The objective of the study was to investigate whether there was any difference in training effects following a training period with or without oxygen supplementation in patients with chronic obstructive pulmonary disease (COPD). Twenty patients with moderate to severe COPD trained with or without supplemental oxygen. Two 6-min walking tests with different instructions, one standardized (6MWD) and one modified (they were stopped if they desaturated below 90%, the mod-6MWD) were performed before and after training. The Oxygen Group increased distance walked after training only in the 6MWD while the Air Group increased distance walked in both tests. The Oxygen Group showed larger increase in lactate levels and a tendency towards longer time of desaturation after compared with before training in the 6MWD. The Oxygen Group walked a longer distance and had higher lactate values after training in the 6MWD compared with the mod-6MWD.
The Oxygen Group showed signs of a larger extent of anaerobic metabolism during the 6MWD and was not able to work to the same extent in the mod-6MWD. Supplemental oxygen during physical training in patients with COPD should not yet be routinely applied.