Open Collections

Abstract

The purpose of this study was to determine the volume of red cells released by the spleen during exercise and to establish the impact of splenic emptying on peripheral hematocrit during exercise. The influences of training status and hypoxic exposure on splenic emptying and exercise hemodynamics were also examined. 6 trained (T) and 6 untrained (N) and 4 splenectomized (S) subjects completed a set of two tests: a maximal aerobic power test and a 30 minute exercise test (ES). The T and N groups also completed the two tests i n hypoxic conditions (FI02 = 0.16). The results of the maximal test determined the power outputs (PO) at which the subjects exercised during the exercise session. The ES consisted of 10 minutes at a FO requiring 25% of maximal VO₂, ten minutes at a PO requiring 50% of maximal VO₂ and 10 minutes at a PO requiring 75% of maximal VO₂. Red cell volume (RCV), plasma volume (PV) were directly measured pre- and post-exercise using radioisotope labeling (⁵¹Cr, ¹²⁵| - RHISA, ¹³¹I-RHISA). Hematocrit (Hct) was measured and the spleen was imaged, using ⁹⁹[sup m]Tc, pre-exercise and after each 10 minute workload. Spleen volume (SV) was calculated using the average count of the anterior and posterior scan and the count of a known volume of blood. There was no difference in pre-exercise RCV between the S group (2033 mL) and the N group (2058 mL). The N group showed a significant increase in RCV in both normoxic and hypoxic conditions post-exercise (p