Date of Award
Honors College Thesis
Previous work has demonstrated a direct relationship between aerobic fitness and indices of vasodilatory function (i.e., Flow-mediated Dilation; FMD). Importantly, recent evidence suggests that vasoconstrictor function to reductions in blood flow (i.e., Low-Flow Mediated Constriction; L-FMC), as well as during sympatho-excitation (i.e., Cold Pressor Test), may compliment the FMD measure, thus, providing an overall range of vascular responsiveness. The purpose of this thesis project was to test the hypothesis that vasoactive range indices (peak vasodilation + nadir vasoconstriction) are sensitive to aerobic fitness levels in healthy young men. Fourteen males (age: 22±4 yrs) were recruited, and divided evenly into a high (HF) vs. low (LF) aerobic fitness group, quantified via YMCA cycle ergometry (VO2 peak extrapolation), and a 3-min step test (1-min HR recovery). Duplex Doppler-ultrasound was used to assess brachial artery responses to the following physiological stimuli: FMD, L-FMC, CPT, and local heating. Vasodilatory responses were calculated from the peak change in artery diameter, and vasoconstrictor responses were determined from the nadir values in response to stimuli, respectively. VO2 peak (HF=55±10 vs. LF=38±6) and HR recovery (HF=38±12 vs. LF=24±9 beats) were greater in the HF group (P<0.05). All vasoactive range indices were similar between groups; however, L-FMC change tended to be greater in HF (HF=0.1±0.06 vs. LF=0.02±0.07mm, P=0.057). A correlational analysis revealed an inverse relationship between L-FMC and HR recovery (r=-0.653, P=0.02). Collectively, these findings suggests that vasoactive range indices are not sensitive to aerobic fitness in healthy young men; however, high fit individuals may exhibit greater vasoconstrictor function to reductions in blood flow.
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Bell, Preston L., "Sensitivity of the Vasoactive Range in Determining Aerobic Fitness" (2016). Honors Theses. 422.