The oxygen cost of breathing in man: effects of altitude, training, and race.

Abstract

AbstractThe oxygen cost of breathing was determined by an open‐circuit method with voluntary hyperventilation over a wide range of volumes. In 11 lowland residents the oxygen cost (ml/1 STPD) of extra ventilation (BTPS) was 3.3 ml/1 at sea level and 2.1 ml/1 after 16 days at 4000 m; the corresponding cost for ventilation STPD was 4.2 ml/1 at altitude and 4.1 ml/1 at sea level. In acclimatized persons at altitude, including both native Indian and European residents, the cost of breathing varied from 2.5 to 3.7 ml/1. On the average, the cost of breathing for acclimatized subjects was 3.1 ml/1 (BTPS), only slightly lower (5 to 10%) than that for lowlanders at sea level. This relatively higher cost with acclimatization, though still lower than at sea level, may reflect pulmonary congestion concomitant with altitude sojourn. Group differences in the cost of breathing could not be ascribed to athletic training, racial background, or permanent altitude residence, nor was there a difference of cost during quiet seated hyperventilation versus cost during free wheel bicycle pedalling. Individual, group, altitude, and acclimatizational differences in the cost of breathing could affect oxygen intake at rest and work, as well as the regulation of ventilation.