Ventilatory work and oxygen consumption during exercise and hyperventilation

Richard J Coast, S. A. Rasmussen, K. M. Krause, J. A. O'Kroy, R. A. Loy, J. Rhodes

Research output: Contribution to journalArticle

73 Citations (Scopus)

Abstract

The work of breathing (W(B)), and thus the energy requirement of the respiratory muscles, is increased any time minute ventilation (V̇E) is elevated, by either exercise or voluntary hyperventilation. Respiratory muscle O2 consumption (V̇RM(O2)) in humans has generally been estimated by having subjects breathe at a level comparable to that during exercise while the change in O2 consumption (V̇O2) is measured. The difference between V̇O2 at rest and during hyperventilation is attributed to the respiratory muscles and is assumed to be similar to V̇RM(O2) during exercise at the same V̇E. However, it has been suggested that W(B) differs between exercise and hyperventilation and that W(B) during exercise is lower than during hyperventilation at the same V̇E. In this study we measured W(B) during exercise and hyperventilation and from these measurements estimated V̇RM(O2). W(B), V̇E, and V̇O2 were measured in five male subjects during rest and during exercise or hyperventilation at levels of V̇E ranging from 30 to 130 l/min. V̇E/W(B) relationship was determined for both hyperventilation and exercise. Multiple regression analysis showed that the shape of the two curves was different (P < 0.0001), with W(B) at high levels of V̇E being ≤25% higher in hyperventilation than in exercise. In a second study in which frequency, tidal volume, and duty cycle were controlled as well as V̇E, there was no difference in W(B) between exercise and hyperventilation. V̇O2 was significantly correlated with W(B), and the estimated V̇RM(O2) did not increase as a fraction of total V̇O2 as exercise intensity rose. From these results we suggest that when carefully controlled for both pattern and V̇E, hyperventilation can be used to mimic exercise and to estimate the metabolic cost of breathing. However, if only V̇E is controlled, it is necessary to measure W(B) to estimate the energy used by the respiratory muscles.

Original languageEnglish (US)
Pages (from-to)793-798
Number of pages6
JournalJournal of Applied Physiology
Volume74
Issue number2
StatePublished - 1993
Externally publishedYes

Fingerprint

Work of Breathing
Hyperventilation
Oxygen Consumption
Ventilation
Respiratory Muscles
Breathing Exercises
Tidal Volume
Respiration
Regression Analysis

Keywords

  • energetics
  • work of breathing

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Coast, R. J., Rasmussen, S. A., Krause, K. M., O'Kroy, J. A., Loy, R. A., & Rhodes, J. (1993). Ventilatory work and oxygen consumption during exercise and hyperventilation. Journal of Applied Physiology, 74(2), 793-798.

Ventilatory work and oxygen consumption during exercise and hyperventilation. / Coast, Richard J; Rasmussen, S. A.; Krause, K. M.; O'Kroy, J. A.; Loy, R. A.; Rhodes, J.

In: Journal of Applied Physiology, Vol. 74, No. 2, 1993, p. 793-798.

Research output: Contribution to journalArticle

Coast, RJ, Rasmussen, SA, Krause, KM, O'Kroy, JA, Loy, RA & Rhodes, J 1993, 'Ventilatory work and oxygen consumption during exercise and hyperventilation', Journal of Applied Physiology, vol. 74, no. 2, pp. 793-798.
Coast RJ, Rasmussen SA, Krause KM, O'Kroy JA, Loy RA, Rhodes J. Ventilatory work and oxygen consumption during exercise and hyperventilation. Journal of Applied Physiology. 1993;74(2):793-798.
Coast, Richard J ; Rasmussen, S. A. ; Krause, K. M. ; O'Kroy, J. A. ; Loy, R. A. ; Rhodes, J. / Ventilatory work and oxygen consumption during exercise and hyperventilation. In: Journal of Applied Physiology. 1993 ; Vol. 74, No. 2. pp. 793-798.
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