Blood O2 affinity and maximal O2 consumption in elite bicycle racers

A. Veicsteinas, M. Samaja, M. Gussoni, P. Cerretelli

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Abstract

The PO2 at which hemoglobin is half-saturated with O2 (P50) at 37°C, PCO2 = 42 Torr, measured pH and 2,3-diphosphoglycerate-to-hemoglobin concentration ratio ([2,3-DPG]/[Hb]) values, Hill's coefficient (n) at rest, and maximal O2 consumption (V̇O2(max)) were determined in 11 world-class professional bicycle racers off-season (control, C), after 3 mo of 3 h daily training (preseason, PrS), and after additional 6 mo of competitions (competitive season, CoS). The results indicate that the P50 observed in trained athletes was the same as that of a comparable group of sedentary subjects (Sed) under the same conditions of pH, PCO2, and [2,3-DPG]/[Hb] and was similar to that obtained after 'normalization' in respect to pH and the [2,3-DPG]/[Hb]; [2,3-DPG]/[Hb] increased as a function of training from 0.72 to 0.95 (P <0.001); the slope of the central portion of the O2 equilibrium curve (OEC) was nearly unaffected by endurance training as indicated by the n value (n(CoS) = 2.70 ± 0.08; n(Sed) = 2.65 ± 0.08); and V̇O2(max) increased in the course of training 7 and 9% (P <0.001), respectively, when expressed in absolute units or per kilogram body weight. The V̇O2(max) predicted on the basis of a computer simulation does not increase significantly as a consequence of the measured rise in [2,3-DPG]. Therefore, the observed increase of V̇O2(max) cannot be explained with adaptive changes of the OEC. The present results differ from previous findings reported in other types of athletes.

Original languageEnglish
Pages (from-to)52-58
Number of pages7
JournalJournal of Applied Physiology Respiratory Environmental and Exercise Physiology
Volume57
Issue number1
Publication statusPublished - 1984

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ASJC Scopus subject areas

  • Endocrinology
  • Physiology

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