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Gough LA, Deb SK, Brown D, Sparks SA, McNaughton LR. The effects of sodium bicarbonate ingestion on cycling performance and acid base balance recovery in acute normobaric hypoxia. J Sports Sci 2019; 37:1464-1471. [PMID: 30668281 DOI: 10.1080/02640414.2019.1568173] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This study investigated the effects of two separate doses of sodium bicarbonate (NaHCO3) on 4 km time trial (TT) cycling performance and post-exercise acid base balance recovery in hypoxia. Fourteen club-level cyclists completed four cycling TT's, followed by a 40 min passive recovery in normobaric hypoxic conditions (FiO2 = 14.5%) following one of either: two doses of NaHCO3 (0.2 g.kg-1 BM; SBC2, or 0.3 g.kg-1 BM; SBC3), a taste-matched placebo (0.07 g.kg-1 BM sodium chloride; PLA), or a control trial in a double-blind, randomized, repeated-measures and crossover design study. Compared to PLA, TT performance was improved following SBC2 (p = 0.04, g = 0.16, very likely beneficial), but was improved to a greater extent following SBC3 (p = 0.01, g = 0.24, very likely beneficial). Furthermore, a likely benefit of ingesting SBC3 over SBC2 was observed (p = 0.13, g = 0.10), although there was a large inter-individual variation. Both SBC treatments achieved full recovery within 40 min, which was not observed in either PLA or CON following the TT. In conclusion, NaHCO3 improves 4 km TT performance and acid base balance recovery in acute moderate hypoxic conditions, however the optimal dose warrants an individual approach.
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Affiliation(s)
- Lewis A Gough
- a Sport and Physical Activity Department, Faculty of Health and Life Sciences , Birmingham City University , Birmingham , UK.,b Sports Nutrition and Performance Group, Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK
| | - Sanjoy K Deb
- b Sports Nutrition and Performance Group, Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK.,c Life Sciences Department , University of Westminster , London , UK
| | - Danny Brown
- b Sports Nutrition and Performance Group, Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK
| | - S Andy Sparks
- b Sports Nutrition and Performance Group, Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK
| | - Lars R McNaughton
- b Sports Nutrition and Performance Group, Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK.,d Department of Sport and Movement Studies, Faculty of Health Science , University of Johannesburg , Johannesburg , South Africa
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Wang R, Fukuda DH, Hoffman JR, La Monica MB, Starling TM, Stout JR, Kang J, Hu Y. Distinct Effects of Repeated-Sprint Training in Normobaric Hypoxia and β-Alanine Supplementation. J Am Coll Nutr 2018; 38:149-161. [DOI: 10.1080/07315724.2018.1475269] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Ran Wang
- School of Physical Education and Sport Training, Shanghai University of Sport, Shanghai, China
| | - David H. Fukuda
- School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, Florida, USA
| | - Jay R. Hoffman
- School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, Florida, USA
| | - Michael B. La Monica
- School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, Florida, USA
| | - Tristan M. Starling
- School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, Florida, USA
| | - Jeffrey R. Stout
- School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, Florida, USA
| | - Jie Kang
- Department of Health & Exercise Science, The College of New Jersey, Ewing Township, New Jersey, USA
| | - Yang Hu
- Sport Science Research Center, Beijing Sport University, Beijing, China
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Johnston RD, Black GM, Harrison PW, Murray NB, Austin DJ. Applied Sport Science of Australian Football: A Systematic Review. Sports Med 2018; 48:1673-1694. [DOI: 10.1007/s40279-018-0919-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Czuba M, Wilk R, Karpiński J, Chalimoniuk M, Zajac A, Langfort J. Intermittent hypoxic training improves anaerobic performance in competitive swimmers when implemented into a direct competition mesocycle. PLoS One 2017; 12:e0180380. [PMID: 28763443 PMCID: PMC5538675 DOI: 10.1371/journal.pone.0180380] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 06/14/2017] [Indexed: 11/18/2022] Open
Abstract
The main objective of this research was to evaluate the efficacy of intermittent hypoxic training (IHT) on anaerobic and aerobic capacity and swimming performance in well-trained swimmers. Sixteen male swimmers were randomly divided into a hypoxia (H) group (n = 8), which trained in a normobaric hypoxia environment, and a control (C) group (n = 8), which exercised under normoxic conditions. However, one participant left the study without explanation. During the experiment group H trained on land twice per week in simulated hypoxia (FiO2 = 15.5%, corresponding to 2,500 m a.s.l); however, they conducted swim training in normoxic conditions. Group C performed the same training program under normoxic conditions. The training program included four weekly microcyles, followed by three days of recovery. During practice sessions on land, the swimmers performed 30 second sprints on an arm-ergometer, alternating with two minute high intensity intervals on a lower limb cycle ergometer. The results showed that the training on land caused a significant (p<0.05) increase in absolute maximal workload (WRmax) by 7.4% in group H and by 3.2% in group C and relative values of VO2max by 6.9% in group H and 3.7% in group C. However, absolute values of VO2max were not significantly changed. Additionally, a significant (p<0.05) increase in mean power (Pmean) during the first (11.7%) and second (11.9%) Wingate tests was only observed in group H. The delta values of lactate concentration (ΔLA) after both Wingate tests were significantly (p<0.05) higher in comparison to baseline levels by 28.8% in group H. Opposite changes were observed in delta values of blood pH (ΔpH) after both Wingate tests in group H, with a significant decrease in values of ΔpH by 33.3%. The IHT caused a significant (p<0.05) improvement in 100m and 200m swimming performance, by 2.1% and 1.8%, respectively in group H. Training in normoxia (group C), resulted in a significant (p<0.05) improvement of swimming performance at 100m and 200m, by 1.1% and 0.8%, respectively. In conclusion, the most important finding of this study includes a significant improvement in anaerobic capacity and swimming performance after high-intensity IHT. However, this training protocol had no effect on absolute values of VO2max and hematological variables.
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Affiliation(s)
- Miłosz Czuba
- Department of Sports Training, the Jerzy Kukuczka Academy of Physical Education in Katowice, Faculty of Physical Education, Katowice, Poland
- * E-mail:
| | - Robert Wilk
- Department of Swimming, the Jerzy Kukuczka Academy of Physical Education in Katowice, Faculty of Physical Education, Katowice, Poland
| | - Jakub Karpiński
- Department of Swimming, the Jerzy Kukuczka Academy of Physical Education in Katowice, Faculty of Physical Education, Katowice, Poland
| | - Małgorzata Chalimoniuk
- Department of Tourism and Health in Biala Podlaska, Józef Piłsudski University of Physical Education in Warsaw, Warsaw, Poland
| | - Adam Zajac
- Department of Sports Training, the Jerzy Kukuczka Academy of Physical Education in Katowice, Faculty of Physical Education, Katowice, Poland
| | - Józef Langfort
- Department of Sports Training, the Jerzy Kukuczka Academy of Physical Education in Katowice, Faculty of Physical Education, Katowice, Poland
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Davie AJ, Wen L, Cust ARE, Beavers R, Fyfe T, Zhou S. The effects of moderate intensity training in a hypoxic environment on transcriptional responses in Thoroughbred horses. Biol Open 2017; 6:1035-1040. [PMID: 28583927 PMCID: PMC5550905 DOI: 10.1242/bio.020388] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
This study investigated the effects of six weeks of normobaric hypoxic training on transcriptional expression of the genes associated with mitochondrial and glycolytic activities in Thoroughbred horses. Eight horses were divided into two groups of four. They completed an identical incremental, moderate intensity training program, except that one group trained in a hypoxic chamber with 15% oxygen for 30 min on alternate days except Sundays (HT), while the other group trained in normal air (NC). Prior to and post training, heart rate and blood lactate were measured during an incremental treadmill test. Muscle biopsy samples were taken prior to and 24 h post the training period for qPCR analysis of mRNA changes in VEGF, PPARγ, HIF-1α, PGC-1α, COX4, AK3, LDH, PFK, PKm and SOD-2. No significant differences between the HT and NC were detected by independent-samples t-test with Bonferroni correction for multiple comparisons (P>0.05) in relative changes of mRNA abundance. There were no significant differences between groups for heart rate and blood lactate during the treadmill test. The outcomes indicated that this hypoxia training program did not cause a significant variation in basal level expression of the selected mRNAs in Thoroughbreds as compared with normoxic training.
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Affiliation(s)
- Allan J Davie
- Southern Cross University, School of Health and Human Sciences, Lismore, NSW 2480, Australia
| | - Li Wen
- Tianjin University of Sports, Tianjin Key Laboratory of Exercise Physiology and Sports Medicine, Tianjin 300381, China
| | | | - Rosalind Beavers
- Southern Cross University, School of Health and Human Sciences, Lismore, NSW 2480, Australia
| | - Tom Fyfe
- Pulford Air and Gas, Sydney, NSW 2141, Australia
| | - Shi Zhou
- Southern Cross University, School of Health and Human Sciences, Lismore, NSW 2480, Australia
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Inness MWH, Billaut F, Walker EJ, Petersen AC, Sweeting AJ, Aughey RJ. Heavy Resistance Training in Hypoxia Enhances 1RM Squat Performance. Front Physiol 2016; 7:502. [PMID: 27857693 PMCID: PMC5093137 DOI: 10.3389/fphys.2016.00502] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 10/13/2016] [Indexed: 12/02/2022] Open
Abstract
Purpose: To determine if heavy resistance training in hypoxia (IHRT) is more effective at improving strength, power, and increasing lean mass than the same training in normoxia. Methods: A pair-matched, placebo-controlled study design included 20 resistance-trained participants assigned to IHRT (FIO2 0.143) or placebo (FIO2 0.20), (n = 10 per group). Participants were matched for strength and training. Both groups performed 20 sessions over 7 weeks either with IHRT or placebo. All participants were tested for 1RM, 20-m sprint, body composition, and countermovement jump pre-, mid-, and post-training and compared via magnitude-based inferences. Presentation of Results: Groups were not clearly different for any test at baseline. Training improved both absolute (IHRT: 13.1 ± 3.9%, effect size (ES) 0.60, placebo 9.8 ± 4.7%, ES 0.31) and relative 1RM (IHRT: 13.4 ± 5.1%, ES 0.76, placebo 9.7 ± 5.3%, ES 0.48) at mid. Similarly, at post both groups increased absolute (IHRT: 20.7 ± 7.6%, ES 0.74, placebo 14.1 ± 6.0%, ES 0.58) and relative 1RM (IHRT: 21.6 ± 8.5%, ES 1.08, placebo 13.2 ± 6.4%, ES 0.78). Importantly, the change in IHRT was greater than placebo at mid for both absolute [4.4% greater change, 90% Confidence Interval (CI) 1.0:8.0%, ES 0.21, and relative strength (5.6% greater change, 90% CI 1.0:9.4%, ES 0.31 (relative)]. There was also a greater change for IHRT at post for both absolute (7.0% greater change, 90% CI 1.3:13%, ES 0.33), and relative 1RM (9.2% greater change, 90% CI 1.6:14.9%, ES 0.49). Only IHRT increased countermovement jump peak power at Post (4.9%, ES 0.35), however the difference between IHRT and placebo was unclear (2.7, 90% CI –2.0:7.6%, ES 0.20) with no clear differences in speed or body composition throughout. Conclusion: Heavy resistance training in hypoxia is more effective than placebo for improving absolute and relative strength.
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Affiliation(s)
- Mathew W H Inness
- Institute of Sport, Exercise and Active Living, Victoria UniversityMelbourne, VIC, Australia; Western Bulldogs Football ClubMelbourne, VIC, Australia
| | - François Billaut
- Institute of Sport, Exercise and Active Living, Victoria UniversityMelbourne, VIC, Australia; Département de Kinesiologie, Université LavalQuebec City, QC, Canada
| | - Emily J Walker
- Institute of Sport, Exercise and Active Living, Victoria UniversityMelbourne, VIC, Australia; Collingwood Football ClubMelbourne, VIC, Australia
| | - Aaron C Petersen
- Institute of Sport, Exercise and Active Living, Victoria University Melbourne, VIC, Australia
| | - Alice J Sweeting
- Institute of Sport, Exercise and Active Living, Victoria University Melbourne, VIC, Australia
| | - Robert J Aughey
- Institute of Sport, Exercise and Active Living, Victoria University Melbourne, VIC, Australia
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Wilson DF. Oxidative phosphorylation: unique regulatory mechanism and role in metabolic homeostasis. J Appl Physiol (1985) 2016; 122:611-619. [PMID: 27789771 DOI: 10.1152/japplphysiol.00715.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 10/12/2016] [Accepted: 10/24/2016] [Indexed: 11/22/2022] Open
Abstract
Oxidative phosphorylation is the primary source of metabolic energy, in the form of ATP, in higher plants and animals, but its regulation in vivo is not well understood. A model has been developed for oxidative phosphorylation in vivo that predicts behavior patterns that are both distinctive and consistent with experimental measurements of metabolism in intact cells and tissues. A major regulatory parameter is the energy state ([ATP]/[ADP][Pi], where brackets denote concentration). Under physiological conditions, the [ATP] and [Pi] are ~100 times that of [ADP], and most of the change in energy state is through change in [ADP]. The rate of oxidative phosphorylation (y-axis) increases slowly with increasing [ADP] until a threshold is reached and then increases very rapidly and linearly with further increase in [ADP]. The dependence on [ADP] can be characterized by a threshold [ADP] (T) and control strength (CS), the normalized slope above threshold (Δy/(Δx/T). For normoxic cells without creatine kinase, T is ~30 µM and CS is ~10 s-1 Myocytes and cells with larger ranges of rates of ATP utilization, however, have the same [ADP]- and [AMP]-dependent mechanisms regulating metabolism and gene expression. To compensate, these cells have creatine kinase, and hydrolysis/synthesis of creatine phosphate increases the change in [Pi] and thereby CS. Cells with creatine kinase have [ADP] and [AMP], which are similar to cells without creatine kinase, despite the large differences in metabolic rate. 31P measurements in human muscles during work-to-rest and rest-to-work transitions are consistent with predictions of the model.NEW & NOTEWORTHY A model developed for oxidative phosphorylation in vivo is shown to predict behavior patterns that are both novel and consistent with experimental measurements of metabolism in working muscle and other cells. The dependence of the rate on ADP concentration shows a pronounced threshold with a steep, nearly linear increase above the threshold. The threshold determines the homeostatic set point, and the slope above threshold determines how much metabolism changes in response to varied energy demand.
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Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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De Smet S, Van Thienen R, Deldicque L, James R, Sale C, Bishop DJ, Hespel P. Nitrate Intake Promotes Shift in Muscle Fiber Type Composition during Sprint Interval Training in Hypoxia. Front Physiol 2016; 7:233. [PMID: 27378942 PMCID: PMC4906611 DOI: 10.3389/fphys.2016.00233] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 05/30/2016] [Indexed: 12/04/2022] Open
Abstract
Purpose: We investigated the effect of sprint interval training (SIT) in normoxia, vs. SIT in hypoxia alone or in conjunction with oral nitrate intake, on buffering capacity of homogenized muscle (βhm) and fiber type distribution, as well as on sprint and endurance performance. Methods: Twenty-seven moderately-trained participants were allocated to one of three experimental groups: SIT in normoxia (20.9% FiO2) + placebo (N), SIT in hypoxia (15% FiO2) + placebo (H), or SIT in hypoxia + nitrate supplementation (HN). All participated in 5 weeks of SIT on a cycle ergometer (30-s sprints interspersed by 4.5 min recovery-intervals, 3 weekly sessions, 4–6 sprints per session). Nitrate (6.45 mmol NaNO3) or placebo capsules were administered 3 h before each session. Before and after SIT participants performed an incremental VO2max-test, a 30-min simulated cycling time-trial, as well as a 30-s cycling sprint test. Muscle biopsies were taken from m. vastus lateralis. Results: SIT decreased the proportion of type IIx muscle fibers in all groups (P < 0.05). The relative number of type IIa fibers increased (P < 0.05) in HN (P < 0.05 vs. H), but not in the other groups. SIT had no significant effect on βhm. Compared with H, SIT tended to enhance 30-s sprint performance more in HN than in H (P = 0.085). VO2max and 30-min time-trial performance increased in all groups to a similar extent. Conclusion: SIT in hypoxia combined with nitrate supplementation increases the proportion of type IIa fibers in muscle, which may be associated with enhanced performance in short maximal exercise. Compared with normoxic training, hypoxic SIT does not alter βhm or endurance and sprinting exercise performance.
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Affiliation(s)
- Stefan De Smet
- Exercise Physiology Research Group, Department of Kinesiology, Katholieke Universiteit Leuven Leuven, Belgium
| | - Ruud Van Thienen
- Exercise Physiology Research Group, Department of Kinesiology, Katholieke Universiteit Leuven Leuven, Belgium
| | - Louise Deldicque
- Exercise Physiology Research Group, Department of Kinesiology, Katholieke Universiteit LeuvenLeuven, Belgium; Institute of Neuroscience, Université Catholique de LouvainLouvain-la-Neuve, Belgium
| | - Ruth James
- Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement Research Centre, School of Science and Technology, Nottingham Trent University Nottingham, UK
| | - Craig Sale
- Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement Research Centre, School of Science and Technology, Nottingham Trent University Nottingham, UK
| | - David J Bishop
- Institute of Sport, Exercise and Active Living, Victoria University Melbourne, VIC, Australia
| | - Peter Hespel
- Exercise Physiology Research Group, Department of Kinesiology, Katholieke Universiteit LeuvenLeuven, Belgium; Department of Kinesiology, Bakala Academy-Athletic Performance Center, KU LeuvenLeuven, Belgium
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Wilson DF. Regulation of metabolism: the work-to-rest transition in skeletal muscle. Am J Physiol Endocrinol Metab 2016; 310:E633-E642. [PMID: 26837809 DOI: 10.1152/ajpendo.00512.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 01/28/2016] [Indexed: 11/22/2022]
Abstract
The behavior of oxidative phosphorylation predicted by a model for the mechanism and kinetics of cytochrome c oxidase is compared with the experimentally observed behavior during the work-to-rest transition in skeletal muscle. For both experiment and model, when work stops, the increase in creatine phosphate and decrease in creatine and inorganic phosphate concentrations ([CrP], [Cr], and [Pi]) begin immediately. The rate of change for each is maximal and then progressively slows as the increasing energy state ([ATP]/[ADP][Pi]) suppresses the rate of oxidative phosphorylation. The time courses can be reasonably fitted to single exponential curves with similar time constants. The energy state in the working and resting steady states at constant Po2 are dependent on the intramitochondrial [NAD+]/[NADH], mitochondrial content, and size of the creatine pool ([CrP] + [Cr]). The rate of change in [CrP] is linearly correlated with [CrP] and with [Pi] and [Cr]. The time constant for [CrP] increase in the resting and working steady states, and the rate of decrease in oxygen consumption are similarly dependent on the Po2 in the inspired gas (experimental) or tissue Po2 (model). Myoglobin strongly buffers intracellular Po2 below ∼15 torr, truncating the low end of the oxygen distribution in the tissue and suppressing intra- and intermyocyte oxygen gradients. The predictions of the model are consistent with the experimental data throughout the work/rest transition, providing valuable insights into the regulation of cellular and tissue metabolism.
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Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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Wilson DF. Regulation of metabolism: the rest-to-work transition in skeletal muscle. Am J Physiol Endocrinol Metab 2015; 309:E793-801. [PMID: 26394666 DOI: 10.1152/ajpendo.00355.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 09/14/2015] [Indexed: 11/22/2022]
Abstract
Mitochondrial oxidative phosphorylation is programmed to set and maintain metabolic homeostasis, and understanding that program is essential for an integrated view of cellular and tissue metabolism. The behavior predicted by a mechanism-based model for oxidative phosphorylation is compared with that experimentally measured for skeletal muscle when work is initiated. For the model, initiation of work is simulated by imposing a rate of ATP utilization of either 0.6 (equivalent of 13.4 ml O2·100 g tissue(-1)·min(-1) or 6 μmol O2·g tissue(-1)·min(-1)) or 0.3 mM ATP/s. Creatine phosphate ([CrP]) decrease, both experimentally measured and predicted by the model, can be fit to a single exponential. Increase in ATP synthesis begins immediately but can show a "lag period," during which the rate accelerates. The length of the lag period is similar for both experiment and model; in the model, the lag depends on intramitochondrial [NAD(+)]/[NADH], mitochondrial content, and size of the creatine pool ([CrP] + [Cr]) as well as the resting [CrP]/[Cr]. For in vivo conditions, increase in oxygen consumption may be linearly correlated with a decrease in [CrP] and an increase in inorganic phosphate ([Pi]) and [Cr]. The decrease in [CrP], resting and working steady state [CrP], and the increase in oxygen consumption are dependent on the Po2 in the inspired gas (experimental) or tissue Po2 (model). The metabolic behavior predicted by the model is consistent with available experimental measurements in muscle upon initiation of work, with the model providing valuable insight into how metabolic homeostasis is set and maintained.
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Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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Lundby C, Robach P. Performance Enhancement: What Are the Physiological Limits? Physiology (Bethesda) 2015; 30:282-92. [DOI: 10.1152/physiol.00052.2014] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Our objective is to highlight some key physiological determinants of endurance exercise performance and to discuss how these can be further improved. V̇o2max remains remarkably stable throughout an athletic career. By contrast, exercise economy, lactate threshold, and critical power may be improved in world-class athletes by specific exercise training regimes and/or with more years of training.
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Affiliation(s)
- C. Lundby
- Zürich Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
- Food & Nutrition & Sport Science, Gothenburg University, Gothenburg, Sweden; and
| | - P. Robach
- Ecole Nationale des Sports de Montagne, Site de l'Ecole Nationale de Ski et d'Alpinisme, Chamonix, France
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12
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Abstract
We address adaptive vs. maladaptive responses to hypoxemia in healthy humans and hypoxic-tolerant species during wakefulness, sleep, and exercise. Types of hypoxemia discussed include short-term and life-long residence at high altitudes, the intermittent hypoxemia attending sleep apnea, or training regimens prescribed for endurance athletes. We propose that hypoxia presents an insult to O2 transport, which is poorly tolerated in most humans because of the physiological cost.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; and
| | - Barbara J Morgan
- John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Department of Orthopedics and Rehabilitation, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
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Schreuder THA, Nyakayiru J, Houben J, Thijssen DHJ, Hopman MTE. Impact of hypoxic versus normoxic training on physical fitness and vasculature in diabetes. High Alt Med Biol 2015; 15:349-55. [PMID: 25251929 DOI: 10.1089/ham.2013.1144] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Exercise training improves physical fitness, insulin resistance, and endothelial function in type 2 diabetes. Hypoxia may further optimize these beneficial effects. The aim of this study was to compare the effects of hypoxic versus normoxic exercise training on physical fitness, endothelial function, and insulin resistance in type 2 diabetes. METHODS Peak oxygen consumption, flow mediated dilation (endothelial function), and glucose homeostasis were assessed in 19 patients (55±7 years) before and after an 8-week intervention. Subjects were randomly allocated to normoxic (21% O2, n=9) or hypoxic (16.5% O2, n=10) exercise training. Endothelium-independent dilation was examined using sublingual administration of glyceryl trinitrate, and used to calculate the ratio between endothelium-dependent and -independent dilation. RESULTS Exercise training improved physical fitness and brachial artery ratio between endothelium-dependent and -independent dilation (both p<0.05), whilst these exercise training-induced changes were similar in both groups (interaction-effects p>0.05). Exercise training did not significantly change brachial artery flow-mediated dilation or glyceryl trinitrate-response, superficial femoral artery flow-mediated dilation, or glucose homeostasis, whilst hypoxia did not alter the impact of exercise training. CONCLUSION Contrary to our hypothesis, hypoxia does not potentiate the effect of exercise training on physical fitness, vascular function, or glucose homeostasis in type 2 diabetes.
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Affiliation(s)
- Tim H A Schreuder
- 1 Department of Physiology, Radboud University Nijmegen Medical Centre , Nijmegen, the Netherlands
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Holliss BA, Burden RJ, Jones AM, Pedlar CR. Eight weeks of intermittent hypoxic training improves submaximal physiological variables in highly trained runners. J Strength Cond Res 2015; 28:2195-203. [PMID: 24513622 DOI: 10.1519/jsc.0000000000000406] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
It is unclear whether intermittent hypoxic training (IHT) results in improvements in physiological variables associated with endurance running. Twelve highly trained runners (VO2peak 70.0 ± 3.5 ml·kg-1·min-1) performed incremental treadmill tests to exhaustion in normobaric normoxia and hypoxia (16.0% FIO2) to assess submaximal and maximal physiological variables and the limit of tolerance (T-Lim). Participants then completed 8 weeks of moderate to heavy intensity normoxic training (control [CONT]) or IHT (twice weekly 40 minutes runs, in combination with habitual training), in a single blinded manner, before repeating the treadmill tests. Submaximal heart rate decreased significantly more after IHT (-5 ± 5 b·min-1; p = 0.001) than after CONT ( -1 ± 5 b·min-1; p = 0.021). Changes in submaximal V[Combining Dot Above]O2 were significantly different between groups (p ≤ 0.05); decreasing in the IHT group in hypoxia (-2.6 ± 1.7 ml·kg-1·min-1; p = 0.001) and increasing in the CONT group in normoxia (+1.1 ± 2.1 ml·kg-1·min-1; p = 0.012). There were no VO2peak changes within either group, and while T-Lim improved post-IHT in hypoxia (p = 0.031), there were no significant differences between groups. Intermittent hypoxic training resulted in a degree of enhanced cardiovascular fitness that was evident during submaximal, but not maximal intensity exercise. These results suggest that moderate to heavy intensity IHT provides a mean of improving the capacity for submaximal exercise and may be useful for pre-acclimatization for subsequent exercise in hypoxia, but additional research is required to establish its efficacy for athletic performance at sea level.
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Affiliation(s)
- Ben A Holliss
- 1College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom; 2British Swimming National Centre, Sports Training Village, University of Bath, Bath, United Kingdom; and 3Centre for Health, Applied Sport and Exercise Science, St. Mary's University College, Twickenham, United Kingdom
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15
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Vanhatalo A, Jones AM, Blackwell JR, Winyard PG, Fulford J. Dietary nitrate accelerates postexercise muscle metabolic recovery and O2 delivery in hypoxia. J Appl Physiol (1985) 2014; 117:1460-70. [PMID: 25301896 DOI: 10.1152/japplphysiol.00096.2014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We tested the hypothesis that the time constants (τ) of postexercise T2* MRI signal intensity (an index of O2 delivery) and muscle [PCr] (an index of metabolic perturbation, measured by (31)P-MRS) in hypoxia would be accelerated after dietary nitrate (NO3 (-)) supplementation. In a double-blind crossover design, eight moderately trained subjects underwent 5 days of NO3 (-) (beetroot juice, BR; 8.2 mmol/day NO3 (-)) and placebo (PL; 0.003 mmol/day NO3 (-)) supplementation in four conditions: normoxic PL (N-PL), hypoxic PL (H-PL; 13% O2), normoxic NO3 (-) (N-BR), and hypoxic NO3 (-) (H-BR). The single-leg knee-extension protocol consisted of 10 min of steady-state exercise and 24 s of high-intensity exercise. The [PCr] recovery τ was greater in H-PL (30 ± 4 s) than H-BR (22 ± 4 s), N-PL (24 ± 4 s) and N-BR (22 ± 4 s) (P < 0.05) and the maximal rate of mitochondrial ATP resynthesis (Qmax) was lower in the H-PL (1.12 ± 0.16 mM/s) compared with H-BR (1.35 ± 0.26 mM/s), N-PL (1.47 ± 0.28 mM/s), and N-BR (1.40 ± 0.21 mM/s) (P < 0.05). The τ of postexercise T2* signal intensity was greater in H-PL (47 ± 14 s) than H-BR (32 ± 10 s), N-PL (38 ± 9 s), and N-BR (27 ± 6 s) (P < 0.05). The postexercise [PCr] and T2* recovery τ were correlated in hypoxia (r = 0.60; P < 0.05), but not in normoxia (r = 0.28; P > 0.05). These findings suggest that the NO3 (-)-NO2 (-)-NO pathway is a significant modulator of muscle energetics and O2 delivery during hypoxic exercise and subsequent recovery.
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Affiliation(s)
- Anni Vanhatalo
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom;
| | - Andrew M Jones
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - James R Blackwell
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Paul G Winyard
- University of Exeter Medical School, Exeter, United Kingdom, University of Exeter, Exeter, United Kingdom; and
| | - Jonathan Fulford
- NIHR Exeter Clinical Research Facility, University of Exeter Medical School, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
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16
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Flinn S, Herbert K, Graham K, Siegler JC. Differential Effect of Metabolic Alkalosis and Hypoxia on High-Intensity Cycling Performance. J Strength Cond Res 2014; 28:2852-8. [DOI: 10.1519/jsc.0000000000000489] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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17
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Billaut F, Aughey RJ. Update in the understanding of altitude-induced limitations to performance in team-sport athletes. Br J Sports Med 2014; 47 Suppl 1:i22-5. [PMID: 24282202 PMCID: PMC3903141 DOI: 10.1136/bjsports-2013-092834] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The internationalism of field-based team sports (TS) such as football and rugby requires teams to compete in tournaments held at low to moderate altitude (∼1200–2500 m). In TS, acceleration, speed and aerobic endurance are physical characteristics associated with ball possession and, ultimately, scoring. While these qualities are affected by the development of neuromuscular fatigue at sea level, arterial hypoxaemia induced by exposure to altitude may further hinder the capacity to perform consecutive accelerations (CAC) or sprint endurance and thereby change the outcome of a match. The higher the altitude, the more severe the hypoxaemia, and thus, the larger the expected decline in aerobic endurance, CAC and match running performance. Therefore, it is critical for athletes and coaches to understand how arterial hypoxaemia affects aerobic endurance and CAC and the magnitude of decline they may face at altitude for optimal preparation and increased chances of success. This mini review summarises the effects of acute altitude/hypoxia exposure on aerobic endurance, CAC and activity profiles of TS athletes performing in the laboratory and during matches at natural altitude, and analyses the latest findings about the consequences of arterial hypoxaemia on the relationship between peripheral perturbations, neural adjustments and performance during repeated sprints or CAC. Finally, we briefly discuss how altitude training can potentially help athletes prepare for competition at altitude.
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Affiliation(s)
- François Billaut
- Institut national du sport du Québec, , Montréal, Québec, Canada
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18
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Faiss R, Girard O, Millet GP. Advancing hypoxic training in team sports: from intermittent hypoxic training to repeated sprint training in hypoxia. Br J Sports Med 2014; 47 Suppl 1:i45-50. [PMID: 24282207 PMCID: PMC3903143 DOI: 10.1136/bjsports-2013-092741] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Over the past two decades, intermittent hypoxic training (IHT), that is, a method where athletes live at or near sea level but train under hypoxic conditions, has gained unprecedented popularity. By adding the stress of hypoxia during 'aerobic' or 'anaerobic' interval training, it is believed that IHT would potentiate greater performance improvements compared to similar training at sea level. A thorough analysis of studies including IHT, however, leads to strikingly poor benefits for sea-level performance improvement, compared to the same training method performed in normoxia. Despite the positive molecular adaptations observed after various IHT modalities, the characteristics of optimal training stimulus in hypoxia are still unclear and their functional translation in terms of whole-body performance enhancement is minimal. To overcome some of the inherent limitations of IHT (lower training stimulus due to hypoxia), recent studies have successfully investigated a new training method based on the repetition of short (<30 s) 'all-out' sprints with incomplete recoveries in hypoxia, the so-called repeated sprint training in hypoxia (RSH). The aims of the present review are therefore threefold: first, to summarise the main mechanisms for interval training and repeated sprint training in normoxia. Second, to critically analyse the results of the studies involving high-intensity exercises performed in hypoxia for sea-level performance enhancement by differentiating IHT and RSH. Third, to discuss the potential mechanisms underpinning the effectiveness of those methods, and their inherent limitations, along with the new research avenues surrounding this topic.
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Affiliation(s)
- Raphaël Faiss
- Department of Physiology, Faculty of Biology and Medicine, Institute of Sports Sciences, University of Lausanne, , Lausanne, Switzerland
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19
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Almendros I, Wang Y, Gozal D. The polymorphic and contradictory aspects of intermittent hypoxia. Am J Physiol Lung Cell Mol Physiol 2014; 307:L129-40. [PMID: 24838748 DOI: 10.1152/ajplung.00089.2014] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Intermittent hypoxia (IH) has been extensively studied during the last decade, primarily as a surrogate model of sleep apnea. However, IH is a much more pervasive phenomenon in human disease, is viewed as a potential therapeutic approach, and has also been used in other disciplines, such as in competitive sports. In this context, adverse outcomes involving cardiovascular, cognitive, metabolic, and cancer problems have emerged in obstructive sleep apnea-based studies, whereas beneficial effects of IH have also been identified. Those a priori contradictory findings may not be as contradictory as initially thought. Indeed, the opposite outcomes triggered by IH can be explained by the specific characteristics of the large diversity of IH patterns applied in each study. The balance between benefits and injury appears to primarily depend on the ability of the organism to respond and activate adaptive mechanisms to IH. In this context, the adaptive or maladaptive responses can be generally predicted by the frequency, severity, and duration of IH. However, the presence of underlying conditions such as hypertension or obesity, as well as age, sex, or genotypic variance, may be important factors tilting the balance between an appropriate homeostatic response and decompensation. Here, the two possible facets of IH as derived from human and experimental animal settings will be reviewed.
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Affiliation(s)
- Isaac Almendros
- Department of Pediatrics, Comer Children's Hospital, Pritzker School of Medicine, The University of Chicago, Chicago, Illinois
| | - Yang Wang
- Department of Pediatrics, Comer Children's Hospital, Pritzker School of Medicine, The University of Chicago, Chicago, Illinois
| | - David Gozal
- Department of Pediatrics, Comer Children's Hospital, Pritzker School of Medicine, The University of Chicago, Chicago, Illinois
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