Accounting for flow dependence of respiratory resistance during exercise.
Studies of airway function during exercise have produced conflicting results both in healthy and diseased subjects. Respiratory resistance (Rrs) was measured using an impulse oscillation technique. A flow/resistance curve was established for each of 16 healthy males during voluntary hyperventilation (VHV) at rest. Then, Rrs and flow were measured immediately (t(0)) and 90 sec (t(90)) after exercise on a cycle ergometer at 60, 70, and 80% of maximal aerobic power. The flow/resistance relationship at rest during VHV was used to assess the flow dependence of Rrs. Rrs at t(0) was higher than at rest (P <0.01) but lower than Rrs obtained at matched flow during VHV (P <0.05). In healthy subjects, the linear increase in Rrs with VHV indicates airflow dependency of Rrs following Rohrer's equation. The relative decrease in Rrs with exercise suggests bronchodilation. The bronchodilating effect disappeared promptly when exercise was stopped suggesting that it may have been related to a reflex mechanism.
de Bisschop
Claire
C
Laboratoire d'Analyse de la Performance Motrice Humaine, Faculté des Sciences du Sport, UPRES EA 2253, 4 allée Jean Monnet, 86000 Poitiers, France. claire.de-bisschop@mshs.univ-poitiers.fr
Pichon
Aurélien
A
Guénard
Hervé
H
Denjean
André
A
D000328:Adult; D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology*; D035641:Chest Wall Oscillation / Q000379:methods; D004305:Dose-Response Relationship, Drug; D015444:Exercise / Q000502:physiology*; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology; D008297:Male; D008449:Maximal Expiratory Flow-Volume Curves; D016210:Methacholine Chloride / Q000494:pharmacology; D018721:Muscarinic Agonists / Q000494:pharmacology; D012123:Pulmonary Ventilation / Q000187:drug effects / Q000502:physiology*; D012146:Rest / Q000502:physiology; D013997:Time Factors
D018721:Muscarinic Agonists; D016210:Methacholine Chloride