|
|
||||||||
Journal of Applied Physiology, Vol 55, Issue 3 884-890, Copyright © 1983 by American Physiological Society
ARTICLES |
S. M. Fortney, C. B. Wenger, J. R. Bove and E. R. Nadel
Five healthy men exercised at 65-70% of maximum O2 uptake (VO2 max) for 30 min in an ambient temperature of 30 degrees C. Duplicate experiments were conducted at three levels of plasma volume:control, hypovolemia, in which blood volume (BV) was reduced an average of 490 ml (9.7%) with diuretics, and hypervolemia, in which BV was increased an average of 440 ml (7.8%) by infusing an isotonic solution containing 5% human serum albumin. Marked venoconstriction occurred during exercise in all conditions and persisted despite large increases in deep body temperature. The degree of venoconstriction was similar during control and hypervolemic conditions, but was potentiated during hypovolemia. The observed venoconstriction appeared to consist of two components: an early one related to autonomic adjustments at the onset of exercise, and a later one possibly related to progressive decreases in cardiac filling. Heart rate, cardiac stroke volume (SV), and cardiac output during exercise were significantly affected by changes in BV. During hypovolemia the average differences from control values were 10 beats X min-1, -14 ml, and -2.2 l X min-1, respectively; during hypervolemia the differences from control were -7 X min-1, 10 ml, and 1.0 l X min-1, respectively. The pattern of SV over the course of exercise indicates that pooling of blood in veins may be quantitatively more important than plasma water loss in reducing cardiac filling pressure in the heat.
This article has been cited by other articles:
![]() |
R. Aardenburg, M. E. Spaanderman, H. W. van Eijndhoven, P. W. de Leeuw, and L. L. Peeters Formerly Preeclamptic Women With a Subnormal Plasma Volume Are Unable to Maintain a Rise in Stroke Volume During Moderate Exercise Reproductive Sciences, December 1, 2005; 12(8): 599 - 603. [Abstract] [PDF] |
||||
![]() |
N. S. Stachenfeld, C. Silva, and D. L. Keefe Estrogen modifies the temperature effects of progesterone J Appl Physiol, May 1, 2000; 88(5): 1643 - 1649. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. G. Fritzsche, T. W. Switzer, B. J. Hodgkinson, and E. F. Coyle Stroke volume decline during prolonged exercise is influenced by the increase in heart rate J Appl Physiol, March 1, 1999; 86(3): 799 - 805. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Nagashima, H. Nose, A. Takamata, and T. Morimoto Effect of continuous negative-pressure breathing on skin blood flow during exercise in a hot environment J Appl Physiol, June 1, 1998; 84(6): 1845 - 1851. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |