Affiliation:
1. School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
Abstract
The primary objective of this study was to determine whether cardiovascular compensatory response phenotypes exist in the face of a reduced perfusion pressure challenge to exercising muscle oxygen delivery (O2D), and whether these responses might be exercise intensity (EI) dependent. Ten healthy men (19.5 ± 0.4 yr) completed two trials of progressive forearm isometric handgrip exercise to exhaustion (24.5 N increments every 3.5 min) in each of forearm above and below heart level [forearm arterial perfusion pressure (FAPP) difference of 29.5 ± 0.97 mmHg]. At the end of each EI, measurements of forearm blood flow (FBF; ml/min) via brachial artery Doppler and echo ultrasound, mean arterial blood pressure (MAP; mmHg) via finger photoplethysmography, and exercising forearm venous effluent via antecubital vein catheter revealed distinct cardiovascular response groups: n = 6 with compensatory vasodilation vs. n = 4 without compensatory vasodilation. Compensatory vasodilators were able to blunt the perfusion pressure-evoked reduction in submaximal O2D in the arm-above-heart condition, whereas nonvasodilators did not (−22.5 ± 13.6 vs. −65.4 ± 14.1 ml O2/min; P < 0.05), and in combination with being able to increase O2 extraction, nonvasodilators defended submaximal V̇o2 and experienced less of an accumulated submaximal O2D deficit (−80.7 ± 24.7 vs. −219.1 ± 36.0 ml O2/min; P < 0.05). As a result, the compensatory vasodilators experienced less of a compromise to peak EI than nonvasodilators (−24.5 ± 3.5 N vs. −52.1 ± 8.9 N; P < 0.05). In conclusion, in the forearm exercise model studied, vasodilatory response phenotypes exist that determine individual susceptibility to hypoperfusion and the degree to which aerobic metabolism and exercise performance are compromised.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
10 articles.
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