Please use this identifier to cite or link to this item: http://buratest.brunel.ac.uk/handle/2438/9138
Title: Restrictions in systemic and locomotor skeletal muscle perfusion, oxygen supply and V(O2) during high-intensity whole-body exercise in humans
Authors: Mortensen, SP
Damsgaard, R
Dawson, EA
Secher, NH
González-Alonso, J
Keywords: Muscle perfusion;Whole-body exercise;Oxygen supply;Skeletal muscle
Issue Date: 2008
Publisher: Wiley-Blackwell
Citation: Journal of Physiology, 586(10), 2621 - 2635, 2008
Abstract: Perfusion to exercising skeletal muscle is regulated to match O2 delivery to the O2 demand, but this regulation might be compromised during or approaching maximal whole-body exercise as muscle blood flow for a given work rate is blunted. Whether muscle perfusion is restricted when there is an extreme metabolic stimulus to vasodilate during supramaximal exercise remains unknown. To examine the regulatory limits of systemic and muscle perfusion in exercising humans, we measured systemic and leg haemodynamics, O2 transport, and Graphic, and estimated non-locomotor tissue perfusion during constant load supramaximal cycling (498 ± 16 W; 110% of peak power; mean ± s.e.m.) in addition to both incremental cycling and knee-extensor exercise to exhaustion in 13 trained males. During supramaximal cycling, cardiac output (Graphic), leg blood flow (LBF), and systemic and leg O2 delivery and Graphic reached peak values after 60–90 s and thereafter levelled off at values similar to or ∼6% (P < 0.05) below maximal cycling, while upper body blood flow remained unchanged (∼5.5 l min−1). In contrast, Graphic and LBF increased linearly until exhaustion during one-legged knee-extensor exercise accompanying increases in non-locomotor tissue blood flow to ∼12 l min−1. At exhaustion during cycling compared to knee-extensor exercise, Graphic, LBF, leg vascular conductance, leg O2 delivery and leg Graphic for a given power were reduced by 32–47% (P < 0.05). In conclusion, locomotor skeletal muscle perfusion is restricted during maximal and supramaximal whole–body exercise in association with a plateau in Graphic and limb vascular conductance. These observations suggest that limits of cardiac function and muscle vasoconstriction underlie the inability of the circulatory system to meet the increasing metabolic demand of skeletal muscles and other tissues during whole-body exercise.
Description: This article is available open access through the publisher’s website at the link below. Copyright @ 2008 The Physiological Society.
URI: http://jp.physoc.org/content/586/10/2621
http://bura.brunel.ac.uk/handle/2438/9138
DOI: http://dx.doi.org/10.1113/jphysiol.2007.149401
ISSN: 0022-3751
Appears in Collections:Sport
Dept of Life Sciences Research Papers

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