Impact of inactivity and exercise on the vasculature in humans : the role of blood flow and shear stress on arterial adaptations in healthy males
type: CreativeWork
description: Exercise training is known to increase endothelial function and provoke arterial remodelling both locally and systemically. This thesis was designed to further examine these relationships by investigating the acute response to different exercise intensities, with and without shear rate modification. Shear rate modification was also used to examine the impact of systemic exercise training on brachial haemodynamics. Finally, the effect of inactivity on vascular function and arterial remodelling were studied using novel models of inactivity. The aim of Study 1 was to examine the effect of shear stress on upper limb brachial artery dilation during acute cycle exercise of different intensities. The impact of three randomised bouts of 30 mins leg cycling (50, 70 and 85% HRmax) on brachial artery blood flow, shear rate (SR) and brachial diameter, was measured bilaterally and simultaneously. SR was further manipulated in one arm via forearm heating (40?1?C) in a water bath (+0C) throughout the exercise bouts. Exercise induced stepwise increases in SR in the unheated arm (~0C) (P<0.05). In the +o( arm, SR was significantly greater than in the ~o( limb. Brachial artery diameter increased post- exercise in ~o( by 3% (50%HRmax; P>0.05 vs. baseline), 7% (70%HRmax; P<0.05) and 9% (85%HRmax; P<0.05). In the+?C arm, post-exercise brachial diameter increased at all exercise intensities (P<0.05) and was significantly greater (P<0.05) than in the ~?C limb at 50% (12%), 70%HRmax (14%) and 85%HRmax (15%). In conclusion, increases in shear rate during incremental lower limb exercise are associated with increases in brachial artery diameter. This response is exaggerated with larger SR induced by localised heating, indicating that leg exercise has systemic effects on arterial diameter and that SR is an important stimulus to vasodilation during exercise in humans. The second study examined brachial artery flow mediated dilation (FMD) (using high resolution echo-Doppler) pre, and post (0, 1,…
abstract: Exercise training is known to increase endothelial function and provoke arterial remodelling both locally and systemically. This thesis was designed to further examine these relationships by investigating the acute response to different exercise intensities, with and without shear rate modification. Shear rate modification was also used to examine the impact of systemic exercise training on brachial haemodynamics. Finally, the effect of inactivity on vascular function and arterial remodelling were studied using novel models of inactivity. The aim of Study 1 was to examine the effect of shear stress on upper limb brachial artery dilation during acute cycle exercise of different intensities. The impact of three randomised bouts of 30 mins leg cycling (50, 70 and 85% HRmax) on brachial artery blood flow, shear rate (SR) and brachial diameter, was measured bilaterally and simultaneously. SR was further manipulated in one arm via forearm heating (40?1?C) in a water bath (+0C) throughout the exercise bouts. Exercise induced stepwise increases in SR in the unheated arm (~0C) (P<0.05). In the +o( arm, SR was significantly greater than in the ~o( limb. Brachial artery diameter increased post- exercise in ~o( by 3% (50%HRmax; P>0.05 vs. baseline), 7% (70%HRmax; P<0.05) and 9% (85%HRmax; P<0.05). In the+?C arm, post-exercise brachial diameter increased at all exercise intensities (P<0.05) and was significantly greater (P<0.05) than in the ~?C limb at 50% (12%), 70%HRmax (14%) and 85%HRmax (15%). In conclusion, increases in shear rate during incremental lower limb exercise are associated with increases in brachial artery diameter. This response is exaggerated with larger SR induced by localised heating, indicating that leg exercise has systemic effects on arterial diameter and that SR is an important stimulus to vasodilation during exercise in humans. The second study examined brachial artery flow mediated dilation (FMD) (using high resolution echo-Doppler) pre, and post (0, 1,…
author: Birk, G K
keywords: QP Physiology, RC1200 Sports Medicine
date published: 2011-01
date modified: 2026-07-24T06:30:16Z
provider: Liverpool Jon Moores University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Liverpool John Moores University

PropertyValue
property ID: DOI
value: 10.24377/LJMU.t.00006102