Changes in stroke volume and maximal aerobic capacity with
increased blood volume in men and women.
Mier, Constance M., Melissa A. Domenick, Nathan S. Turner, Jack H.
Wilmore.
Human Performance Laboratory, Department of Kinesiology and Health
Education, The University of Texas at Austin, Austin, Texas 78712
APStracts 2:0506A, 1995.
This study determined whether the effects of acute plasma volume
expansion (PVX) or 10 days of training on stroke volume during
submaximal cycling and on treadmill O2max were similar between men
and women. Subjects performed a submaximal cycle test and a treadmill
test to exhaustion under three conditions: control, PVX, and
following training. Cycle O2peak and blood volume were measured
before and after training. Training consisted of daily 1-hour bouts
(30 min at 80% HRpeak and ten 2-min intervals at 95% HRpeak
alternating with 1-min low intensity pedaling) on a cycle ergometer
for 10 consecutive days. Training increased cycle O2peak in men (p
< 0.05, mean +/- SE) (3.14 +/- 0.13 vs. 3.42 +/- 0.13 l.min-1)
and women (2.11 +/- 0.10 vs. 2.37 +/- 0.12 l.min-1), and increased
blood volume in men (67.6 +/- 3.0 vs. 72.3 +/- 3.1 ml.kg-1) and women
(62.7 +/- 2.2 vs. 65.6 +/- 2.4 ml.kg-1). As a result of the greater
blood volume with PVX and with training, stroke volume (ml) during
submaximal cycling increased in men (control: 110 +/- 4, PVX: 123 +/-
4, trained: 121 +/- 4) and women (control: 87 +/- 5, PVX: 95 +/- 6,
trained: 96 +/- 7). Treadmill O2max (ml.kg.min-1) did not change with
PVX despite a 6-7% reduction in [Hb], while training resulted in an
increase in O2max in men (control: 47.9 +/- 2.8, PVX: 46.7 +/- 2.8,
trained: 49.9 +/- 2.6) and women (control: 38.0 +/- 1.2, PVX: 36.9
+/- 1.2, trained: 39.2 +/- 1.2). The effects of PVX or training on
stroke volume or O2max did not differ between men and women. An
additional finding was an increase in diastolic and mean blood
pressures at 65% of cycle O2peak with PVX and with training in women.
Thus, men and women hold similar cardiac reserve capacities for
increasing stroke volume and as a result O2max is maintained despite
a reduction in [Hb]. However, sex differences in blood pressure
regulation with increased blood volume might exist.
Received 14 June 1995; accepted in final form 2 November 1995.
APS Manuscript Number A630-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95