Vascular volumes and hematology in male and female runners and cyclists

To examine the hypothesis that foot-strike hemolysis alters vascular volume s and selected hematological properties is trained athletes, we have measur ed total blood volume (TBV). red cell volume (RCV) and plasma volume (PV) i n cyclists (n = 21) and runners (n = 17) and compared them to those of untr ained controls(n = 20). TBV (ml . kg(-1)) was calculated as the sum of RCV (ml . kg(-1)) and PV (ml . kg(-1)) obtained using Cr-51 and I-125-labelled albumin, respectively. Hematological assessment was carried out using a Cou lter counter. Peak aerobic power ((V) over dot O-2peak) was measured during progressive exercise to fatigue using both cycle and treadmill ergometry. RCV was 15% higher (P < 0.05) in male cyclists [35.4 (1.0), mean (SE); n = 12] and runners [35.3 (0.98); n = 9] compared to the controls [30.7 (0.92); n = 12]. Similar differences existed between the female cyclists [28.2 (2. 1): n = 9] and runners [28.4 (1.0); n = 8] compared to the untrained contro ls [24.9 (1.4); n = 8]. For the male athletes, PV was between 19% (cyclists ) and 28% (runners) higher (P < 0.05) in the trained athletes compared to t he untrained controls. The differences in PV between the female groups were not significant. Although the males had a higher (P < 0.05) TBV, RCV and P V than the females, no differences between cyclists and runners were found for either gender. Mean cell volume was not different between the athletic groups. (V) over dot O-2peak (ml . kg(-1) . min(-1)) was higher (P < 0.05) in both male [68.4 (1.5)] and female [54.8 (2.1)] runners when compared to the untrained males [47.1 (1.0)] and females [40.5 (2.1)]. Although differe nces existed between the genders in (V) over dot O-2peak for both cyclists and runners, no differences were found between the athletic groups within a gender. Since the vascular volumes were not different between cyclists and runners for either the males or females, foot-strike hemolysis would not a ppear to have an effect on that parameter. The significant correlations (P < 0.05) found between (V) over dot O-2peak and RCV (r = 0.64 and 0.64) and TBV(r = 0.82 and 0.63) for the males and females, respectively, suggests a role for the vascular system in realizing a high aerobic power.