Women have lower tolerance to lower body negative pressure than do
men.
White, Deborah D., Robert W. Gotshall, Alan Tucker.
Departments of Physiology and Exercise and Sport Science, Colorado
State University, Ft. Collins, CO 80523
APStracts 2:0502A, 1995.
Studies of the cardiovascular response to lower body negative pressure
(LBNP) in men and women, have suggested that women may have less
tolerance to LBNP than men, although tolerance per se was not
determined. To investigate the effect of gender on tolerance to LBNP,
10 men and 10 women were subjected to increasing levels of LBNP until
presyncopal symptoms developed. The Cumulative Stress Index (CSI)
score was determined, as were cardiovascular variables. Women had 62%
less tolerance to LBNP with a CSI of 412 + 43 min-mmHg compared to a
CSI of 1070 + 149 min-mmHg for men. Cardiovascular changes associated
with LBNP were similar for men and women when expressed as relative
to the occurrence of presyncope, but women had a higher heart rate
response when the data were expressed at absolute levels of LBNP (-30
and -50 mmHg LBNP). Thus, men and women had similar cardiovascular
adjustments to the LBNP, with the changes in women occurring at lower
levels of LBNP. These data are important when considering the
development of anti-G countermeasures for women. These data raise
questions as to the manner in which blood pools within the lower body
in men and women under LBNP.
Received 5 December 1994; accepted in final form 6 November 1995.
APS Manuscript Number A1238-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95