Airflow limitation and control of end-expiratory lung volume during exercise

To test the hypothesis that the presence of airflow limitation (AFL) influe nces the control of end-expiratory lung volume (EELV) during exerciser 11 s ubjects with normal lung function, performed submaximal exercise (SM) on a cycle ergometer, with and without AFL. AFL was achieved during exercise by increasing the density of the air via a hyperbaric chamber, compressed to a depth of 3 atm (3 ATA; with AFL). Five subjects achieved AFL during SM exe rcise at 3 ATA while the remaining six subjects did not achieve AFL. SM exe rcise was performed with the same apparatus in the hyperbaric chamber at se a level pressure with none of the subjects achieving AFL (SL; no-AFL). EELV (% of TLC, BTPS), was significantly larger during exercise at 3 ATA than d uring exercise at SL for the AFL group SL = 44 +/- 6%; 3 ATA-AFL = 51 +/- 9 %, P < 0.05; but, was not for the no-AFL group (SL = 46 +/- 6%; 3 ATA-no AF L = 46 +/- 7%). End inspiratory lung volume was significantly elevated duri ng exercise at 3 ATA compared with SL in the AFL group (SL = 80 +/- 6%; 3 A TA-AFL = 86 +/- 6%; P = 0.01) but not in the no-AFL group (SL=82 +/- 4%; 3 ATA-no AFL=84 +/- 3%). Tidal volume and ventilation were not different for any condition. These data suggest that the occurrence of AFL influences the control of EELV. (C) 2000 Elsevier Science B.V. All rights reserved.