• Anelise Bauer Munari, Isabela Julia Cristiana Santos Silva, Aline Almeida Gulart, Raysa Silva Venâncio, Suelen Roberta Klein, Júlia Zanotto, and MayerAnamaria FleigAFNúcleo de Assistência, Ensino e Pesquisa em Reabilitação Pulmonar, Universidade do Estado de Santa Catarina, Florianópolis, Santa Catarina, Brazil. anamaria.mayer@udesc.br.Programa de Pós-Graduação em Ciências do Movimento Humano, Cen.
• Núcleo de Assistência, Ensino e Pesquisa em Reabilitação Pulmonar, Universidade do Estado de Santa Catarina, Florianópolis, Santa Catarina, Brazil.
• Respir Care. 2021 Feb 1; 66 (2): 292299292-299.

BackgroundTest-retest reproducibility of the 6-min step test (6MST) is controversial in patients with COPD because the decision to perform a second test is influenced by interruptions, physiological overload, and the patient's exercise tolerance. The aim of this study was to analyze the reproducibility of performance on the 6MST (ie, number of steps climbed and interruptions) and physiological variables in subjects with COPD, with and without poor exercise tolerance, and with and without interruptions during the test.MethodsSubjects performed 2 6MST (6MST1, 6MST2) with a minimum of 30 min rest between tests. Physiological variables were assessed with a gas analyzer. Subjects who performed ≤ 78 steps in the 6MST1 and ≤ 86 steps in the test with the higher number of steps performed (6MSTBEST) were considered to have poor exercise tolerance. Subjects were also stratified according to those who interrupted the 6MSTBEST and those who did not interrupt the 6MSTBEST.Results40 subjects (31 men; FEV1 percent of predicted = 50.4 ± 13.5) participated in the study. The number of steps, interruptions, and physiological variables showed moderate to high reliability (intraclass correlation coefficient: 0.70-0.99, P < .001). Thirty-one (77.5%) subjects had a better performance during 6MST2 than 6MST1 (mean difference: 4.65 ± 5.59, P < .001). Although the number of times subjects were interrupted was similar between the 2 tests (P = .66), the duration of these interruptions was shorter during 6MST2 (mean difference: -0.12 ± 0.39 s, P = .040). The difference in the number of steps (6MST2 - 6MST1) did not differ between subjects who performed ≤78 steps (mean difference: 5.64 ± 5.32 steps; 10.3%; P < 0.001) and ≥ 79 steps (3.00 ± 5.82 steps; 6.13%; P = 0.08) on the 6MST1 (P = 0.15) and between subjects who performed ≤ 86 steps (5.39 ± 5.14 steps; 9.39%; P < 0.001) and ≥ 87 steps (2.92 ± 6.43 steps; 2.74%; P = 0.14) steps on the 6MSTBEST (P = 0.20).ConclusionsPerformance and physiological variables in the 6MST were reproducible, and a second test did not impose greater physiological overload. Two tests were essential for patients with poor exercise tolerance.Copyright © 2021 by Daedalus Enterprises.

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