Oxygen cost of exercise hyperpnea: Implications for performance

E. A. Aaron, K. C. Seow, B. D. Johnson, J. A. Dempsey

Research output: Contribution to journalArticlepeer-review

249 Scopus citations


We addressed two questions concerned with the metabolic cost and performance of respiratory muscles in healthy young subjects during exercise: 1) does exercise hyperpnea ever attain a 'critical useful level'? and 2) is the work of breathing (Ẇ(v)) at maximum O2 uptake (V̇O(2 max)) fatiguing to the respiratory muscles? During progressive exercise to maximum, we measured tidal expiratory flow-volume and transpulmonary pressure- (Ptp) volume loops. At rest, subjects mimicked their maximum and moderate exercise Ptp-volume loops, and we measured the O2 cost of the hyperpnea (V̇O(2 RM)) and the length of time subjects could maintain reproduction of their maximum exercise loop. At maximum exercise, the O2 cost of ventilation (V̇E) averaged 10 ± 0.7% of the V̇O(2 max). In subjects who used most of their maximum reserve for expiratory flow and for inspiratory muscle pressure development during maximum exercise, the V̇O(2 RM) required 13-15% of V̇O(2 max). The O2 cost of increasing V̇E from one work rate to the next rose from 8% of the increase in total body V̇O2 (V̇O(2 T)) during moderate exercise to 39 ± 10% in the transition from heavy to maximum exercise; but in only one case of extreme hyperventilation, combined with a plateauing of the V̇O(2 T), did the increase in V̇O(2 RM) equal the increase in V̇O(2 T). All subjects were able to voluntarily mimic maximum exercise Ẇ(v) for 3-10 times longer than the duration of the maximum exercise. We conclude that the O2 cost of exercise hyperpnea is a significant fraction of the total V̇O(2 max) but is not sufficient to cause a critical level of 'useful' hyperpnea to be achieved in healthy subjects. The V̇E and Ẇ(v) during maximum exercise are nonfatiguing and sustainable.

Original languageEnglish (US)
Pages (from-to)1818-1825
Number of pages8
JournalJournal of applied physiology
Issue number5
StatePublished - 1992


  • 'useful' hyperpnea
  • exercise limitation
  • hyperventilation
  • respiratory muscle fatigue

ASJC Scopus subject areas

  • General Medicine


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