Blood Gas Transport Properties in Endurance-Trained Athletes Living at Different Altitudes

Abstract

Hemoglobin oxygen binding properties and acid-base status were investigated in Colombian athletes (A) and controls (C) from Cali (C-1000 m) and Bogotá (B-2600 m). [Hb] and Hct values were not influenced by altitude, but Hct was lower in the blood of athletes (in Cali 2.6%, in Bogotá 1.4%). Both training and altitude produced a right-shift of the standard oxygen dissociation curve (P₅₀ in CC 28.5 ± 0.9 mmHg, AC 31.0 ± 1.4 mmHg, CB 29.6 ± 1.5 mmHg) leading to highest P₅₀ in blood of altitude athletes (32.3 ± 1.1 mmHg). Opposite to the position of the ODC the slope “n” was only increased by altitude influence (Δ “n” in controls 0.07, in athletes 0.28). The BCCO₂ was increased in AC over the whole saturation range, whereas BC_Lac was neither significantly influenced by training nor by altitude. All altitude effects can be explained by higher [DPG] (Δ[DPG] in controls 5.0 µmol/gHb, in athletes 3.9 µmol/gHb), but the cause for the training effects still remains unclear. The acid base status in altitude residents was characterized by low BE and pCO₂, which was most pronounced in altitude athletes, the latter correcting the actual venous pH to normal values. No significant variations of the Hb-O₂-binding properties could be detected in athletes one day after leaving high altitude when compared with blood samples of athletes taken at high altitude, whereas BE and venous pCO₂ were already increased. It is concluded that high altitude athletes are favoured during aerobic and handicapped during anaerobic exercise after the rapid descent to low altitude.

Key words

bohr effect - oxygen dissociation curve - Donnan equilibrium - electrolytes - acid-base-status