BACKGROUND: COPD is characterized by reduced exercise tolerance, and improving physical performance is an important therapeutic goal. A variety of exercise tests are commonly used to assess exercise tolerance, including laboratory and field-based tests. The responsiveness of these various tests to common COPD interventions is yet to be compared, but the results may inform test selection in clinical and research settings. RESEARCH QUESTION: What exercise test possesses the greatest sensitivity to change from before to after intervention in patients with COPD? STUDY DESIGN AND METHODS: One hundred fifty-four patients with symptomatic COPD were recruited and randomized (2:1:1) to 6 weeks of long-acting muscarinic antagonist, pulmonary rehabilitation (PR), or usual care. Before and after intervention, participants performed an incremental cycle exercise test and constant work rate cycle test (CWRCT), incremental shuttle walk test and endurance shuttle walk test (ESWT), 6-min walk test, and 4-m gait speed test. RESULTS: One hundred three participants (mean +/- SD age, 67 +/- 8 years; 75 male participants (73%); FEV1, 50.6 +/- 16.8% predicted) completed the study. Significant improvements in the incremental cycle exercise test, CWRCT, incremental cycle exercise test, ESWT, and 6-min walk test results were observed after PR (p < 0.05), with the greatest improvements seen in the constant work rate protocols (percentages change: CWRCT 42%; ESWT 41%). INTERPRETATION: The ESWT and CWRCT seemed to be the most responsive exercise test protocols to long-acting muscarinic antagonist and PR therapy. The magnitude of change was much greater after a program of rehabilitation compared with bronchodilator therapy. CLINICAL TRIAL REGISTRY: International Standard Randomised Controlled Trial Number (ISRCTN): No. 64759523; URL: https://www.isrctn.com/ISRCTN64759523.

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