
| | - Danilo Bondi
- Department of Neuroscience, Imaging and Clinical Sciences, University "G. d'Annunzio" of Chieti - Pescara, Chieti.
| | - Carmen Santangelo
- Department of Neuroscience, Imaging and Clinical Sciences, University "G. d'Annunzio" of Chieti - Pescara, Chieti.
| | - Pamela Pignatelli
- Department of Medical, Oral and Biotechnological Sciences, University "G. d'Annunzio" of Chieti-Pescara, Chieti.
| | - Tiziana Pietrangelo
- Department of Neuroscience, Imaging and Clinical Sciences, University "G. d'Annunzio" of Chieti - Pescara, Chieti.
| | - Stefania Fulle
- Department of Neuroscience, Imaging and Clinical Sciences, University "G. d'Annunzio" of Chieti - Pescara, Chieti.
| | - Vito Fanelli
- Department of Surgical Science, Anaesthesia and Critical Care, University of Turin, Torino.
| | - Vittore Verratti
- Department of Psychological, Health and Territorial Sciences, University "G. d'Annunzio" of Chieti-Pescara, Chieti.
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Smith CM, Salmon OF, Jenkins JR. Neuromuscular and Muscle Tissue Hemodynamic Responses When Exposed to Normobaric Hypoxia during Lower-Body Fatiguing Muscle Actions. JOURNAL OF MUSCULOSKELETAL & NEURONAL INTERACTIONS 2023; 23:26-35. [PMID: 36856097 PMCID: PMC9976181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
OBJECTIVES This study examined effects of acute hypoxia on the neuromuscular responses (electromyographic (EMG) amplitude and EMG frequency) and localized muscle tissue oxygenated hemoglobin (oxygenated hemoglobin (OxyHb), deoxygenated hemoglobin (DeoxyHb), total hemoglobin (TotalHb), and muscle tissue oxygenation saturation (StO2) during the process of fatigue. METHODS Fifteen male participants (21.4±2.8yr) performed leg extension repetitions to failure at 70% 1-repetition maximum until volitional exhaustion under Normoxic (FiO2:21%) and Hypoxic (FiO2:12.9%) conditions. Electromyographic amplitude, EMG frequency, OxyHb, DeoxyHb, TotalHb, and StO2 were measured from the vastus lateralis at Initial, 20, 40, 60, 80, and 100% of the repetitions to failure. RESULTS There was no significant difference in the patterns of responses for EMG amplitude, OxyHb, or DeoxyHb between Normoxia and Hypoxia. For EMG frequency, Hypoxia was greater than Normoxia and decreased with fatigue. TotalHb and StO2 were greater under Normoxia compared to Hypoxia. The patterns of responses for EMG amplitude, DeoxyHb, and TotalHb increased throughout the repetitions to failure. OxyHb and StO2 exhibited decreases throughout the repetitions to failure for Normoxic and Hypoxic conditions. CONCLUSION The EMG and oxygenation measurements non-invasively suggest a sympathoexcitatory response (indicated by EMG frequency) and provided complimentary information regarding the process of fatigue in normoxic and hypoxic states.
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Affiliation(s)
- Cory M Smith
- Robbins College of Health and Human Sciences, Department of HHPR, Baylor University, USA
| | - Owen F Salmon
- Robbins College of Health and Human Sciences, Department of HHPR, Baylor University, USA
| | - Jasmin R Jenkins
- Interdisciplinary Health Sciences PhD Program, Department of Kinesiology, The University of Texas at El Paso, El Paso, TX, USA
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Gallego-Selles A, Galvan-Alvarez V, Martinez-Canton M, Garcia-Gonzalez E, Morales-Alamo D, Santana A, Gonzalez-Henriquez JJ, Dorado C, Calbet JAL, Martin-Rincon M. Fast regulation of the NF-κB signalling pathway in human skeletal muscle revealed by high-intensity exercise and ischaemia at exhaustion: Role of oxygenation and metabolite accumulation. Redox Biol 2022; 55:102398. [PMID: 35841628 PMCID: PMC9287614 DOI: 10.1016/j.redox.2022.102398] [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: 05/21/2022] [Accepted: 07/05/2022] [Indexed: 11/25/2022] Open
Abstract
The NF-κB signalling pathway plays a critical role in inflammation, immunity, cell proliferation, apoptosis, and muscle metabolism. NF-κB is activated by extracellular signals and intracellular changes in Ca2+, Pi, H+, metabolites and reactive oxygen and nitrogen species (RONS). However, it remains unknown how NF-κB signalling is activated during exercise and how metabolite accumulation and PO2 influence this process. Eleven active men performed incremental exercise to exhaustion (IE) in normoxia and hypoxia (PIO2:73 mmHg). Immediately after IE, the circulation of one leg was instantaneously occluded (300 mmHg). Muscle biopsies from m. vastus lateralis were taken before (Pre), and 10s (Post, occluded leg) and 60s after exercise from the occluded (Oc1m) and free circulation (FC1m) legs simultaneously together with femoral vein blood samples. NF-κB signalling was activated by exercise to exhaustion, with similar responses in normoxia and acute hypoxia, as reflected by the increase of p105, p50, IKKα, IκBβ and glutathione reductase (GR) protein levels, and the activation of the main kinases implicated, particularly IKKα and CaMKII δD, while IKKβ remained unchanged. Postexercise ischaemia maintained and stimulated further NF-κB signalling by impeding muscle reoxygenation. These changes were quickly reverted at the end of exercise when the muscles recovered with open circulation. Finally, we have shown that Thioredoxin 1 (Trx1) protein expression was reduced immediately after IE and after 1 min of occlusion while the protein expression levels of glutathione peroxidase 1 (Gpx1) and thioredoxin reductase 1 (TrxR1) remained unchanged. These novel data demonstrate that exercising to exhaustion activates NF-κB signalling in human skeletal muscle and regulates the expression levels of antioxidant enzymes in human skeletal muscle. The fast regulation of NF-κB at exercise cessation has implications for the interpretation of published studies and the design of new experiments.
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Affiliation(s)
- Angel Gallego-Selles
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Victor Galvan-Alvarez
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Miriam Martinez-Canton
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Eduardo Garcia-Gonzalez
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Canary Islands, Spain
| | - David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Alfredo Santana
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Canary Islands, Spain; Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Clinical Genetics Unit, 35016, Las Palmas de Gran Canaria, Spain
| | - Juan Jose Gonzalez-Henriquez
- Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Canary Islands, Spain; Department of Mathematics, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain
| | - Cecilia Dorado
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Jose A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Canary Islands, Spain; Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
| | - Marcos Martin-Rincon
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Canary Islands, Spain
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Interdisciplinary Co-Design Research Practice in the Rehabilitation of Elderly Individuals with Chronic Low Back Pain from a Senior Care Center in South Korea. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12094687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
The rehabilitation practices encounter multifaceted problems inherent in the current context of the elderly with chronic low back pain (LBP). We addressed a particular multifaceted problem in the current context using an interdisciplinary co-design research practice that consists of three phases: context exploration, patient-expert interaction, and patient-centered rehabilitation. Using an empirical study integrated with this practice, we investigated 30 Korean elderly patients suffering from LBP and introduced an exercise program design. In the context exploration phase, we found that the elderly patients neglected proper posture during work causing spine instability and resultantly developing chronic LBP. The patient–expert interaction phase explored latissimus dorsi (LD) and lumbar erector spinae (LES) muscles as the back trunk muscles that had caused LBP in most of these elderly patients. In the patient-centered rehabilitation phase, we designed an exercise program with exercise protocols and an exercise object for flexion and extension of trunk muscle relaxation and stabilization. Using electromyography (EMG), we found that the exercise program significantly increased the muscle activation levels of the muscles and reduced LBP. Our practice defines and addresses a multifaceted problem with several challenges both in healthcare design and the problem itself. This integrated approach can easily be expanded and adapted to other domain-related research projects that possess characteristics of complex problems.
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Jenkins JR, Salmon OF, Hill EC, Boyle JB, Smith CM. Neuromuscular responses at acute moderate and severe hypoxic exposure during fatiguing exercise of the biceps brachii. Curr Res Physiol 2021; 4:209-215. [PMID: 34746840 PMCID: PMC8562136 DOI: 10.1016/j.crphys.2021.09.002] [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: 08/03/2021] [Revised: 09/10/2021] [Accepted: 09/14/2021] [Indexed: 12/02/2022] Open
Abstract
Purpose The present study examined acute normobaric hypoxic exposure on the number of repetitions to failure, electromyographic (EMG) repetition duration (Time), EMG root mean square (RMS) and EMG mean power frequency (MPF) during biceps brachii (BB) dynamic constant external resistance (DCER) exercise. Methods Thirteen subjects performed two sets of fatiguing DCER arm curl repetitions to failure at 70% of their one repetition maximum under normoxic (NH), moderate hypoxia FiO2 = 15% (MH) and severe hypoxia FiO2 = 13% (SH). Electromyography of the BB was analyzed for EMG Time, EMG RMS, and EMG MPF. Repetitions were selected as 25%, 50%, 75%, and 100% of total repetitions (%Fail) completed. Pulse oximetry (SpO2) was measured pre-and post-fatigue. Results There was no significant three-way (Condition x Set x %Fail) or two-way (Condition x Set) interaction for any variable. The number of repetitions to failure significantly decreased from (mean ± SEM) 18.2 ± 1.4 to 9.5 ± 1.0 with each Set. In addition, EMG Time increased (25% < 50%<75% < 100%), EMG RMS decreased (50% > 75%>100%), and EMG MPF decreased (75% > 100%) as a result of fatiguing exercise. SpO2 was lower during MH (Δ5.3%) and SH (Δ9.2%) compared to NH and as a result of fatiguing exercise increased only in MH (Δ2.1%) and SH (Δ5.7%). Conclusion The changes in BB EMG variables indicated exercise caused myoelectric manifestations of fatigue, however, acute moderate or severe hypoxia had no additional influence on the rate of fatigue development or neuromuscular parameters. Acute MH (FiO2 15%) and SH (FiO2 14%) did not alter the muscle contractile process. Arm curl repetitions to failure decreased MU recruitment and conduction velocity. EMG fatigue analysis, hypoxia and arm curls to failure, EMG RMS, EMG MPF and Time. SpO2 was lower at MH and SH which increased following fatiguing exercise.
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Affiliation(s)
- Jasmin R Jenkins
- Interdisciplinary Health Sciences PhD Program, The University of Texas at El Paso, El Paso, TX, USA
| | - Owen F Salmon
- Interdisciplinary Health Sciences PhD Program, The University of Texas at El Paso, El Paso, TX, USA
| | - Ethan C Hill
- School of Kinesiology & Physical Therapy, Division of Kinesiology, University of Central Florida, Orlando, FL, USA
| | - Jason B Boyle
- Department of Kinesiology, The University of Texas at El Paso, El Paso, TX, USA
| | - Cory M Smith
- Interdisciplinary Health Sciences PhD Program, The University of Texas at El Paso, El Paso, TX, USA.,Department of Kinesiology, The University of Texas at El Paso, El Paso, TX, USA
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Electromyography: A Simple and Accessible Tool to Assess Physical Performance and Health during Hypoxia Training. A Systematic Review. SUSTAINABILITY 2020. [DOI: 10.3390/su12219137] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypoxia causes reduced partial pressure of oxygen in arterial blood and induces adaptations in skeletal muscle that may affect individuals’ physical performance and muscular health. These muscular changes are detectable and quantifiable by electromyography (EMG), an instrument that assesses electrical activity during active contraction at rest. EMG is a relatively simple and accessible technique for all patients, one that can show the degree of the sensory and motor functions because it provides information about the status of the peripheral nerves and muscles. The main goal of this review is to evaluate the scientific evidence of EMG as an instrument for monitoring different responses of skeletal muscles subjected to external stimuli such as hypoxia and physical activity. A structured search was conducted following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines in Medline/PubMed, Scielo, Google Scholar, Web of Science, and Cochrane Library Plus. The search included articles published in the last 25 years until May 2020 and was restricted to English- and Spanish-language publications. As such, investigators identified nine articles that met the search criteria. The results determined that EMG was able to detect muscle fatigue from changes in the frequency spectrum. When a muscle was fatigued, high frequency components decreased and low frequency components increased. In other studies, EMG determined muscle activation increased during exercise by recruiting motor units and by increasing the intensity of muscle contractions. Finally, it was also possible to calculate the mean quadriceps quadratic activity used to obtain an image of muscle activation. In conclusion, EMG offers a suitable tool for monitoring the different skeletal muscle responses and has sufficient sensitivity to detect hypoxia-induced muscle changes produced by hypoxic stimuli. Moreover, EMG enhances an extension of physical examination and tests motor-system integrity.
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Gallego-Selles A, Martin-Rincon M, Martinez-Canton M, Perez-Valera M, Martín-Rodríguez S, Gelabert-Rebato M, Santana A, Morales-Alamo D, Dorado C, Calbet JAL. Regulation of Nrf2/Keap1 signalling in human skeletal muscle during exercise to exhaustion in normoxia, severe acute hypoxia and post-exercise ischaemia: Influence of metabolite accumulation and oxygenation. Redox Biol 2020; 36:101627. [PMID: 32863217 PMCID: PMC7358388 DOI: 10.1016/j.redox.2020.101627] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/09/2020] [Accepted: 06/26/2020] [Indexed: 01/07/2023] Open
Abstract
The Nrf2 transcription factor is induced by reactive oxygen and nitrogen species and is necessary for the adaptive response to exercise in mice. It remains unknown whether Nrf2 signalling is activated by exercise in human skeletal muscle. Here we show that Nrf2 signalling is activated by exercise to exhaustion with similar responses in normoxia (PIO2: 143 mmHg) and severe acute hypoxia (PIO2: 73 mmHg). CaMKII and AMPKα phosphorylation were similarly induced in both conditions. Enhanced Nrf2 signalling was achieved by raising Nrf2 total protein and Ser40 Nrf2 phosphorylation, accompanied by a reduction of Keap1. Keap1 protein degradation is facilitated by the phosphorylation of p62/SQSTM1 at Ser349 by AMPK, which targets Keap1 for autophagic degradation. Consequently, the Nrf2-to-Keap1 ratio was markedly elevated and closely associated with a 2-3-fold increase in Catalase protein. No relationship was observed between Nrf2 signalling and SOD1 and SOD2 protein levels. Application of ischaemia immediately at the end of exercise maintained these changes, which were reverted within 1 min of recovery with free circulation. While SOD2 did not change significantly during either exercise or ischaemia, SOD1 protein expression was marginally downregulated and upregulated during exercise in normoxia and hypoxia, respectively. We conclude that Nrf2/Keap1/Catalase pathway is rapidly regulated during exercise and recovery in human skeletal muscle. Catalase emerges as an essential antioxidant enzyme acutely upregulated during exercise and ischaemia. Post-exercise ischaemia maintains Nrf2 signalling at the level reached at exhaustion and can be used to avoid early post-exercise recovery, which is O2-dependent.
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Affiliation(s)
- Angel Gallego-Selles
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe "Físico" s/n, 35017, Las Palmas de Gran Canaria, Spain
| | - Marcos Martin-Rincon
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe "Físico" s/n, 35017, Las Palmas de Gran Canaria, Spain
| | - Miriam Martinez-Canton
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe "Físico" s/n, 35017, Las Palmas de Gran Canaria, Spain
| | - Mario Perez-Valera
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe "Físico" s/n, 35017, Las Palmas de Gran Canaria, Spain
| | - Saúl Martín-Rodríguez
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe "Físico" s/n, 35017, Las Palmas de Gran Canaria, Spain
| | - Miriam Gelabert-Rebato
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe "Físico" s/n, 35017, Las Palmas de Gran Canaria, Spain
| | - Alfredo Santana
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas de Gran Canaria, 35017, Spain; Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Clinical Genetics Unit, 35016, Las Palmas de Gran Canaria, Spain
| | - David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe "Físico" s/n, 35017, Las Palmas de Gran Canaria, Spain
| | - Cecilia Dorado
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe "Físico" s/n, 35017, Las Palmas de Gran Canaria, Spain
| | - Jose A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas de Gran Canaria, 35017, Spain; Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Paseo Blas Cabrera Felipe "Físico" s/n, 35017, Las Palmas de Gran Canaria, Spain; Department of Physical Performance, The Norwegian School of Sport Sciences, Postboks, 4014 Ulleval Stadion, 0806, Oslo, Norway.
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10
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Jacunski M, Rafferty GF. The effects of hypoxia and fatigue on skeletal muscle electromechanical delay. Exp Physiol 2020; 105:842-851. [PMID: 32134528 DOI: 10.1113/ep088180] [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: 09/16/2019] [Accepted: 03/02/2020] [Indexed: 12/20/2022]
Abstract
NEW FINDINGS What is the central question of this study? What are the mechanisms underlying impaired muscular endurance and accelerated fatigue during acute hypoxia? What is the main finding and its importance? Hypoxia had no effect on the electrochemical latency associated with muscle contraction elicited by supramaximal electrical motor nerve stimulation in vivo. This provides greater insight into the effects of hypoxia and fatigue on the mechanisms of muscle contraction in vivo. ABSTRACT Acute hypoxia impairs muscle endurance and accelerates fatigue, but the underlying mechanisms, including any effects on muscle electrical activation, are incompletely understood. Electromyographic, mechanomyographic and force signals, elicited by common fibular nerve stimulation, were used to determine electromechanical delay (EMDTOT ) of the tibialis anterior muscle in normoxia and hypoxia ( F I O 2 0.125) at rest and following fatiguing ankle dorsiflexor exercise (60% maximum voluntary contraction, 5 s on, 3 s off) in 12 healthy participants (mean (SD) age 27.4 (9.0) years). EMDTOT was determined from electromyographic to force signal onset, electrical activation latency from electromyographic to mechanomyographic (EMDE-M ) and mechanical latency from mechanomyographic to force (EMDM-F ). Twitch force fell significantly following fatiguing exercise in normoxia (46.8 (14.7) vs. 20.6 (14.3) N, P = 0.0002) and hypoxia (52.9 (15.4) vs. 28.8 (15.2) N, P = 0.0006). No effect of hypoxia on twitch force at rest was observed. Fatiguing exercise resulted in significant increases in mean (SD) EMDTOT in normoxia (Δ 4.7 (4.57) ms P = 0.0152) and hypoxia (Δ 3.7 (4.06) ms P = 0.0384) resulting from increased mean (SD) EMDM-F only (normoxia Δ 4.1 (4.1) ms P = 0.0391, hypoxia Δ 3.4 (3.6) ms P = 0.0303). Mean (SD) EMDE-M remained unchanged during normoxic (Δ 0.6 (1.08) ms) and hypoxic (Δ 0.25 (0.75) ms) fatiguing exercise. No differences in percentage change from baseline for twitch force, EMDTOT , EMDE-M and EMDM-F between normoxic and hypoxic fatigue conditions were observed. Hypoxia in isolation or in combination with fatigue had no effect on the electrochemical latency associated with electrically evoked muscle contraction.
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Affiliation(s)
- Mark Jacunski
- Guy's, King's & St Thomas' School of Medical Education, Faculty of Life Sciences & Medicine, King's College London, London, UK
| | - Gerrard F Rafferty
- Centre for Human & Applied Physiological Sciences, School of Basic & Medical Biosciences, Faculty of Life Sciences & Medicine, King's College London, London, UK
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Inglis EC, Iannetta D, Murias JM. The plateau in the NIRS-derived [HHb] signal near the end of a ramp incremental test does not indicate the upper limit of O 2 extraction in the vastus lateralis. Am J Physiol Regul Integr Comp Physiol 2017; 313:R723-R729. [PMID: 28931547 DOI: 10.1152/ajpregu.00261.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 09/18/2017] [Accepted: 09/18/2017] [Indexed: 01/08/2023]
Abstract
This study aimed to examine, at the level of the active muscles, whether the plateau in oxygen (O2) extraction normally observed near the end of a ramp incremental (RI) exercise test to exhaustion is caused by the achievement of an upper limit in O2 extraction. Eleven healthy men (27.3 ± 3.0 yr, 81.6 ± 8.1 kg, 183.9 ± 6.3 cm) performed a RI cycling test to exhaustion. O2 extraction of the vastus lateralis (VL) was measured continuously throughout the test using the near-infrared spectroscopy (NIRS)-derived deoxygenated hemoglobin [HHb] signal. A leg blood flow occlusion was performed at rest (LBFOCC1) and immediately after the RI test (LBFOCC2). The [HHb] values during the resting occlusion (108.1 ± 21.7%; LBFOCC1) and the peak values during exercise (100 ± 0%; [HHb]plateau) were significantly greater than those observed at baseline (0.84 ± 10.6% at baseline 1 and 0 ± 0% at baseline 2) (P < 0.05). No significant difference was found between LBFOCC1 and [HHb]plateau (P > 0.05) or between the baseline measurements (P > 0.05). [HHb] values at LBFOCC2 (130.5 ± 19.7%) were significantly greater than all other time points (P < 0.05). These results support the existence of an O2 extraction reserve in the VL muscle at the end of a RI cycling test and suggest that the observed plateau in the [HHb] signal toward the end of a RI test is not representative of an upper limit in O2 extraction.
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Affiliation(s)
| | - Danilo Iannetta
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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Casuso RA, Aragón-Vela J, López-Contreras G, Gomes SN, Casals C, Barranco-Ruiz Y, Mercadé JJ, Huertas JR. Does Swimming at a Moderate Altitude Favor a Lower Oxidative Stress in an Intensity-Dependent Manner? Role of Nonenzymatic Antioxidants. High Alt Med Biol 2016; 18:46-55. [PMID: 27906593 DOI: 10.1089/ham.2016.0046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Casuso, Rafael A., Jerónimo Aragón-Vela, Gracia López-Contreras, Silvana N. Gomes, Cristina Casals, Yaira Barranco-Ruiz, Jordi J. Mercadé, and Jesus R. Huertas. Does swimming at a moderate altitude favor a lower oxidative stress in an intensity-dependent manner? Role of nonenzymatic antioxidants. High-Alt Med Biol. 18:46-55, 2017.-we aimed to describe oxidative damage and enzymatic and nonenzymatic antioxidant responses to swimming at different intensities in hypoxia. We recruited 12 highly experienced swimmers who have been involved in competitive swimming for at least 9 years. They performed a total of six swimming sessions carried out at low (LOW), moderate (MOD), or high (HIGH) intensity at low altitude (630 m) and at 2320 m above sea level. Blood samples were collected before the session (Pre), after the cool down (Post), and after 15 minutes of recovery (Rec). Blood lactate (BL) and heart rate were recorded throughout the main part of the session. Average velocities did not change between hypoxia and normoxia. We found a higher BL in response to MOD intensity in hypoxia. Plasmatic hydroperoxide level decreased at all intensities when swimming in hypoxia. This effect coincided with a lower glutation peroxidase activity and a marked mobilization of the circulating levels of α-tocopherol and coenzyme Q10 in an intensity-dependent manner. Our results suggest that, regardless of the intensity, no oxidative damage is found in response to hypoxic swimming in well-trained swimmers. Indeed, swimmers show a highly efficient antioxidant system by stimulating the mobilization of nonenzymatic antioxidants.
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Affiliation(s)
- Rafael A Casuso
- 1 Institute of Nutrition and Food Technology, Biomedical Research Centre, Department of Physiology, Faculty of Sport Sciences, University of Granada , Granada, Spain
| | - Jerónimo Aragón-Vela
- 1 Institute of Nutrition and Food Technology, Biomedical Research Centre, Department of Physiology, Faculty of Sport Sciences, University of Granada , Granada, Spain
| | - Gracia López-Contreras
- 2 Department of Physical Education and Sports, Faculty of Sport Sciences, University of Granada , Granada, Spain
| | - Silvana N Gomes
- 1 Institute of Nutrition and Food Technology, Biomedical Research Centre, Department of Physiology, Faculty of Sport Sciences, University of Granada , Granada, Spain
| | - Cristina Casals
- 1 Institute of Nutrition and Food Technology, Biomedical Research Centre, Department of Physiology, Faculty of Sport Sciences, University of Granada , Granada, Spain
| | - Yaira Barranco-Ruiz
- 3 Department of Physical Culture, Faculty of Health Sciences, School of Health Sciences, National University of Chimborazo Riobamba , Riobamba, Ecuador
| | - Jordi J Mercadé
- 4 Department of Athletic and Sport Management. University of Granada , Granada, Spain
| | - Jesus R Huertas
- 1 Institute of Nutrition and Food Technology, Biomedical Research Centre, Department of Physiology, Faculty of Sport Sciences, University of Granada , Granada, Spain
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Zinner C, Morales-Alamo D, Ørtenblad N, Larsen FJ, Schiffer TA, Willis SJ, Gelabert-Rebato M, Perez-Valera M, Boushel R, Calbet JAL, Holmberg HC. The Physiological Mechanisms of Performance Enhancement with Sprint Interval Training Differ between the Upper and Lower Extremities in Humans. Front Physiol 2016; 7:426. [PMID: 27746738 PMCID: PMC5043010 DOI: 10.3389/fphys.2016.00426] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 09/08/2016] [Indexed: 01/15/2023] Open
Abstract
To elucidate the mechanisms underlying the differences in adaptation of arm and leg muscles to sprint training, over a period of 11 days 16 untrained men performed six sessions of 4–6 × 30-s all-out sprints (SIT) with the legs and arms, separately, with a 1-h interval of recovery. Limb-specific VO2peak, sprint performance (two 30-s Wingate tests with 4-min recovery), muscle efficiency and time-trial performance (TT, 5-min all-out) were assessed and biopsies from the m. vastus lateralis and m. triceps brachii taken before and after training. VO2peak and Wmax increased 3–11% after training, with a more pronounced change in the arms (P < 0.05). Gross efficiency improved for the arms (+8.8%, P < 0.05), but not the legs (−0.6%). Wingate peak and mean power outputs improved similarly for the arms and legs, as did TT performance. After training, VO2 during the two Wingate tests was increased by 52 and 6% for the arms and legs, respectively (P < 0.001). In the case of the arms, VO2 was higher during the first than second Wingate test (64 vs. 44%, P < 0.05). During the TT, relative exercise intensity, HR, VO2, VCO2, VE, and Vt were all lower during arm-cranking than leg-pedaling, and oxidation of fat was minimal, remaining so after training. Despite the higher relative intensity, fat oxidation was 70% greater during leg-pedaling (P = 0.017). The aerobic energy contribution in the legs was larger than for the arms during the Wingate tests, although VO2 for the arms was enhanced more by training, reducing the O2 deficit after SIT. The levels of muscle glycogen, as well as the myosin heavy chain composition were unchanged in both cases, while the activities of 3-hydroxyacyl-CoA-dehydrogenase and citrate synthase were elevated only in the legs and capillarization enhanced in both limbs. Multiple regression analysis demonstrated that the variables that predict TT performance differ for the arms and legs. The primary mechanism of adaptation to SIT by both the arms and legs is enhancement of aerobic energy production. However, with their higher proportion of fast muscle fibers, the arms exhibit greater plasticity.
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Affiliation(s)
- Christoph Zinner
- Department of Sport Science, Julius Maximilians University WürzburgWürzburg, Germany; Swedish Winter Sports Research Centre, Mid Sweden UniversityÖstersund, Sweden
| | - David Morales-Alamo
- Research Institute of Biomedical and Health Sciences (IUIBS) and Department of Physical Education, University of Las Palmas de Gran Canaria Las Palmas, Spain
| | - Niels Ørtenblad
- Swedish Winter Sports Research Centre, Mid Sweden UniversityÖstersund, Sweden; Institute of Sports Science and Clinical Biomechanics, University of Southern DenmarkOdense, Denmark
| | - Filip J Larsen
- Swedish School of Sport and Health Sciences Stockholm, Sweden
| | - Tomas A Schiffer
- Department of Medical and Health Sciences, Linköping University Linköping, Sweden
| | - Sarah J Willis
- Swedish Winter Sports Research Centre, Mid Sweden University Östersund, Sweden
| | - Miriam Gelabert-Rebato
- Research Institute of Biomedical and Health Sciences (IUIBS) and Department of Physical Education, University of Las Palmas de Gran Canaria Las Palmas, Spain
| | - Mario Perez-Valera
- Research Institute of Biomedical and Health Sciences (IUIBS) and Department of Physical Education, University of Las Palmas de Gran Canaria Las Palmas, Spain
| | - Robert Boushel
- School of Kinesiology, University of British Columbia Vancouver, BC, Canada
| | - Jose A L Calbet
- Research Institute of Biomedical and Health Sciences (IUIBS) and Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas, Spain; School of Kinesiology, University of British ColumbiaVancouver, BC, Canada
| | - Hans-Christer Holmberg
- Swedish Winter Sports Research Centre, Mid Sweden UniversityÖstersund, Sweden; School of Kinesiology, University of British ColumbiaVancouver, BC, Canada; School of Sport Sciences, UiT Arctic University of NorwayTromsø, Norway
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14
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Torres-Peralta R, Losa-Reyna J, Morales-Alamo D, González-Izal M, Pérez-Suárez I, Ponce-González JG, Izquierdo M, Calbet JAL. Increased PIO2 at Exhaustion in Hypoxia Enhances Muscle Activation and Swiftly Relieves Fatigue: A Placebo or a PIO2 Dependent Effect? Front Physiol 2016; 7:333. [PMID: 27582710 PMCID: PMC4987359 DOI: 10.3389/fphys.2016.00333] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 07/20/2016] [Indexed: 12/30/2022] Open
Abstract
To determine the level of hypoxia from which muscle activation (MA) is reduced during incremental exercise to exhaustion (IE), and the role played by PIO2 in this process, ten volunteers (21 ± 2 years) performed four IE in severe acute hypoxia (SAH) (PIO2 = 73 mmHg). Upon exhaustion, subjects were asked to continue exercising while the breathing gas mixture was swiftly changed to a placebo (73 mmHg) or to a higher PIO2 (82, 92, 99, and 142 mmHg), and the IE continued until a new exhaustion. At the second exhaustion, the breathing gas was changed to room air (normoxia) and the IE continued until the final exhaustion. MA, as reflected by the vastus medialis (VM) and lateralis (VL) EMG raw and normalized root mean square (RMSraw, and RMSNz, respectively), normalized total activation index (TAINz), and burst duration were 8–20% lower at exhaustion in SAH than in normoxia (P < 0.05). The switch to a placebo or higher PIO2 allowed for the continuation of exercise in all instances. RMSraw, RMSNz, and TAINz were increased by 5–11% when the PIO2 was raised from 73 to 92, or 99 mmHg, and VL and VM averaged RMSraw by 7% when the PIO2 was elevated from 73 to 142 mmHg (P < 0.05). The increase of VM-VL average RMSraw was linearly related to the increase in PIO2, during the transition from SAH to higher PIO2 (R2 = 0.915, P < 0.05). In conclusion, increased PIO2 at exhaustion reduces fatigue and allows for the continuation of exercise in moderate and SAH, regardless of the effects of PIO2 on MA. At task failure, MA is increased during the first 10 s of increased PIO2 when the IE is performed at a PIO2 close to 73 mmHg and the PIO2 is increased to 92 mmHg or higher. Overall, these findings indicate that one of the central mechanisms by which severe hypoxia may cause central fatigue and task failure is by reducing the capacity for reaching the appropriate level of MA to sustain the task. The fact that at exhaustion in severe hypoxia the exercise was continued with the placebo-gas mixture demonstrates that this central mechanism has a cognitive component.
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Affiliation(s)
- Rafael Torres-Peralta
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas, Spain; Research Institute of Biomedical and Health Sciences, Instituto Universitario de Investigaciones Biomédicas y SanitariasLas Palmas, Spain
| | - José Losa-Reyna
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas, Spain; Research Institute of Biomedical and Health Sciences, Instituto Universitario de Investigaciones Biomédicas y SanitariasLas Palmas, Spain
| | - David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas, Spain; Research Institute of Biomedical and Health Sciences, Instituto Universitario de Investigaciones Biomédicas y SanitariasLas Palmas, Spain
| | | | - Ismael Pérez-Suárez
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas, Spain; Research Institute of Biomedical and Health Sciences, Instituto Universitario de Investigaciones Biomédicas y SanitariasLas Palmas, Spain
| | - Jesús G Ponce-González
- Department of Physical Education, University of Las Palmas de Gran Canaria Las Palmas, 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, Spain; Research Institute of Biomedical and Health Sciences, Instituto Universitario de Investigaciones Biomédicas y SanitariasLas Palmas, Spain
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15
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Girard O, Bula S, Faiss R, Brocherie F, Millet GY, Millet GP. Does altitude level of a prior time-trial modify subsequent exercise performance in hypoxia and associated neuromuscular responses? Physiol Rep 2016. [PMCID: PMC4962066 DOI: 10.14814/phy2.12804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We examined the influence of prior time‐trials performed at different altitudes on subsequent exercise in moderate hypoxia and associated cardiometabolic and neuromuscular responses. In normobaric hypoxia (simulated altitude 2000 m; FiO2: 0.163), 10 healthy males performed (1) an incremental test to exhaustion (VO2max_2000) and (2) a test to exhaustion at 80% of the power output associated to VO2max_2000 for a reference time (947 ± 336 sec). Thereafter, two sessions were conducted in a randomized order: a cycle time‐trial corresponding to the reference time (TT1) followed 22 min later (passive rest at 2000 m) by a 6‐min cycle time‐trial (TT2). TT1 was either performed at 2000 or 3500 m (FiO2: 0.135), while TT2 was always performed at 2000 m. As expected, during TT1, the mean power output (247 ± 42 vs. 227 ± 37 W; P < 0.001) was higher at 2000 than 3500 m. During TT2, the mean power output (256 ± 42 vs. 252 ± 36 W) did not differ between conditions. Before and after TT1, maximal isometric voluntary contraction torque in knee extensors (pooled conditions: −7.9 ± 8.4%; P < 0.01), voluntary activation (−4.1 ± 3.1%; P < 0.05), and indices of muscle contractility (peak twitch torque: −39.1 ± 11.9%; doublet torques at 100 Hz: −15.4 ± 8.9%; 10/100 Hz ratio: −25.8 ± 7.7%; all P < 0.001) were equally reduced at 2000 m or 3500 m. Irrespective of the altitude of TT1, neuromuscular function remained similarly depressed after TT1 both before and after TT2 at 2000 m. A prior time‐trial performed at different altitude influenced to the same extent performance and associated cardiometabolic and neuromuscular responses during a subsequent exercise in moderate hypoxia.
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Affiliation(s)
- Olivier Girard
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Simone Bula
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Raphaël Faiss
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Franck Brocherie
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Guillaume Y. Millet
- Human Performance Laboratory; Faculty of Kinesiology; University of Calgary; Calgary AB Canada
| | - Grégoire P. Millet
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
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Farra SD, Kessler C, Duffin J, Wells GD, Jacobs I. Clamping end-tidal carbon dioxide during graded exercise with control of inspired oxygen. Respir Physiol Neurobiol 2016; 231:28-36. [PMID: 27236039 DOI: 10.1016/j.resp.2016.05.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 03/31/2016] [Accepted: 05/25/2016] [Indexed: 11/29/2022]
Abstract
Exercise- and hypoxia-induced hyperventilation decreases the partial pressure of end-tidal carbon dioxide (PETCO2), which in turn exerts many physiological effects. Several breathing circuits that control PETCO2 have been previously described, but their designs are not satisfactory for exercise studies where changes in inspired oxygen (FIO2) may be desired. This study is the first report of a breathing system that can maintain PETCO2 constant within a single session of graded submaximal exercise and graded hypoxia. Thirteen fit and healthy subjects completed two bouts of exercise consisting of three 3min stages on a cycle ergometer with increasing exercise intensity in normoxia (Part A; 142±14, 167±14, 192±14W) or with decreasing FIO2 at a constant exercise intensity (Part B; 21, 18, and 14%). One bout was a control (CON) where PETCO2 was not manipulated, while during the other bout the investigator clamped PETCO2 within 2mmHg (CO2Clamp) using sequential gas delivery (SGD). During the final 30s of each exercise stage during CO2Clamp, PETCO2 was successfully maintained in Part A (43±4, 44±4, 44±3mmHg; P=0.44) and Part B (45±3, 46±3, 45±3mmHg; P=0.68) despite the increases in ventilation due to exercise. These findings demonstrate that this SGD circuit can be used to maintain isocapania in exercising humans during progressively increasing exercise intensities and changing FIO2.
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Affiliation(s)
- Saro D Farra
- Faculty of Kinesiology & Physical Education, University of Toronto, Toronto, Canada
| | - Cathie Kessler
- Faculty of Kinesiology & Physical Education, University of Toronto, Toronto, Canada
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, Canada
| | - Greg D Wells
- Faculty of Kinesiology & Physical Education, University of Toronto, Toronto, Canada
| | - Ira Jacobs
- Faculty of Kinesiology & Physical Education, University of Toronto, Toronto, 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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Morales-Artacho AJ, Padial P, Rodríguez-Matoso D, Rodríguez-Ruiz D, García-Ramos A, García-Manso JM, Calderón C, Feriche B. Assessment of Muscle Contractile Properties at Acute Moderate Altitude Through Tensiomyography. High Alt Med Biol 2015; 16:343-9. [PMID: 26562625 DOI: 10.1089/ham.2015.0078] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Under hypoxia, alterations in muscle contractile properties and faster fatigue development have been reported. This study investigated the efficacy of tensiomyography (TMG) in assessing muscle contractile function at acute moderate altitude. Biceps femoris (BF) and vastus lateralis (VL) muscles of 18 athletes (age 20.1 ± 6.1 years; body mass 65.4 ± 13.9 kg; height 174.6 ± 9.5 cm) were assessed at sea level and moderate altitude using electrically evoked contractions on two consecutive days. Maximum radial displacement (Dm), time of contraction (Tc), reaction time (Td), sustained contraction time (Ts), and relaxation time (Tr) were recorded at 40, 60, 80, and 100 mA. At altitude, VL showed lower Dm values at 40 mA (p = 0.008; ES = -0.237). Biceps femoris showed Dm decrements in all electrical stimulations (p < 0.001, ES > 0.61). In VL, Tc was longer at altitude at 40 (p = 0.031, ES = 0.56), and 100 mA (p = 0.03, ES = 0.51). Regarding Td, VL showed significant increases in all electrical intensities under hypoxia (p ≤ 0.03, ES ≥ 0.33). TMG appears effective at detecting slight changes in the muscle contractile properties at moderate altitude. Further research involving TMG along with other muscle function assessment methods is needed to provide additional insight into peripheral neuromuscular alterations at moderate altitude.
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Affiliation(s)
- Antonio J Morales-Artacho
- 1 Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada , Granada, Spain
| | - Paulino Padial
- 1 Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada , Granada, Spain
| | | | | | - Amador García-Ramos
- 1 Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada , Granada, Spain
| | | | - Carmen Calderón
- 3 Sport Performance Centre of Sierra Nevada , Granada, Spain
| | - Belén Feriche
- 1 Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada , Granada, Spain
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Influence of Hypoxic Interval Training and Hyperoxic Recovery on Muscle Activation and Oxygenation in Connection with Double-Poling Exercise. PLoS One 2015; 10:e0140616. [PMID: 26468885 PMCID: PMC4607305 DOI: 10.1371/journal.pone.0140616] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/27/2015] [Indexed: 12/19/2022] Open
Abstract
Here, we evaluated the influence of breathing oxygen at different partial pressures during recovery from exercise on performance at sea-level and a simulated altitude of 1800 m, as reflected in activation of different upper body muscles, and oxygenation of the m. triceps brachii. Ten well-trained, male endurance athletes (25.3±4.1 yrs; 179.2±4.5 cm; 74.2±3.4 kg) performed four test trials, each involving three 3-min sessions on a double-poling ergometer with 3-min intervals of recovery. One trial was conducted entirely under normoxic (No) and another under hypoxic conditions (Ho; FiO2 = 0.165). In the third and fourth trials, the exercise was performed in normoxia and hypoxia, respectively, with hyperoxic recovery (HOX; FiO2 = 1.00) in both cases. Arterial hemoglobin saturation was higher under the two HOX conditions than without HOX (p<0.05). Integrated muscle electrical activity was not influenced by the oxygen content (best d = 0.51). Furthermore, the only difference in tissue saturation index measured via near-infrared spectroscopy observed was between the recovery periods during the NoNo and HoHOX interventions (P<0.05, d = 0.93). In the case of HoHo the athletes’ Pmean declined from the first to the third interval (P < 0.05), whereas Pmean was unaltered under the HoHOX, NoHOX and NoNo conditions. We conclude that the less pronounced decline in Pmean during 3 x 3-min double-poling sprints in normoxia and hypoxia with hyperoxic recovery is not related to changes in muscle activity or oxygenation. Moreover, we conclude that hyperoxia (FiO2 = 1.00) used in conjunction with hypoxic or normoxic work intervals may serve as an effective aid when inhaled during the subsequent recovery intervals.
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Morales-Alamo D, Losa-Reyna J, Torres-Peralta R, Martin-Rincon M, Perez-Valera M, Curtelin D, Ponce-González JG, Santana A, Calbet JAL. What limits performance during whole-body incremental exercise to exhaustion in humans? J Physiol 2015; 593:4631-48. [PMID: 26250346 DOI: 10.1113/jp270487] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 07/29/2015] [Indexed: 12/13/2022] Open
Abstract
To determine the mechanisms causing task failure during incremental exercise to exhaustion (IE), sprint performance (10 s all-out isokinetic) and muscle metabolites were measured before (control) and immediately after IE in normoxia (P(IO2) 143 mmHg) and hypoxia (P(IO2): 73 mmHg) in 22 men (22 ± 3 years). After IE, subjects recovered for either 10 or 60 s, with open circulation or bilateral leg occlusion (300 mmHg) in random order. This was followed by a 10 s sprint with open circulation. Post-IE peak power output (W(peak)) was higher than the power output reached at exhaustion during IE (P < 0.05). After 10 and 60 s recovery in normoxia, W(peak) was reduced by 38 ± 9 and 22 ± 10% without occlusion, and 61 ± 8 and 47 ± 10% with occlusion (P < 0.05). Following 10 s occlusion, W(peak) was 20% higher in hypoxia than normoxia (P < 0.05), despite similar muscle lactate accumulation ([La]) and phosphocreatine and ATP reduction. Sprint performance and anaerobic ATP resynthesis were greater after 60 s compared with 10 s occlusions, despite the higher [La] and [H(+)] after 60 s compared with 10 s occlusion recovery (P < 0.05). The mean rate of ATP turnover during the 60 s occlusion was 0.180 ± 0.133 mmol (kg wet wt)(-1) s(-1), i.e. equivalent to 32% of leg peak O2 uptake (the energy expended by the ion pumps). A greater degree of recovery is achieved, however, without occlusion. In conclusion, during incremental exercise task failure is not due to metabolite accumulation or lack of energy resources. Anaerobic metabolism, despite the accumulation of lactate and H(+), facilitates early recovery even in anoxia. This points to central mechanisms as the principal determinants of task failure both in normoxia and hypoxia, with lower peripheral contribution in hypoxia.
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Affiliation(s)
- David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las 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 Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - Rafael Torres-Peralta
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - Marcos Martin-Rincon
- Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain.,Department of Sports and Informatics, Pablo de Olavide University, Seville, Spain
| | - Mario Perez-Valera
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - David Curtelin
- Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain.,Emergency Medicine Department, Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Avenida Marítima del Sur, s/n, 35016, Las Palmas de Gran Canaria, Spain
| | - Jesús Gustavo Ponce-González
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain
| | - Alfredo Santana
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain.,Clinical Genetics Unit, Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Avenida Marítima, del Sur, s/n, 35016, Las Palmas de Gran Canaria, Spain
| | - José A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
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21
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Calbet JAL, Losa-Reyna J, Torres-Peralta R, Rasmussen P, Ponce-González JG, Sheel AW, de la Calle-Herrero J, Guadalupe-Grau A, Morales-Alamo D, Fuentes T, Rodríguez-García L, Siebenmann C, Boushel R, Lundby C. Limitations to oxygen transport and utilization during sprint exercise in humans: evidence for a functional reserve in muscle O2 diffusing capacity. J Physiol 2015; 593:4649-64. [PMID: 26258623 DOI: 10.1113/jp270408] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 08/05/2015] [Indexed: 12/14/2022] Open
Abstract
To determine the contribution of convective and diffusive limitations to V̇(O2peak) during exercise in humans, oxygen transport and haemodynamics were measured in 11 men (22 ± 2 years) during incremental (IE) and 30 s all-out cycling sprints (Wingate test, WgT), in normoxia (Nx, P(IO2): 143 mmHg) and hypoxia (Hyp, P(IO2): 73 mmHg). Carboxyhaemoglobin (COHb) was increased to 6-7% before both WgTs to left-shift the oxyhaemoglobin dissociation curve. Leg V̇(O2) was measured by the Fick method and leg blood flow (BF) with thermodilution, and muscle O2 diffusing capacity (D(MO2)) was calculated. In the WgT mean power output, leg BF, leg O2 delivery and leg V̇(O2) were 7, 5, 28 and 23% lower in Hyp than Nx (P < 0.05); however, peak WgT D(MO2) was higher in Hyp (51.5 ± 9.7) than Nx (20.5 ± 3.0 ml min(-1) mmHg(-1), P < 0.05). Despite a similar P(aO2) (33.3 ± 2.4 and 34.1 ± 3.3 mmHg), mean capillary P(O2) (16.7 ± 1.2 and 17.1 ± 1.6 mmHg), and peak perfusion during IE and WgT in Hyp, D(MO2) and leg V̇(O2) were 12 and 14% higher, respectively, during WgT than IE in Hyp (both P < 0.05). D(MO2) was insensitive to COHb (COHb: 0.7 vs. 7%, in IE Hyp and WgT Hyp). At exhaustion, the Y equilibration index was well above 1.0 in both conditions, reflecting greater convective than diffusive limitation to the O2 transfer in both Nx and Hyp. In conclusion, muscle V̇(O2) during sprint exercise is not limited by O2 delivery, O2 offloading from haemoglobin or structure-dependent diffusion constraints in the skeletal muscle. These findings reveal a remarkable functional reserve in muscle O2 diffusing capacity.
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Affiliation(s)
- José A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, Canary Islands, 35017, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, 35016 Las Palmas de Gran Canaria, Canary Islands, Spain
| | - José Losa-Reyna
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, Canary Islands, 35017, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, 35016 Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Rafael Torres-Peralta
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, Canary Islands, 35017, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, 35016 Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Peter Rasmussen
- Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Jesús Gustavo Ponce-González
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, Canary Islands, 35017, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, 35016 Las Palmas de Gran Canaria, Canary Islands, Spain
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jaime de la Calle-Herrero
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, Canary Islands, 35017, Spain
| | - Amelia Guadalupe-Grau
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, Canary Islands, 35017, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, 35016 Las Palmas de Gran Canaria, Canary Islands, Spain
| | - David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, Canary Islands, 35017, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, 35016 Las Palmas de Gran Canaria, Canary Islands, Spain
| | - Teresa Fuentes
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, Canary Islands, 35017, Spain
| | - Lorena Rodríguez-García
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, Canary Islands, 35017, Spain
| | - Christoph Siebenmann
- Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Robert Boushel
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada.,Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Carsten Lundby
- Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
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