Low-density gas breathing during exercise in chronic obstructive lung disease.

Because breathing low-density helium-oxygen gas mixture has been reported as improving ventilatory mechanics in chronic obstructive pulmonary disease (COPD) patients and reducing the oxygen cost of ventilation in exercising normal subjects, it might prove useful in COPD physical conditioning programs. 7 COPD patients performed incremental exercise to tolerance while breathing either air on 79% helium-21% oxygen mixture. There was a tendency for low-density gas breathing to stimulate a higher ventilation at any given work load. As a result there was a tendency to greater tolerance with air breathing. Throughout exercise there was no statistically significant difference in endurance, oxygen consumption, heart rate, or ventilatory parameters suggesting that the helium-oxygen mixture was not beneficial to exercise performance.