Affiliations: [a] Department of Human Sciences – Kinesiology Program, The Ohio State University, Columbus, OH, USA | [b] College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
Correspondence:
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Corresponding author: Steven T. Devor, Ph.D., Department of Health and Exercise Science, The Ohio State University, A50 PAES Building, 305 West 17th Avenue, Columbus, OH 43210-1224, USA. Tel.: +1 614 688 8436; Fax: +1 614 688 3432; [email protected]
Abstract: This study examined the relationship between hematocrit, blood viscosity, plasma viscosity, erythrocyte deformability, and fibrinogen concentration during maximal oxygen uptake in aerobically trained (AT) and resistance trained (RT) athletes. Maximal oxygen uptake was assessed using a Bruce graded exercise treadmill test to exhaustion, and blood samples were collected at rest and immediately following exercise using a venous catheter. Viscometric analyses were performed using a cone and plate viscometer at varying shear rates. Hematocrit was measured as the fraction of erythrocytes suspended in plasma following centrifugation. Erythrocyte rigidity was estimated using the Dintenfass index of red blood cell rigidity. Following maximal treadmill exercise, an increase of blood viscosity at varying shear rates (22.50, 45.00, 90.00, and 225.00 s- 1; P < 0.05) was observed in RT athletes only. Plasma viscosity @ 225.00 s- 1 (1.88 ± 0.09 vs. 1.78 ± 0.03 mPa.s; P < 0.05), erythrocyte rigidity (0.52 ± 0.08 vs. 0.40 ± 0.09; P < 0.05), and plasma fibrinogen (434 ± 7 vs. 295 ± 25 mg/dL; P < 0.01) were all significantly greater in RT than AT athletes following maximal exercise. In summary, AT, but not RT, is associated with a hemorheological profile that promotes both oxygen transport and delivery. The results indicate that hematocrit alone should not be the focus of training and ergogenic supplementation to increase aerobic performance.
