The Responsiveness of Exercise Tests in COPD

<h4>Background</h4>COPD is characterized by reduced exercise tolerance, and improving physical performance is an important therapeutic goal. A variety of exercise tests commonly are used to assess exercise tolerance, including laboratory and field-based tests. The responsiveness of these tests to common COPD interventions is yet to be compared, but the results may inform test selection in clinical and research settings.<h4>Research question</h4>What exercise test possesses the greatest sensitivity to change from before to after intervention in patients with COPD?<h4>Study design and methods</h4>One hundred fifty-four patients with symptomatic COPD were recruited and randomized (2:1:1) to 6 weeks of long-acting muscarinic antagonist (LAMA), pulmonary rehabilitation (PR), or usual care. Before and after intervention, participants performed a ramp-incremental cycle exercise test (ICET) and constant work rate cycle test (CWRCT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT), 6-min walk test (6MWT), and 4-m gait speed test.<h4>Results</h4>One hundred three participants (mean ± SD age, 67 ± 8 years; 75 male participants [73%]; FEV<sub>1</sub>, 50.6 ± 16.8% predicted) completed the study. Significant improvements in the ICET, CWRCT, ISWT, ESWT, and 6MWT results were observed after PR (P < .05), with the greatest improvements seen in the constant work rate protocols (percentages change: CWRCT, 42%; ESWT, 41%).<h4>Interpretation</h4>The ESWT and CWRCT seemed to be the most responsive exercise test protocols to LAMA and PR therapy. The magnitude of change was much greater after a program of rehabilitation compared with bronchodilator therapy.<h4>Trial registry</h4>ISRCTN; No. 64759523.