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Diminished Baroreflex Control of Forearm Vascular Resistance Following TrainingThe stimulus-response characteristics of cardiopulmonary baroreflex control of forearm vascular resistance (FVR units in mm Hg x min x I00 ml/ml) were studied in 14 volunteers before and after 10 wk of endurance training. We assessed the relationship betaleen reflex stimulus (changes in central venous pressure, CVP) and response (FVR) during unloading of cardiopulmonary baroreceptors with lower body negative pressure (LBNP, 0 to - 2O mm Hg). Changes in CVP during LBNP were estimated from pressure changes in a large peripheral vein in the dependent arm of the subject in the right lateral decubitus position. Maximal oxygen uptake (VO(sub 2max)) and total blood volume increased with endurance training from 37.8 +/- 1.4 ml/min x kg and 63.6 +/- 2.1 ml/kg to 45.3 +/- 1.4 ml/ min x kg and 69.3 +/- 2.8 ml/kg respectively (P less than 0.05). Reflex forearm vasoconstriction occurred in response to a reduction in estimated CVP, and the absolute change in FVR per unit of CVP was reduced from -5.96 +/- 0.79 to -4.06 +/- 0.52 units x mm/ Hg (P less than 0.05) following exercise training but was unchanged from -6.10 to 0.57 to -6.22 +/- 0.94 units x mm/ Hg for the time control group (N = 7). Resting values for FVR were similar before and after exercise training; however, resting estimated CVP was elevated from 9.5 +/- 0.5 mm x Hg before training to 11.3 +/- 0.6 mm x Hg after training. The reduction in sensitivity of the cardiopulmonary baroreflex control of FVR was linearly related to the increase in blood volume (r = 0.65, P less than 0.05). suggesting that diminished cardiopulmonary baroreflex control of FVR in physically fit individuals is related, in part, to a training-induced blood volume expansion.
Document ID
19970012369
Acquisition Source
Kennedy Space Center
Document Type
Reprint (Version printed in journal)
Authors
Mack, G. W.
(Yale Univ. New Haven, CT United States)
Thompson, C. A.
(Yale Univ. New Haven, CT United States)
Doerr, D. F.
(Yale Univ. New Haven, CT United States)
Nadel, E. R.
(Yale Univ. New Haven, CT United States)
Convertino, V. A.
(Yale Univ. New Haven, CT United States)
Date Acquired
August 17, 2013
Publication Date
April 1, 1991
Publication Information
Publication: Medcine and Science in Sports and Exercise
Volume: 23
Issue: 12
ISSN: 0195-9131
Subject Category
Aerospace Medicine
Report/Patent Number
NAS 1.15:112285
NASA-TM-112285
Accession Number
97N70961
Funding Number(s)
CONTRACT_GRANT: NAS10-10285
CONTRACT_GRANT: NIH HL-39818
Distribution Limits
Public
Copyright
Public Use Permitted.
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