Relationship Between Dyspnea and Oxygen Consumption among COPD Patients after Exercise Training

Abstract

1455 Purpose: The purpose of this study was to examine the relationship between dyspnea ratings and oxygen consumption (VO2) before and after three months of exercise training in patients with mild and moderate chronic obstructive pulmonary disease (COPD). Methods: Maximal graded exercise tests were performed by 99 COPD patients (14 mild, 85 moderate) before and after three months of exercise training. Dyspnea was recorded every minute of the exercise test and VO2 was measured using expired gases and reported as a percent of VO2peak. Individual regression equations were developed to predict dyspnea from VO2 prior to and following exercise training. Twoway ANOVA was used to compare slopes and intercepts between mild and moderate COPD patients before and after training. Results: Slopes of the regression lines were significantly different for moderate COPD patients between 0 and 3 months (0.14 ± 0.10 vs. 0.10 ± 0.05, p = 0.001). Intercepts of the regression lines were also significantly different for moderate COPD patients between 0 and 3 months (−6.83 ± 6.55 vs −4.39 ± 4.22, p = 0.017). However, in mild COPD patients, no significant changes were seen from 0 to 3 months in slopes (0.11 ± 0.03 vs. 0.10 ± 0.03, p = 0.256) or intercepts (−4.76 ± 2.14 vs −4.24 ± 2.30, p = 0.545). Conclusion: Following exercise training, moderate COPD patients reported a lower slope and greater intercept in the regression equation predicting dyspnea from VO2. These results suggest that exercise training allows patients with moderate COPD to perform physical activity at a given level of VO2 with less dyspnea.