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 ataltitude; the red cell pH decreased by 0.05 units. In vitro buffering of bloodagainst C02 improved remarkably at the end of the mountain stay by 14 mmol/l; similarly, in vivo of blood was increased by 11 mmol/l 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. Afterreturn 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. Verf.-Referat