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Journal of Nutrition and Metabolism
Volume 2010 (2010), Article ID 905612, 13 pages
Review Article

Interaction among Skeletal Muscle Metabolic Energy Systems during Intense Exercise

1Health and Exercise Science Research Laboratory, School of Science, University of the West of Scotland, Hamilton Campus, Almada Street, Hamilton ML3 0JB, UK
2School of Human Movement Studies, Charles Sturt University, Bathurst, NSW 2795, Australia

Received 15 July 2010; Revised 5 October 2010; Accepted 7 October 2010

Academic Editor: Michael M. Müller

Copyright © 2010 Julien S. Baker et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


High-intensity exercise can result in up to a 1,000-fold increase in the rate of ATP demand compared to that at rest (Newsholme et al., 1983). To sustain muscle contraction, ATP needs to be regenerated at a rate complementary to ATP demand. Three energy systems function to replenish ATP in muscle: (1) Phosphagen, (2) Glycolytic, and (3) Mitochondrial Respiration. The three systems differ in the substrates used, products, maximal rate of ATP regeneration, capacity of ATP regeneration, and their associated contributions to fatigue. In this exercise context, fatigue is best defined as a decreasing force production during muscle contraction despite constant or increasing effort. The replenishment of ATP during intense exercise is the result of a coordinated metabolic response in which all energy systems contribute to different degrees based on an interaction between the intensity and duration of the exercise, and consequently the proportional contribution of the different skeletal muscle motor units. Such relative contributions also determine to a large extent the involvement of specific metabolic and central nervous system events that contribute to fatigue. The purpose of this paper is to provide a contemporary explanation of the muscle metabolic response to different exercise intensities and durations, with emphasis given to recent improvements in understanding and research methodology.