Influence of endurance training on muscle [PCr] kinetics during high-intensity exercise

Am J Physiol Regul Integr Comp Physiol. 2007 Jul;293(1):R392-401. doi: 10.1152/ajpregu.00056.2007. Epub 2007 May 2.

Abstract

We hypothesized that a period of endurance training would result in a speeding of muscle phosphocreatine concentration ([PCr]) kinetics over the fundamental phase of the response and a reduction in the amplitude of the [PCr] slow component during high-intensity exercise. Six male subjects (age 26 +/- 5 yr) completed 5 wk of single-legged knee-extension exercise training with the alternate leg serving as a control. Before and after the intervention period, the subjects completed incremental and high-intensity step exercise tests of 6-min duration with both legs separately inside the bore of a whole-body magnetic resonance spectrometer. The time-to-exhaustion during incremental exercise was not changed in the control leg [preintervention group (PRE): 19.4 +/- 2.3 min vs. postintervention group (POST): 19.4 +/- 1.9 min] but was significantly increased in the trained leg (PRE: 19.6 +/- 1.6 min vs. POST: 22.0 +/- 2.2 min; P < 0.05). During step exercise, there were no significant changes in the control leg, but end-exercise pH and [PCr] were higher after vs. before training. The time constant for the [PCr] kinetics over the fundamental exponential region of the response was not significantly altered in either the control leg (PRE: 40 +/- 13 s vs. POST: 43 +/- 10 s) or the trained leg (PRE: 38 +/- 8 s vs. POST: 40 +/- 12 s). However, the amplitude of the [PCr] slow component was significantly reduced in the trained leg (PRE: 15 +/- 7 vs. POST: 7 +/- 7% change in [PCr]; P < 0.05) with there being no change in the control leg (PRE: 13 +/- 8 vs. POST: 12 +/- 10% change in [PCr]). The attenuation of the [PCr] slow component might be mechanistically linked with enhanced exercise tolerance following endurance training.

MeSH terms

  • Adult
  • Algorithms
  • Bicycling
  • Ergometry
  • Exercise / physiology*
  • Humans
  • Hydrogen-Ion Concentration
  • Kinetics
  • Magnetic Resonance Spectroscopy
  • Male
  • Models, Statistical
  • Muscle, Skeletal / chemistry
  • Muscle, Skeletal / metabolism*
  • Phosphocreatine / metabolism*
  • Physical Endurance / physiology*
  • Physical Fitness / physiology*

Substances

  • Phosphocreatine