Augmented baroreflex heart rate gain after moderate-intensity, dynamic exercise

• DOI: 10.1152/ajpregu.1996.270.2.r420
• Publication Date: 2017-12-24T23:15:35Z
• Authors: J. R. Halliwill; J. A. Taylor; T. D. Hartwig; D. L. Eckberg
• Keywords: Intensity

The occurrence of a sustained vasodilation and hypotension after acute, dynamic exercise suggests that may alter arterial baroreflex mechanisms. Therefore, we assessed systemic hemodynamics, regulation heart rate, cardiac vagal tone 60 min cycling at 60% peak oxygen consumption in 12 healthy, untrained men women (ages 21-28 yr). We derived sigmoidal carotid-cardiac relations by measurement R-R interval changes induced ramped, stepwise, R-wave-triggered external neck pressure from 40 to -65 mmHg. estimated tonic control with power spectral analysis variability the respiratory frequency band (0.2-0.3 Hz) during frequency- tidal volume-controlled breathing. Both mean total peripheral resistance were reduced postexercise [pressure: 86 +/- 2 (mean SE) 81 mmHg; resistance: 23 16 1 units; both P < 0.05]. Cardiac output was increased (from 3.9 0.3 5.5 0.5 l/min, 0.05). slope range relation (slope: 4.7 0.7 6.1 0.9 ms/mmHg; range: 186 238 30 ms, Respiratory (cardiac tone) not changed any time exercise, whereas rate plasma norepinephrine levels elevated. Thus moderate-intensity, increases output, reduces vascular resistance, augments responsiveness. Our data suggest augmented gain restrains rather than contributes hypotension, which appears be mediated predominately vasodilation.