Journal of Applied Physiology, Vol 57, Issue 1 52-58, Copyright © 1984 by American Physiological Society
Blood O2 affinity and maximal O2 consumption in elite bicycle racers
A. Veicsteinas, M. Samaja, M. Gussoni and P. Cerretelli
The PO2 at which hemoglobin is half-saturated with O2 (P50) at 37 degrees
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 (VO2max) 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 less than 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 (NCoS = 2.70 +/- 0.08; nSed = 2.65 +/- 0.08); and
VO2max increased in the course of training 7 and 9% (P less than 0.001),
respectively, when expressed in absolute units or per kilogram body weight.
The VO2max 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 VO2max cannot be explained with
adaptive changes of the OEC. The present results differ from previous
findings reported in other types of athletes.
