Greater erythrocyte deformability in world-class endurance athletes

Because athletes during endurance events require rapid uptake of oxygen, th e ability of red blood cells (RBC) to move through capillaries may limit pe rformance. Using ektacytometry, we determined whether RBC deformability (RC D) differed between elite road cyclists (n = 9) and sedentary controls (n = 5). Density profiles and standard hematological measurements were also per formed. The deformability index (DI) was higher in the cyclists (0.723 +/- 0.027) compared with that in controls (0.619 +/- 0.040, P < 0.001). Cyclist s also had a larger percentage of low-density RBCs (P < 0.001), and mean ce ll volume (MCV) was also higher (P = 0.013). These findings are indicative of a larger proportion of "young" RBCs in the blood of elite cyclists and p rovide further evidence that the turnover of RBCs in endurance athletes is higher than in the general population. With a younger more deformable RBC p opulation and providing the destruction does not exceed replacement, perfor mance potential should be enhanced. Furthermore, examination of factors tha t contribute to increased RBC turnover in athletes may help us understand t he mechanisms that cause RBC aging.