Multiple-day high-dose beetroot juice supplementation does not improve pulmonary or muscle deoxygenation kinetics of well-trained cyclists in normoxia and hypoxia.

Autor: Rokkedal-Lausch T; Sport Sciences - Performance and Technology, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark. Electronic address: torben@hst.aau.dk., Franch J; Sport Sciences - Performance and Technology, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark., Poulsen MK; Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark., Thomsen LP; Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark., Weitzberg E; Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden., Kamavuako EN; Center for Robotics Research, Department of Engineering, King's College London, London, United Kingdom., Karbing DS; Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark., Larsen RG; Sport Sciences - Performance and Technology, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark.
Jazyk: angličtina
Zdroj: Nitric oxide : biology and chemistry [Nitric Oxide] 2021 Jun 01; Vol. 111-112, pp. 37-44. Date of Electronic Publication: 2021 Apr 05.
DOI: 10.1016/j.niox.2021.03.006
Abstrakt: Dietary nitrate (NO 3 - ) supplementation via beetroot juice (BR) has been reported to lower oxygen cost (i.e., increased exercise efficiency) and speed up oxygen uptake (VO 2 ) kinetics in untrained and moderately trained individuals, particularly during conditions of low oxygen availability (i.e., hypoxia). However, the effects of multiple-day, high dose (12.4 mmol NO 3- per day) BR supplementation on exercise efficiency and VO 2 kinetics during normoxia and hypoxia in well-trained individuals are not resolved. In a double-blinded, randomized crossover study, 12 well-trained cyclists (66.4 ± 5.3 ml min -1 ∙kg -1 ) completed three transitions from rest to moderate-intensity (~70% of gas exchange threshold) cycling in hypoxia and normoxia with supplementation of BR or nitrate-depleted BR as placebo. Continuous measures of VO 2 and muscle (vastus lateralis) deoxygenation (ΔHHb, using near-infrared spectroscopy) were acquired during all transitions. Kinetics of VO 2 and deoxygenation (ΔHHb) were modeled using mono-exponential functions. Our results showed that BR supplementation did not alter the primary time constant for VO 2 or ΔHHb during the transition from rest to moderate-intensity cycling. While BR supplementation lowered the amplitude of the VO 2 response (2.1%, p = 0.038), BR did not alter steady state VO 2 derived from the fit (p = 0.258), raw VO 2 data (p = 0.231), moderate intensity exercise efficiency (p = 0.333) nor steady state ΔHHb (p = 0.224). Altogether, these results demonstrate that multiple-day, high-dose BR supplementation does not alter exercise efficiency or oxygen uptake kinetics during normoxia and hypoxia in well-trained athletes.
(Copyright © 2021 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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