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Pasiakos SM, Karl JP, Margolis LM. Challenging traditional carbohydrate intake recommendations for optimizing performance at high altitude. Curr Opin Clin Nutr Metab Care 2021; 24:483-489. [PMID: 34284412 DOI: 10.1097/mco.0000000000000782] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW To highlight emerging evidence challenging traditional recommendations to increase carbohydrate intake to optimize performance at high altitude. RECENT FINDINGS Several studies have now clearly demonstrated that, compared with sea level, exogenous carbohydrate oxidation during aerobic exercise is blunted in lowlanders during initial exposure to high altitude. There is also no apparent ergogenic effect of ingesting carbohydrate during aerobic exercise on subsequent performance at high altitude, either initially after arriving or even after up to 22 days of acclimatization. The inability to oxidize and functionally benefit from exogenous carbohydrate intake during exercise after arriving at high altitude coincides with hyperinsulinemia, accelerated glycogenolysis, and reduced peripheral glucose uptake. Collectively, these responses are consistent with a hypoxia-mediated metabolic dysregulation reflective of insulin resistance. Parallel lines of evidence have also recently demonstrated roles for the gut microbiome in host metabolism, bioenergetics, and physiologic responses to high altitude, implicating the gut microbiome as one potential mediator of hypoxia-mediated metabolic dysregulation. SUMMARY Identification of novel and well tolerated nutrition and/or pharmacological approaches for alleviating hypoxia-mediated metabolic dysregulation and enhancing exogenous carbohydrate oxidation may be more effective for optimizing performance of lowlanders newly arrived at high altitude than traditional carbohydrate recommendations.
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Affiliation(s)
- Stefan M Pasiakos
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
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2
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Paris HL, Sinai EC, Shei RJ, Keller AM, Mickleborough TD. The influence of carbohydrate ingestion on peripheral and central fatigue during exercise in hypoxia: A narrative review. Eur J Sport Sci 2021; 21:1423-1435. [PMID: 33106121 PMCID: PMC8140067 DOI: 10.1080/17461391.2020.1842512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Hypoxia impairs aerobic performance by accelerating fatiguing processes. These processes may originate from sites either distal (peripheral) or proximal (central) to the neuromuscular junction, though these are not mutually exclusive. Peripheral mechanisms include decrements in muscle glycogen or fluctuations in intramuscular metabolites, whereas central responses commonly refer to reductions in central motor drive elicited by alterations in blood glucose and neurotransmitter concentrations as well as arterial hypoxemia. Hypoxia may accelerate both peripheral and central pathways of fatigue, with the level of hypoxia strongly dictating the degree and primary locus of impairment. As more people journey to hypoxic settings for work and recreation, developing strategies to improve work capacity in these environments becomes increasingly relevant. Given that sea level performance improves with nutritional interventions such as carbohydrate (CHO) ingestion, a similar strategy may prove effective in delaying fatigue in hypoxia, particularly considering how the metabolic pathways enhanced with CHO supplementation overlap the fatiguing pathways upregulated in hypoxia. Many questions regarding the relationship between CHO, hypoxia, and fatigue remain unanswered, including specifics on when to ingest, what to ingest, and how varying altitudes influence supplementation effectiveness. Therefore, the purpose of this narrative review is to examine the peripheral and central mechanisms contributing to fatigue during aerobic exercise at varying degrees of hypoxia and to assess the role of CHO ingestion in attenuating fatigue onset.
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Affiliation(s)
- Hunter L Paris
- Department of Sports Medicine, Pepperdine University, Malibu, CA, USA
| | - Erin C Sinai
- Department of Sports Medicine, Pepperdine University, Malibu, CA, USA
| | - Ren-Jay Shei
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, and Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Timothy D Mickleborough
- Department of Kinesiology, School of Public Health-Bloomington, Indiana University, Bloomington, IN, USA
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Margolis LM, Karl JP, Wilson MA, Coleman JL, Ferrando AA, Young AJ, Pasiakos SM. Metabolomic profiles are reflective of hypoxia-induced insulin resistance during exercise in healthy young adult males. Am J Physiol Regul Integr Comp Physiol 2021; 321:R1-R11. [PMID: 33949213 PMCID: PMC8321788 DOI: 10.1152/ajpregu.00076.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hypoxia-induced insulin resistance appears to suppress exogenous glucose oxidation during metabolically matched aerobic exercise during acute (<8 h) high-altitude (HA) exposure. However, a better understanding of this metabolic dysregulation is needed to identify interventions to mitigate these effects. The objective of this study was to determine if differences in metabolomic profiles during exercise at sea level (SL) and HA are reflective of hypoxia-induced insulin resistance. Native lowlanders (n = 8 males) consumed 145 g (1.8 g/min) of glucose while performing 80-min of metabolically matched treadmill exercise at SL (757 mmHg) and HA (460 mmHg) after 5-h exposure. Exogenous glucose oxidation and glucose turnover were determined using indirect calorimetry and dual tracer technique ([13C]glucose and [6,6-2H2]glucose). Metabolite profiles were analyzed in serum as change (Δ), calculated by subtracting postprandial/exercised state SL (ΔSL) and HA (ΔHA) from fasted, rested conditions at SL. Compared with SL, exogenous glucose oxidation, glucose rate of disappearance, and glucose metabolic clearance rate (MCR) were lower (P < 0.05) during exercise at HA. One hundred and eighteen metabolites differed between ΔSL and ΔHA (P < 0.05, Q < 0.10). Differences in metabolites indicated increased glycolysis, tricarboxylic acid cycle, amino acid catabolism, oxidative stress, and fatty acid storage, and decreased fatty acid mobilization for ΔHA. Branched-chain amino acids and oxidative stress metabolites, Δ3-methyl-2-oxobutyrate (r = -0.738) and Δγ-glutamylalanine (r = -0.810), were inversely associated (P < 0.05) with Δexogenous glucose oxidation. Δ3-Hydroxyisobutyrate (r = -0.762) and Δ2-hydroxybutyrate/2-hydroxyisobutyrate (r = -0.738) were inversely associated (P < 0.05) with glucose MCR. Coupling global metabolomics and glucose kinetic data suggest that the underlying cause for diminished exogenous glucose oxidative capacity during aerobic exercise is acute hypoxia-mediated peripheral insulin resistance.
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Affiliation(s)
- Lee M Margolis
- United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - J Philip Karl
- United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Marques A Wilson
- United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Julie L Coleman
- United States Army Research Institute of Environmental Medicine, Natick, Massachusetts.,Oak Ridge Institute of Science and Education, Oak Ridge, Tennessee
| | - Arny A Ferrando
- Department of Geriatrics, Center for Translational Research in Aging and Longevity, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Andrew J Young
- United States Army Research Institute of Environmental Medicine, Natick, Massachusetts.,Henry Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland
| | - Stefan M Pasiakos
- United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
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Koivisto-Mørk AE, Paur I, Paulsen G, Garthe I, Raastad T, Bastani NE, Blomhoff R, Bøhn SK. Dietary Adjustments to Altitude Training in Elite Endurance Athletes; Impact of a Randomized Clinical Trial With Antioxidant-Rich Foods. Front Sports Act Living 2020; 2:106. [PMID: 33345095 PMCID: PMC7739752 DOI: 10.3389/fspor.2020.00106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/14/2020] [Indexed: 11/13/2022] Open
Abstract
Background: Altitude training stresses several physiological and metabolic processes and alters the dietary needs of the athletes. International Olympic Committee (IOC)'s Nutrition Expert Group suggests that athletes should increase intake of energy, carbohydrate, iron, fluid, and antioxidant-rich foods while training at altitude. Objective: We investigated whether athletes adjust their dietary intake according to the IOC's altitude-specific dietary recommendations, and whether an in-between meal intervention with antioxidant-rich foods altered the athletes' dietary composition and nutrition-related blood parameters (mineral, vitamin, carotenoid, and hormone concentrations). Design: The dietary adjustments to altitude training (3 weeks at 2,320 m) were determined for 31 elite endurance athletes (23 ± 5 years, 23 males, 8 females) by six interviewer-administered 24-h dietary recalls on non-consecutive days; three before and during the altitude camp. The additional effect of in -between meal intervention with eucaloric antioxidant-rich or control snacks (1,000 kcal/day) was tested in a randomized controlled trial with parallel design. Results: At altitude the athletes increased their energy intake by 35% (1,430 ± 630 kcal/day, p < 0.001), the provided snacks accounting for 70% of this increase. Carbohydrate intake increased from 6.5 ± 1.8 g/kg body weight (BW) (50 E%) to 9.3 ± 2.1 g/kg BW (53 E%) (p < 0.001), with no difference between the antioxidant and control group. Dietary iron, fluid, and antioxidant-rich food intake increased by 37, 38, and 104%, respectively, in the whole cohort. The intervention group had larger increases in polyunsaturated fatty acids (PUFA), ω3 PUFA (n-3 fatty acids), ω6 PUFA (n-6 fatty acids), fiber, vitamin C, folic acid, and copper intake, while protein intake increased more among the controls, reflecting the nutritional content of the snacks. Changes in the measured blood minerals, vitamins, and hormones were not differentially affected by the intervention except for the carotenoid; zeaxanthin, which increased more in the intervention group (p < 0.001). Conclusions: Experienced elite endurance athletes increased their daily energy, carbohydrate, iron, fluid, and antioxidant-rich food intake during a 3-week training camp at moderate altitude meeting most of the altitude-specific dietary recommendations. The intervention with antioxidant-rich snacks improved the composition of the athletes' diets but had minimal impact on the measured nutrition-related blood parameters. Clinical Trial Registry Number: NCT03088891 (www.clinicaltrials.gov), Norwegian registry number: 626539 (https://rekportalen.no/).
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Affiliation(s)
- Anu E Koivisto-Mørk
- Norwegian Olympic Sports Centre, Norwegian Olympic and Paralympic Committee and Confederation of Sports, Oslo, Norway
| | - Ingvild Paur
- Norwegian National Advisory Unit on Disease-Related Undernutrition, Oslo University Hospital, Oslo, Norway
| | - Gøran Paulsen
- Norwegian Olympic Sports Centre, Norwegian Olympic and Paralympic Committee and Confederation of Sports, Oslo, Norway.,Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Ina Garthe
- Norwegian Olympic Sports Centre, Norwegian Olympic and Paralympic Committee and Confederation of Sports, Oslo, Norway
| | - Truls Raastad
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Nasser E Bastani
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Rune Blomhoff
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Division of Cancer Medicine, Oslo University Hospital, Oslo, Norway
| | - Siv K Bøhn
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Ås, Norway
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Pasiakos SM. Nutritional Requirements for Sustaining Health and Performance During Exposure to Extreme Environments. Annu Rev Nutr 2020; 40:221-245. [PMID: 32530730 DOI: 10.1146/annurev-nutr-011720-122637] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Dietary guidelines are formulated to meet minimum nutrient requirements, which prevent deficiencies and maintain health, growth, development, and function. These guidelines can be inadequate and contribute to disrupted homeostasis, lean body mass loss, and deteriorated performance in individuals who are working long, arduous hours with limited access to food in environmentally challenging locations. Environmental extremes can elicit physiological adjustments that alone alter nutrition requirements by upregulating energy expenditure, altering substrate metabolism, and accelerating body water and muscle protein loss. The mechanisms by which the environment, including high-altitude, heat, and cold exposure, alters nutrition requirements have been studied extensively. This contemporary review discusses physiological adjustments to environmental extremes, particularly when those adjustments alter dietary requirements.
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Affiliation(s)
- Stefan M Pasiakos
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760, USA;
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Margolis LM, Wilson MA, Whitney CC, Carrigan CT, Murphy NE, Radcliffe PN, Gwin JA, Church DD, Wolfe RR, Ferrando AA, Young AJ, Pasiakos SM. Acute hypoxia reduces exogenous glucose oxidation, glucose turnover, and metabolic clearance rate during steady-state aerobic exercise. Metabolism 2020; 103:154030. [PMID: 31778707 DOI: 10.1016/j.metabol.2019.154030] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/30/2019] [Accepted: 11/25/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND Exogenous carbohydrate oxidation is lower during steady-state aerobic exercise in native lowlanders sojourning at high altitude (HA) compared to sea level (SL). However, the underlying mechanism contributing to reduction in exogenous carbohydrate oxidation during steady-state aerobic exercise performed at HA has not been explored. OBJECTIVE To determine if alterations in glucose rate of appearance (Ra), disappearance (Rd) and metabolic clearance rate (MCR) at HA provide a mechanism for explaining the observation of lower exogenous carbohydrate oxidation compared to during metabolically-matched, steady-state exercise at SL. METHODS Using a randomized, crossover design, native lowlanders (n = 8 males, mean ± SD, age: 23 ± 2 yr, body mass: 87 ± 10 kg, and VO2peak: SL 4.3 ± 0.2 L/min and HA 2.9 ± 0.2 L/min) consumed 145 g (1.8 g/min) of glucose while performing 80-min of metabolically-matched (SL: 1.66 ± 0.14 V̇O2 L/min 329 ± 28 kcal, HA: 1.59 ± 0.10 V̇O2 L/min, 320 ± 19 kcal) treadmill exercise in SL (757 mmHg) and HA (460 mmHg) conditions after a 5-h exposure. Substrate oxidation rates (g/min) and glucose turnover (mg/kg/min) during exercise were determined using indirect calorimetry and dual tracer technique (13C-glucose oral ingestion and [6,6-2H2]-glucose primed, continuous infusion). RESULTS Total carbohydrate oxidation was higher (P < 0.05) at HA (2.15 ± 0.32) compared to SL (1.39 ± 0.14). Exogenous glucose oxidation rate was lower (P < 0.05) at HA (0.35 ± 0.07) than SL (0.44 ± 0.05). Muscle glycogen oxidation was higher at HA (1.67 ± 0.26) compared to SL (0.83 ± 0.13). Total glucose Ra was lower (P < 0.05) at HA (12.3 ± 1.5) compared to SL (13.8 ± 2.0). Exogenous glucose Ra was lower (P < 0.05) at HA (8.9 ± 1.3) compared to SL (10.9 ± 2.2). Glucose Rd was lower (P < 0.05) at HA (12.7 ± 1.7) compared to SL (14.3 ± 2.0). MCR was lower (P < 0.05) at HA (9.0 ± 1.8) compared to SL (12.1 ± 2.3). Circulating glucose and insulin concentrations were higher in response carbohydrate intake during exercise at HA compared to SL. CONCLUSION Novel results from this investigation suggest that reductions in exogenous carbohydrate oxidation at HA may be multifactorial; however, the apparent insensitivity of peripheral tissue to glucose uptake may be a primary determinate.
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Affiliation(s)
- Lee M Margolis
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America.
| | - Marques A Wilson
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Claire C Whitney
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Christopher T Carrigan
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Nancy E Murphy
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Patrick N Radcliffe
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America; Oak Ridge Institute of Science and Education, Oak Ridge, TN, United States of America
| | - Jess A Gwin
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America; Oak Ridge Institute of Science and Education, Oak Ridge, TN, United States of America
| | - David D Church
- Department of Geriatrics, Center for Translational Research in Aging and Longevity, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Robert R Wolfe
- Department of Geriatrics, Center for Translational Research in Aging and Longevity, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Arny A Ferrando
- Department of Geriatrics, Center for Translational Research in Aging and Longevity, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Andrew J Young
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America; Oak Ridge Institute of Science and Education, Oak Ridge, TN, United States of America
| | - Stefan M Pasiakos
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America
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Effects of carbohydrate supplementation on aerobic exercise performance during acute high altitude exposure and after 22 days of acclimatization and energy deficit. J Int Soc Sports Nutr 2020; 17:4. [PMID: 31918720 PMCID: PMC6953153 DOI: 10.1186/s12970-020-0335-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 01/03/2020] [Indexed: 11/18/2022] Open
Abstract
Background The ergogenic effects of supplemental carbohydrate on aerobic exercise performance at high altitude (HA) may be modulated by acclimatization status. Longitudinal evaluation of potential performance benefits of carbohydrate supplementation in the same volunteers before and after acclimatization to HA have not been reported. Purpose This study examined how consuming carbohydrate affected 2-mile time trial performance in lowlanders at HA (4300 m) before and after acclimatization. Methods Fourteen unacclimatized men performed 80 min of metabolically-matched (~ 1.7 L/min) treadmill walking at sea level (SL), after ~ 5 h of acute HA exposure, and after 22 days of HA acclimatization and concomitant 40% energy deficit (chronic HA). Before, and every 20 min during walking, participants consumed either carbohydrate (CHO, n = 8; 65.25 g fructose + 79.75 g glucose, 1.8 g carbohydrate/min) or flavor-matched placebo (PLA, n = 6) beverages. A self-paced 2-mile treadmill time trial was performed immediately after completing the 80-min walk. Results There were no differences (P > 0.05) in time trial duration between CHO and PLA at SL, acute HA, or chronic HA. Time trial duration was longer (P < 0.05) at acute HA (mean ± SD; 27.3 ± 6.3 min) compared to chronic HA (23.6 ± 4.5 min) and SL (17.6 ± 3.6 min); however, time trial duration at chronic HA was still longer than SL (P < 0.05). Conclusion These data suggest that carbohydrate supplementation does not enhance aerobic exercise performance in lowlanders acutely exposed or acclimatized to HA. Trial registration NCT, NCT02731066, Registered March 292,016
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Griffiths A, Shannon O, Matu J, King R, Deighton K, O'Hara JP. Response: Commentary on the effects of hypoxia on energy substrate use during exercise. J Int Soc Sports Nutr 2019; 16:61. [PMID: 31856846 PMCID: PMC6924012 DOI: 10.1186/s12970-019-0330-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 12/10/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND A recent commentary has been published on our meta-analysis, which investigated substrate oxidation during exercise matched for relative intensities in hypoxia compared with normoxia. Within this commentary, the authors proposed that exercise matched for absolute intensities in hypoxia compared with normoxia, should have been included within the analysis, as this model provides a more suitable experimental design when considering nutritional interventions in hypoxia. MAIN BODY Within this response, we provide a rationale for the use of exercise matched for relative intensities in hypoxia compared with normoxia. Specifically, we argue that this model provides a physiological stimulus replicable of real world situations, by reducing the absolute workload undertaken in hypoxia. Further, the use of exercise matched for relative intensities isolates the metabolic response to hypoxia, rather than the increased relative exercise intensity experienced in hypoxia when utilising exercise matched for absolute intensities. In addition, we also report previously unpublished data analysed at the time of the original meta-analysis, assessing substrate oxidation during exercise matched for absolute intensities in hypoxia compared with normoxia. CONCLUSION An increased reliance on carbohydrate oxidation was observed during exercise matched for absolute intensities in hypoxia compared with normoxia. These data now provide a comparable dataset for the use of researchers and practitioners alike in the design of nutritional interventions for relevant populations.
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Affiliation(s)
- Alex Griffiths
- Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, LS6 3QS, UK.
| | - Oliver Shannon
- Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, LS6 3QS, UK.,Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Leech Building, Framlington Place, Newcastle Upon Tyne, NE2 4HH, UK
| | - Jamie Matu
- School of Clinical and Applied Science, Leeds Beckett University, Leeds, LS1 3HE, UK
| | - Roderick King
- Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, LS6 3QS, UK
| | - Kevin Deighton
- Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, LS6 3QS, UK
| | - John P O'Hara
- Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, LS6 3QS, UK
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