HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 93/4/468    most recent expphysiol.2007.041897v1 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 Google Scholar Articles by Jones, A. M. Articles by Wilkerson, D. P. PubMed PubMed Citation Articles by Jones, A. M. Articles by Wilkerson, D. P.

¹ School of Sport and Health Sciences, St Luke's Campus, University of Exeter, Heavitree Road, Exeter EX1 2LU, UK

³¹Phosphate-magnetic resonance spectroscopy and near infrared spectroscopy (NIRS) were used for the simultaneous assessment of changes in quadriceps muscle metabolism and oxygenation during consecutive bouts of high-intensity exercise. Six male subjects completed two 6 min bouts of single-legged knee-extension exercise at 80% of the peak work rate separated by 6 min of rest while positioned inside the bore of a 1.5 T superconducting magnet. The total haemoglobin and oxyhaemoglobin concentrations in the area of the quadriceps muscle interrogated with NIRS were significantly higher in the baseline period prior to the second compared with the first exercise bout, consistent with an enhanced muscle oxygenation. Intramuscular phosphorylcreatine concentration ([PCr]) dynamics were not different over the fundamental region of the response (time constant for bout 1, 51 ± 15 s versus bout 2, 52 ± 17 s). However, the [PCr] dynamics over the entire response were faster in the second bout (mean response time for bout 1, 72 ± 16 s versus bout 2, 57 ± 8 s; P < 0.05), as a consequence of a greater fall in [PCr] in the fundamental phase and a reduction in the magnitude of the ‘slow component’ in [PCr] beyond 3 min of exercise (bout 1, 10 ± 6% versus bout 2, 5 ± 3%; P < 0.05). These data suggest that the increased muscle O₂ availability afforded by the performance of a prior bout of high-intensity exercise does not significantly alter the kinetics of [PCr] hydrolysis at the onset of a subsequent bout of high-intensity exercise. The greater fall in [PCr] over the fundamental phase of the response following prior high-intensity exercise indicates that residual fatigue acutely reduces muscle efficiency.

(Received 20 December 2007; accepted after revision 25 January 2008; first published online 1 February 2008)
Corresponding author A. M. Jones: School of Sport and Health Sciences, St Luke's Campus, University of Exeter, Heavitree Road, Exeter EX1 2LU, UK. Email: a.m.jones{at}exeter.ac.uk

This article has been cited by other articles:

				F. J. DiMenna, D. P. Wilkerson, M. Burnley, and A. M. Jones Influence of priming exercise on pulmonary O2 uptake kinetics during transitions to high-intensity exercise from an elevated baseline J Appl Physiol, August 1, 2008; 105(2): 538 - 546. [Abstract] [Full Text] [PDF]