Oxygen supplementation is known to improve exercise capacity in patients with
chronic obstructive pulmonary disease (
COPD). Although some
COPD patients use
oxygen after exercise to relieve
dyspnea, the effect of
oxygen during recovery from exercise is not clearly understood. Exercise duration and
dyspnea recovery time were studied in 18 patients with stable
COPD. Patients exercised at a constant submaximal work rate on a treadmill ergometer until they no longer wished to continue.
Oxygen, room air and
compressed air were randomly administered in three consecutive post-exercise recovery periods.
Dyspnea was scored on a 100 mm visual analog scale at 30 s intervals until return to baseline. An additional 20 minute post-recovery resting period was allowed between each test. No significant differences were found in
dyspnea recovery time breathing
oxygen (271 s), room air (290 s) or
compressed air (311 s) When the groups were sorted by sequence of testing, there was a highly significant increase in recovery time (208 s, 307 s and 358 s for the first, second and third tests; P < 0.005) and a non-statistically significant decrease in exercise duration (89 s, 79 s and 76 s). Post-exercise
oxygen supplementation had no effect on
dyspnea recovery time in these
COPD patients. Repeated bouts of exercise increased
dyspnea recovery time and tended to decrease exercise duration. These findings suggest that, despite recovery of symptoms, physiological recovery from prior exercise is incomplete.