Respiratory effort sensation during exercise with induced expiratory-flow limitation in healthy humans.
Nine healthy subjects (age 31 +/- 4 yr) exercised with and without expiratory-flow limitation (maximal flow approximately 1 l/s). We monitored flow, end-tidal PCO2, esophageal (Pes) and gastric pressures, changes in end-expiratory lung volume, and perception (sensation) of difficulty in breathing. Subjects cycled at increasing intensity (+25 W/30 s) until symptom limitation. During the flow-limited run, exercise performance was limited in all subjects by maximum sensation. Sensation was equally determined by inspiratory and expiratory pressure changes. In both runs, 90% of the variance in sensation could be explained by the Pes swings (difference between peak inspiratory and peak expiratory Pes). End-tidal PCO2 did not explain any variance in sensation in the control run and added only 3% to the explained variance in the flow-limited run. We conclude that in healthy subjects, during normal as well as expiratory flow-limited exercise, the pleural pressure generation of the expiratory muscles is equally related to the perception of difficulty in breathing as that of the inspiratory muscles.
Kayser
B
B
Meakins-Christie Laboratories, McGill University Clinics, Montreal, Quebec, Canada H2X 2P2. bengt.kayser@medicine.unige.ch
Sliwinski
P
P
Yan
S
S
Tobiasz
M
M
Macklem
P T
PT
D000328:Adult; D002245:Carbon Dioxide / Q000097:blood; D003964:Diaphragm / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008954:Models, Biological; D012044:Regression Analysis; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics / Q000502:physiology*; D012132:Respiratory Muscles / Q000502:physiology
D002245:Carbon Dioxide