Both exercise and passive heating cause acute reductions in blood pressure. It is unknown if exercise-heat stress causes likewise reductions or greater when combined. PURPOSE: This project tested the hypothesis that the resting and exercise-heat stress cause hypotension and improvements in arterial stiffness. METHODS: Seven healthy active (7 day activity: 9887±3564 steps/day; VO2max: 52±10 mL/kg/min ) subjects (5M/2F, 24±9y, 171±6cm, 68±7kg) completed a 30 min baseline rest followed by 60 min at an exercise intensity of their choice that represented their perceived exertion (RPE) of 12 (between light and somewhat hard) on a 20-point rating scale while being blinded to the ergometer (watts) in a hot dry to humid (42.3±0.3℃; initial 10.4±0.4% relative humidity [Rh] that increased to 62.2±5.3%Rh) and control neutral dry (22.9±1.0℃; 11.5±1.9%Rh) condition in random order separated by at least 7 days. Heart rate (HR), peripheral blood pressure (systolic [SYS], diastolic [DIA], mean arterial pressure [MAP]), arterial stiffness (augmentation index [AIX@75]; pulse wave velocity [PWV]) and total vascular resistance (TVR), and central blood pressures (cSYS, cDIA) were measured after the 30 min baseline rest and 60 min of exercise recovery. A 2-way repeated measures analysis of variance was used to examine interaction and main effects for condition x time. RESULTS: Exercise intensity was slightly greater (54±1 vs 48±3%VO2max, P Pre- and post-exercise heat stress resulted in an increase in heart rate (pre-: ∆14±11BPM, post-: ∆26±12BPM) and AIX@75 (pre-: ∆7±7%, post-: ∆14±12%) and a decrease in post-exercise TVR (∆0.1±0.2s*mmHg/ml) (Main effect: Condition; P≤0.03). Only post-exercise heat stress reduced SYS (: ∆12±14mmHg), cSYS (∆9±12mmHg), and PWV(∆0.4±0.4m/s) (Condition x Time; P≤0.03). CONCLUSION: Low intensity exercise heat stress has greater acute cardiovascular benefits for reducing arterial stiffness and peripheral and central systolic pressures compared to exercise in neutral conditions.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.