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Beever AT, Zhuang AY, Murias JM, Aboodarda SJ, MacInnis MJ. Effects of acute simulated altitude on the maximal lactate steady state in humans. Am J Physiol Regul Integr Comp Physiol 2024; 327:R195-R207. [PMID: 38842515 DOI: 10.1152/ajpregu.00065.2024] [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: 03/12/2024] [Revised: 05/03/2024] [Accepted: 05/17/2024] [Indexed: 06/07/2024]
Abstract
We sought to determine the effects of acute simulated altitude on the maximal lactate steady state (MLSS) and physiological responses to cycling at and 10 W above the MLSS-associated power output (PO) (MLSSp and MLSSp+10, respectively). Eleven (4 females) participants (means [SD]; 28 [4] yr; V̇o2max: 54.3 [6.9] mL·kg-1·min-1) acclimatized to ∼1,100 m performed 30-min constant PO trials in simulated altitudes of 0 m sea level (SL), 1,111 m mild altitude (MILD), and 2,222 m moderate altitude (MOD). MLSSp, defined as the highest PO with stable (<1 mM change) blood lactate concentration ([BLa]) between 10 and 30 min, was significantly lower in MOD (209 [54] W) compared with SL (230 [56] W; P < 0.001) and MILD (225 [58] W; P = 0.001), but MILD and SL were not different (P = 0.12). V̇o2 and V̇co2 decreased at higher simulated altitudes due to lower POs (P < 0.05), but other end-exercise physiological responses (e.g., [BLa], ventilation [V̇e], heart rate [HR]) were not different between conditions at MLSSp or MLSSp + 10 (P > 0.05). At the same absolute intensity (MLSSp for MILD), [BLa], HR, and V̇E and all perceptual variables were exacerbated in MOD compared with SL and MILD (P < 0.05). Maximum voluntary contraction, voluntary activation, and potentiated twitch forces were exacerbated at MLSSp + 10 relative to MLSSp within conditions (P < 0.05); however, condition did not affect performance fatiguability at the same relative or absolute intensity (P > 0.05). As MLSSp decreased in hypoxia, adjustments in PO are needed to ensure the same relative intensity across altitudes, but common indices of exercise intensity may facilitate exercise prescription and monitoring in hypoxia.NEW & NOTEWORTHY This study demonstrates the power output and metabolic rate associated with the maximal lactate steady-state (MLSS) decline in response to simulated altitude; however, common indices of exercise intensity remained unchanged when cycling was performed at the work rate associated with MLSS at each simulated altitude. These results support previous studies that investigated the effects of hypoxia on alternative measures of the critical intensity of exercise and will inform exercise prescription/monitoring across altitudes.
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Affiliation(s)
- Austin T Beever
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Andrea Y Zhuang
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Saied J Aboodarda
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Martin J MacInnis
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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2
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Caswell AM, Tripp TR, Kontro H, Edgett BA, Wiley JP, Lun V, MacInnis MJ. The influence of sex, hemoglobin mass, and skeletal muscle characteristics on cycling critical power. J Appl Physiol (1985) 2024; 137:10-22. [PMID: 38779761 DOI: 10.1152/japplphysiol.00120.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 04/29/2024] [Accepted: 05/15/2024] [Indexed: 05/25/2024] Open
Abstract
Critical power (CP) represents an important threshold for exercise performance and fatiguability. We sought to determine the extent to which sex, hemoglobin mass (Hbmass), and skeletal muscle characteristics influence CP. Before CP determination (i.e., 3-5 constant work rate trials to task failure), Hbmass and skeletal muscle oxidative capacity (τ) were measured and vastus lateralis (VL) muscle biopsy samples were collected from 12 females and 12 males matched for aerobic fitness relative to fat-free mass (FFM) [means (SD); V̇o2max: 59.2 (7.7) vs. 59.5 (7.1) mL·kg·FFM-1·min-1, respectively]. Males had a significantly greater CP than females in absolute units [225 (28) vs. 170 (43) W; P = 0.001] but not relative to body mass [3.0 (0.6) vs. 2.7 (0.6) W·kg·BM-1; P = 0.267] or FFM [3.6 (0.7) vs. 3.7 (0.8) W·kg·FFM-1; P = 0.622]. Males had significantly greater W' (P ≤ 0.030) and greater Hbmass (P ≤ 0.016) than females, regardless of the normalization approach; however, there were no differences in mitochondrial protein content (P = 0.375), τ (P = 0.603), or MHC I proportionality (P = 0.574) between males and females. Whether it was expressed in absolute or relative units, CP was positively correlated with Hbmass (0.444 ≤ r ≤ 0.695; P < 0.05), mitochondrial protein content (0.413 ≤ r ≤ 0.708; P < 0.05), and MHC I proportionality (0.506 ≤ r ≤ 0.585; P < 0.05), and negatively correlated with τ when expressed in relative units only (-0.588 ≤ r ≤ -0.527; P < 0.05). Overall, CP was independent of sex, but variability in CP was related to Hbmass and skeletal muscle characteristics. The extent to which manipulations in these physiological parameters influence CP warrants further investigation to better understand the factors underpinning CP.NEW & NOTEWORTHY In males and females matched for aerobic fitness [maximal oxygen uptake normalized to fat-free mass (FFM)], absolute critical power (CP) was greater in males, but relative CP (per kilogram body mass or FFM) was similar between sexes. CP correlated with hemoglobin mass, mitochondrial protein content, myosin heavy chain type I proportion, and skeletal muscle oxidative capacity. These findings demonstrate the importance of matching sexes for aerobic fitness, but further experiments are needed to determine causality.
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Affiliation(s)
- Allison M Caswell
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Thomas R Tripp
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Hilkka Kontro
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Brittany A Edgett
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - J Preston Wiley
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Sport Medicine Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Victor Lun
- Sport Medicine Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Martin J MacInnis
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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3
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Richard NA, Koehle MS. Influence and Mechanisms of Action of Environmental Stimuli on Work Near and Above the Severe Domain Boundary (Critical Power). SPORTS MEDICINE - OPEN 2022; 8:42. [PMID: 35347469 PMCID: PMC8960528 DOI: 10.1186/s40798-022-00430-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 02/26/2022] [Indexed: 11/10/2022]
Abstract
Abstract
The critical power (CP) concept represents the uppermost rate of steady state aerobic metabolism during work. Work above CP is limited by a fixed capacity (W′) with exercise intensity being an accelerant of its depletion rate. Exercise at CP is a considerable insult to homeostasis and any work done above it will rapidly become intolerable. Humans live and exercise in situations of hypoxia, heat, cold and air pollution all of which impose a new environmental stress in addition to that of exercise. Hypoxia disrupts the oxygen cascade and consequently aerobic energy production, whereas heat impacts the circulatory system’s ability to solely support exercise performance. Cold lowers efficiency and increases the metabolic cost of exercise, whereas air pollution negatively impacts the respiratory system. This review will examine the effects imposed by environmental conditions on CP and W′ and describe the key physiological mechanisms which are affected by the environment.
Graphical Abstract
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4
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Valenzuela PL, Mateo-March M, Muriel X, Zabala M, Lucia A, Barranco-Gil D, Millet GP, Brocherie F, Burtscher J, Burtscher M, Ryan BJ, Gioscia-Ryan RA, Perrey S, Rodrigo-Carranza V, González-Mohíno F, González-Ravé JM, Santos-Concejero J, Denadai BS, Greco CC, Casado A, Foster C, Mazzolari R, Baldrighi GN, Pastorio E, Malatesta D, Patoz A, Borrani F, Ives SJ, DeBlauw JA, Dantas de Lucas R, Borszcz FK, Fernandes Nascimento EM, Antonacci Guglielmo LG, Turnes T, Jaspers RT, van der Zwaard S, Lepers R, Louis J, Meireles A, de Souza HLR, de Oliveira GT, dos Santos MP, Arriel RA, Marocolo M, Hunter B, Meyler S, Muniz-Pumares D, Ferreira RM, Sogard AS, Carter SJ, Mickleborough TD, Saborosa GP, de Oliveira Freitas RD, Alves dos Santos PS, de Souza Ferreira JP, de Assis Manoel F, da Silva SF, Triska C, Karsten B, Sanders D, Lipksi ES, Spindler DJ, Hesselink MKC, Zacca R, Goethel MF, Pyne DB, Wood BM, Allen PE, Gabelhausen JL, Keller AM, Lige MT, Oumsang AS, Smart GL, Paris HL, Dewolf AH, Toffoli G, Martinez-Gonzalez B, Marcora SM, Terson de Paleville D, Fernandes RJ, Soares SM, Abraldes JA, Matta G, Bossi AH, McCarthy DG, Bostad W, Gibala J, Vagula M. Commentaries on Viewpoint: Using V̇o 2max as a marker of training status in athletes - can we do better? J Appl Physiol (1985) 2022; 133:148-164. [PMID: 35819399 DOI: 10.1152/japplphysiol.00224.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Pedro L Valenzuela
- Grupo de Investigación en Actividad física y Salud (PaHerg), Instituto de Investigación Hospital 12 de Octubre (imas12), Madrid, Spain
| | - Manuel Mateo-March
- Faculty of Sport Sciences, Universidad Europea de Madrid, Madrid, Spain,Sport Science Department. Universidad Miguel Hernández, Elche, Spain
| | - Xabier Muriel
- Human Performance and Sports Science Laboratory, Faculty of Sport Sciences, University of Murcia, Murcia, Spain
| | - Mikel Zabala
- Department of Physical Education & Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain
| | - Alejandro Lucia
- Grupo de Investigación en Actividad física y Salud (PaHerg), Instituto de Investigación Hospital 12 de Octubre (imas12), Madrid, Spain,Faculty of Sport Sciences, Universidad Europea de Madrid, Madrid, Spain
| | | | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Franck Brocherie
- Laboratory Sport, Expertise and Performance (EA 7370), French Institute of Sport (INSEP), Paris, France
| | - Johannes Burtscher
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Benjamin J Ryan
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | | | - Stephane Perrey
- EuroMov Digital Health in Motion, University of Montpellier, Montpellier, France
| | | | - Fernando González-Mohíno
- Sport Training Lab, University of Castilla-La Mancha, Toledo, Spain,Facultad de Ciencias de la Vida y de la Naturaleza, Universidad Nebrija, Madrid, Spain
| | | | - Jordan Santos-Concejero
- Department of Physical Education and Sport, University of the Basque Country UPV/EHU, Vitoria-Gasteiz, Spain
| | - Benedito S Denadai
- Human Performance Laboratory, São Paulo State University, Rio Claro, Brazil
| | - Camila C Greco
- Human Performance Laboratory, São Paulo State University, Rio Claro, Brazil
| | - Arturo Casado
- Center for Sport Studies, Rey Juan Carlos University, Madrid, Spain
| | - Carl Foster
- University of Wisconsin-La Crosse, La Crosse, Wisconsin
| | - Raffaele Mazzolari
- Department of Physical Education and Sport, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain,Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Giulia Nicole Baldrighi
- Department of Brain and Behavioural Sciences − Medical and Genomic Statistics Unit, University of Pavia, Pavia, Italy
| | - Elisa Pastorio
- Department of Molecular Medicine, University of Pavia, Pavia, Italy,Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Davide Malatesta
- Institute of Sport Sciences of University of Lausanne (ISSUL), University of Lausanne, Lausanne, Switzerland
| | - Aurélien Patoz
- Institute of Sport Sciences of University of Lausanne (ISSUL), University of Lausanne, Lausanne, Switzerland
| | - Fabio Borrani
- Institute of Sport Sciences of University of Lausanne (ISSUL), University of Lausanne, Lausanne, Switzerland
| | - Stephen J Ives
- Health and Human Physiological Sciences, Skidmore College, Saratoga Springs, New York
| | - Justin A DeBlauw
- Health and Human Physiological Sciences, Skidmore College, Saratoga Springs, New York
| | | | | | | | | | - Tiago Turnes
- Physical Effort Laboratory, Federal University of Santa Catarina, Florianopolis, Brazil
| | - Richard T Jaspers
- Department of Human Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands,Laboratory for Myology, Department of Human Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Stephan van der Zwaard
- Department of Human Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands,Laboratory for Myology, Department of Human Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands,Leiden Institute of Advanced Computer Science, Leiden University, Leiden, The Netherlands
| | - Romuald Lepers
- INSERM UMR1093 CAPS, Faculty of Sport Sciences, University of Bourgogne Franche-Comté, Dijon, France
| | - Julien Louis
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Anderson Meireles
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| | - Hiago L. R. de Souza
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| | - Géssyca T de Oliveira
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| | - Marcelo P dos Santos
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| | - Rhaí A Arriel
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| | - Moacir Marocolo
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| | - B Hunter
- Department of Psychology, Sport, and Geography, School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
| | - S Meyler
- Department of Psychology, Sport, and Geography, School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
| | - D Muniz-Pumares
- Department of Psychology, Sport, and Geography, School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
| | - Renato M Ferreira
- Aquatic Activities Research Group, Department of Physical Education, Federal University of Ouro Preto, Ouro Preto, Brazil
| | - Abigail S Sogard
- Department of Kinesiology, School of Public Health-Bloomington, Indiana University, Bloomington, Indiana
| | - Stephen J Carter
- Department of Kinesiology, School of Public Health-Bloomington, Indiana University, Bloomington, Indiana,Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana
| | - Timothy D Mickleborough
- Department of Kinesiology, School of Public Health-Bloomington, Indiana University, Bloomington, Indiana
| | - Guilherme Pereira Saborosa
- Study Group and Research in Neuromuscular Responses, University of Lavras, Lavras, Brazil,Postgraduate Program in Nutrition and Health, University of Lavras, Lavras, Brazil
| | - Raphael Dinalli de Oliveira Freitas
- Study Group and Research in Neuromuscular Responses, University of Lavras, Lavras, Brazil,Postgraduate Program in Nutrition and Health, University of Lavras, Lavras, Brazil
| | - Paula Souza Alves dos Santos
- Study Group and Research in Neuromuscular Responses, University of Lavras, Lavras, Brazil,Postgraduate Program in Nutrition and Health, University of Lavras, Lavras, Brazil
| | - João Pedro de Souza Ferreira
- Study Group and Research in Neuromuscular Responses, University of Lavras, Lavras, Brazil,Postgraduate Program in Nutrition and Health, University of Lavras, Lavras, Brazil
| | | | - Sandro Fernandes da Silva
- Study Group and Research in Neuromuscular Responses, University of Lavras, Lavras, Brazil,Postgraduate Program in Nutrition and Health, University of Lavras, Lavras, Brazil
| | - Christoph Triska
- Institute of Sport Science, Centre for Sport Science and University Sports, University of Vienna, Vienna, Austria,Leistungssport Austria, Brunn am Gebirge, Austria
| | - Bettina Karsten
- European University of Applied Sciences (EUFH), Berlin, Germany
| | - Dajo Sanders
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Elliot S Lipksi
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - David J Spindler
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Matthijs K. C. Hesselink
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Rodrigo Zacca
- Research Center in Physical Activity, Health and Leisure (CIAFEL), Faculty of Sports, University of Porto (FADEUP), Porto, Portugal,Laboratory for Integrative and Translational Research in Population Health (ITR), Porto, Portugal
| | - Márcio Fagundes Goethel
- Porto Biomechanics Laboratory (LABIOMEP-UP), University of Porto, Porto, Portugal,Centre of Research, Education, Innovation, and Intervention in Sport (CIFI2D), Faculty of Sports, University of Porto, Porto, Portugal
| | - David Bruce Pyne
- University of Canberra Research Institute for Sport and Exercise (UCRISE), University of Canberra, Canberra, Australia
| | - Brayden M Wood
- Exercise Physiology Laboratory, Department of Sports Medicine, Pepperdine University, Malibu, California
| | - Peyton E Allen
- Exercise Physiology Laboratory, Department of Sports Medicine, Pepperdine University, Malibu, California
| | - Jaden L Gabelhausen
- Exercise Physiology Laboratory, Department of Sports Medicine, Pepperdine University, Malibu, California
| | - Alexandra M Keller
- Exercise Physiology Laboratory, Department of Sports Medicine, Pepperdine University, Malibu, California
| | - Mast T Lige
- Exercise Physiology Laboratory, Department of Sports Medicine, Pepperdine University, Malibu, California
| | - Alicia S Oumsang
- Exercise Physiology Laboratory, Department of Sports Medicine, Pepperdine University, Malibu, California
| | - Greg L Smart
- Exercise Physiology Laboratory, Department of Sports Medicine, Pepperdine University, Malibu, California
| | - Hunter L Paris
- Exercise Physiology Laboratory, Department of Sports Medicine, Pepperdine University, Malibu, California
| | - Arthur H Dewolf
- Laboratory of Physiology and Biomechanics of Human Locomotion, Institute of Neuroscience, Université catholique de Louvain-la-Neuve, Louvain-la-Neuve, Belgium
| | - Guillaume Toffoli
- Department for Life Quality Studies, University of Bologna, Bologna, Italy
| | | | - Samuele M Marcora
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | | | - Ricardo J Fernandes
- Research Center in Physical Activity, Health and Leisure (CIAFEL), Faculty of Sports, University of Porto (FADEUP), Porto, Portugal,Porto Biomechanics Laboratory (LABIOMEP-UP), University of Porto, Porto, Portugal
| | - Susana M Soares
- Research Center in Physical Activity, Health and Leisure (CIAFEL), Faculty of Sports, University of Porto (FADEUP), Porto, Portugal,Porto Biomechanics Laboratory (LABIOMEP-UP), University of Porto, Porto, Portugal
| | - J. Arturo Abraldes
- Research Group MS&SPORT, Faculty of Sports Sciences, University of Murcia, Murcia, Spain
| | - Guilherme Matta
- Faculty of Science, Engineering and Social Sciences, School of Psychology and Life Sciences, Canterbury Christ Church University, Canterbury, United Kingdom
| | - Arthur Henrique Bossi
- MeFit Prehabilitation Service, Medway NHS Foundation Trust, Gillingham, United Kingdom
| | - D G McCarthy
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - W Bostad
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - J Gibala
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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5
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Kaiser BW, Kruse KK, Gibson BM, Santisteban KJ, Larson EA, Wilkins BW, Jones AM, Halliwill JR, Minson CT. The impact of elevated body core temperature on critical power as determined by a 3-min all-out test. J Appl Physiol (1985) 2021; 131:1543-1551. [DOI: 10.1152/japplphysiol.00253.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The parameters of the power-duration relationship (critical power and W′) estimated by a 3-min all-out test were not altered by elevated body core temperature as compared with a thermoneutral condition.
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Affiliation(s)
- Brendan W. Kaiser
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Ka'eo K. Kruse
- Department of Human Evolutionary Biology, Harvard University, Cambridge, Massachusetts
| | - Brandon M. Gibson
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | | | - Emily A. Larson
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Brad W. Wilkins
- Department of Human Physiology, University of Oregon, Eugene, Oregon
- Department of Human Physiology, Gonzaga University, Spokane, Washington
| | - Andrew M. Jones
- Department of Sport and Health Sciences, University of Exeter, St. Luke’s Campus, Exeter, United Kingdom
| | - John R. Halliwill
- Department of Human Physiology, University of Oregon, Eugene, Oregon
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6
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Goulding RP, Rossiter HB, Marwood S, Ferguson C. Bioenergetic Mechanisms Linking V˙O2 Kinetics and Exercise Tolerance. Exerc Sport Sci Rev 2021; 49:274-283. [PMID: 34547760 PMCID: PMC8528340 DOI: 10.1249/jes.0000000000000267] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We hypothesize that the V˙O2 time constant (τV˙O2) determines exercise tolerance by defining the power output associated with a "critical threshold" of intramuscular metabolite accumulation (e.g., inorganic phosphate), above which muscle fatigue and work inefficiency are apparent. Thereafter, the V˙O2 "slow component" and its consequences (increased pulmonary, circulatory, and neuromuscular demands) determine performance limits.
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Affiliation(s)
- Richie P. Goulding
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
- Laboratory for Myology, Vrije Universiteit, Amsterdam, The Netherlands
| | - Harry B. Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance CA, 90254, USA
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, L16 9JD, UK
| | - Carrie Ferguson
- School of Biomedical Sciences, Faculty of Biological Sciences & Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, LS 2 9JT, UK
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7
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Azevedo RDA, J E BS, Inglis EC, Iannetta D, Murias JM. Hypoxia equally reduces the respiratory compensation point and the NIRS-derived [HHb] breakpoint during a ramp-incremental test in young active males. Physiol Rep 2021; 8:e14478. [PMID: 32592338 PMCID: PMC7319946 DOI: 10.14814/phy2.14478] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 05/13/2020] [Indexed: 12/20/2022] Open
Abstract
This study investigated the effect of reduced inspired fraction of O2 (FiO2) in the correspondence between the respiratory compensation point (RCP) and the breakpoint in the near‐infrared spectroscopy‐derived deoxygenated hemoglobin signal ([HHb]bp) during a ramp‐incremental (RI) test to exhaustion. Eleven young males performed, on two separated occasions, a RI test either in normoxia (NORM, FiO2 = 20.9%) or hypoxia (HYPO, FiO2 = 16%). Oxygen uptake (
V˙O2), and [HHb] signal from the vastus lateralis muscle were continuously measured. Peak
V˙O2 (2.98 ± 0.36 vs. 3.39 ± 0.26 L min−1) and PO (282 ± 29 vs. 310 ± 19 W) were lower in HYPO compared to NORM condition, respectively. The
V˙O2 and PO associated with RCP and [HHb]bp were lower in HYPO (2.35 ± 0.24 and 2.34 ± 0.26 L min−1; 198 ± 37 and 197 ± 30 W, respectively) when compared to NORM (2.75 ± 0.26 and 2.75 ± 0.28 L min−1; 244 ± 29 and 241 ± 28 W, respectively) (p < .05). Within the same condition, the
V˙O2 and PO associated with RCP and [HHb]bp were not different (p > .05). Bland–Altman plots mean average errors between RCP and [HHb]bp were not different from zero in HYPO (0.01 L min−1 and 1.1 W) and NORM (0.00 L min−1 and 3.6 W) conditions. The intra‐individual changes between thresholds associated with
V˙O2 and PO in HYPO from NORM were strongly correlated (r = .626 and 0.752, p < .05). Therefore, breathing a lower FiO2 during a RI test resulted in proportional reduction in the RCP and the [HHb]bp in terms of
V˙O2 and PO, which further supports the notion that these physiological responses may arise from similar metabolic changes reflecting a common phenomenon.
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Affiliation(s)
| | - Béjar Saona J E
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | | | - Danilo Iannetta
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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8
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Feldmann A, Erlacher D. Critical oxygenation: Can muscle oxygenation inform us about critical power? Med Hypotheses 2021; 150:110575. [PMID: 33857860 DOI: 10.1016/j.mehy.2021.110575] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/17/2021] [Accepted: 03/14/2021] [Indexed: 11/19/2022]
Abstract
The power-duration relationship is well documented for athletic performance and is formulated out mathematically in the critical power (CP) model. The CP model, when applied properly, has great predictive power, e.g. pedaling at a specific power output on an ergometer the model precisely calculates the time over which an athlete can sustain this power. However, CP presents physiological inconsistencies and process-oriented problems. The rapid development of near-infrared spectroscopy (NIRS) to measure muscle oxygenation (SmO2) dynamics provides a physiological exploration of the CP model on a conceptual and empirical level. Conceptually, the CP model provides two components: first CP is defined as the highest metabolic rate that can be achieved through oxidative means. And second, work capacity above CP named W'. SmO2 presents a steady-state in oxygen supply and demand and thereby represents CP specifically at a local level of analysis. Empirically, exploratory data quickly illustrates the relationship between performance and SmO2, as shown during 3-min all-out cycling tests to assess CP. During these tests, performance and SmO2 essentially mirror each other, and both CP and W' generate solid correlation with what would be deemed their SmO2 counterparts: first, the steady-state of SmO2 correlates with CP. And second, the tissue oxygen reserve represented in SmO2, when calculated as an integral corresponds to W'. While the empirical data presented is preliminary, the proposition of a concurring physiological model to the current CP model is a plausible inference. Here we propose that SmO2 steady-state representing CP as critical oxygenation or CO. And the tissue oxygen reserve above CO would then be identified as O'. This new CO model could fill in the physiological gap between the highly predictive CP model and at times its inability to track human physiology consistently. For simplicity's sake, this would include acute changes in physiology as a result of changing climate or elevation with travel, which can affect performance. These types of acute fluctuations, but not limited to, would be manageable when applying a CO model in conjunction with the CP model. Further, modeling is needed to investigate the true potential of NIRS to model CP, with a focus on repeatability, recovery, and systemic vs local workloads.
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Affiliation(s)
- Andri Feldmann
- Institute of Sport Science, University of Bern, Bern Bremgartenstrasse 145, 3012 Bern, Switzerland.
| | - Daniel Erlacher
- Institute of Sport Science, University of Bern, Bern Bremgartenstrasse 145, 3012 Bern, Switzerland
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9
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Gifford JR, Collins J. Critical Speed throughout Aging: Insight into the World Masters Championships. Med Sci Sports Exerc 2021; 53:524-533. [PMID: 33560767 DOI: 10.1249/mss.0000000000002501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
PURPOSE This study aimed to determine how the speed-distance relationship, described by critical speed (CS) and distance prime (D'), is altered with aging. METHODS Official race data from the past eight World Masters Athletics Indoor Track and Field World Championships were used for this study. CS and D' were calculated for female and male athletes (35-90 yr of age) who registered times for the 800-, 1500-, and 3000-m runs during a single championship to determine the relationship between age and CS and D'. Twenty-six athletes completed sufficient races in multiple championships to retrospectively assess the change in CS and D' over time. RESULTS Cross-sectional data indicated that CS continuously decreases after age 35 yr in a curvilinear manner with advancing age (R2 = 0.73, P < 0.001, n = 187), with even greater decreases in CS occurring after ~70 yr of age. D' also changed in a curvilinear manner with age (R2 = 0.45, P < 0.001, n = 103), such that decreases were observed between 35 and 70 yr, followed by an increase in D' thereafter. Retrospective, longitudinal data, with an average follow-up of 6.38 ± 1.73 yr, support these findings, indicating that the annual decrease in CS grows with advancing age (e.g., ~1% vs ~3% annual decrease in CS at age 55 vs 80 yr, respectively) and that D' shifts from an annual decrease (e.g., ~2.5% annual decrease at 55 yr) to an annual increase (e.g., ~2.5% annual increase at 80 yr) around 70 yr of age. Importantly, the relationship between CS and race pace was unaffected by age, supporting the relevance of CS throughout aging. CONCLUSION Even among world-class athletes, CS decreases and D' changes with aging. These adaptations may contribute to the diminished exercise ability associated with aging.
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Affiliation(s)
| | - Jessica Collins
- Department of Exercise Sciences, Brigham Young University, Provo, UT
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10
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Poole DC, Behnke BJ, Musch TI. The role of vascular function on exercise capacity in health and disease. J Physiol 2021; 599:889-910. [PMID: 31977068 PMCID: PMC7874303 DOI: 10.1113/jp278931] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/10/2019] [Indexed: 12/16/2022] Open
Abstract
Three sentinel parameters of aerobic performance are the maximal oxygen uptake ( V ̇ O 2 max ), critical power (CP) and speed of the V ̇ O 2 kinetics following exercise onset. Of these, the latter is, perhaps, the cardinal test of integrated function along the O2 transport pathway from lungs to skeletal muscle mitochondria. Fast V ̇ O 2 kinetics demands that the cardiovascular system distributes exercise-induced blood flow elevations among and within those vascular beds subserving the contracting muscle(s). Ideally, this process must occur at least as rapidly as mitochondrial metabolism elevates V ̇ O 2 . Chronic disease and ageing create an O2 delivery (i.e. blood flow × arterial [O2 ], Q ̇ O 2 ) dependency that slows V ̇ O 2 kinetics, decreasing CP and V ̇ O 2 max , increasing the O2 deficit and sowing the seeds of exercise intolerance. Exercise training, in contrast, does the opposite. Within the context of these three parameters (see Graphical Abstract), this brief review examines the training-induced plasticity of key elements in the O2 transport pathway. It asks how structural and functional vascular adaptations accelerate and redistribute muscle Q ̇ O 2 and thus defend microvascular O2 partial pressures and capillary blood-myocyte O2 diffusion across a ∼100-fold range of muscle V ̇ O 2 values. Recent discoveries, especially in the muscle microcirculation and Q ̇ O 2 -to- V ̇ O 2 heterogeneity, are integrated with the O2 transport pathway to appreciate how local and systemic vascular control helps defend V ̇ O 2 kinetics and determine CP and V ̇ O 2 max in health and how vascular dysfunction in disease predicates exercise intolerance. Finally, the latest evidence that nitrate supplementation improves vascular and therefore aerobic function in health and disease is presented.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Brad J Behnke
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Timothy I Musch
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
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11
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The Application of Critical Power, the Work Capacity above Critical Power (W'), and its Reconstitution: A Narrative Review of Current Evidence and Implications for Cycling Training Prescription. Sports (Basel) 2020; 8:sports8090123. [PMID: 32899777 PMCID: PMC7552657 DOI: 10.3390/sports8090123] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/28/2020] [Accepted: 09/02/2020] [Indexed: 12/17/2022] Open
Abstract
The two-parameter critical power (CP) model is a robust mathematical interpretation of the power–duration relationship, with CP being the rate associated with the maximal aerobic steady state, and W′ the fixed amount of tolerable work above CP available without any recovery. The aim of this narrative review is to describe the CP concept and the methodologies used to assess it, and to summarize the research applying it to intermittent cycle training techniques. CP and W′ are traditionally assessed using a number of constant work rate cycling tests spread over several days. Alternatively, both the 3-min all-out and ramp all-out protocols provide valid measurements of CP and W′ from a single test, thereby enhancing their suitability to athletes and likely reducing errors associated with the assumptions of the CP model. As CP represents the physiological landmark that is the boundary between heavy and severe intensity domains, it presents several advantages over the de facto arbitrarily defined functional threshold power as the basis for cycle training prescription at intensities up to CP. For intensities above CP, precise prescription is not possible based solely on aerobic measures; however, the addition of the W′ parameter does facilitate the prescription of individualized training intensities and durations within the severe intensity domain. Modelling of W′ reconstitution extends this application, although more research is needed to identify the individual parameters that govern W′ reconstitution rates and their kinetics.
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12
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Limmer M, de Marées M, Platen P. Alterations in acid-base balance and high-intensity exercise performance after short-term and long-term exposure to acute normobaric hypoxic conditions. Sci Rep 2020; 10:13732. [PMID: 32792614 PMCID: PMC7426914 DOI: 10.1038/s41598-020-70762-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 08/04/2020] [Indexed: 11/21/2022] Open
Abstract
This investigation assessed the course of renal compensation of hypoxia-induced respiratory alkalosis by elimination of bicarbonate ions and impairments in anaerobic exercise after different durations of hypoxic exposure. Study A: 16 participants underwent a resting 12-h exposure to normobaric hypoxia (3,000 m). Blood gas analysis was assessed hourly. While blood pH was significantly increased, PO2, PCO2, and SaO2 were decreased within the first hour of hypoxia, and changes remained consistent. A substantial reduction in [HCO3-] levels was observed after 12 h of hypoxic exposure (- 1.35 ± 0.29 mmol/L, p ≤ 0.05). Study B: 24 participants performed in a randomized, cross-over trial portable tethered sprint running (PTSR) tests under normoxia and after either 1 h (n = 12) or 12 h (n = 12) of normobaric hypoxia (3,000 m). No differences occurred for PTSR-related performance parameters, but the reduction in blood lactate levels was greater after 12 h compared with 1 h (- 1.9 ± 2.2 vs 0.0 ± 2.3 mmol/L, p ≤ 0.05). These results indicate uncompensated respiratory alkalosis after 12 h of hypoxia and similar impairment of high-intensity exercise after 1 and 12 h of hypoxic exposure, despite a greater reduction in blood lactate responses after 12 h compared with 1 h of hypoxic exposure.
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Affiliation(s)
- Mirjam Limmer
- Institute of Sports Medicine and Sports Nutrition, Ruhr-University Bochum, Bochum, Germany.
- Institute of Outdoor Sports and Environmental Science, German Sports University Cologne, Cologne, Germany.
| | - Markus de Marées
- Institute of Sports Medicine and Sports Nutrition, Ruhr-University Bochum, Bochum, Germany
| | - Petra Platen
- Institute of Sports Medicine and Sports Nutrition, Ruhr-University Bochum, Bochum, Germany
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13
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Chorley A, Bott RP, Marwood S, Lamb KL. Physiological and anthropometric determinants of critical power, W' and the reconstitution of W' in trained and untrained male cyclists. Eur J Appl Physiol 2020; 120:2349-2359. [PMID: 32776219 PMCID: PMC7560916 DOI: 10.1007/s00421-020-04459-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 07/31/2020] [Indexed: 11/26/2022]
Abstract
Purpose This study examined the relationship of physiological and anthropometric characteristics with parameters of the critical power (CP) model, and in particular the reconstitution of W′ following successive bouts of maximal exercise, amongst trained and untrained cyclists. Methods Twenty male adults (trained nine; untrained 11; age 39 ± 15 year; mass 74.7 ± 8.7 kg; V̇O2max 58.0 ± 8.7 mL kg−1 min−1) completed three incremental ramps (20 W min−1) to exhaustion interspersed with 2-min recoveries. Pearson’s correlation coefficients were used to assess relationships for W′ reconstitution after the first recovery (W′rec1), the delta in W′ reconstituted between recoveries (∆W′rec), CP and W′. Results CP was strongly related to V̇O2max for both trained (r = 0.82) and untrained participants (r = 0.71), whereas W′ was related to V̇O2max when both groups were considered together (r = 0.54). W′rec1 was strongly related to V̇O2max for the trained (r = 0.81) but not untrained (r = 0.18); similarly, ∆W′rec was strongly related to V̇O2max (r = − 0.85) and CP (r = − 0.71) in the trained group only. Conclusions Notable physiological relationships between parameters of aerobic fitness and the measurements of W′ reconstitution were observed, which differed among groups. The amount of W′ reconstitution and the maintenance of W′ reconstitution that occurred with repeated bouts of maximal exercise were found to be related to key measures of aerobic fitness such as CP and V̇O2max. This data demonstrates that trained cyclists wishing to improve their rate of W′ reconstitution following repeated efforts should focus training on improving key aspects of aerobic fitness such as V̇O2max and CP.
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Affiliation(s)
- Alan Chorley
- Department of Sport and Exercise Sciences, University of Chester, Chester, CH1 4BJ, UK.
| | - Richard P Bott
- Department of Sport and Exercise Sciences, University of Chester, Chester, CH1 4BJ, UK
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, L16 9JD, UK
| | - Kevin L Lamb
- Department of Sport and Exercise Sciences, University of Chester, Chester, CH1 4BJ, UK
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14
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Limmer M, de Marées M, Platen P. Effects of daily ingestion of sodium bicarbonate on acid-base status and anaerobic performance during an altitude sojourn at high altitude: a randomized controlled trial. J Int Soc Sports Nutr 2020; 17:22. [PMID: 32307012 PMCID: PMC7168960 DOI: 10.1186/s12970-020-00351-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 04/03/2020] [Indexed: 01/18/2023] Open
Abstract
Background The present study investigated the effects of chronic sodium bicarbonate (NaHCO3) ingestion on a single bout of high-intensity exercise and on acid-base balance during 7-day high-altitude exposure. Methods Ten recreationally active subjects participated in a pre-test at sea level and a 7-day hiking tour in the Swiss Alps up to 4554 m above sea level. Subjects received either a daily dose of 0.3 g/kg NaHCO3 solution (n = 5) or water as a placebo (n = 5) for 7 days. Anaerobic high-intensity exercise performance was assessed using the portable tethered sprint running (PTSR) test under normoxic and hypoxic conditions (3585 m). PTSR tests assessed overall peak force, mean force, and fatigue index. Blood lactate levels and blood gas parameters were assessed pre- and post-PTSR. Urinary pH and blood gas parameters were further analyzed daily at rest in early morning samples under normoxic and hypoxic conditions. Results There were no significant differences between the bicarbonate and control group in any of the PTSR-related parameters. However, urinary pH (p = 0.003, ηp2 = 0.458), early morning blood bicarbonate concentration (p < 0.001, ηp2 = 0.457) and base excess (p = 0.002, ηp2 = 0.436) were significantly higher in the bicarbonate group compared with the control group under hypoxic conditions. Conclusions These results indicate that oral NaHCO3 ingestion does not ameliorate the hypoxia-induced impairment in anaerobic, high-intensity exercise performance, represented by PTSR-related test parameters, under hypobaric, hypoxic conditions, but the maximal performance measurements may have been negatively affected by other factors, such as poor implementation of PTSR test instructions, pre-acclimatization, the time course of hypoxia-induced renal [HCO3−] compensation, changes in the concentrations of intra- and extracellular ions others than [H+] and [HCO3−], or gastrointestinal disturbances caused by NaHCO3 ingestion. However, chronic NaHCO3 ingestion improves blood bicarbonate concentration and base excess at altitude, which partially represent the blood buffering capacity.
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Affiliation(s)
- Mirjam Limmer
- Department of Sports Medicine and Sports Nutrition, Ruhr-Universität Bochum, Gesundheitscampus Nord 10, 44801, Bochum, Germany. .,Institute of Outdoor Sports and Environmental Science, German Sport University Cologne, Cologne, Germany.
| | - Markus de Marées
- Department of Sports Medicine and Sports Nutrition, Ruhr-Universität Bochum, Gesundheitscampus Nord 10, 44801, Bochum, Germany
| | - Petra Platen
- Department of Sports Medicine and Sports Nutrition, Ruhr-Universität Bochum, Gesundheitscampus Nord 10, 44801, Bochum, Germany
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15
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Effects of an Alkalizing or Acidizing Diet on High-Intensity Exercise Performance under Normoxic and Hypoxic Conditions in Physically Active Adults: A Randomized, Crossover Trial. Nutrients 2020; 12:nu12030688. [PMID: 32143278 PMCID: PMC7146607 DOI: 10.3390/nu12030688] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 02/29/2020] [Accepted: 03/02/2020] [Indexed: 12/17/2022] Open
Abstract
Pre-alkalization caused by dietary supplements such as sodium bicarbonate improves anaerobic exercise performance. However, the influence of a base-forming nutrition on anaerobic performance in hypoxia remains unknown. Herein, we investigated the effects of an alkalizing or acidizing diet on high-intensity performance and associated metabolic parameters in normoxia and hypoxia. In a randomized crossover design, 15 participants (24.5 ± 3.9 years old) performed two trials following four days of either an alkalizing (BASE) or an acidizing (ACID) diet in normoxia. Subsequently, participants performed two trials (BASE; ACID) after 12 h of normobaric hypoxic exposure. Anaerobic exercise performance was assessed using the portable tethered sprint running (PTSR) test. PTSR assessed overall peak force, mean force, and fatigue index. Blood lactate levels, blood gas parameters, heart rate, and rate of perceived exertion were assessed post-PTSR. Urinary pH was analyzed daily. There were no differences between BASE and ACID conditions for any of the PTSR-related parameters. However, urinary pH, blood pH, blood bicarbonate concentration, and base excess were significantly higher in BASE compared with ACID (p < 0.001). These findings show a diet-induced increase in blood buffer capacity, represented by blood bicarbonate concentration and base excess. However, diet-induced metabolic changes did not improve PTSR-related anaerobic performance.
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16
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Clark IE, Vanhatalo A, Thompson C, Joseph C, Black MI, Blackwell JR, Wylie LJ, Tan R, Bailey SJ, Wilkins BW, Kirby BS, Jones AM. Dynamics of the power-duration relationship during prolonged endurance exercise and influence of carbohydrate ingestion. J Appl Physiol (1985) 2019; 127:726-736. [PMID: 31295069 DOI: 10.1152/japplphysiol.00207.2019] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We tested the hypotheses that the parameters of the power-duration relationship, estimated as the end-test power (EP) and work done above EP (WEP) during a 3-min all-out exercise test (3MT), would be reduced progressively after 40 min, 80 min, and 2 h of heavy-intensity cycling and that carbohydrate (CHO) ingestion would attenuate the reduction in EP and WEP. Sixteen participants completed a 3MT without prior exercise (control), immediately after 40 min, 80 min, and 2 h of heavy-intensity exercise while consuming a placebo beverage, and also after 2 h of heavy-intensity exercise while consuming a CHO supplement (60 g/h CHO). There was no difference in EP measured without prior exercise (260 ± 37 W) compared with EP after 40 min (268 ± 39 W) or 80 min (260 ± 40 W) of heavy-intensity exercise; however, after 2 h EP was 9% lower compared with control (236 ± 47 W; P < 0.05). There was no difference in WEP measured without prior exercise (17.9 ± 3.3 kJ) compared with after 40 min of heavy-intensity exercise (16.1 ± 3.3 kJ), but WEP was lower (P < 0.05) than control after 80 min (14.7 ± 2.9 kJ) and 2 h (13.8 ± 2.7 kJ). Compared with placebo, CHO ingestion negated the reduction of EP following 2 h of heavy-intensity exercise (254 ± 49 W) but had no effect on WEP (13.5 ± 3.4 kJ). These results reveal a different time course for the deterioration of EP and WEP during prolonged endurance exercise and indicate that EP is sensitive to CHO availability.NEW & NOTEWORTHY The parameters of the power-duration relationship [critical power (CP) and the curvature constant (W')] have typically been considered to be static. Here we report the time course for reductions in CP and W', as estimated with the 3-min all-out cycle test, during 2 h of heavy-intensity exercise. We also show that carbohydrate ingestion during exercise preserves CP, but not W', without altering muscle glycogen depletion. These results provide new mechanistic and practical insight into the power-duration curve and its relationship to exercise-related fatigue development.
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Affiliation(s)
- Ida E Clark
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Anni Vanhatalo
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Christopher Thompson
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Charlotte Joseph
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Matthew I Black
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Jamie R Blackwell
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Lee J Wylie
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Rachel Tan
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Stephen J Bailey
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | | | | | - Andrew M Jones
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
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17
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Jones AM, Burnley M, Black MI, Poole DC, Vanhatalo A. The maximal metabolic steady state: redefining the 'gold standard'. Physiol Rep 2019; 7:e14098. [PMID: 31124324 PMCID: PMC6533178 DOI: 10.14814/phy2.14098] [Citation(s) in RCA: 156] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/25/2019] [Accepted: 04/27/2019] [Indexed: 02/06/2023] Open
Abstract
The maximal lactate steady state (MLSS) and the critical power (CP) are two widely used indices of the highest oxidative metabolic rate that can be sustained during continuous exercise and are often considered to be synonymous. However, while perhaps having similarities in principle, methodological differences in the assessment of these parameters typically result in MLSS occurring at a somewhat lower power output or running speed and exercise at CP being sustainable for no more than approximately 20-30 min. This has led to the view that CP overestimates the 'actual' maximal metabolic steady state and that MLSS should be considered the 'gold standard' metric for the evaluation of endurance exercise capacity. In this article we will present evidence consistent with the contrary conclusion: i.e., that (1) as presently defined, MLSS naturally underestimates the actual maximal metabolic steady state; and (2) CP alone represents the boundary between discrete exercise intensity domains within which the dynamic cardiorespiratory and muscle metabolic responses to exercise differ profoundly. While both MLSS and CP may have relevance for athletic training and performance, we urge that the distinction between the two concepts/metrics be better appreciated and that comparisons between MLSS and CP, undertaken in the mistaken belief that they are theoretically synonymous, is discontinued. CP represents the genuine boundary separating exercise in which physiological homeostasis can be maintained from exercise in which it cannot, and should be considered the gold standard when the goal is to determine the maximal metabolic steady state.
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Affiliation(s)
- Andrew M. Jones
- Sport and Health SciencesUniversity of ExeterSt. Luke's CampusExeterUnited Kingdom
| | - Mark Burnley
- School of Sport and Exercise SciencesUniversity of KentMedwayUnited Kingdom
| | - Matthew I. Black
- Sport and Health SciencesUniversity of ExeterSt. Luke's CampusExeterUnited Kingdom
| | - David C. Poole
- Department of KinesiologyKansas State UniversityManhattanKansas
| | - Anni Vanhatalo
- Sport and Health SciencesUniversity of ExeterSt. Luke's CampusExeterUnited Kingdom
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18
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Puchowicz MJ, Mizelman E, Yogev A, Koehle MS, Townsend NE, Clarke DC. The Critical Power Model as a Potential Tool for Anti-doping. Front Physiol 2018; 9:643. [PMID: 29928234 PMCID: PMC5997808 DOI: 10.3389/fphys.2018.00643] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 05/11/2018] [Indexed: 11/13/2022] Open
Abstract
Existing doping detection strategies rely on direct and indirect biochemical measurement methods focused on detecting banned substances, their metabolites, or biomarkers related to their use. However, the goal of doping is to improve performance, and yet evidence from performance data is not considered by these strategies. The emergence of portable sensors for measuring exercise intensities and of player tracking technologies may enable the widespread collection of performance data. How these data should be used for doping detection is an open question. Herein, we review the basis by which performance models could be used for doping detection, followed by critically reviewing the potential of the critical power (CP) model as a prototypical performance model that could be used in this regard. Performance models are mathematical representations of performance data specific to the athlete. Some models feature parameters with physiological interpretations, changes to which may provide clues regarding the specific doping method. The CP model is a simple model of the power-duration curve and features two physiologically interpretable parameters, CP and W′. We argue that the CP model could be useful for doping detection mainly based on the predictable sensitivities of its parameters to ergogenic aids and other performance-enhancing interventions. However, our argument is counterbalanced by the existence of important limitations and unresolved questions that need to be addressed before the model is used for doping detection. We conclude by providing a simple worked example showing how it could be used and propose recommendations for its implementation.
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Affiliation(s)
- Michael J Puchowicz
- Department of Health Services, Arizona State University, Tempe, AZ, United States
| | - Eliran Mizelman
- Department of Biomedical Physiology and Kinesiology and Sports Analytics Group, Simon Fraser University, Burnaby, BC, Canada
| | - Assaf Yogev
- School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada
| | - Michael S Koehle
- School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada.,Division of Sport and Exercise Medicine, The University of British Columbia, Vancouver, BC, Canada
| | - Nathan E Townsend
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - David C Clarke
- Department of Biomedical Physiology and Kinesiology and Sports Analytics Group, Simon Fraser University, Burnaby, BC, Canada.,Canadian Sport Institute Pacific, Victoria, BC, Canada
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19
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Jones AM, Vanhatalo A. The 'Critical Power' Concept: Applications to Sports Performance with a Focus on Intermittent High-Intensity Exercise. Sports Med 2018; 47:65-78. [PMID: 28332113 PMCID: PMC5371646 DOI: 10.1007/s40279-017-0688-0] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The curvilinear relationship between power output and the time for which it can be sustained is a fundamental and well-known feature of high-intensity exercise performance. This relationship 'levels off' at a 'critical power' (CP) that separates power outputs that can be sustained with stable values of, for example, muscle phosphocreatine, blood lactate, and pulmonary oxygen uptake ([Formula: see text]), from power outputs where these variables change continuously with time until their respective minimum and maximum values are reached and exercise intolerance occurs. The amount of work that can be done during exercise above CP (the so-called W') is constant but may be utilized at different rates depending on the proximity of the exercise power output to CP. Traditionally, this two-parameter CP model has been employed to provide insights into physiological responses, fatigue mechanisms, and performance capacity during continuous constant power output exercise in discrete exercise intensity domains. However, many team sports (e.g., basketball, football, hockey, rugby) involve frequent changes in exercise intensity and, even in endurance sports (e.g., cycling, running), intensity may vary considerably with environmental/course conditions and pacing strategy. In recent years, the appeal of the CP concept has been broadened through its application to intermittent high-intensity exercise. With the assumptions that W' is utilized during work intervals above CP and reconstituted during recovery intervals below CP, it can be shown that performance during intermittent exercise is related to four factors: the intensity and duration of the work intervals and the intensity and duration of the recovery intervals. However, while the utilization of W' may be assumed to be linear, studies indicate that the reconstitution of W' may be curvilinear with kinetics that are highly variable between individuals. This has led to the development of a new CP model for intermittent exercise in which the balance of W' remaining ([Formula: see text]) may be calculated with greater accuracy. Field trials of athletes performing stochastic exercise indicate that this [Formula: see text] model can accurately predict the time at which W' tends to zero and exhaustion is imminent. The [Formula: see text] model potentially has important applications in the real-time monitoring of athlete fatigue progression in endurance and team sports, which may inform tactics and influence pacing strategy.
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Affiliation(s)
- Andrew M Jones
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Heavitree Road, Exeter, EX12LU, UK.
| | - Anni Vanhatalo
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Heavitree Road, Exeter, EX12LU, UK
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Black MI, Jones AM, Morgan PT, Bailey SJ, Fulford J, Vanhatalo A. The Effects of β-Alanine Supplementation on Muscle pH and the Power-Duration Relationship during High-Intensity Exercise. Front Physiol 2018. [PMID: 29515455 PMCID: PMC5826376 DOI: 10.3389/fphys.2018.00111] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Purpose: To investigate the influence of β-alanine (BA) supplementation on muscle carnosine content, muscle pH and the power-duration relationship (i.e., critical power and W′). Methods: In a double-blind, randomized, placebo-controlled study, 20 recreationally-active males (22 ± 3 y, V°O2peak 3.73 ± 0.44 L·min−1) ingested either BA (6.4 g/d for 28 d) or placebo (PL) (6.4 g/d) for 28 d. Subjects completed an incremental test and two 3-min all-out tests separated by 1-min on a cycle ergometer pre- and post-supplementation. Muscle pH was assessed using 31P-magnetic resonance spectroscopy (MRS) during incremental (INC KEE) and intermittent knee-extension exercise (INT KEE). Muscle carnosine content was determined using 1H-MRS. Results: There were no differences in the change in muscle carnosine content from pre- to post-intervention (PL: 1 ± 16% vs. BA: −4 ± 25%) or in muscle pH during INC KEE or INT KEE (P > 0.05) between PL and BA, but blood pH (PL: −0.06 ± 0.10 vs. BA: 0.09 ± 0.13) during the incremental test was elevated post-supplementation in the BA group only (P < 0.05). The changes from pre- to post-supplementation in critical power (PL: −8 ± 18 W vs. BA: −6 ± 17 W) and W′ (PL: 1.8 ± 3.3 kJ vs. BA: 1.5 ± 1.7 kJ) were not different between groups. No relationships were detected between muscle carnosine content and indices of exercise performance. Conclusions: BA supplementation had no significant effect on muscle carnosine content and no influence on intramuscular pH during incremental or high-intensity intermittent knee-extension exercise. The small increase in blood pH following BA supplementation was not sufficient to significantly alter the power-duration relationship or exercise performance.
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Affiliation(s)
- Matthew I Black
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Andrew M Jones
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Paul T Morgan
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Stephen J Bailey
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Jonathan Fulford
- NIHR Exeter Clinical Research Facility, University of Exeter, Exeter, United Kingdom
| | - Anni Vanhatalo
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
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Gama MCT, dos Reis IGM, Sousa FADB, Gobatto CA. The 3-min all-out test is valid for determining critical power but not anaerobic work capacity in tethered running. PLoS One 2018; 13:e0192552. [PMID: 29444141 PMCID: PMC5812641 DOI: 10.1371/journal.pone.0192552] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 01/25/2018] [Indexed: 11/19/2022] Open
Abstract
The purpose of the study was to investigate if the 3-min all-out test (3MT) is valid for obtaining critical power intensity (CP) and the amount of work that can be performed above CP (W’) on non-motorized treadmills in tethered running. Eight physically active individuals (24 ± 3 years; 78.3 ± 8.7 kg; 179 ± 5 cm; 9.0 ± 2.5% body fat) performed four different efforts at constant intensity to exhaustion in order to determine CP and W’. The mechanical power values obtained were subsequently plotted with their corresponding time to exhaustion (limit time) for application of three mathematical models: power hyperbolic versus time limit (Hyp), linear power versus 1/time (P vs 1/t) and linear work versus time limit (Ԏ vs t). The 3MT test was carried out on the last day to determine end power (EP) and anaerobic capacity (WEP) using this methodology. EP value of 181.7 ± 52 was similar (p = 0.486) to 178.2 ± 61 (CP Hyp), 191.4 ± 55 (Ԏ vs t) and 188.3 ± 55 (P vs 1/t). WEP value of 17.9 ± 4.8 was not similar (p = 0.000) to 50.2 ± 15.3 (CP Hyp), 44.8 ± 8.7 (Ԏ vs t) and 45.5 ± 8.4 (P vs 1/t). Positive results (r = 0.78–0.98 and ICC = 0.88–0.99) of Pearson correlation and intraclass correlation (ICC–absolute agreement) were found for aerobic applications of conventional CP and 3MT. For anaerobic data, only the three models of conventional CP were correlated (r = 0.76–0.93); however, W’ from the three models was not correlated with WEP (r = 0.37–0.52). The results of this study suggest that 3MT in tethered running on non-motorized treadmills is a valid test for estimating CP aerobic parameters in a single day of application but not anaerobic parameters of W’.
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Relationship between power–duration parameters and mechanical and anthropometric properties of the thigh in elite cyclists. Eur J Appl Physiol 2018; 118:637-645. [DOI: 10.1007/s00421-018-3807-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 01/14/2018] [Indexed: 10/18/2022]
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Townsend NE, Nichols DS, Skiba PF, Racinais S, Périard JD. Prediction of Critical Power and W' in Hypoxia: Application to Work-Balance Modelling. Front Physiol 2017; 8:180. [PMID: 28386237 PMCID: PMC5362642 DOI: 10.3389/fphys.2017.00180] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/08/2017] [Indexed: 11/23/2022] Open
Abstract
Purpose: Develop a prediction equation for critical power (CP) and work above CP (W′) in hypoxia for use in the work-balance (WBAL′) model. Methods: Nine trained male cyclists completed cycling time trials (TT; 12, 7, and 3 min) to determine CP and W′ at five altitudes (250, 1,250, 2,250, 3,250, and 4,250 m). Least squares regression was used to predict CP and W′ at altitude. A high-intensity intermittent test (HIIT) was performed at 250 and 2,250 m. Actual and predicted CP and W′ were used to compute W′ during HIIT using differential (WBALdiff′) and integral (WBALint′) forms of the WBAL′ model. Results: CP decreased at altitude (P < 0.001) as described by 3rd order polynomial function (R2 = 0.99). W′ decreased at 4,250 m only (P < 0.001). A double-linear function characterized the effect of altitude on W′ (R2 = 0.99). There was no significant effect of parameter input (actual vs. predicted CP and W′) on modelled WBAL′ at 2,250 m (P = 0.24). WBALdiff′ returned higher values than WBALint′ throughout HIIT (P < 0.001). During HIIT, WBALdiff′ was not different to 0 kJ at completion, at 250 m (0.7 ± 2.0 kJ; P = 0.33) and 2,250 m (−1.3 ± 3.5 kJ; P = 0.30). However, WBALint′ was lower than 0 kJ at 250 m (−0.9 ± 1.3 kJ; P = 0.058) and 2,250 m (−2.8 ± 2.8 kJ; P = 0.02). Conclusion: The altitude prediction equations for CP and W′ developed in this study are suitable for use with the WBAL′ model in acute hypoxia. This enables the application of WBAL′ modelling to training prescription and competition analysis at altitude.
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Affiliation(s)
- Nathan E Townsend
- Athlete Health and Performance Centre, Aspetar Orthopaedic and Sports Medicine Hospital Doha, Qatar
| | - David S Nichols
- Athlete Health and Performance Centre, Aspetar Orthopaedic and Sports Medicine Hospital Doha, Qatar
| | - Philip F Skiba
- Department of Sports Medicine, Advocate Lutheran General Hospital Park Ridge, IL, USA
| | - Sebastien Racinais
- Athlete Health and Performance Centre, Aspetar Orthopaedic and Sports Medicine Hospital Doha, Qatar
| | - Julien D Périard
- Athlete Health and Performance Centre, Aspetar Orthopaedic and Sports Medicine Hospital Doha, Qatar
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Determinants of curvature constant (W') of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis. Eur J Appl Physiol 2017; 117:901-912. [PMID: 28280973 PMCID: PMC5388723 DOI: 10.1007/s00421-017-3574-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 02/15/2017] [Indexed: 01/08/2023]
Abstract
Purpose This study investigated the effect of induced alkalosis on the curvature constant (W’) of the power-duration relationship under normoxic and hypoxic conditions. Methods Eleven trained cyclists (mean ± SD) Age: 32 ± 7.2 years; body mass (bm): 77.0 ± 9.2 kg; VO2peak: 59.2 ± 6.8 ml·kg−1·min−1 completed seven laboratory visits which involved the determination of individual time to peak alkalosis following sodium bicarbonate (NaHCO3) ingestion, an environment specific ramp test (e.g. normoxia and hypoxia) and four x 3 min critical power (CP) tests under different experimental conditions. Participants completed four trials: alkalosis normoxia (ALN); placebo normoxia (PLN); alkalosis hypoxia (ALH); and placebo hypoxia (PLH). Pre-exercise administration of 0.3 g.kg−1 BM of NaHCO3 was used to induce alkalosis. Environmental conditions were set at either normobaric hypoxia (FiO2: 14.5%) or normoxia (FiO2: 20.93%). Results An increase in W’ was observed with pre-exercise alkalosis under both normoxic (PLN: 15.1 ± 6.2 kJ vs. ALN: 17.4 ± 5.1 kJ; P = 0.006) and hypoxic conditions (ALN: 15.2 ± 4.9 kJ vs. ALN: 17.9 ± 5.2 kJ; P < 0.001). Pre-exercise alkalosis resulted in a larger reduction in bicarbonate ion (HCO3−) concentrations during exercise in both environmental conditions (p < 0.001) and a greater blood lactate accumulation under hypoxia (P = 0.012). Conclusion Pre-exercise alkalosis substantially increased W’ and, therefore, may determine tolerance to exercise above CP under normoxic and hypoxic conditions. This may be due to NaHCO3 increasing HCO3− buffering capacity to delay exercise-induced acidosis, which may, therefore, enhance anaerobic energy contribution.
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Muniz-Pumares D, Pedlar C, Godfrey R, Glaister M. A comparison of methods to estimate anaerobic capacity: Accumulated oxygen deficit and W' during constant and all-out work-rate profiles. J Sports Sci 2016; 35:2357-2364. [PMID: 28019724 DOI: 10.1080/02640414.2016.1267386] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
This study investigated (i) whether the accumulated oxygen deficit (AOD) and curvature constant of the power-duration relationship (W') are different during constant work-rate to exhaustion (CWR) and 3-min all-out (3MT) tests and (ii) the relationship between AOD and W' during CWR and 3MT. Twenty-one male cyclists (age: 40 ± 6 years; maximal oxygen uptake [V̇O2max]: 58 ± 7 ml · kg-1 · min-1) completed preliminary tests to determine the V̇O2-power output relationship and V̇O2max. Subsequently, AOD and W' were determined as the difference between oxygen demand and oxygen uptake and work completed above critical power, respectively, in CWR and 3MT. There were no differences between tests for duration, work, or average power output (P ≥ 0.05). AOD was greater in the CWR test (4.18 ± 0.95 vs. 3.68 ± 0.98 L; P = 0.004), whereas W' was greater in 3MT (9.55 ± 4.00 vs. 11.37 ± 3.84 kJ; P = 0.010). AOD and W' were significantly correlated in both CWR (P < 0.001, r = 0.654) and 3MT (P < 0.001, r = 0.654). In conclusion, despite positive correlations between AOD and W' in CWR and 3MT, between-test differences in the magnitude of AOD and W', suggest that both measures have different underpinning mechanisms.
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Affiliation(s)
- Daniel Muniz-Pumares
- a School of Sport, Health and Applied Science , St Mary's University , Twickenham , UK.,b Department of Psychology and Sport Science, School of Life and Medical Sciences , University of Hertfordshire , Hatfield , UK
| | - Charles Pedlar
- a School of Sport, Health and Applied Science , St Mary's University , Twickenham , UK
| | - Richard Godfrey
- c The Centre for Sports Medicine and Human Performance , Brunel University , Uxbridge , UK
| | - Mark Glaister
- a School of Sport, Health and Applied Science , St Mary's University , Twickenham , UK
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Poole DC, Burnley M, Vanhatalo A, Rossiter HB, Jones AM. Critical Power: An Important Fatigue Threshold in Exercise Physiology. Med Sci Sports Exerc 2016; 48:2320-2334. [PMID: 27031742 PMCID: PMC5070974 DOI: 10.1249/mss.0000000000000939] [Citation(s) in RCA: 313] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
: The hyperbolic form of the power-duration relationship is rigorous and highly conserved across species, forms of exercise, and individual muscles/muscle groups. For modalities such as cycling, the relationship resolves to two parameters, the asymptote for power (critical power [CP]) and the so-called W' (work doable above CP), which together predict the tolerable duration of exercise above CP. Crucially, the CP concept integrates sentinel physiological profiles-respiratory, metabolic, and contractile-within a coherent framework that has great scientific and practical utility. Rather than calibrating equivalent exercise intensities relative to metabolically distant parameters such as the lactate threshold or V˙O2max, setting the exercise intensity relative to CP unifies the profile of systemic and intramuscular responses and, if greater than CP, predicts the tolerable duration of exercise until W' is expended, V˙O2max is attained, and intolerance is manifested. CP may be regarded as a "fatigue threshold" in the sense that it separates exercise intensity domains within which the physiological responses to exercise can (CP) be stabilized. The CP concept therefore enables important insights into 1) the principal loci of fatigue development (central vs. peripheral) at different intensities of exercise and 2) mechanisms of cardiovascular and metabolic control and their modulation by factors such as O2 delivery. Practically, the CP concept has great potential application in optimizing athletic training programs and performance as well as improving the life quality for individuals enduring chronic disease.
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Affiliation(s)
- David C. Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas, U.S.A
| | - Mark Burnley
- School of Sport and Exercise Sciences, University of Kent, Chatham, U.K
| | - Anni Vanhatalo
- Sport and Health Sciences, St. Luke’s Campus, University of Exeter, Exeter, U.K
| | - Harry B. Rossiter
- Faculty of Biological Sciences University of Leeds, Leeds, U.K
- Rehabilitaion Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, U.S.A
| | - Andrew M. Jones
- Sport and Health Sciences, St. Luke’s Campus, University of Exeter, Exeter, U.K
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Black MI, Jones AM, Kelly JA, Bailey SJ, Vanhatalo A. The constant work rate critical power protocol overestimates ramp incremental exercise performance. Eur J Appl Physiol 2016; 116:2415-2422. [PMID: 27787608 PMCID: PMC5118414 DOI: 10.1007/s00421-016-3491-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 10/13/2016] [Indexed: 12/02/2022]
Abstract
Purpose The parameters of the power-duration relationship (i.e., the critical power, CP, and the curvature constant, W′) may theoretically predict maximal performance capability for exercise above the CP. The CP and Wʹ are associated with the parameters of oxygen uptake (\documentclass[12pt]{minimal}
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\begin{document}$${\dot{\text{V}}}$$\end{document}V˙O2) kinetics, which can be altered by manipulation of the work-rate forcing function. We tested the hypothesis that the CP and Wʹ derived from constant work-rate (CWR) prediction trials would overestimate ramp incremental exercise performance. Methods Thirty subjects (males, n = 28; females, n = 2) performed a ramp incremental test, and 3–5 CWR prediction trials for the determination of the CP and Wʹ. Multiple ramp incremental tests and corresponding CP and Wʹ estimates were available for some subjects such that in total 51 ramp test performances were predicted. Results The ramp incremental test performance (729 ± 113 s) was overestimated by the CP and Wʹ estimates derived from the best (751 ± 114 s, P < 0.05) and worst (749 ± 111 s, P < 0.05) individual fits of CWR prediction trial data. The error in the prediction was inversely correlated with the magnitude of the Wʹ for the best (r = −0.56, P < 0.05) and worst individual fits (r = −0.36, P < 0.05). Conclusions The overestimation of ramp incremental performance suggests that the CP and Wʹ derived from different work-rate forcing functions, thus resulting in different \documentclass[12pt]{minimal}
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\begin{document}$${\dot{\text{V}}}$$\end{document}V˙O2 kinetics, cannot be used interchangeably. The present findings highlight a potential source of error in performance prediction that is of importance to both researchers and applied practitioners.
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Affiliation(s)
- Matthew I Black
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK
- School of Sport, Exercise and Health Sciences, Loughborough University, Epinal Way, LE11 3TU, UK
| | - Andrew M Jones
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK
| | - James A Kelly
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK
| | - Stephen J Bailey
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK
- School of Sport, Exercise and Health Sciences, Loughborough University, Epinal Way, LE11 3TU, UK
| | - Anni Vanhatalo
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK.
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Vanhatalo A, Black MI, DiMenna FJ, Blackwell JR, Schmidt JF, Thompson C, Wylie LJ, Mohr M, Bangsbo J, Krustrup P, Jones AM. The mechanistic bases of the power-time relationship: muscle metabolic responses and relationships to muscle fibre type. J Physiol 2016; 594:4407-23. [PMID: 26940850 DOI: 10.1113/jp271879] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 03/01/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The power-asymptote (critical power; CP) of the hyperbolic power-time relationship for high-intensity exercise defines a threshold between steady-state and non-steady-state exercise intensities and the curvature constant (W') indicates a fixed capacity for work >CP that is related to a loss of muscular efficiency. The present study reports novel evidence on the muscle metabolic underpinnings of CP and W' during whole-body exercise and their relationships to muscle fibre type. We show that the W' is not correlated with muscle fibre type distribution and that it represents an elevated energy contribution from both oxidative and glycolytic/glycogenolytic metabolism. We show that there is a positive correlation between CP and highly oxidative type I muscle fibres and that muscle metabolic steady-state is attainable <CP but not >CP. Our findings indicate a mechanistic link between the bioenergetic characteristics of muscle fibre types and the power-time relationship for high-intensity exercise. ABSTRACT We hypothesized that: (1) the critical power (CP) will represent a boundary separating steady-state from non-steady-state muscle metabolic responses during whole-body exercise and (2) that the CP and the curvature constant (W') of the power-time relationship for high-intensity exercise will be correlated with type I and type IIx muscle fibre distributions, respectively. Four men and four women performed a 3 min all-out cycling test for the estimation of CP and constant work rate (CWR) tests slightly >CP until exhaustion (Tlim ), slightly <CP for 24 min and until the >CP Tlim isotime to test the first hypothesis. Eleven men performed 3 min all-out tests and donated muscle biopsies to test the second hypothesis. Below CP, muscle [PCr] [42.6 ± 7.1 vs. 49.4 ± 6.9 mmol (kg d.w.)(-1) ], [La(-) ] [34.8 ± 12.6 vs. 35.5 ± 13.2 mmol (kg d.w.)(-1) ] and pH (7.11 ± 0.08 vs. 7.10 ± 0.11) remained stable between ∼12 and 24 min (P > 0.05 for all), whereas these variables changed with time >CP such that they were greater [[La(-) ] 95.6 ± 14.1 mmol (kg d.w.)(-1) ] and lower [[PCr] 24.2 ± 3.9 mmol (kg d.w.)(-1) ; pH 6.84 ± 0.06] (P < 0.05) at Tlim (740 ± 186 s) than during the <CP trial. The CP (234 ± 53 W) was correlated with muscle type I (r = 0.67, P = 0.025) and inversely correlated with muscle type IIx fibre proportion (r = -0.76, P = 0.01). There was no relationship between W' (19.4 ± 6.3 kJ) and muscle fibre type. These data indicate a mechanistic link between the bioenergetic characteristics of different muscle fibre types and the power-duration relationship. The CP reflects the bioenergetic characteristics of highly oxidative type I muscle fibres, such that a muscle metabolic steady-state is attainable below and not above CP.
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Affiliation(s)
- Anni Vanhatalo
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
| | - Matthew I Black
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
| | - Fred J DiMenna
- Teachers College, Department of Biobehavioral Sciences, Columbia University, New York, NY, USA
| | - Jamie R Blackwell
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
| | - Jakob Friis Schmidt
- Department of Nutrition, Exercise and Sports, The August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Christopher Thompson
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
| | - Lee J Wylie
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
| | - Magni Mohr
- Faculty of Natural and Health Sciences, University of the Faroe Islands, Tórshavn, Faroe Islands.,Center of Health and Human Performance, Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden
| | - Jens Bangsbo
- Department of Nutrition, Exercise and Sports, The August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Peter Krustrup
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK.,Department of Nutrition, Exercise and Sports, The August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Andrew M Jones
- College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK
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Hirai DM, Musch TI, Poole DC. Exercise training in chronic heart failure: improving skeletal muscle O2 transport and utilization. Am J Physiol Heart Circ Physiol 2015; 309:H1419-39. [PMID: 26320036 DOI: 10.1152/ajpheart.00469.2015] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/23/2015] [Indexed: 01/13/2023]
Abstract
Chronic heart failure (CHF) impairs critical structural and functional components of the O2 transport pathway resulting in exercise intolerance and, consequently, reduced quality of life. In contrast, exercise training is capable of combating many of the CHF-induced impairments and enhancing the matching between skeletal muscle O2 delivery and utilization (Q̇mO2 and V̇mO2 , respectively). The Q̇mO2 /V̇mO2 ratio determines the microvascular O2 partial pressure (PmvO2 ), which represents the ultimate force driving blood-myocyte O2 flux (see Fig. 1). Improvements in perfusive and diffusive O2 conductances are essential to support faster rates of oxidative phosphorylation (reflected as faster V̇mO2 kinetics during transitions in metabolic demand) and reduce the reliance on anaerobic glycolysis and utilization of finite energy sources (thus lowering the magnitude of the O2 deficit) in trained CHF muscle. These adaptations contribute to attenuated muscle metabolic perturbations (e.g., changes in [PCr], [Cr], [ADP], and pH) and improved physical capacity (i.e., elevated critical power and maximal V̇mO2 ). Preservation of such plasticity in response to exercise training is crucial considering the dominant role of skeletal muscle dysfunction in the pathophysiology and increased morbidity/mortality of the CHF patient. This brief review focuses on the mechanistic bases for improved Q̇mO2 /V̇mO2 matching (and enhanced PmvO2 ) with exercise training in CHF with both preserved and reduced ejection fraction (HFpEF and HFrEF, respectively). Specifically, O2 convection within the skeletal muscle microcirculation, O2 diffusion from the red blood cell to the mitochondria, and muscle metabolic control are particularly susceptive to exercise training adaptations in CHF. Alternatives to traditional whole body endurance exercise training programs such as small muscle mass and inspiratory muscle training, pharmacological treatment (e.g., sildenafil and pentoxifylline), and dietary nitrate supplementation are also presented in light of their therapeutic potential. Adaptations within the skeletal muscle O2 transport and utilization system underlie improvements in physical capacity and quality of life in CHF and thus take center stage in the therapeutic management of these patients.
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Affiliation(s)
- Daniel M Hirai
- Department of Medicine, Queen's University, Kingston, Ontario, Canada; Department of Medicine, Federal University of São Paulo (UNIFESP), São Paulo, São Paulo, Brazil; and
| | - Timothy I Musch
- Departments of Anatomy and Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Departments of Anatomy and Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
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