Am. J. Respir. Crit. Care Med., Volume 163, Number 5, April 2001, 1128-1134

Breathing He-O₂ Increases Ventilation but Does Not Decrease the Work of Breathing during Exercise

T. G. BABB

Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas; and University of Texas Southwestern Medical Center, Dallas, Texas

We previously observed an increase in minute ventilation ( E) with resistive unloading (He-O₂ breathing) in healthy elderly subjects with normal pulmonary function. To investigate the effects of resistive unloading in elderly subjects with mild chronic airflow limitation (FEV₁/FVC: 61 ± 4%), we studied 10 elderly men and women 70 ± 3 yr of age. These subjects performed graded cycle ergometry to exhaustion, once breathing room air and once breathing a He-O₂ gas mixture (79% He, 21% O₂). E, pulmonary mechanics, and PET_CO2 were measured during each 1-min increment in work rate. Data were analyzed by paired t test at rest, at ventilatory threshold (VTh), and during maximal exercise. E was significantly (p < 0.05) increased at VTh (3.4 ± 4.0 L/min or 12 ± 15% increase) and maximal exercise (15.2 ± 9.7 L/min or 22 ± 13% increase) while breathing He-O₂. Concomitant to the increase in E, PET_CO2 was decreased at all levels (p < 0.01), whereas total work of breathing against the lung was not different. We concluded that E is increased during He-O₂ breathing because of resistive unloading of the airways and the maintenance of the relationship between the work of breathing and exercise work rate.

This article has been cited by other articles:

				L Ansley, D Petersen, A Thomas, A St Clair Gibson, P Robson-Ansley, T D Noakes, and A M Hunter The effect of breathing an ambient low-density, hyperoxic gas on the perceived effort of breathing and maximal performance of exercise in well-trained athletes * Commentary Br. J. Sports Med., January 1, 2007; 41(1): 2 - 7. [Abstract] [Full Text] [PDF]

				E. A. Laude, N. C. Duffy, C. Baveystock, B. Dougill, M. J. Campbell, R. Lawson, P. W. Jones, and P. M. Calverley The Effect of Helium and Oxygen on Exercise Performance in Chronic Obstructive Pulmonary Disease: A Randomized Crossover Trial Am. J. Respir. Crit. Care Med., April 15, 2006; 173(8): 865 - 870. [Abstract] [Full Text] [PDF]

				C. Nourry, F. Deruelle, C. Fabre, G. Baquet, F. Bart, J.-M. Grosbois, S. Berthoin, and P. Mucci Exercise flow-volume loops in prepubescent aerobically trained children J Appl Physiol, November 1, 2005; 99(5): 1912 - 1921. [Abstract] [Full Text] [PDF]

				P. Palange, G. Valli, P. Onorati, R. Antonucci, P. Paoletti, A. Rosato, F. Manfredi, and P. Serra Effect of heliox on lung dynamic hyperinflation, dyspnea, and exercise endurance capacity in COPD patients J Appl Physiol, November 1, 2004; 97(5): 1637 - 1642. [Abstract] [Full Text] [PDF]

				K. N. Stark-Leyva, K. C. Beck, and B. D. Johnson Influence of expiratory loading and hyperinflation on cardiac output during exercise J Appl Physiol, May 1, 2004; 96(5): 1920 - 1927. [Abstract] [Full Text] [PDF]

				T. G. Babb, D. S. DeLorey, and B. L. Wyrick Ventilatory response to exercise in aged runners breathing He-O2 or inspired CO2 J Appl Physiol, February 1, 2003; 94(2): 685 - 693. [Abstract] [Full Text] [PDF]

				ATS/ACCP Statement on Cardiopulmonary Exercise Testing Am. J. Respir. Crit. Care Med., January 15, 2003; 167(2): 211 - 277. [Full Text] [PDF]

				M. J. TOBIN Chronic Obstructive Pulmonary Disease, Pollution, Pulmonary Vascular Disease, Transplantation, Pleural Disease, and Lung Cancer in AJRCCM 2001 Am. J. Respir. Crit. Care Med., March 1, 2002; 165(5): 642 - 662. [Full Text] [PDF]