Comparison of dyspnea ratings during submaximal constant work exercise with incremental testing

PURPOSE: The purpose of this study was to determine whether dyspnea ratings would be similar during submaximal (as used for training) and incremental (as used in testing) exercise at specific intensities in patients with chronic obstructive pulmonary disease (COPD). METHODS: We studied 20 patients with COPD. Age was 66 +/- 9 yr (mean +/- SD); FEV1 was 43 +/- 14% pred. At Visit 1 patients provided dyspnea ratings (0 to 10 scale) each minute during incremental exercise on the cycle ergometer. At Visit 2 patients rated dyspnea during production of submaximal exercise for 10 min at two intensities. RESULTS: Peak oxygen consumption (VO2) was 13.9 +/- 3.2 mL.kg-1.min-1. At visit 2 VO2 was stable, but dyspnea ratings increased slightly. Dyspnea ratings (2.0 +/- 1.2) during submaximal exercise were higher than during incremental exercise (1.1 +/- 0.7) at 55 +/- 8% of peak VO2 (P = 0.02) but were similar (4.3 +/- 1.5 vs 3.9 +/- 1.5) at 77 +/- 8% of peak VO2 (P = 0.40). CONCLUSIONS: In patients with COPD, dyspnea ratings were similar during steady state compared with equivalent levels of incremental exercise at a "high" intensity, but were slightly higher at the "low" exercise intensity. These data support the potential use of dyspnea ratings obtained during incremental exercise as a target for exercise training in patients with respiratory disease.