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Reihlen P, Blobel M, Weiß P, Harth J, Wittmann J, Leenders F, Thevis M. Introduction of a PEGylated EPO conjugate as internal standard for EPO analysis in doping controls. Drug Test Anal 2024; 16:743-749. [PMID: 34905300 DOI: 10.1002/dta.3211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/22/2021] [Accepted: 11/22/2021] [Indexed: 11/07/2022]
Abstract
Immunopurification of doping control samples is a mandatory necessity in erythropoietin (EPO) analysis during a confirmation procedure; moreover, it has become common practice to also immunopurify samples for the initial testing procedure. Typically used materials (e.g., Stemcell purification plate and MAIIA purification kit) rely on anti-EPO antibodies for purification. Also, the detection of EPO after electrophoretic separation and western blotting is based on a monoclonal anti-EPO antibody, clone AE7A5, directed against a 26 amino acid sequence of the N-terminal region of human EPO. While the electrophoretic separation and blot transfer efficiency can be monitored with reference standards and quality control samples, it is presently not possible to monitor the functionality of the entire sample preparation procedure. The reliance on antibodies for both purification and detection has complicated the implementation of an internal standard (ISTD). In this study, customized EPO-polyethylene glycol (PEG) conjugates were synthesized as potential ISTDs and assessed as to their compatibility with existing sample preparation procedures for urine and blood sample analysis using the most common immunopurification techniques. Moreover, probing for the impact of the ISTD on sodium N-lauroylsarcosinate ("sarcosyl") polyacrylamide gel electrophoresis (SAR-PAGE)-based EPO analysis concerning potential interference with target analytes was conducted. The presented data demonstrate that a 12-kDa PEG residue attached to human EPO represents a particularly useful construct to serve as ISTD for erythropoietin-receptor agonist (ERA) analysis. The conjugate is applicable to both urine and blood testing using the commonly employed purification techniques, supporting and improving result interpretations especially concerning specimens where the natural abundance of human EPO is low.
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Affiliation(s)
- Phillipp Reihlen
- Intitute of Biochemistry, German Sport University Cologne, Cologne, Germany
| | - Mike Blobel
- Intitute of Biochemistry, German Sport University Cologne, Cologne, Germany
| | - Patrick Weiß
- Intitute of Biochemistry, German Sport University Cologne, Cologne, Germany
| | - Judith Harth
- Intitute of Biochemistry, German Sport University Cologne, Cologne, Germany
| | | | | | - Mario Thevis
- Center for Preventive Doping Research, Institute of Biochemistry, German Sport University Cologne, Cologne, Germany
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2
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Lichtman MA, Prchal JT. Measurement of red cell, plasma and blood volume: Essential components of diagnostic and research studies of oxygen transport. Blood Cells Mol Dis 2024; 105:102819. [PMID: 38101224 DOI: 10.1016/j.bcmd.2023.102819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 12/04/2023] [Indexed: 12/17/2023]
Affiliation(s)
- Marshall A Lichtman
- Department of Medicine, James P. Wilmot Cancer Institute, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642-0001, USA.
| | - Josef T Prchal
- Division of Hematology & Hematologic Malignancies, Huntsman Cancer Institute, The University of Utah School of Medicine, 30 North 1900 East, Salt Lake City, UT 84132, USA.
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3
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Endo Y, Zhu C, Giunta E, Guo C, Koh DJ, Sinha I. The Role of Hypoxia and Hypoxia Signaling in Skeletal Muscle Physiology. Adv Biol (Weinh) 2024; 8:e2200300. [PMID: 37817370 DOI: 10.1002/adbi.202200300] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 04/06/2023] [Indexed: 10/12/2023]
Abstract
Hypoxia and hypoxia signaling play an integral role in regulating skeletal muscle physiology. Environmental hypoxia and tissue hypoxia in muscles cue for their appropriate physiological response and adaptation, and cause an array of cellular and metabolic changes. In addition, muscle stem cells (satellite cells), exist in a hypoxic state, and this intrinsic hypoxic state correlates with their quiescence and stemness. The mechanisms of hypoxia-mediated regulation of satellite cells and myogenesis are yet to be characterized, and their seemingly contradicting effects reported leave their exact roles somewhat perplexing. This review summarizes the recent findings on the effect of hypoxia and hypoxia signaling on the key aspects of muscle physiology, namely, stem cell maintenance and myogenesis with a particular attention given to distinguish the intrinsic versus local hypoxia in an attempt to better understand their respective regulatory roles and how their relationship affects the overall response. This review further describes their mechanistic links and their possible implications on the relevant pathologies and therapeutics.
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Affiliation(s)
- Yori Endo
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Brigham and Women's Hospital, Harvard University, Boston, MA, 02115, USA
| | - Christina Zhu
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Brigham and Women's Hospital, Harvard University, Boston, MA, 02115, USA
- Texas Tech University Health Sciences Center School of Medicine, Lubbock, TX, 79430, USA
| | - Elena Giunta
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Brigham and Women's Hospital, Harvard University, Boston, MA, 02115, USA
- Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539, München, Germany
| | - Cynthia Guo
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Brigham and Women's Hospital, Harvard University, Boston, MA, 02115, USA
- Warren Alpert Medical School, Brown University, Providence, RI, 02903, USA
| | - Daniel J Koh
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Brigham and Women's Hospital, Harvard University, Boston, MA, 02115, USA
| | - Indranil Sinha
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Brigham and Women's Hospital, Harvard University, Boston, MA, 02115, USA
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4
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Prchal JT, Lichtman MA. Measurement of red cell, plasma, and blood volume: A perspective. Am J Hematol 2024; 99:9-11. [PMID: 37966977 DOI: 10.1002/ajh.27158] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 11/03/2023] [Indexed: 11/17/2023]
Affiliation(s)
- Josef T Prchal
- Division of Hematology & Hematologic Malignancies, Huntsman Cancer Institute, The University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Marshall A Lichtman
- Department of Medicine (Hematology), James P. Wilmot Cancer Institute, University of Rochester Medical Center, Rochester, New York, USA
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Breenfeldt Andersen A, Nordsborg NB, Bonne TC, Bejder J. Contemporary blood doping-Performance, mechanism, and detection. Scand J Med Sci Sports 2024; 34:e14243. [PMID: 36229224 DOI: 10.1111/sms.14243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 10/04/2022] [Accepted: 10/09/2022] [Indexed: 10/17/2022]
Abstract
Blood doping is prohibited for athletes but has been a well-described practice within endurance sports throughout the years. With improved direct and indirect detection methods, the practice has allegedly moved towards micro-dosing, that is, reducing the blood doping regime amplitude. This narrative review evaluates whether blood doping, specifically recombinant human erythropoietin (rhEpo) treatment and blood transfusions are performance-enhancing, the responsible mechanism as well as detection possibilities with a special emphasis on micro-dosing. In general, studies evaluating micro-doses of blood doping are limited. However, in randomized, double-blinded, placebo-controlled trials, three studies find that infusing as little as 130 ml red blood cells or injecting 9 IU × kg bw-1 rhEpo three times per week for 4 weeks improve endurance performance ~4%-6%. The responsible mechanism for a performance-enhancing effect following rhEpo or blood transfusions appear to be increased O2 -carrying capacity, which is accompanied by an increased muscular O2 extraction and likely increased blood flow to the working muscles, enabling the ability to sustain a higher exercise intensity for a given period. Blood doping in micro-doses challenges indirect detection by the Athlete Biological Passport, albeit it can identify ~20%-60% of the individuals depending on the sample timing. However, novel biomarkers are emerging, and some may provide additive value for detection of micro blood doping such as the immature reticulocytes or the iron regulatory hormones hepcidin and erythroferrone. Future studies should attempt to validate these biomarkers for implementation in real-world anti-doping efforts and continue the biomarker discovery.
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Affiliation(s)
- Andreas Breenfeldt Andersen
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
- Department of Public Health, Section for Sport Science, Aarhus University, Aarhus, Denmark
| | | | - Thomas Christian Bonne
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Jacob Bejder
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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Lundby C, Mazza O, Nielsen J, Haubro M, Kvorning T, Ørtenblad N, Gejl KD. Eight weeks of heavy strength training increases hemoglobin mass and V̇o 2peak in well-trained to elite female and male rowers. J Appl Physiol (1985) 2024; 136:1-12. [PMID: 37942530 DOI: 10.1152/japplphysiol.00587.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 10/19/2023] [Accepted: 11/06/2023] [Indexed: 11/10/2023] Open
Abstract
O2-transport and endurance exercise performance are greatly influenced by hemoglobin mass (Hbmass), which largely depends on lean body mass (LBM). This study investigated the effects of 8 wk with three weekly sessions of conventional (3-SET: 3 × 10 reps) or high-volume strength training (10-SET: 5-10 × 10 reps) on LBM, Hbmass, muscle strength, and exercise performance in female and male rowers. Hematological parameters were obtained through CO rebreathing and body composition by dual-energy X-ray absorptiometry (DEXA) scans before and after the training period. Concomitantly, V̇o2peak was determined during 2-km ergometer rowing and muscle strength by isometric midthigh pull. There were no differences in training responses between groups for any of the parameters. Pooled data revealed overall increments for Hbmass (10-SET: 882 ± 199 g to 897 ± 213 g; 3-SET: 936 ± 245 g to 962 ± 247 g, P = 0.02) and V̇o2peak (10-SET: 4.3 ± 1.0 to 4.4 ± 0.9 L·min-1; 3-SET: 4.5 ± 0.9 to 4.6 ± 0.9 L·min-1, P = 0.03), whereas LBM remained unchanged (10-SET: 58.7 ± 10.5 to 58.7 ± 10.1 kg; 3-SET: 64.1 ± 10.8 to 64.5 ± 10.6 kg, P = 0.42). Maximal isometric midthigh pull strength increased (10-SET: 224 ± 47 kg to 237 ± 55 kg; 3-SET: 256 ± 77 kg to 281 ± 83 kg, P = 0.001). Strong associations were observed between LBM and Hbmass and V̇o2peak (r2 = 0.88-0.90), entailing sex differences in Hbmass and V̇o2peak. Normalizing V̇o2peak to LBM reduced the sex difference to ∼10%, aligning with the sex difference in Hbmass·LBM-1. Strength training successfully increased Hbmass and V̇o2peak in elite female and male rowers, without an additional effect from increased training volume. Moreover, sex differences in V̇o2peak were mainly explained by differences in LBM, but likely also by differences in Hbmass·LBM-1.NEW & NOTEWORTHY This study in female and male rowers demonstrates that hemoglobin mass (Hbmass), V̇o2peak, and muscle strength increases with 8 wk of heavy strength training and that this response is not different between conventional (3 × 10 repetitions) and high-volume strength training (10 × 10 repetitions). Moreover, female rowers exhibited less hemoglobin per kilogram of lean body mass compared with their male counterparts, which likely contributes to sex differences in V̇o2peak and rowing performance.
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Affiliation(s)
- Carsten Lundby
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, Norway
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Oscar Mazza
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Joachim Nielsen
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Mads Haubro
- The Danish Rowing Federation, Bagsvaerd, Denmark
| | - Thue Kvorning
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Kasper Degn Gejl
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
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Hassanpour M, Salybekov AA. Whispers in the Blood: Leveraging MicroRNAs for Unveiling Autologous Blood Doping in Athletes. Int J Mol Sci 2023; 25:249. [PMID: 38203416 PMCID: PMC10779309 DOI: 10.3390/ijms25010249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 01/12/2024] Open
Abstract
The prevalence of autologous blood transfusions (ABTs) presents a formidable challenge in maintaining fair competition in sports, as it significantly enhances hemoglobin mass and oxygen capacity. In recognizing ABT as a prohibited form of doping, the World Anti-Doping Agency (WADA) mandates stringent detection methodologies. While current methods effectively identify homologous erythrocyte transfusions, a critical gap persists in detecting autologous transfusions. The gold standard practice of longitudinally monitoring hematological markers exhibits promise but is encumbered by limitations. Despite its potential, instances of blood doping often go undetected due to the absence of definitive verification processes. Moreover, some cases remain unpenalized due to conservative athlete-sanctioning approaches. This gap underscores the imperative need for a more reliable and comprehensive detection method capable of unequivocally differentiating autologous transfusions, addressing the challenges faced in accurately identifying such prohibited practices. The development of an advanced detection methodology is crucial to uphold the integrity of anti-doping measures, effectively identifying and penalizing instances of autologous blood transfusion. This, in turn, safeguards the fairness and equality essential to competitive sports. Our review tackles this critical gap by harnessing the potential of microRNAs in ABT doping detection. We aim to summarize alterations in the total microRNA profiles of erythrocyte concentrates during storage and explore the viability of observing these changes post-transfusion. This innovative approach opens avenues for anti-doping technologies and commercialization, positioning it as a cornerstone in the ongoing fight against doping in sports and beyond. The significance of developing a robust detection method cannot be overstated, as it ensures the credibility of anti-doping efforts and promotes a level playing field for all athletes.
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8
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Poffé C, Robberechts R, Van Thienen R, Hespel P. Exogenous ketosis elevates circulating erythropoietin and stimulates muscular angiogenesis during endurance training overload. J Physiol 2023; 601:2345-2358. [PMID: 37062892 DOI: 10.1113/jp284346] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 04/12/2023] [Indexed: 04/18/2023] Open
Abstract
De novo capillarization is a primary muscular adaptation to endurance exercise training and is crucial to improving performance. Excess training load, however, impedes such beneficial adaptations, yet we recently demonstrated that such downregulation may be counteracted by ketone ester ingestion (KE) post-exercise. Therefore, we investigated whether KE could increase pro-angiogenic factors and thereby stimulate muscular angiogenesis during a 3-week endurance training-overload period involving 10 training sessions/week in healthy, male volunteers. Subjects received either 25 g of a ketone ester (KE, n = 9) or a control drink (CON, n = 9) immediately after each training session and before sleep. In KE, but not in CON, the training intervention increased the number of capillary contacts and the capillary-to-fibre perimeter exchange index by 44% and 42%, respectively. Furthermore, KE also substantially increased vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) expression both at the protein and at the mRNA level. Serum erythropoietin concentration was concomitantly increased by 26%. Conversely, in CON the training intervention increased only the protein content of eNOS. These data indicate that intermittent exogenous ketosis during endurance overload training stimulates muscular angiogenesis. This likely resulted from a direct stimulation of muscle angiogenesis, which may be at least partly due to stimulation of erythropoietin secretion and elevated VEGF activity, and/or an inhibition of the suppressive effect of overload training on the normal angiogenic response to training. This study provides novel evidence to support the potential of exogenous ketosis to benefit endurance training-induced muscular adaptation. KEY POINTS: Increased capillarization is a primary muscular adaptation to endurance exercise training. However, excess training load may impede such response. We previously observed that intermittent exogenous ketosis by post-exercise and pre-sleep ketone ester ingestion (KE) counteracted physiological dysregulations induced by endurance overload training. Therefore, we investigated whether KE could increase pro-angiogenic factors thereby stimulating muscular angiogenesis during a 3-week endurance training overload period. We show that the overload training period in the presence, but not in the absence, of KE markedly increased muscle capillarization (+40%). This increase was accompanied by higher circulating erythropoietin concentration and stimulation of the pro-angiogenic factors vascular endothelial growth factor and endothelial nitric oxide synthase in skeletal muscle. Collectively, our data indicate that intermittent exogenous ketosis may evolve as a potent nutritional strategy to facilitate recovery from strenuous endurance exercise, thereby stimulating beneficial muscular adaptations.
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Affiliation(s)
- Chiel Poffé
- Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium
| | - Ruben Robberechts
- Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium
| | - Ruud Van Thienen
- Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium
| | - Peter Hespel
- Department of Movement Sciences, KU Leuven, Leuven, Belgium
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9
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Breenfeldt Andersen A, Graae J, Bejder J, Bonne TC, Seier S, Debertin M, Eibye K, Hostrup M, Nordsborg NB. Microdoses of Recombinant Human Erythropoietin Enhance Time Trial Performance in Trained Males and Females. Med Sci Sports Exerc 2023; 55:311-321. [PMID: 36317927 DOI: 10.1249/mss.0000000000003052] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
PURPOSE We investigated the effects of recombinant human erythropoietin (rHuEPO) administration on exercise endurance, maximal aerobic performance, and total hemoglobin mass (tHb). We hypothesized that frequent, small intravenous injections of epoetin β would increase time trial performance, peak oxygen uptake (V̇O 2peak ), and tHb in both males and females. METHODS We included 48 healthy, recreational to trained males ( n = 24, mean ± SD V̇O 2peak = 55 ± 5 mL O 2 ·kg -1 ⋅min -1 ) and females ( n = 24; V̇O 2peak of 46 ± 4 mL O 2 ·kg -1 ⋅min -1 ) in a counterbalanced, double-blind, randomized, placebo-controlled study design stratified by sex. Time trial performance, V̇O 2peak , and tHb were determined before and after intravenous injections of either rHuEPO (9 IU·kg bw -1 epoetin β) or saline (0.9% NaCl) three times weekly for 4 wk. RESULTS A time-treatment effect ( P < 0.05) existed for time trial performance. Within the rHuEPO group, mean power output increased by 4.1% ± 4.2% ( P < 0.001). Likewise, a time-treatment effect ( P < 0.001) existed for V̇O 2peak , where the rHuEPO group improved V̇O 2peak and peak aerobic power by 4.2% ± 6.1% ( P < 0.001) and 2.9% ± 4.0% ( P < 0.01), respectively. A time-treatment effect ( P < 0.001) existed for tHb, where the rHuEPO group increased tHb by 6.7% ± 3.4% ( P < 0.001). A main effect of "sex" alone was also evident ( P < 0.001), but no sex-specific interactions were found. No changes were observed in the placebo group for mean power output, V̇O 2peak , peak aerobic power, or tHb. CONCLUSIONS Microdoses with intravenous rHuEPO provide a sufficient erythropoietic stimuli to augment tHb and enhance aerobic-dominated performance in both trained males and females.
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Affiliation(s)
| | - Jonathan Graae
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, DENMARK
| | - Jacob Bejder
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, DENMARK
| | - Thomas C Bonne
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, DENMARK
| | - Søren Seier
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, DENMARK
| | - Maren Debertin
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, DENMARK
| | - Kasper Eibye
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, DENMARK
| | - Morten Hostrup
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, DENMARK
| | - Nikolai B Nordsborg
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, DENMARK
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10
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Diaz-Canestro C, Siebenmann C, Montero D. Blood Oxygen Carrying Capacity Determines Cardiorespiratory Fitness in Middle-Age and Older Women and Men. Med Sci Sports Exerc 2021; 53:2274-2282. [PMID: 34107511 DOI: 10.1249/mss.0000000000002720] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
PURPOSE Whether blood oxygen (O2)-carrying capacity plays a substantial role in determining cardiorespiratory fitness, a strong predictor of mortality, remains uncertain in women and elderly individuals because of the scarcity of experimental investigations. This study experimentally assessed the role of blood O2-carrying capacity on cardiorespiratory fitness in middle-age and older individuals. METHODS Healthy women and men (n = 31, 35-76 yr) matched by age and fitness were recruited. Transthoracic echocardiography, central hemodynamics, and O2 uptake were assessed throughout incremental exercise in (i) control conditions and (ii) after a 10% reduction of blood O2-carrying capacity via carbon monoxide administration, in a blinded manner. Effects on cardiac function, blood pressure, peak O2 uptake, and effective hemoglobin (Hb) were determined with established methods. RESULTS Blood O2-carrying capacity, represented by effective Hb, was similarly reduced in women (11.8 ± 0.6 vs 10.7 ± 0.6 g·dL-1, P < 0.001) and men (13.0 ± 0.9 vs 11.7 ± 0.6 g·dL-1, P < 0.001) (P for sex effect = 0.580). Reduced O2-carrying capacity did not induce major effects on cardiac function and hemodynamics during exercise, except for a 10%-15% decrement in peak systolic blood pressure in both sexes (P ≤ 0.034). Peak O2 uptake decreased from 35 ± 6 to 31 ± 6 mL·min-1·kg-1, P < 0.001) in women and from 35 ± 9 to 32 ± 9 mL·min-1·kg-1 (P = 0.024) in men in approximate proportion to the reduction of O2-carrying capacity, an effect that did not differ between sexes (P = 0.778). CONCLUSIONS Blood O2-carrying capacity stands out as a major determinant of cardiorespiratory fitness in healthy mature women and men, with no differential effect of sex.
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11
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Larsen S, Dam Søndergård S, Eg Sahl R, Frandsen J, Morville T, Dela F, Helge JW. Acute erythropoietin injection increases muscle mitochondrial respiratory capacity in young men: a double-blinded randomized crossover trial. J Appl Physiol (1985) 2021; 131:1340-1347. [PMID: 34498946 DOI: 10.1152/japplphysiol.00995.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The aim was to investigate if acute recombinant human erythropoietin (rHuEPO) injection had an effect on mitochondrial function and if exercise would have an additive effect. Furthermore, to investigate if in vitro incubation with rHuEPO had an effect on muscle mitochondrial respiratory capacity. Eight healthy young men were recruited for this double-blinded randomized placebo-controlled crossover study. rHuEPO (400 IU/kg body wt) or saline injection was given intravenously, before an acute bout of exercise. Resting metabolic rate and fat oxidation were measured. Biopsies were obtained at baseline, 120 min after injection, and right after the acute exercise bout. Mitochondrial function (mitochondrial respiration and H2O2 emission) was measured in permeabilized skeletal muscle using high-resolution respirometry and fluorometry. Specific gene expression and enzyme activity were measured. Skeletal muscle mitochondrial respiratory capacity was measured with and without incubation with rHuEPO. Fat oxidation at rest increased after rHuEPO injection, but no difference was found in fat oxidation during exercise. Mitochondrial respiratory capacity was increased after rHuEPO injection when pyruvate was in the assay, which was not the case when saline was injected. No changes were seen in H2O2 emission after rHuEPO injection or acute exercise. Incubation of skeletal muscle fibers in vitro with rHuEPO increased mitochondrial respiratory capacity. Acute rHuEPO injection increased mitochondrial respiratory capacity when pyruvate was used in the assay. No statistical difference was found in H2O2 emission capacity, although a numerical increase was seen after rHuEPO injection. In vitro incubation of the skeletal muscle sample with rHuEPO increases mitochondrial respiratory capacity.NEW & NOTEWORTHY The effect of an acute rHuEPO injection on skeletal muscle mitochondrial function was investigated in young healthy male subjects. rHuEPO has an acute effect on skeletal muscle mitochondrial respiratory capacity in humans, where an increased mitochondrial respiratory capacity was seen. This could be the first step leading to increased mitochondrial biogenesis.
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Affiliation(s)
- Steen Larsen
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,Clinical Research Centre, Medical University of Bialystok, Bialystok, Poland
| | - Stine Dam Søndergård
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ronni Eg Sahl
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jacob Frandsen
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Morville
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Flemming Dela
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Geriatrics, Bispebjerg University Hospital, Copenhagen, Denmark
| | - Jørn W Helge
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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12
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An Abductive Inference Approach to Assess the Performance-Enhancing Effects of Drugs Included on the World Anti-Doping Agency Prohibited List. Sports Med 2021; 51:1353-1376. [PMID: 33811295 DOI: 10.1007/s40279-021-01450-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2021] [Indexed: 12/18/2022]
Abstract
Some have questioned the evidence for performance-enhancing effects of several substances included on the World Anti-Doping Agency's Prohibited List due to the divergent or inconclusive findings in randomized controlled trials (RCTs). However, inductive statistical inference based on RCTs-only may result in biased conclusions because of the scarcity of studies, inter-study heterogeneity, too few outcome events, or insufficient power. An abductive inference approach, where the body of evidence is evaluated beyond considerations of statistical significance, may serve as a tool to assess the plausibility of performance-enhancing effects of substances by also considering observations and facts not solely obtained from RCTs. Herein, we explored the applicability of an abductive inference approach as a tool to assess the performance-enhancing effects of substances included on the Prohibited List. We applied an abductive inference approach to make inferences on debated issues pertaining to the ergogenic effects of recombinant human erythropoietin (rHuEPO), beta2-agonists and anabolic androgenic steroids (AAS), and extended the approach to more controversial drug classes where RCTs are limited. We report that an abductive inference approach is a useful tool to assess the ergogenic effect of substances included on the Prohibited List-particularly for substances where inductive inference is inconclusive. Specifically, a systematic abductive inference approach can aid researchers in assessing the effects of doping substances, either by leading to suggestions of causal relationships or identifying the need for additional research.
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13
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Jeppesen JS, Breenfeldt Andersen A, Bonne TC, Thomassen M, Sørensen H, Nordsborg NB, Olsen NV, Huertas JR, Bejder J. Immature reticulocytes are sensitive and specific to low-dose erythropoietin treatment at sea level and altitude. Drug Test Anal 2021; 13:1331-1340. [PMID: 33739618 DOI: 10.1002/dta.3031] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/16/2021] [Accepted: 03/16/2021] [Indexed: 11/07/2022]
Abstract
We investigated whether immature reticulocyte fraction (IRF) and immature reticulocytes to red blood cells ratio (IR/RBC) are sensitive biomarkers for low-dose recombinant human erythropoietin (rhEpo) treatment at sea level (SL) and moderate altitude (AL) and whether multi (FACS) or single (Sysmex-XN) fluorescence flow cytometry is superior for IRF and IR/RBC determination. Thirty-nine participants completed two interventions, each containing a 4-week baseline, a 4-week SL or AL (2,230 m) exposure, and a 4-week follow-up. During exposure, rhEpo (20 IU kg-1 ) or placebo (PLA) was injected at SL (SLrhEpo , n = 25, SLPLA n = 9) and AL (ALrhEpo , n = 12, ALPLA n = 27) every second day for 3 weeks. Venous blood was collected weekly. Sysmex measurements revealed that IRF and IR/RBC were up to ~70% (P < 0.01) and ~190% (P < 0.001) higher in SLrhEpo than SLPLA during treatment and up to ~45% (P < 0.001) and ~55% (P < 0.01) lower post-treatment, respectively. Compared with ALPLA , IRF and IR/RBC were up to ~20% (P < 0.05) and ~45% (P < 0.001) lower post-treatment in SLrhEpo , respectively. In ALrhEpo , IRF and IR/RBC were up to ~40% (P < 0.05) and ~110% (P < 0.001) higher during treatment and up to ~25% (P < 0.05) and ~40% (P < 0.05) lower post-treatment, respectively, compared with ALPLA . Calculated thresholds provided ~90% sensitivity for both biomarkers at SL and 33% (IRF) and 66% (IR/RBC) at AL. Specificity was >99%. Single-fluorescence flow cytometry coefficient of variation was >twofold higher at baseline (P < 0.001) and provided larger or similar changes compared to multi-fluorescence, albeit with smaller precision. In conclusion, IRF and IR/RBC were sensitive and specific biomarkers for low-dose rhEpo misuse at SL and AL.
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Affiliation(s)
- Jan Sommer Jeppesen
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, Denmark
| | | | - Thomas Christian Bonne
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, Denmark
| | - Martin Thomassen
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, Denmark
| | - Helle Sørensen
- Data Science Lab, Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Niels Vidiendal Olsen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Jesús Rodríguez Huertas
- Department of Physiology, Faculty of Sport Sciences, Institute of Nutrition and Food Technology, Biomedical Research Centre, University of Granada, Armilla, Spain
| | - Jacob Bejder
- Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, Denmark
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14
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Risikesan J, Nellemann B, Christensen B, Jørgensen JOL, Nielsen S. No effect of 10 weeks erythropoietin treatment on lipid oxidation in healthy men. Endocr Connect 2020; 9:1148-1155. [PMID: 33112835 PMCID: PMC7774772 DOI: 10.1530/ec-20-0305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/13/2020] [Indexed: 11/21/2022]
Abstract
Studies indicate that erythropoietin (EPO) has effect on lipid and energy metabolism; however, the impact of EPO on lipid oxidation in vivo has not been well documented. Here, we evaluate whether long-term erythropoiesis-stimulating agent (ESA) treatment affects the oxidation of plasma very low-density lipoprotein triglycerides (VLDL-TG) fatty acids (FA), plasma free fatty acids (FFA) and non-plasma (residual) FA in healthy, young, sedentary men. Infusion of [1-14C]VLDL-TG and [9,10-3H]palmitate was used in combination with indirect calorimetry to assess resting lipid fuel utilization and kinetics, and resting energy expenditure (REE) before and after 10 weeks of ESA exposure compared with placebo. REE increased significantly during ESA compared with placebo (P = 0.023, RM-ANOVA). Oxidation rates of VLDL-TG FA, FFA, and residual FA remained unchanged during ESA compared with placebo. The relative contribution of the lipid stores was greatest for FFA (47.1%) and the total lipid oxidation rate and was not significantly different between ESA and placebo-treated subjects. We conclude that long-term ESA treatment of healthy young men increases REE but does not alter the oxidation rates of plasma and non-plasma FA sources.
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Affiliation(s)
- Jeyanthini Risikesan
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Birgitte Nellemann
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
- Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway
| | - Britt Christensen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | | | - Søren Nielsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark
- Correspondence should be addressed to S Nielsen:
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15
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Skattebo Ø, Calbet JAL, Rud B, Capelli C, Hallén J. Contribution of oxygen extraction fraction to maximal oxygen uptake in healthy young men. Acta Physiol (Oxf) 2020; 230:e13486. [PMID: 32365270 PMCID: PMC7540168 DOI: 10.1111/apha.13486] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 12/16/2022]
Abstract
We analysed the importance of systemic and peripheral arteriovenous O2 difference (
a-v¯O2 difference and a‐vfO2 difference, respectively) and O2 extraction fraction for maximal oxygen uptake (
V˙O2max). Fick law of diffusion and the Piiper and Scheid model were applied to investigate whether diffusion versus perfusion limitations vary with
V˙O2max. Articles (n = 17) publishing individual data (n = 154) on
V˙O2max, maximal cardiac output (
Q˙max; indicator‐dilution or the Fick method),
a-v¯O2 difference (catheters or the Fick equation) and systemic O2 extraction fraction were identified. For the peripheral responses, group‐mean data (articles: n = 27; subjects: n = 234) on leg blood flow (LBF; thermodilution), a‐vfO2 difference and O2 extraction fraction (arterial and femoral venous catheters) were obtained.
Q˙max and two‐LBF increased linearly by 4.9‐6.0 L · min–1 per 1 L · min–1 increase in
V˙O2max (R2 = .73 and R2 = .67, respectively; both P < .001). The
a-v¯O2 difference increased from 118‐168 mL · L–1 from a
V˙O2max of 2‐4.5 L · min–1 followed by a reduction (second‐order polynomial: R2 = .27). After accounting for a hypoxemia‐induced decrease in arterial O2 content with increasing
V˙O2max (R2 = .17; P < .001), systemic O2 extraction fraction increased up to ~90% (
V˙O2max: 4.5 L · min–1) with no further change (exponential decay model: R2 = .42). Likewise, leg O2 extraction fraction increased with
V˙O2max to approach a maximal value of ~90‐95% (R2 = .83). Muscle O2 diffusing capacity and the equilibration index Y increased linearly with
V˙O2max (R2 = .77 and R2 = .31, respectively; both P < .01), reflecting decreasing O2 diffusional limitations and accentuating O2 delivery limitations. In conclusion, although O2 delivery is the main limiting factor to
V˙O2max, enhanced O2 extraction fraction (≥90%) contributes to the remarkably high
V˙O2max in endurance‐trained individuals.
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Affiliation(s)
- Øyvind Skattebo
- Department of Physical Performance Norwegian School of Sport Sciences Oslo Norway
| | - Jose A. L. Calbet
- Department of Physical Performance Norwegian School of Sport Sciences Oslo Norway
- Department of Physical Education and Research Institute of Biomedical and Health Sciences (IUIBS) University of Las Palmas de Gran Canaria Gran Canaria Spain
| | - Bjarne Rud
- Department of Physical Performance Norwegian School of Sport Sciences Oslo Norway
| | - Carlo Capelli
- Department of Physical Performance Norwegian School of Sport Sciences Oslo Norway
- Department of Neurosciences, Biomedicine and Movement Sciences University of Verona Verona Italy
| | - Jostein Hallén
- Department of Physical Performance Norwegian School of Sport Sciences Oslo Norway
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16
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Haider T, Diaz V, Albert J, Alvarez-Sanchez M, Thiersch M, Maggiorini M, Hilty MP, Spengler CM, Gassmann M. A Single 60.000 IU Dose of Erythropoietin Does Not Improve Short-Term Aerobic Exercise Performance in Healthy Subjects: A Randomized, Double-Blind, Placebo-Controlled Crossover Trial. Front Physiol 2020; 11:537389. [PMID: 33117187 PMCID: PMC7550763 DOI: 10.3389/fphys.2020.537389] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 08/26/2020] [Indexed: 01/13/2023] Open
Abstract
Erythropoietin (EPO) boosts exercise performance through increase in oxygen transport capacity following regular administration of EPO but preclinical study results suggest that single high dose of EPO also may improve exercise capacity. Twenty-nine healthy subjects (14 males/15 females; age: 25 ± 3 years) were included in a randomized, double-blind, placebo-controlled crossover study to assess peak work load and cardiopulmonary variables during submaximal and maximal cycling tests following a single dose of 60.000 IU of recombinant erythropoietin (EPO) or placebo (PLA). Submaximal exercise at 40%/60% of peak work load revealed no main effect of EPO on oxygen uptake (27.9 ± 8.7 ml min–1⋅kg–1/ 37.1 ± 13.2 ml min–1⋅kg–1) versus PLA (25.2 ± 3.7 ml min–1⋅kg–1/ 33.1 ± 5.3 ml min–1⋅kg–1) condition (p = 0.447/p = 0.756). During maximal exercise peak work load (PLA: 3.5 ± 0.6 W⋅kg–1 vs. EPO: 3.5 ± 0.6 W kg–1, p = 0.892) and peak oxygen uptake (PLA: 45.1 ± 10.4 ml⋅min–1 kg–1 vs. EPO: 46.1 ± 14.2 ml⋅min–1 kg–1, p = 0.344) reached comparable values in the two treatment conditions. Other cardiopulmonary variables (ventilation, cardiac output, heart rate) also reached similar levels in the two treatment conditions. An interaction effect was found between treatment condition and sex resulting in higher peak oxygen consumption (p = 0.048) and ventilation (p = 0.044) in EPO-treated males. In conclusion, in a carefully conducted study using placebo-controlled design the present data failed to support the hypothesis that a single high dose of EPO has a measurable impact on work capacity in healthy subjects.
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Affiliation(s)
- Thomas Haider
- Institute for Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), Zurich, Switzerland.,Department of Cardiology, University Hospital Zürich, Zurich, Switzerland
| | - Victor Diaz
- Institute for Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Jamie Albert
- Institute of Human Movement Science and Sport, ETH Zürich, Zurich, Switzerland
| | - Maria Alvarez-Sanchez
- Institute for Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Markus Thiersch
- Institute for Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Marco Maggiorini
- Institute of Intensive Care Medicine, University Hospital of Zürich, Zurich, Switzerland
| | - Matthias P Hilty
- Institute of Intensive Care Medicine, University Hospital of Zürich, Zurich, Switzerland
| | - Christina M Spengler
- Zurich Center for Integrative Human Physiology (ZIHP), Zurich, Switzerland.,Institute of Human Movement Science and Sport, ETH Zürich, Zurich, Switzerland
| | - Max Gassmann
- Institute for Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), Zurich, Switzerland
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Blood volume expansion does not explain the increase in peak oxygen uptake induced by 10 weeks of endurance training. Eur J Appl Physiol 2020; 120:985-999. [PMID: 32172291 PMCID: PMC7181565 DOI: 10.1007/s00421-020-04336-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 02/25/2020] [Indexed: 12/20/2022]
Abstract
Purpose The endurance training (ET)-induced increases in peak oxygen uptake (\documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}$$\end{document}V˙O2peak) and cardiac output (\documentclass[12pt]{minimal}
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\begin{document}$$\dot{Q}$$\end{document}Q˙peak) during upright cycling are reversed to pre-ET levels after removing the training-induced increase in blood volume (BV). We hypothesised that ET-induced improvements in \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}$$\end{document}V˙O2peak and \documentclass[12pt]{minimal}
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\begin{document}$$\dot{Q}$$\end{document}Q˙peak are preserved following phlebotomy of the BV gained with ET during supine but not during upright cycling. Arteriovenous O2 difference (a-\documentclass[12pt]{minimal}
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\begin{document}$$\bar{\text{v}}$$\end{document}v¯O2diff; \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}$$\end{document}V˙O2/\documentclass[12pt]{minimal}
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\begin{document}$$\dot{Q}$$\end{document}Q˙), cardiac dimensions and muscle morphology were studied to assess their role for the \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}$$\end{document}V˙O2peak improvement. Methods Twelve untrained subjects (\documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}$$\end{document}V˙O2peak: 44 ± 6 ml kg−1 min−1) completed 10 weeks of supervised ET (3 sessions/week). Echocardiography, muscle biopsies, haemoglobin mass (Hbmass) and BV were assessed pre- and post-ET. \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}$$\end{document}V˙O2peak and \documentclass[12pt]{minimal}
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\begin{document}$$\dot{Q}$$\end{document}Q˙peak during upright and supine cycling were measured pre-ET, post-ET and immediately after Hbmass was reversed to the individual pre-ET level by phlebotomy. Results ET increased the Hbmass (3.3 ± 2.9%; P = 0.005), BV (3.7 ± 5.6%; P = 0.044) and \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}$$\end{document}V˙O2peak during upright and supine cycling (11 ± 6% and 10 ± 8%, respectively; P ≤ 0.003). After phlebotomy, improvements in \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}$$\end{document}V˙O2peak compared with pre-ET were preserved in both postures (11 ± 4% and 11 ± 9%; P ≤ 0.005), as was \documentclass[12pt]{minimal}
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\begin{document}$$\dot{Q}$$\end{document}Q˙peak (9 ± 14% and 9 ± 10%; P ≤ 0.081). The increased \documentclass[12pt]{minimal}
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\begin{document}$$\dot{Q}$$\end{document}Q˙peak and a-\documentclass[12pt]{minimal}
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\begin{document}$$\bar{\text{v}}$$\end{document}v¯O2diff accounted for 70% and 30% of the \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}$$\end{document}V˙O2peak improvements, respectively. Markers of mitochondrial density (CS and COX-IV; P ≤ 0.007) and left ventricular mass (P = 0.027) increased. Conclusion The ET-induced increase in \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}$$\end{document}V˙O2peak was preserved despite removing the increases in Hbmass and BV by phlebotomy, independent of posture. \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}$$\end{document}V˙O2peak increased primarily through elevated \documentclass[12pt]{minimal}
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\begin{document}$$\dot{Q}$$\end{document}Q˙peak but also through a widened a-\documentclass[12pt]{minimal}
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\begin{document}$$\bar{\text{v}}$$\end{document}v¯O2diff, potentially mediated by cardiac remodelling and mitochondrial biogenesis.
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Suresh S, Rajvanshi PK, Noguchi CT. The Many Facets of Erythropoietin Physiologic and Metabolic Response. Front Physiol 2020; 10:1534. [PMID: 32038269 PMCID: PMC6984352 DOI: 10.3389/fphys.2019.01534] [Citation(s) in RCA: 109] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 12/05/2019] [Indexed: 12/30/2022] Open
Abstract
In mammals, erythropoietin (EPO), produced in the kidney, is essential for bone marrow erythropoiesis, and hypoxia induction of EPO production provides for the important erythropoietic response to ischemic stress, such as during blood loss and at high altitude. Erythropoietin acts by binding to its cell surface receptor which is expressed at the highest level on erythroid progenitor cells to promote cell survival, proliferation, and differentiation in production of mature red blood cells. In addition to bone marrow erythropoiesis, EPO causes multi-tissue responses associated with erythropoietin receptor (EPOR) expression in non-erythroid cells such neural cells, endothelial cells, and skeletal muscle myoblasts. Animal and cell models of ischemic stress have been useful in elucidating the potential benefit of EPO affecting maintenance and repair of several non-hematopoietic organs including brain, heart and skeletal muscle. Metabolic and glucose homeostasis are affected by endogenous EPO and erythropoietin administration affect, in part via EPOR expression in white adipose tissue. In diet-induced obese mice, EPO is protective for white adipose tissue inflammation and gives rise to a gender specific response in weight control associated with white fat mass accumulation. Erythropoietin regulation of fat mass is masked in female mice due to estrogen production. EPOR is also expressed in bone marrow stromal cells (BMSC) and EPO administration in mice results in reduced bone independent of the increase in hematocrit. Concomitant reduction in bone marrow adipocytes and bone morphogenic protein suggests that high EPO inhibits adipogenesis and osteogenesis. These multi-tissue responses underscore the pleiotropic potential of the EPO response and may contribute to various physiological manifestations accompanying anemia or ischemic response and pharmacological uses of EPO.
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Affiliation(s)
- Sukanya Suresh
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Praveen Kumar Rajvanshi
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Constance T Noguchi
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
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19
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Chinnappa S, White E, Lewis N, Baldo O, Tu YK, Glorieux G, Vanholder R, El Nahas M, Mooney A. Early and asymptomatic cardiac dysfunction in chronic kidney disease. Nephrol Dial Transplant 2019; 33:450-458. [PMID: 28525624 DOI: 10.1093/ndt/gfx064] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 03/14/2017] [Indexed: 11/13/2022] Open
Abstract
Background Heart failure (HF) is highly prevalent and associated with high mortality in chronic kidney disease (CKD). However, the pathophysiology of cardiac dysfunction in CKD, especially in the early asymptomatic stage, is not well understood. We studied subclinical cardiac dysfunction in asymptomatic CKD patients without comorbid cardiac disease or diabetes mellitus by evaluating peak cardiac performance. Methods In a cross-sectional study (n = 130) we investigated 70 male non-diabetic CKD patients (21 CKD stage 2-3a, 27 CKD stage 3b-4 and 22 CKD stage 5) employing specialized cardiopulmonary exercise testing to measure peak cardiac output and cardiac power output non-invasively. Data from 35 age-matched healthy male volunteers were obtained for comparison. In addition, as a positive control, data from 25 age-matched male HF patients in New York Heart Association class II and III were also obtained. Results The study subjects showed a graded reduction in peak cardiac power, with 6.13 ± 1.11 W in controls, 5.02 ± 0.78 W in CKD 2-3a, 4.59 ± 0.53 W in CKD 3b-4 and 4.02 ± 0.73 W in CKD 5, although not as impaired as in HF, with 2.34 ± 0.63 W (all P < 0.005 versus control). The central haemodynamic characteristics of the cardiac impairment in CKD mirrored that of HF, with reduced flow and pressure-generating capacities, reduced chronotropic reserve and impaired contractility. Conclusions The study demonstrates for the first time impaired peak cardiac performance and cardiac functional reserve in asymptomatic CKD patients. The evidence of myocardial dysfunction in the absence of comorbid cardiac disease and diabetes warrants further evaluation of current pathophysiological concepts of cardiovascular disease in CKD.
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Affiliation(s)
- Shanmugakumar Chinnappa
- Department of Nephrology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK.,Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Edward White
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Nigel Lewis
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Omer Baldo
- Department of Urology, Airedale NHS Foundation Trust, Keighley, UK
| | - Yu-Kang Tu
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National University of Taiwan, Taiwan
| | - Griet Glorieux
- Department of Nephrology, Ghent University Hospital, Ghent, Belgium
| | | | - Meguid El Nahas
- Department of Nephrology, University of Sheffield, Sheffield, UK
| | - Andrew Mooney
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK.,Department of Nephrology, Leeds Teaching Hospitals NHS Trust, Leeds, UK
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20
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Enhancement of Exercise Performance by 48 Hours, and 15-Day Supplementation with Mangiferin and Luteolin in Men. Nutrients 2019; 11:nu11020344. [PMID: 30736383 PMCID: PMC6412949 DOI: 10.3390/nu11020344] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 01/26/2019] [Accepted: 01/29/2019] [Indexed: 12/27/2022] Open
Abstract
The natural polyphenols mangiferin and luteolin have free radical-scavenging properties, induce the antioxidant gene program and down-regulate the expression of superoxide-producing enzymes. However, the effects of these two polyphenols on exercise capacity remains mostly unknown. To determine whether a combination of luteolin (peanut husk extract containing 95% luteolin, PHE) and mangiferin (mango leave extract (MLE), Zynamite®) at low (PHE: 50 mg/day; and 140 mg/day of MLE containing 100 mg of mangiferin; L) and high doses (PHE: 100 mg/day; MLE: 420 mg/day; H) may enhance exercise performance, twelve physically active men performed incremental exercise to exhaustion, followed by sprint and endurance exercise after 48 h (acute effects) and 15 days of supplementation (prolonged effects) with polyphenols or placebo, following a double-blind crossover design. During sprint exercise, mangiferin + luteolin supplementation enhanced exercise performance, facilitated muscle oxygen extraction, and improved brain oxygenation, without increasing the VO₂. Compared to placebo, mangiferin + luteolin increased muscle O₂ extraction during post-exercise ischemia, and improved sprint performance after ischemia-reperfusion likely by increasing glycolytic energy production, as reflected by higher blood lactate concentrations after the sprints. Similar responses were elicited by the two doses tested. In conclusion, acute and prolonged supplementation with mangiferin combined with luteolin enhances performance, muscle O₂ extraction, and brain oxygenation during sprint exercise, at high and low doses.
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HAILE DIRESIBACHEWW, DURUSSEL JÉRÔME, MEKONEN WONDYEFRAW, ONGARO NEFORD, ANJILA EDWIN, MOOSES MARTIN, DASKALAKI EVANGELIA, MOOSES KERLI, MCCLURE JOHND, SUTEHALL SHAUN, PITSILADIS YANNISP. Effects of EPO on Blood Parameters and Running Performance in Kenyan Athletes. Med Sci Sports Exerc 2019; 51:299-307. [DOI: 10.1249/mss.0000000000001777] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Birkhoff WAJ, Heuberger JAAC, Post TE, Gal P, Stuurman FE, Burggraaf J, Cohen AF. Recombinant human erythropoietin does not affect several microvascular parameters in well-trained cyclists. Physiol Rep 2018; 6:e13924. [PMID: 30592183 PMCID: PMC6308108 DOI: 10.14814/phy2.13924] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 10/19/2018] [Indexed: 12/23/2022] Open
Abstract
Recombinant human erythropoietin (rHuEPO) has been used as a performance-enhancing agent by athletes in a variety of sports. The resulting increase in hematocrit levels leads to increased blood viscosity and can affect blood flow, potentially increasing the athlete's risk of developing health complications. However, the actual effects of using rHuEPO on microvascular blood flow and post-occlusive reactive hyperemia are currently unknown. We therefore evaluated the effect of rHuEPO on the cutaneous microcirculation in well-trained cyclists using laser speckle contrast imaging (LSCI). This study was part of a randomized, double-blind, placebo-controlled, parallel trial designed to investigate the effects of rHuEPO in 47 well-trained adult cyclists (age 18-50 years). Subjects received a weekly dose of either rHuEPO or placebo for 8 weeks, and LSCI was performed at baseline, after a maximal exercise test in week 6, and before maximal exercise in week 8. Endpoints included basal blood flux, maximum post-occlusion reperfusion, and time to return to baseline. Despite an increase in hematocrit levels in the rHuEPO-treated group, we found no statistically significant difference in microvascular function measured between the rHuEPO-treated group and the placebo group. Our results suggest that the increased hematocrit levels in rHuEPO-treated well-trained cyclists are not associated with changes in microvascular blood flow or post-occlusive reactive hyperemia measured using LSCI.
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Affiliation(s)
- Willem A. J. Birkhoff
- Centre for Human Drug ResearchLeidenThe Netherlands
- Leiden University Medical CenterLeidenThe Netherlands
| | | | - Titiaan E. Post
- Centre for Human Drug ResearchLeidenThe Netherlands
- Leiden Academic Centre for Drug ResearchLeidenThe Netherlands
| | - Pim Gal
- Centre for Human Drug ResearchLeidenThe Netherlands
| | | | - Jacobus Burggraaf
- Centre for Human Drug ResearchLeidenThe Netherlands
- Leiden Academic Centre for Drug ResearchLeidenThe Netherlands
| | - Adam F. Cohen
- Centre for Human Drug ResearchLeidenThe Netherlands
- Leiden University Medical CenterLeidenThe Netherlands
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Overbye M. An (un)desirable trade of harms? How elite athletes might react to medically supervised ‘doping’ and their considerations of side-effects in this situation. THE INTERNATIONAL JOURNAL OF DRUG POLICY 2018; 55:14-30. [DOI: 10.1016/j.drugpo.2017.12.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 11/24/2017] [Accepted: 12/22/2017] [Indexed: 11/16/2022]
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Hawley JA, Lundby C, Cotter JD, Burke LM. Maximizing Cellular Adaptation to Endurance Exercise in Skeletal Muscle. Cell Metab 2018; 27:962-976. [PMID: 29719234 DOI: 10.1016/j.cmet.2018.04.014] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The application of molecular techniques to exercise biology has provided novel insight into the complexity and breadth of intracellular signaling networks involved in response to endurance-based exercise. Here we discuss several strategies that have high uptake by athletes and, on mechanistic grounds, have the potential to promote cellular adaptation to endurance training in skeletal muscle. Such approaches are based on the underlying premise that imposing a greater metabolic load and provoking extreme perturbations in cellular homeostasis will augment acute exercise responses that, when repeated over months and years, will amplify training adaptation.
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Affiliation(s)
- John A Hawley
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC 3000, Australia.
| | - Carsten Lundby
- Centre for Physical Activity Research, Copenhagen University Hospital, Copenhagen, Denmark
| | - James D Cotter
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Louise M Burke
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC 3000, Australia; Department of Sport Nutrition, Australian Institute of Sport, Belconnen, ACT, Australia
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Sgrò P, Sansone M, Sansone A, Romanelli F, Di Luigi L. Effects of erythropoietin abuse on exercise performance. PHYSICIAN SPORTSMED 2018; 46:105-115. [PMID: 29113535 DOI: 10.1080/00913847.2018.1402663] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The present review provides a comprehensive overview on the erythropoietic and non-erythropoietic effects of rHuEpo on human sport performance, paying attention to quantifying numerically how rHuEpo affects exercise performance and describing physiological changes regarding the most important exercise variables. Much attention has been paid to treatment schedules, in particular, to assess the effects of microdoses of rHuEpo and the prolonged effects on sport performance following withdrawal. Moreover, the review takes into account non-erythropoietic ergogenic effects of rHuEpo, including cognitive benefits of rHuEpo. A significant increase in both Vo2max and maximal cycling power was evidenced in studies taken into account for this review. rHuEpo, administered at clinical dosage, may have significant effects on haematological values, maximal and submaximal physiological variables, whereas few reports show positive effects on exercise perfomance. However, the influence of micro-dose rHuEpo on endurance performance in athletes is still unclear and further studies are warranted.
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Affiliation(s)
- Paolo Sgrò
- a Department of Movement, Human and Health Sciences, Unit of Endocrinology , Università degli Studi di Roma "Foro Italico" Piazza Lauro de Bosis , Rome , Italy
| | - Massimiliano Sansone
- b Department of Experimental Medicine , "Sapienza" Università di Roma , Rome , Italy
| | - Andrea Sansone
- b Department of Experimental Medicine , "Sapienza" Università di Roma , Rome , Italy
| | - Francesco Romanelli
- b Department of Experimental Medicine , "Sapienza" Università di Roma , Rome , Italy
| | - Luigi Di Luigi
- a Department of Movement, Human and Health Sciences, Unit of Endocrinology , Università degli Studi di Roma "Foro Italico" Piazza Lauro de Bosis , Rome , Italy
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Keramidas ME, Mekjavic IB, Eiken O. LunHab: interactive effects of a 10 day sustained exposure to hypoxia and bedrest on aerobic exercise capacity in male lowlanders. Exp Physiol 2017; 102:694-710. [DOI: 10.1113/ep086167] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 03/20/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Michail E. Keramidas
- Department of Environmental Physiology; Swedish Aerospace Physiology Center; School of Technology and Health; Royal Institute of Technology; Stockholm Sweden
| | - Igor B. Mekjavic
- Department of Automation; Biocybernetics and Robotics; Jozef Stefan Institute; Ljubljana Slovenia
- Department of Biomedical Physiology and Kinesiology; Simon Fraser University; Burnaby BC Canada
| | - Ola Eiken
- Department of Environmental Physiology; Swedish Aerospace Physiology Center; School of Technology and Health; Royal Institute of Technology; Stockholm Sweden
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Abstract
The hematocrit (Hct) determines the oxygen carrying capacity of blood, but also increases blood viscosity and thus flow resistance. From this dual role the concept of an optimum Hct for tissue oxygenation has been derived. Viscometric studies using the ratio Hct/blood viscosity at high shear rate showed an optimum Hct of 50-60% for red blood cell (RBC) suspensions in plasma. For the perfusion of an artificial microvascular network with 5-70μm channels the optimum Hct was 60-70% for high driving pressures. With lower shear rates or driving pressures the optimum Hct shifted towards lower values. In healthy, well trained athletes an increase of the Hct to supra-normal levels can increase exercise performance. These data with healthy individuals suggest that the optimum Hct for oxygen transport may be higher than the physiological range (35-40% in women, 39-50% in men). This is in contrast to clinical observations. Large clinical studies have repeatedly shown that a correction of anemia in a variety of disorders such as chronic kidney disease, heart failure, coronary syndrome, oncology, acute gastrointestinal bleeding, critical care, or surgery have better clinical outcomes when restrictive transfusion strategies are applied. Actual guidelines, therefore, recommend a transfusion threshold of 7-8 g/dL hemoglobin (Hct 20-24%) in stable, hospitalized patients. The discrepancy between the optimum Hct in health and disease may be due to factors such as decreased perfusion pressures (low cardiac output, vascular stenoses, change in vascular tone), endothelial cell dysfunction, leukocyte adhesion and others.
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Pichon AP, Connes P, Robach P. Effects of acute and chronic hematocrit modulations on blood viscosity in endurance athletes. Clin Hemorheol Microcirc 2016; 64:115-123. [DOI: 10.3233/ch-162050] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Aurélien P. Pichon
- Laboratory Mobility, aging & exercise (MOVE) - EA 6314, Faculty of Sport Sciences, University of Poitiers, Poitiers, France
- Laboratory Hypoxia & Lung - EA 2363, UFR SMBH, University Paris 13, Bobigny, France
- Association pour la Recherche en Physiologie de l’Environnement (ARPE), UFR de Médecine, 74 rue Marcel Cachin, Bobigny, France
| | - Philippe Connes
- Institut Universitaire de France, Paris, France
- Laboratoire CRIS EA647 –Section “Vascular biology and red blood cell”, University of Lyon 1, Villeurbanne, France
- Laboratoire d’Excellence GR-Ex, Paris, France
| | - Paul Robach
- Département Médical, Ecole Nationale des Sports de Montagne, site de l’Ecole Nationale de Ski et d’Alpinisme, Chamonix, France
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Sieljacks P, Thams L, Nellemann B, Larsen MS, Vissing K, Christensen B. Comparative Effects of Aerobic Training and Erythropoietin on Oxygen Uptake in Untrained Humans. J Strength Cond Res 2016; 30:2307-17. [DOI: 10.1519/jsc.0000000000001314] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Lamon S, Zacharewicz E, Arentson-Lantz E, Gatta PAD, Ghobrial L, Gerlinger-Romero F, Garnham A, Paddon-Jones D, Russell AP. Erythropoietin Does Not Enhance Skeletal Muscle Protein Synthesis Following Exercise in Young and Older Adults. Front Physiol 2016; 7:292. [PMID: 27458387 PMCID: PMC4937030 DOI: 10.3389/fphys.2016.00292] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 06/27/2016] [Indexed: 01/07/2023] Open
Abstract
Purpose: Erythropoietin (EPO) is a renal cytokine that is primarily involved in hematopoiesis while also playing a role in non-hematopoietic tissues expressing the EPO-receptor (EPOR). The EPOR is present in human skeletal muscle. In mouse skeletal muscle, EPO stimulation can activate the AKT serine/threonine kinase 1 (AKT) signaling pathway, the main positive regulator of muscle protein synthesis. We hypothesized that a single intravenous EPO injection combined with acute resistance exercise would have a synergistic effect on skeletal muscle protein synthesis via activation of the AKT pathway. Methods: Ten young (24.2 ± 0.9 years) and 10 older (66.6 ± 1.1 years) healthy subjects received a primed, constant infusion of [ring-13C6] L-phenylalanine and a single injection of 10,000 IU epoetin-beta or placebo in a double-blind randomized, cross-over design. 2 h after the injection, the subjects completed an acute bout of leg extension resistance exercise to stimulate skeletal muscle protein synthesis. Results: Significant interaction effects in the phosphorylation levels of the members of the AKT signaling pathway indicated a differential activation of protein synthesis signaling in older subjects when compared to young subjects. However, EPO offered no synergistic effect on vastus lateralis mixed muscle protein synthesis rate in young or older subjects. Conclusions: Despite its ability to activate the AKT pathway in skeletal muscle, an acute EPO injection had no additive or synergistic effect on the exercise-induced activation of muscle protein synthesis or muscle protein synthesis signaling pathways.
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Affiliation(s)
- Séverine Lamon
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University Geelong, VIC, Australia
| | - Evelyn Zacharewicz
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University Geelong, VIC, Australia
| | - Emily Arentson-Lantz
- Department of Nutrition and Metabolism, University of Texas Medical Branch Galveston, TX, USA
| | - Paul A Della Gatta
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University Geelong, VIC, Australia
| | - Lobna Ghobrial
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University Geelong, VIC, Australia
| | - Frederico Gerlinger-Romero
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University Geelong, VIC, Australia
| | - Andrew Garnham
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University Geelong, VIC, Australia
| | - Douglas Paddon-Jones
- Department of Nutrition and Metabolism, University of Texas Medical Branch Galveston, TX, USA
| | - Aaron P Russell
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University Geelong, VIC, Australia
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McKeever KH, McNally BA, Hinchcliff KW, Lehnhard RA, Poole DC. Effects of erythropoietin on systemic hematocrit and oxygen transport in the splenectomized horse. Respir Physiol Neurobiol 2016; 225:38-47. [PMID: 26853328 DOI: 10.1016/j.resp.2016.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Revised: 01/30/2016] [Accepted: 02/02/2016] [Indexed: 11/16/2022]
Abstract
To test the hypotheses that erythropoietin (rhuEPO) treatment increases systemic hematocrit, maximal O2 uptake (VO2max, by elevated perfusive and diffusive O2 conductances) and performance five female horses (4-13 years) received 15 IU/kg rhuEPO (erythropoietin) three times per week for three weeks. These horses had been splenectomized over 1 year previously to avoid confounding effects from the mobilization of splenic red blood cell reserves. Each horse performed three maximal exercise tests (one per month) on an inclined (4°) treadmill to the limit of tolerance; two control trials and one following EPO treatment. Measurements of hemoglobin concentration ([Hb] and hematocrit), plasma and blood volume, VO2, cardiac output as well as arterial and mixed venous blood gases were made at rest and during maximal exercise. EPO increased resting [Hb] by 18% from 13.3 ± 0.6 to 15.7 ± 0.8 g/dL (mean ± SD) corresponding to an increased hematocrit from 36 ± 2 to 46 ± 2% concurrent with 23 and 10% reductions in plasma and blood volume, respectively (all P<0.05). EPO elevated VO2max by 20% from 25.7 ± 1.7 to 30.9 ± 3.4 L/min (P<0.05) via a 17% increase in arterial O2 content and 18% greater arteriovenous O2 difference in the face of an unchanged cardiac output. To achieve the greater VO2max after EPO, diffusive O2 conductance increased ∼ 30% (from 580 ± 76 to 752 ± 166 mL O2/mmHg/min, P<0.05) which was substantially greater than the elevation of perfusive O2 conductance. These effects of EPO were associated with an increased exercise performance (total running time: control, 216 ± 72; EPO, 264 ± 48 s, P<0.05). We conclude that EPO substantially increases VO2max and performance in the splenectomized horse via improved perfusive and diffusive O2 transport.
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Affiliation(s)
- Kenneth H McKeever
- Department of Animal Science, Rutgers the State University of New Jersey, New Brunswick, NJ 08903, United States.
| | - Beth A McNally
- School of Health, Physical Education and Recreation, The Ohio State University, Columbus, OH 43210, United States
| | - Kenneth W Hinchcliff
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Australia
| | - Robert A Lehnhard
- Department of Kinesiology, University of Maine, Orono, ME, United States
| | - David C Poole
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, United States
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Integrative Conductance of Oxygen During Exercise at Altitude. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 903:395-408. [PMID: 27343110 DOI: 10.1007/978-1-4899-7678-9_26] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In the oxygen (O2) cascade downstream steps can never achieve higher flows of O2 than the preceding ones. At the lung the transfer of O2 is determined by the O2 gradient between the alveolar space and the lung capillaries and the O2 diffusing capacity (DLO2). While DLO2 may be increased several times during exercise by recruiting more lung capillaries and by increasing the oxygen carrying capacity of blood due to higher peripheral extraction of O2, the capacity to enhance the alveolocapillary PO2 gradient is more limited. The transfer of oxygen from the alveolar space to the hemoglobin (Hb) must overcome first the resistance offered by the alveolocapillary membrane (1/DM) and the capillary blood (1/θVc). The fractional contribution of each of these two components to DLO2 remains unknown. During exercise these resistances are reduced by the recruitment of lung capillaries. The factors that reduce the slope of the oxygen dissociation curve of the Hb (ODC) (i.e., lactic acidosis and hyperthermia) increase 1/θVc contributing to limit DLO2. These effects are accentuated in hypoxia. Reducing the size of the active muscle mass improves pulmonary gas exchange during exercise and reduces the rightward shift of the ODC. The flow of oxygen from the muscle capillaries to the mitochondria is pressumably limited by muscle O2 conductance (DmcO2) (an estimation of muscle oxygen diffusing capacity). However, during maximal whole body exercise in normoxia, a higher flow of O2 is achieved at the same pressure gradients after increasing blood [Hb], implying that in healthy humans exercising in normoxia there is a functional reserve in DmcO2. This conclusion is supported by the fact that during small muscle exercise in chronic hypoxia, peak exercise DmcO2 is similar to that observed during exercise in normoxia despite a markedly lower O2 pressure gradient driving diffusion.
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Bejder J, Aachmann-Andersen NJ, Bonne TC, Olsen NV, Nordsborg NB. Detection of erythropoietin misuse by the Athlete Biological Passport combined with reticulocyte percentage. Drug Test Anal 2015; 8:1049-1055. [DOI: 10.1002/dta.1932] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 11/12/2015] [Accepted: 11/16/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Jacob Bejder
- Department of Nutrition, Exercise and Sport Sciences; University of Copenhagen; Copenhagen Denmark
| | | | - Thomas Christian Bonne
- Department of Nutrition, Exercise and Sport Sciences; University of Copenhagen; Copenhagen Denmark
| | - Niels Vidiendal Olsen
- Department of Neuroscience and Pharmacology; University of Copenhagen
- Department of Neuroanesthesia, The Neuroscience Center; Copenhagen University Hospital (Rigshospitalet); Copenhagen Denmark
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Lundby C, Robach P. Performance Enhancement: What Are the Physiological Limits? Physiology (Bethesda) 2015; 30:282-92. [DOI: 10.1152/physiol.00052.2014] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Our objective is to highlight some key physiological determinants of endurance exercise performance and to discuss how these can be further improved. V̇o2max remains remarkably stable throughout an athletic career. By contrast, exercise economy, lactate threshold, and critical power may be improved in world-class athletes by specific exercise training regimes and/or with more years of training.
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Affiliation(s)
- C. Lundby
- Zürich Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
- Food & Nutrition & Sport Science, Gothenburg University, Gothenburg, Sweden; and
| | - P. Robach
- Ecole Nationale des Sports de Montagne, Site de l'Ecole Nationale de Ski et d'Alpinisme, Chamonix, France
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Abstract
We address adaptive vs. maladaptive responses to hypoxemia in healthy humans and hypoxic-tolerant species during wakefulness, sleep, and exercise. Types of hypoxemia discussed include short-term and life-long residence at high altitudes, the intermittent hypoxemia attending sleep apnea, or training regimens prescribed for endurance athletes. We propose that hypoxia presents an insult to O2 transport, which is poorly tolerated in most humans because of the physiological cost.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; and
| | - Barbara J Morgan
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Department of Orthopedics and Rehabilitation, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
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Nordsborg NB, Robach P, Boushel R, Calbet JAL, Lundby C. Erythropoietin does not reduce plasma lactate, H+, and K+during intense exercise. Scand J Med Sci Sports 2014; 25:e566-75. [DOI: 10.1111/sms.12374] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/23/2014] [Indexed: 11/28/2022]
Affiliation(s)
- N. B. Nordsborg
- Department of Nutrition, Exercise and Sport (NEXS); University of Copenhagen; Copenhagen Denmark
| | - P. Robach
- Site de l'Ecole Nationale de Ski et d'Alpinisme; Ecole Nationale des Sports de Montagne; Chamonix France
| | - R. Boushel
- Åstrand Laboratory; The Swedish School of Sport and Health Sciences; Stockholm Sweden
| | - J. A. L. Calbet
- Department of Physical Education; University of Las Palmas de Gran Canaria; Las Palmas Spain
| | - C. Lundby
- Institute of Physiology and Center for Integrative Human Physiology; University of Zürich; Zurich Switzerland
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Wang L, Di L, Noguchi CT. Erythropoietin, a novel versatile player regulating energy metabolism beyond the erythroid system. Int J Biol Sci 2014; 10:921-39. [PMID: 25170305 PMCID: PMC4147225 DOI: 10.7150/ijbs.9518] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 06/04/2014] [Indexed: 12/12/2022] Open
Abstract
Erythropoietin (EPO), the required cytokine for promoting the proliferation and differentiation of erythroid cells to stimulate erythropoiesis, has been reported to act as a pleiotropic cytokine beyond hematopoietic system. The various activities of EPO are determined by the widespread distribution of its cell surface EPO receptor (EpoR) in multiple tissues including endothelial, neural, myoblasts, adipocytes and other cell types. EPO activity has been linked to angiogenesis, neuroprotection, cardioprotection, stress protection, anti-inflammation and especially the energy metabolism regulation that is recently revealed. The investigations of EPO activity in animals and the expression analysis of EpoR provide more insights on the potential of EPO in regulating energy metabolism and homeostasis. The findings of crosstalk between EPO and some important energy sensors and the regulation of EPO in the cellular respiration and mitochondrial function further provide molecular mechanisms for EPO activity in metabolic activity regulation. In this review, we will summarize the roles of EPO in energy metabolism regulation and the activity of EPO in tissues that are tightly associated with energy metabolism. We will also discuss the effects of EPO in regulating oxidative metabolism and mitochondrial function, the interactions between EPO and important energy regulation factors, and the protective role of EPO from stresses that are related to metabolism, providing a brief overview of previously less appreciated EPO biological function in energy metabolism and homeostasis.
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Affiliation(s)
- Li Wang
- 1. Faculty of Health Sciences, University of Macau, SAR of People's Republic of China
| | - Lijun Di
- 1. Faculty of Health Sciences, University of Macau, SAR of People's Republic of China
| | - Constance Tom Noguchi
- 2. Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, U.S.A
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Radiloff D, Zhao Y, Boico A, Blueschke G, Palmer G, Fontanella A, Dewhirst M, Piantadosi CA, Noveck R, Irwin D, Hamilton K, Klitzman B, Schroeder T. Anti-hypotensive treatment and endothelin blockade synergistically antagonize exercise fatigue in rats under simulated high altitude. PLoS One 2014; 9:e99309. [PMID: 24960187 PMCID: PMC4068990 DOI: 10.1371/journal.pone.0099309] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 05/12/2014] [Indexed: 02/04/2023] Open
Abstract
Rapid ascent to high altitude causes illness and fatigue, and there is a demand for effective acute treatments to alleviate such effects. We hypothesized that increased oxygen delivery to the tissue using a combination of a hypertensive agent and an endothelin receptor A antagonist drugs would limit exercise-induced fatigue at simulated high altitude. Our data showed that the combination of 0.1 mg/kg ambrisentan with either 20 mg/kg ephedrine or 10 mg/kg methylphenidate significantly improved exercise duration in rats at simulated altitude of 4,267 m, whereas the individual compounds did not. In normoxic, anesthetized rats, ephedrine alone and in combination with ambrisentan increased heart rate, peripheral blood flow, carotid and pulmonary arterial pressures, breathing rate, and vastus lateralis muscle oxygenation, but under inspired hypoxia, only the combination treatment significantly enhanced muscle oxygenation. Our results suggest that sympathomimetic agents combined with endothelin-A receptor blockers offset altitude-induced fatigue in rats by synergistically increasing the delivery rate of oxygen to hypoxic muscle by concomitantly augmenting perfusion pressure and improving capillary conductance in the skeletal muscle. Our findings might therefore serve as a basis to develop an effective treatment to prevent high-altitude illness and fatigue in humans.
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Affiliation(s)
- Daniel Radiloff
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Yulin Zhao
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Alina Boico
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Gert Blueschke
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Gregory Palmer
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Andrew Fontanella
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Mark Dewhirst
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Claude A. Piantadosi
- Department of Medicine-Pulmonary, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Robert Noveck
- Department of Medicine-Clinical Pharmacology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - David Irwin
- Department of Cardiology, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Karyn Hamilton
- Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado, United States of America
| | - Bruce Klitzman
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Thies Schroeder
- Department of Physical Chemistry, University of Mainz, Mainz, Germany
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39
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Bonne TC, Doucende G, Flück D, Jacobs RA, Nordsborg NB, Robach P, Walther G, Lundby C. Phlebotomy eliminates the maximal cardiac output response to six weeks of exercise training. Am J Physiol Regul Integr Comp Physiol 2014; 306:R752-60. [DOI: 10.1152/ajpregu.00028.2014] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
With this study we tested the hypothesis that 6 wk of endurance training increases maximal cardiac output (Q̇max) relatively more by elevating blood volume (BV) than by inducing structural and functional changes within the heart. Nine healthy but untrained volunteers (V̇o2max 47 ± 5 ml·min−1·kg−1) underwent supervised training (60 min; 4 times weekly at 65% V̇o2max for 6 wk), and Q̇max was determined by inert gas rebreathing during cycle ergometer exercise before and after the training period. After the training period, blood volume (determined in duplicates by CO rebreathing) was reestablished to pretraining values by phlebotomy and Q̇max was quantified again. Resting echography revealed no structural heart adaptations as a consequence of the training intervention. After the training period, plasma volume (PV), red blood cell volume (RBCV), and BV increased ( P < 0.05) by 147 ± 168 (5 ± 5%), 235 ± 64 (10 ± 3%), and 382 ± 204 ml (7 ± 4%), respectively. V̇o2max was augmented ( P < 0.05) by 10 ± 7% after the training period and decreased ( P < 0.05) by 8 ± 7% with phlebotomy. Concomitantly, Q̇max was increased ( P < 0.05) from 18.9 ± 2.1 to 20.4 ± 2.3 l/min (9 ± 6%) as a consequence of the training intervention, and after normalization of BV by phlebotomy Q̇max returned to pretraining values (18.1 ± 2.5 l/min; 12 ± 5% reversal). Thus the exercise training-induced increase in BV is the main mechanism increasing Q̇max after 6 wk of endurance training in previously untrained subjects.
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Affiliation(s)
- Thomas C. Bonne
- Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gregory Doucende
- Laboratoire Performance et Santé en Altitude, Université de Perpignan, Font-Romeu, France
| | - Daniela Flück
- Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Robert A. Jacobs
- Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Nikolai B. Nordsborg
- Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Paul Robach
- Ecole Nationale des Sports de Montagne, site de l'Ecole Nationale de Ski et d'Alpinisme, Chamonix, France
| | - Guillaume Walther
- Laboratoire de Pharm-Ecologie Cardiovasculaire, Université d'Avignon, Avignon, France
| | - Carsten Lundby
- Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
- Food & Nutrition & Sport Science, Gothenburg University, Sweden
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40
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Chapman RF, Karlsen T, Resaland GK, Ge RL, Harber MP, Witkowski S, Stray-Gundersen J, Levine BD. Defining the “dose” of altitude training: how high to live for optimal sea level performance enhancement. J Appl Physiol (1985) 2014; 116:595-603. [DOI: 10.1152/japplphysiol.00634.2013] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic living at altitudes of ∼2,500 m causes consistent hematological acclimatization in most, but not all, groups of athletes; however, responses of erythropoietin (EPO) and red cell mass to a given altitude show substantial individual variability. We hypothesized that athletes living at higher altitudes would experience greater improvements in sea level performance, secondary to greater hematological acclimatization, compared with athletes living at lower altitudes. After 4 wk of group sea level training and testing, 48 collegiate distance runners (32 men, 16 women) were randomly assigned to one of four living altitudes (1,780, 2,085, 2,454, or 2,800 m). All athletes trained together daily at a common altitude from 1,250–3,000 m following a modified live high-train low model. Subjects completed hematological, metabolic, and performance measures at sea level, before and after altitude training; EPO was assessed at various time points while at altitude. On return from altitude, 3,000-m time trial performance was significantly improved in groups living at the middle two altitudes (2,085 and 2,454 m), but not in groups living at 1,780 and 2,800 m. EPO was significantly higher in all groups at 24 and 48 h, but returned to sea level baseline after 72 h in the 1,780-m group. Erythrocyte volume was significantly higher within all groups after return from altitude and was not different between groups. These data suggest that, when completing a 4-wk altitude camp following the live high-train low model, there is a target altitude between 2,000 and 2,500 m that produces an optimal acclimatization response for sea level performance.
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Affiliation(s)
| | - Trine Karlsen
- Norwegian University of Sport and Physical Education, Oslo, Norway
| | - Geir K. Resaland
- Norwegian University of Sport and Physical Education, Oslo, Norway
| | - R.-L. Ge
- Research Center for High Altitude Medicine, Qinghai University, Xining, Qinghai, China; and
| | - Matthew P. Harber
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Sarah Witkowski
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, The University of Texas Southwestern Medical Center, Dallas, Texas
| | | | - Benjamin D. Levine
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, The University of Texas Southwestern Medical Center, Dallas, Texas
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41
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Heuberger JAAC, Cohen Tervaert JM, Schepers FML, Vliegenthart ADB, Rotmans JI, Daniels JMA, Burggraaf J, Cohen AF. Erythropoietin doping in cycling: lack of evidence for efficacy and a negative risk-benefit. Br J Clin Pharmacol 2014; 75:1406-21. [PMID: 23216370 DOI: 10.1111/bcp.12034] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 11/09/2012] [Indexed: 11/29/2022] Open
Abstract
Imagine a medicine that is expected to have very limited effects based upon knowledge of its pharmacology and (patho)physiology and that is studied in the wrong population, with low-quality studies that use a surrogate end-point that relates to the clinical end-point in a partial manner at most. Such a medicine would surely not be recommended. The use of recombinant human erythropoietin (rHuEPO) to enhance performance in cycling is very common. A qualitative systematic review of the available literature was performed to examine the evidence for the ergogenic properties of this drug, which is normally used to treat anaemia in chronic renal failure patients. The results of this literature search show that there is no scientific basis from which to conclude that rHuEPO has performance-enhancing properties in elite cyclists. The reported studies have many shortcomings regarding translation of the results to professional cycling endurance performance. Additionally, the possibly harmful side-effects have not been adequately researched for this population but appear to be worrying, at least. The use of rHuEPO in cycling is rife but scientifically unsupported by evidence, and its use in sports is medical malpractice. What its use would have been, if the involved team physicians had been trained in clinical pharmacology and had investigated this properly, remains a matter of speculation. A single well-controlled trial in athletes in real-life circumstances would give a better indication of the real advantages and risk factors of rHuEPO use, but it would be an oversimplification to suggest that this would eradicate its use.
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Scharhag-Rosenberger F, Carlsohn A, Lundby C, Schüler S, Mayer F, Scharhag J. Can more than one incremental cycling test be performed within one day? Eur J Sport Sci 2013; 14:459-67. [DOI: 10.1080/17461391.2013.853208] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Cacic DL, Hervig T, Seghatchian J. Blood doping: The flip side of transfusion and transfusion alternatives. Transfus Apher Sci 2013; 49:90-4. [DOI: 10.1016/j.transci.2013.05.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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44
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Lamon S, Russell AP. The role and regulation of erythropoietin (EPO) and its receptor in skeletal muscle: how much do we really know? Front Physiol 2013; 4:176. [PMID: 23874302 PMCID: PMC3710958 DOI: 10.3389/fphys.2013.00176] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 06/22/2013] [Indexed: 12/22/2022] Open
Abstract
Erythropoietin (EPO) primarily activates erythroid cell proliferation and growth and is active in several types of non-hematopoietic cells via its interaction with the EPO-receptor (EPO-R). This review focuses on the role of EPO in skeletal muscle. The EPO-R is expressed in skeletal muscle cells and EPO may promote myoblast differentiation and survival via the activation of the same signaling cascades as in hematopoietic cells, such as STAT5, MAPK and Akt. Inconsistent results exist with respect to the detection of the EPO-R mRNA and protein in muscle cells, tissue and across species and the use of non-specific EPO-R antibodies contributes to this problem. Additionally, the inability to reproducibly detect an activation of the known EPO-induced signaling pathways in skeletal muscle questions the functionality of the EPO-R in muscle in vivo. These equivocal findings make it difficult to distinguish between a direct effect of EPO on skeletal muscle, via the activation of its receptor, and an indirect effect resulting from a better oxygen supply to the muscle. Consequently, the precise role of EPO in skeletal muscle and its regulatory mechanism/s remain to be elucidated. Further studies are required to comprehensively establish the importance of EPO and its function in skeletal muscle health.
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Affiliation(s)
- Séverine Lamon
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University Burwood, VIC, Australia
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45
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Detection of EPO injections using a rapid lateral flow isoform test. Anal Bioanal Chem 2013; 405:9685-91. [DOI: 10.1007/s00216-013-6997-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 04/08/2013] [Accepted: 04/17/2013] [Indexed: 10/26/2022]
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46
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Haemoglobin mass and running time trial performance after recombinant human erythropoietin administration in trained men. PLoS One 2013; 8:e56151. [PMID: 23418527 PMCID: PMC3571963 DOI: 10.1371/journal.pone.0056151] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 01/05/2013] [Indexed: 11/19/2022] Open
Abstract
Recombinant human erythropoietin (rHuEpo) increases haemoglobin mass (Hbmass) and maximal oxygen uptake ( O2 max).
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47
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Jacobs RA, Lundby C, Robach P, Gassmann M. Red blood cell volume and the capacity for exercise at moderate to high altitude. Sports Med 2012; 42:643-63. [PMID: 22741918 DOI: 10.1007/bf03262286] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Hypoxia-stimulated erythropoiesis, such as that observed when red blood cell volume (RCV) increases in response to high-altitude exposure, is well understood while the physiological importance is not. Maximal exercise tests are often performed in hypoxic conditions following some form of RCV manipulation in an attempt to elucidate oxygen transport limitations at moderate to high altitudes. Such attempts, however, have not made clear the extent to which RCV is of benefit to exercise at such elevations. Changes in RCV at sea level clearly have a direct influence on maximal exercise capacity. Nonetheless, at elevations above 3000 m, the evidence is not that clear. Certain studies demonstrate either a direct benefit or decrement to exercise capacity in response to an increase or decrease, respectively, in RCV whereas other studies report negligible effects of RCV manipulation on exercise capacity. Adding to the uncertainty regarding the importance of RCV at high altitude is the observation that Andean and Tibetan high-altitude natives exhibit similar exercise capacities at high altitude (3900 m) even though Andean natives often present with a higher percent haematocrit (Hct) when compared with both lowland natives and Tibetans. The current review summarizes past literature that has examined the effect of RCV changes on maximal exercise capacity at moderate to high altitudes, and discusses the explanation elucidating these seemingly paradoxical observations.
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Affiliation(s)
- Robert A Jacobs
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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48
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Robach P, Lundby C. Is live high-train low altitude training relevant for elite athletes with already high total hemoglobin mass? Scand J Med Sci Sports 2012; 22:303-5. [PMID: 22612361 DOI: 10.1111/j.1600-0838.2012.01457.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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49
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Pasipoularides A. Optimal hematocrit: a Procrustean bed for maximum oxygen transport rate? J Appl Physiol (1985) 2012; 113:353-4. [PMID: 22678962 DOI: 10.1152/japplphysiol.00654.2012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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50
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Robach P, Boisson RC, Vincent L, Lundby C, Moutereau S, Gergelé L, Michel N, Duthil E, Féasson L, Millet GY. Hemolysis induced by an extreme mountain ultra-marathon is not associated with a decrease in total red blood cell volume. Scand J Med Sci Sports 2012; 24:18-27. [PMID: 22672635 DOI: 10.1111/j.1600-0838.2012.01481.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2012] [Indexed: 12/14/2022]
Abstract
Prolonged running is known to induce hemolysis. It has been suggested that hemolysis may lead to a significant loss of red blood cells; however, its actual impact on the erythrocyte pool is unknown. Here, we test the hypothesis that prolonged running with high hemolytic potential decreases total red blood cell volume (RCV). Hemolysis (n = 22) and RCV (n = 19) were quantified in ultra-marathon runners before and after a 166-km long mountain ultra-endurance marathon (RUN) with 9500 m of altitude gain/loss. Assessment of total hemoglobin mass (Hbmass) and RCV was performed using a carbon monoxide rebreathing technique. RUN induced a marked acute-phase response and promoted hemolysis, as shown by a decrease in serum haptoglobin (P < 0.05). Elevated serum erythropoietin concentration and reticulocyte count after RUN were indicative of erythropoietic stimulation. Following RUN, runners experienced hemodilution, mediated by a large plasma volume expansion and associated with a large increase in plasma aldosterone. However, neither Hbmass nor RCV were found to be altered after RUN. Our findings indicate that mechanical/physiological stress associated with RUN promotes hemolysis but this has no impact on total erythrocyte volume. We therefore suggest that exercise 'anemia' is entirely due to plasma volume expansion and not to a concomitant decrease in RCV.
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Affiliation(s)
- P Robach
- Medical Department, National School for Skiing and Mountaineering, Site of the National School for Mountain Sports, Chamonix, France
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