Serum erythropoietin in cross-country skiers.

Serum erythropoietin concentration and hemoglobin concentration were determined during the winter season in 41 male and 31 female well-trained, cross-country skiers. The athletes both lived and trained at low altitude (below 300 m above sea level). No significant differences in serum erythropoietin concentration were seen between male skiers (13.6 +/- 5.0 mU.ml-1), female skiers, (14.9 +/- 5.6 mU.ml-1), and normal controls (12.6 +/- 3.9 mU.ml-1) (mean +/- SD). In 18 of the skiers (12 males and 6 females), a second sample was taken after 2.3 +/- 0.18 months. No significant difference in either serum erythropoietin concentration or hemoglobin concentration was detected between the two samples in this combined group of skiers. The present study indicates that normal serum erythropoietin concentration is to be expected during the winter season at sea level in cross-country skiers living and training at low altitude.