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This Article Full Text Full Text (PDF) All Versions of this Article: 91/3/499    most recent expphysiol.2005.032805v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Burnley, M. Articles by Jones, A. M. Search for Related Content PubMed PubMed Citation Articles by Burnley, M. Articles by Jones, A. M.

¹ Department of Sport and Exercise Science, Carwyn James Building, The University of Wales Aberystwyth, Penglais Campus, Aberystwyth, Ceredigion SY23 3FD, UK² Department of Exercise and Sport Science, Manchester Metropolitan University, Hassall Road, Alsager ST7 2HL, UK

We hypothesized that the reduction of O₂-carrying capacity caused by the withdrawal of 450 ml blood would result in slower phase II O₂ uptake kinetics, a lower and a reduced time to exhaustion during severe-intensity cycle exercise. Eleven healthy subjects (mean ±S.D. age 23 ± 6 years, body mass 77.2 ± 11.0 kg) completed ‘step’ exercise tests from unloaded cycling to a severe-intensity work rate (80% of the difference between the predetermined gas exchange threshold and the ) on two occasions before, and 24 h following, the voluntary donation of 450 ml blood. Oxygen uptake was measured breath-by-breath, and kinetics estimated using non-linear regression techniques. The blood withdrawal resulted in a significant reduction in haemoglobin concentration (pre: 15.4 ± 0.9 versus post: 14.7 ± 1.3 g dl^–1; 95% confidence limits (CL): –0.04, –1.38) and haematocrit (pre: 44 ± 2 versus post: 41 ± 3%; 95% CL: –1.3, –5.1). Compared to the control condition, blood withdrawal resulted in significant reductions in (pre: 3.79 ± 0.64 versus post: 3.64 ± 0.61 l min^–1; 95% CL: –0.04, – 0.27) and time to exhaustion (pre: 375 ± 129 versus post: 321 ± 99 s; 95% CL: –24, –85). However, the kinetic parameters of the fundamental response, including the phase II time constant (pre: 29 ± 8 versus post: 30 ± 6 s; 95% CL: 5, –3), were not altered by blood withdrawal. The magnitude of the slow component was significantly reduced following blood donation owing to the lower attained. We conclude that a reduction in blood O₂-carrying capacity, achieved through the withdrawal of 450 ml blood, results in a significant reduction in and exercise tolerance but has no effect on the fundamental phase of the on-kinetics during severe-intensity exercise.

(Received 21 November 2005; accepted after revision 17 January 2006; first published online 23 January 2006)
Corresponding author A. M. Jones: School of Sport and Health Sciences, University of Exeter, St Luke's Campus, Exeter EX1 2LU, UK. Email: a.m.jones{at}exeter.ac.uk

This article has been cited by other articles:

				N. J. A. Berger, I. T. Campbell, D. P. Wilkerson, and A. M. Jones Influence of acute plasma volume expansion on VO2 kinetics, VO2peak, and performance during high-intensity cycle exercise J Appl Physiol, September 1, 2006; 101(3): 707 - 714. [Abstract] [Full Text] [PDF]