Descripción
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I expected the Stirling and Zakynthinaki Counterpoint (2) to provide alternative physiological explanations for the discernibly different oxygen uptake (V¿ O2) kinetics at different exercise intensities. Some of their points seem warranted: the lack of justification for an exponential phase () 1 fit and the ¿slow-phase¿ exponential fit reflecting a process with a single time constant () and gain. But so many of their assertions demand challenge. For example, they state that the problems regarding the decrease of ¿R¿ as an indicator of what they term TD2, ¿are due to trying to fit time-delayed phases to data with no such features.¿ Well, there are such features! The 1¿2 transition often coincides with a time-delayed transient R decrease (4); where not, it is not that the delayed component is not there but that it is ¿smeared¿ by increased perfusion from other regions and/or transient hyperventilation. Its presence is physiologically justified: the transient alkalosis (1, 3), resulting from proton trapping as [phosphocreatine] decreases, retains CO2 intramuscularly. When the 1¿2 transition cannot be clearly determined from R, a portion of the 1 response should not be allowed to influence the 2- estimation: this is a physiological control parameter not a parameter of convenience (6), as are the 1 and slow-component s. Deleting a portion of the early response slightly greater than the real delay may influence the confidence of the 2- estimation; deleting too little will affect its value¿a greater concern. Also, we disagree with their assertion | |
Internacional
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Si |
JCR del ISI
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Si |
Título de la revista
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JOURNAL OF APPLIED PHYSIOLOGY |
ISSN
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8750-7587 |
Factor de impacto JCR
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3,658 |
Información de impacto
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Volumen
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DOI
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Número de revista
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0 |
Desde la página
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1667 |
Hasta la página
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1668 |
Mes
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ENERO |
Ranking
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