Complete blood cell counts in top level cyclists : an example of biological variability

We report data about 50 caucasian top-level cyclists (45 males, 5 womens, aged between 16 and 36 years, mean 25 ± 4.5). Recruitment was by controling top-level athletes in order to follow their blood cell counts to detect variation in haemoglobin concentration and hematocrit level (prevention of erythropoietin abuse). All samples were drawn in the morning, when the cyclists were at rest, according to a standardized protocol. Erythroblastic serie was abnormal in several cases (4 anaemias, 3 macrocytosis, 6 low haematocrit level, 10 mean cell haemoglobin higher than 32 pg, low reticulocyte count). White blood cells showed a trend toward low counts for neutrophils and lymphocytes. Two cyclists had platelets counts below 150.109/l. Our data indicated that top-level cyclism had some effects on the blood cell counts, which is likely to indicate an effect of intense aerobic training on physiological status.