Purpose: Exercise testing modalities to assess the effects of a given intervention should prove to be reliable and reproducible. This study reports on test-retest reproducibility of the 3-min shuttle walking and step testing exercise protocols to assess exertional dyspnea and exercise physiology in COPD patients. / Methods: Stable COPD patients (N=43; 65 +/- 6.5 years; FEV1 = 49 +/- 16% pred.) equipped with a portable Jaeger Oxycon MobileRTM metabolic system repeated the walking or stepping tests on two occasions separated by 7 to 14 days. At each visit, participants performed, in a randomized order, four externally paced 3-min bouts of shuttle walking at speeds of 1.5, 2.5, 4.0 and 6.0 km·h-1 or of stepping at a constant rate of 18, 22, 26 and 32 steps·min-1, respectively. Each exercise bout was separated by a 10-min rest period. Ventilation, heart rate, gas exchange parameters and Borg dyspnea score were obtained for each bout during the last 30-seconds of exercise. / Results: The majority of patients completed stepping or walking at the slowest cadence but only 33% completed walking at 6.0 km·h -1 and 40% completed stepping at 32 steps·min-1. Test-retest Pearson correlation coefficients for ventilation, heart rate, gas exchange parameters and dyspnea scores over the four exercise bouts, all exceeded 0.80 with the highest coefficient found for ventilation (r≥.95). Intra-class correlation coefficients were similar to Pearson. Bland & Altman representation showed that a similar proportion of dyspnea data points (92 vs. 96%) lied within 2 SD of the mean difference between test-retest values for dyspnea Borg scores during walking and stepping. / Conclusion: Results show very good reproducibility for both 3-min shuttle walking and stepping exercise protocols in patients with COPD. / This study was supported by an unrestricted grant from Boehringer-Ingelheim/Pfizer.

Rationale. There is a need for the development of a field test to evaluate exertional dyspnea in the primary care setting. This study examined the applicability of a 3-minute constant rate step test in patients with COPD. / Methods. This test involved 4 stepping rates (18, 22, 26, 32 steps.min-1) equivalent to approximately 4.5, 5.3, 6.0, and 7.2 MET with the ultimate goal that in its final development, the assessment will be made a single stepping rate based on disease severity. Stable COPD patients (N = 43; 65 +/- 6.5 years; FEV1 = 49 +/- 16% pred.; SpO2 (%) rest: 95 +/- 2) were equipped with a portable Jaeger Oxycon MobileRTM metabolic system and followed an audio signal for stepping up and down a single 20 cm step for 3 minutes. Borg dyspnea scores were obtained at the end each stepping bout. A 10-min rest was given between each stepping bout. / Results. Of the 43 patients, 80% completed stages 1 and 2, 74 and 37% stages 3 and 4 while no patient of MRC class 4 or 5 (N = 8) completed stage 1. Breathing frequency (breaths.min-1) spanned from 26.5 +/- 4.1 to 39.0 +/- 6.4 but VT (L) remained unchanged (1.4 +/- 0.3 vs. 1.5 +/- 0.4) from stage 1 to 4 while Borg scores were 3 +/- 1, 4 +/- 1, 5 +/- 2, 6 +/- 3 respectively and SpO2 (%) were 92 +/- 5, 91 +/- 4, 91 +/- 4 and 90 +/- 4. / Conclusions. Preliminary findings indicate that a 3-minute constant rate step test may present a feasible alternative to laboratory testing to assess exertional dyspnea in moderately severe COPD. In this population, a stepping rate of 26 steps.min-1 could be sustained by the majority of patients while producing a level of dyspnea potentially amenable to therapy. / This study was supported by an unrestricted grant from Boehringer-Ingelheim/Pfizer.

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