Abstract
PURPOSE: Exercise training in patients with chronic obstructive pulmonary disease (COPD) can be challenging because whole-body exercise often elicits disabling symptoms of dyspnea before the exercising muscles reach their critical limits. The extent that this factor limits training has not been totally defined. The purpose of this study was to compare the response to training of patients with moderate to severe COPD with that achieved by healthy elderly subjects who were exercising using an identical program.
METHODS: Eight healthy subjects and 20 patients with COPD (forced expiratory volume in 1 second 42 +/- 13% predicted) exercised 3 times a week for 8 weeks. Outcome measures included 6-minute walk distance, maximal exercise capacity (Wmax) during an incremental cycle ergometer test, and submaximal constant workload (60%-70% of subject Wmax) exercise time.
RESULTS: Six-minute walk distance and Wmax increased after training to a significantly greater extent in the healthy controls compared with the patients with COPD; 65 +/- 24 versus 32 +/- 50 m, P = .03; and 25.1+/-13.9 versus 11.5+/-13.1 watts, P = .025, respectively. However, these differences disappeared when data were expressed as percent improvement, 12.1 +/- 5.3% versus 10.0 +/- 15.8%, and 25.6 +/- 13.5% versus 23.1 +/- 33.3%. Improvement in submaximal constant workload exercise time after training was similar in healthy controls 21.6 +/- 6.1 versus patients with COPD 18.8 +/- 11.2 minutes.
CONCLUSIONS: Patients with COPD can show similar relative improvements in exercise capacity compared with healthy elderly subjects. The difference in absolute values reflects, at least in part, the greater baseline exercise capacity.