TY - JOUR
T1 - Effects of dynamic exercise on cardiovascular regulation during lower body negative pressure
AU - Nishiyasu, T.
AU - Shi, X.
AU - Gillen, C. M.
AU - Mack, G. W.
AU - Nadel, E. R.
PY - 1993
Y1 - 1993
N2 - The purpose of this study was to compare the cardiovascular control mechanisms that defend arterial blood pressure against blood pooling between rest and moderate dynamic exercise. We studied ten physically active men during rest and five 12-min graded supine cycle ergometer exercise bouts with and without application of LBNP in 25°C and 35°C. Exercise intensities were 10, 50, and 100 watts (W), each for 4 min, and LBNP was applied at 0 (control), -20, -40, and -60 mm Hg in 25°C and -40 mm Hg in 35°C. At rest, cardiac stroke volume (SV) decreased from 120 ± 5 ml during control to 94 ± 6, 67 ± 5 and 49 ± 3 ml during -20, -40, and -60 mm Hg LBNP, respectively, and to 55 ± 3 ml during -40 mm Hg at 35°C. Exercise elevated SV toward the control level during LBNP due to muscle pumping action. Heart rate (HR) did not increase significantly during application of LBNP until SV decreased by 20-25 ml during LBNP, both during rest and exercise. The magnitude of HR increase per decrease in SV, once an increase in HR occurred, was similar between rest and exercise, regardless of exercise intensity. The change in total peripheral resistance (TPR) with respect to SV was linear, confirming that peripheral vascular adjustments were proportional to changes in the heart's preload. The slopes of the TPR-SV relation were similar during rest and exercise, although shifted to the left with increasing exercise intensity. Our results support the notion that the control characteristics of arterial blood pressure regulation are similar during rest and moderate dynamic exercise.
AB - The purpose of this study was to compare the cardiovascular control mechanisms that defend arterial blood pressure against blood pooling between rest and moderate dynamic exercise. We studied ten physically active men during rest and five 12-min graded supine cycle ergometer exercise bouts with and without application of LBNP in 25°C and 35°C. Exercise intensities were 10, 50, and 100 watts (W), each for 4 min, and LBNP was applied at 0 (control), -20, -40, and -60 mm Hg in 25°C and -40 mm Hg in 35°C. At rest, cardiac stroke volume (SV) decreased from 120 ± 5 ml during control to 94 ± 6, 67 ± 5 and 49 ± 3 ml during -20, -40, and -60 mm Hg LBNP, respectively, and to 55 ± 3 ml during -40 mm Hg at 35°C. Exercise elevated SV toward the control level during LBNP due to muscle pumping action. Heart rate (HR) did not increase significantly during application of LBNP until SV decreased by 20-25 ml during LBNP, both during rest and exercise. The magnitude of HR increase per decrease in SV, once an increase in HR occurred, was similar between rest and exercise, regardless of exercise intensity. The change in total peripheral resistance (TPR) with respect to SV was linear, confirming that peripheral vascular adjustments were proportional to changes in the heart's preload. The slopes of the TPR-SV relation were similar during rest and exercise, although shifted to the left with increasing exercise intensity. Our results support the notion that the control characteristics of arterial blood pressure regulation are similar during rest and moderate dynamic exercise.
UR - http://www.scopus.com/inward/record.url?scp=0027293102&partnerID=8YFLogxK
M3 - Article
C2 - 8338498
AN - SCOPUS:0027293102
SN - 0095-6562
VL - 64
SP - 517
EP - 521
JO - Aviation Space and Environmental Medicine
JF - Aviation Space and Environmental Medicine
IS - 6
ER -