Objective: To evaluate the construct validity and reproducibility of the six-minute step test (6MST) in individuals with obstructive sleep apnea (OSA) treated with continuous positive airway pressure (CPAP). Methods: We evaluated 48 volunteers diagnosed with OSA and treated with CPAP for at least two months. The volunteers underwent the six-minute walk test (6MWT) and the 6MST, in random order and on different days, with an interval of, at most, seven days between the two tests. Results: A moderate positive correlation was found between the distance walked on the 6MWT and the number of steps climbed on the 6MST (r = 0.520; p < 0.001). There was no significant difference between the two 6MSTs in terms of the number of steps climbed (121.7 ± 27.1 vs. 123.6 ± 26.7). Reproducibility for performance on the 6MST and for cardiovascular variables was considered excellent (intraclass correlation coefficient > 0.8). Regarding cardiovascular responses, the 6MST produced higher values than did the 6MWT for HR at six minutes, percent predicted maximum HR, and leg fatigue at six minutes, as well as for systolic blood pressure at six minutes and at one minute of recovery. Conclusions: The 6MST is valid and reproducible, producing greater cardiovascular stress than does the 6MWT. However, the 6MST is also characterized as a submaximal test for the assessment of exercise tolerance in individuals with OSA treated with CPAP.

Purpose To determine clinical safety and cardiovascular, cardiac autonomic and inflammatory responses to a single session of inspiratory muscle training (IMT) in obstructive sleep apnea (OSA) subjects. Methods In a randomized controlled trial individuals of both sexes, aged between 30 and 70 years old with diagnosis of moderate to severe OSA were enrolled. Volunteers with OSA (n = 40) performed an IMT session with three sets of 30 repetitions with a 1-min interval between them. The IMT group (n = 20) used a load of 70% of the maximum inspiratory pressure (MIP), and the placebo group (n = 20) performed the IMT without load. Measurements of systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), heart rate variability (HRV), and inflammatory markers were performed pre, post-immediate and 1 h after the IMT session. Results No differences were shown in SBP, DBP, HRV, or inflammatory markers at any of the intervals analyzed. However, HR in the IMT group was lower 1 h after the IMT session compared to the pre-session values (p = 0002). HR was higher in the placebo group when comparing pre × post-immediate (p < 0.001). HR decreased after the first hour in relation to the pre (p < 0.001) and post-immediate (p < 0.001) values. Conclusion IMT sessions promote discreet hemodynamic, cardiac autonomic and inflammatory responses. Therefore, IMT is considered clinically safe and can be performed at home, guided but unsupervised, with lower cost and greater adherence to exercise program for subjects with OSA.

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Objetivo: Validar o teste de degrau de seis minutos (TD6M) e avaliar sua reprodutibilidade para determinação da tolerância ao esforço em crianças saudáveis de 7-11 anos. Métodos: Foram incluídas na pesquisa 66 crianças saudáveis, com idade entre 7 e 11 anos completos. Os voluntários foram submetidos ao teste de caminhada de seis minutos (TC6M) e ao TD6M, em ordem aleatória e dias diferentes, com intervalo de no máximo sete dias. Resultados: Foi observada uma correlação positiva moderada entre a distância percorrida no TC6M e o número de subidas no TD6M (r=0,43; p<0,001). A reprodutibilidade das variáveis no TD6M foi considerada excelente em relação às variáveis desempenho (número de degraus) (r=0,92; IC=0,87 a 0,87; p<0,001), pressão arterial sistólica (PAS) imediatamente após (r=0,87; IC=0,79 a 0,92; p<0,001), PAS-1’recuperação (r=0,84; IC=0,74 a 0,90; p<0,001), frequência cardíaca (FC) máxima (r=0,90; IC=0,83 a 0,94; p<0,001), FC-imediatamente após (r=0,88; IC=0,81 a 0,93; p<0,001) e Fadiga de membros inferiores (MMII)-durante o teste (3o min) (0,86; IC=0,78 a 0,92; p<0,001). Apresentaram também uma reprodutibilidade muito boa a PAS-repouso (r=0,75; IC=0,59 a 0,84; p<0,001), PAS-5’recuperação (r=0,78; IC=0,56 a 0,83; p<0,001), PAD-repouso (r=0,74; IC=0,58 a 0,84; p<0,001), pressão arterial diastólica (PAD) imediatamente após (r=0,72; IC=0,55 a 0,83; p<0,001), PAD-1’recuperação (r=0,77; IC=0,63 a 0,86; p<0,001), PAD-5’recuperação (r=0,73; IC=0,56 a 0,83; p<0,001), FC-repouso (r=0,73; IC=0,60 a 0,86; p<0,001), Fadiga de MMII-imediatamente após (r=0,72; IC=0,54 a 0,83; p<0,001). Conclusão: O TD6M é seguro, válido e com boa reprodutibilidade intra-avaliador na avaliação da tolerância ao esforço em crianças saudáveis entre 7-11 anos.

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