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This Article Full Text Full Text (PDF) All Versions of this Article: 92/2/357    most recent expphysiol.2006.034371v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ward, S. A. Search for Related Content PubMed PubMed Citation Articles by Ward, S. A. Related Collections Symposia Papers

¹ Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, UK

Abstract

Below the lactate threshold (_L), ventilation responds in close proportion to CO₂ output to regulate arterial partial pressure of CO₂ . While ventilatory control models have traditionally included proportional feedback (central and carotid chemosensory) and feedforward (central and peripheral neurogenic) elements, the mechanisms involved remain unclear. Regardless, putative control schemes have to accommodate the close dynamic ‘coupling’ between and . Above _L, is driven down to constrain the fall of arterial pH by a compensatory hyperventilation, probably of carotid body origin. When requirements are high (as in highly fit endurance athletes), can attain limiting proportions. Not only does this impair gas exchange at these work rates, but there may be an associated high metabolic cost for generation of respiratory muscle power, which may be sufficient to divert a fraction of the cardiac output away from the muscles of locomotion to the respiratory muscles, further compromising exercise tolerance.

(Received 18 December 2006; accepted after revision 15 January 2007; first published online 18 January 2007)
Corresponding author S. A. Ward: Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, UK. Email: s.a.ward{at}leeds.ac.uk

This article has been cited by other articles:

				S. A. Ward Muscle-energetic and cardio-pulmonary determinants of exercise tolerance in humans: Muscle-energetic and cardio-pulmonary determinants of exercise tolerance in humans Exp Physiol, March 1, 2007; 92(2): 321 - 322. [Full Text] [PDF]