Effect of Exercise on Baroreflex at Different Altitudes

Various studies have been performed to analyze and asses the baroreflex sensitivity (BRS) in different settings. Our study aims at analyzing the BRS at rest and during different exercise stages and altitudes. Twenty-one young, healthy subjects underwent experimental trials near sea level, and two times at high altitude. BRS was calculated using the sequence method (spontaneous trends of three or more inter-beat interval and systolic blood pressure) in order to analyze the baroreflex response at rest and during incremental exercise. Results show that BRS exponentially decreases during exercise at all altitudes. Moreover, BRS decays much faster with acute hypoxia (ALT1), indicating that the baroreceptors respond with a quick loss of sensitivity when exercising. After 16 days at high altitude (ALT16), BRS at rest resets to smaller values but the evolution of BRS during exercise has the same behavior as at SL, indicating BRS acclimation to altitude.