Respiratory Muscle Power And The Slow Component Of O2 Uptake

“The slow component of O2 uptake represents a progressive decline in work efficiency during strenuous, constant work rate cycling. Although most of this “excess” O2 uptake can be explained by factors intrinsic to the exercising muscles, it has been proposed that respiratory muscle work rate may also contribute to the O2 uptake response.”


“This investigation supports the thesis that the energetic contribution from respiratory muscles to the O2 uptake amplitude is disproportionately higher during severe-intensity exercise compared with that during heavy-intensity exercise.”

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Limitation to running performance – the role of respiratory work

Published in the Journal of Sports Science and Medicine this year was a study that looked into the occurrence of core muscle fatigue during high-intensity running exercise and its limitation to performance. Secondary to this was to discover if the work of the respiratory muscles contributed to this core muscle fatigue.

Key points from the study revealed:

  • A high-intensity maximum run may induce core muscle fatigue in runners. The core muscle fatigue, which may be partly attributed to the corresponding respiratory work, may limit their running endurance.
  • In support of previous notion, inspiratory muscles may share the work of core stabilization during intense exercise, while simultaneously increasing the demand for breathing.
  • Inspiratory muscle training incorporated into a running specific-core training regime potentially enhances the training effect on the core muscles in a functional manner to deal with the challenges faced during intense exercise.

Anatomically the inspiratory and expiratory muscles play a dual role in breathing and core stability during exercise but it wasn’t known if respiratory work during intense continuous running contributed to change in global core muscle function.

The major inspiratory muscle, the diaphragm, has been shown to be activated during non-respiratory activities including power lifting and bicep curls (Al-bilbeisi and McCool, 2000) but the interaction of core muscle and inspiratory muscle functions in core stabilization during intense continuous running has not yet been made clear.

So the purpose of the study below was to investigate:

  1. The occurrence of core muscle fatigue and its limitation to exercise performance during continuous high-intensity running to exhaustion
  2. Whether respiratory muscle work performed during intense running would contribute to the potential occurrence of core muscle fatigue. (The newly validated sport-specific endurance plank test was used for examining the changes in global core muscle function with fatigue.)


The Occurrence of Core Muscle Fatigue During High-Intensity Running Exercise and its Limitation to Performance: The Role of Respiratory Work
J Sports Sci Med. May 2014; 13(2): 244–251.
Tomas K. Tong, Shing Wu, Jinlei Nie, Julien S. Baker, Hua Lin


Following the experimental trials, the study demonstrated that intense running to exhaustion does induce core muscle fatigue in endurance runners and that it may be partly attributed to exercise-induced increase in respiratory work.

Also, evidence from this study of the dual role of respiratory work in breathing and core stabilization during intense running suggests that “inspiratory muscle training incorporated into a running specific-core training regime potentially enhances the effectiveness of the core training in a functional manner to deal with the challenge faced during intense exercise.”

Find more published research on our Inspiratory Muscle Training Research blog.