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Determinants of curvature constant (W’) of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis

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; VO(2peak): 59.2 ± 6.8 ml·kg(−1)·m...

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Autores principales: Deb, Sanjoy K., Gough, Lewis A., Sparks, S. Andy, McNaughton, Lars R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer Berlin Heidelberg 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5388723/
https://www.ncbi.nlm.nih.gov/pubmed/28280973
http://dx.doi.org/10.1007/s00421-017-3574-4
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author Deb, Sanjoy K.
Gough, Lewis A.
Sparks, S. Andy
McNaughton, Lars R.
author_facet Deb, Sanjoy K.
Gough, Lewis A.
Sparks, S. Andy
McNaughton, Lars R.
author_sort Deb, Sanjoy K.
collection PubMed
description 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; VO(2peak): 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 (NaHCO(3)) 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 NaHCO(3) was used to induce alkalosis. Environmental conditions were set at either normobaric hypoxia (FiO(2): 14.5%) or normoxia (FiO(2): 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 (HCO(3) (−)) 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 NaHCO(3) increasing HCO(3) (−) buffering capacity to delay exercise-induced acidosis, which may, therefore, enhance anaerobic energy contribution.
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spelling pubmed-53887232017-04-27 Determinants of curvature constant (W’) of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis Deb, Sanjoy K. Gough, Lewis A. Sparks, S. Andy McNaughton, Lars R. Eur J Appl Physiol Original Article 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; VO(2peak): 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 (NaHCO(3)) 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 NaHCO(3) was used to induce alkalosis. Environmental conditions were set at either normobaric hypoxia (FiO(2): 14.5%) or normoxia (FiO(2): 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 (HCO(3) (−)) 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 NaHCO(3) increasing HCO(3) (−) buffering capacity to delay exercise-induced acidosis, which may, therefore, enhance anaerobic energy contribution. Springer Berlin Heidelberg 2017-03-09 2017 /pmc/articles/PMC5388723/ /pubmed/28280973 http://dx.doi.org/10.1007/s00421-017-3574-4 Text en © The Author(s) 2017 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
spellingShingle Original Article
Deb, Sanjoy K.
Gough, Lewis A.
Sparks, S. Andy
McNaughton, Lars R.
Determinants of curvature constant (W’) of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis
title Determinants of curvature constant (W’) of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis
title_full Determinants of curvature constant (W’) of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis
title_fullStr Determinants of curvature constant (W’) of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis
title_full_unstemmed Determinants of curvature constant (W’) of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis
title_short Determinants of curvature constant (W’) of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis
title_sort determinants of curvature constant (w’) of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5388723/
https://www.ncbi.nlm.nih.gov/pubmed/28280973
http://dx.doi.org/10.1007/s00421-017-3574-4
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