Abstract
Influences exerted by altitude were investigated in eight male and three female physical
education students (age 26 ± 1 SE years) during and after a ski course lasting 2 weeks.
Measurements of acid-base status, oxygen dissociation curve (ODC), and different constituents
of blood were performed before ascent at Hannover (55 m above sea level), after 7
and 14 days in the mountains (2200 m), and after 5, 11, and 17 days back at Hannover.
Physical performance was tested at Hannover only. No significant alkalosis was observed
at altitude; the red cell pH decreased by 0.05 units. In vitro buffering of blood
against CO2 (-Δ[HCO-
3 ]/ΔpH) improved remarkably at the end of the mountain stay by 14 mmol/1; similarly,
in vivo Δ[Lac]/ΔpH of blood was increased by 11 mmol/1 during the 1st week after return.
The ODC showed an elevation of the standard half saturation pressure (P50 , pH 7.4) at altitude from 3.75 + 0.08 to 3.98 ± 0.03 kPa.
The cause was a changed Donnan equilibrium of the erythrocytes resulting from increased
2,3-diphosphoglycerate and decreased potassium concentrations. After return to Hannover
the slope n of the ODC rose from 2.7 ± 0.1 to 3.1 ± 0.1, possibly because of a greater
percentage of young red cells. The changes of buffering and ODC might contribute to
a slightly improved exercise performance after the altitude stay.
Key Words
altitude - skiing - physical performance - buffering - oxygen-dissociation curve -
blood - hormones
