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Ventilatory control in humans: constraints and limitations
Author(s) -
Ward Susan A.
Publication year - 2007
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.2006.034371
Subject(s) - hyperventilation , limiting , respiration , ventilation (architecture) , control of respiration , respiratory system , peripheral , cardiology , feed forward , carotid body , medicine , physical medicine and rehabilitation , anesthesia , anatomy , physics , carotid arteries , control engineering , engineering , thermodynamics , mechanical engineering
Below the lactate threshold (θ L ), ventilation responds in close proportion to CO 2 output to regulate arterial partial pressure of CO 2 . 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 θ 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.