Clinical safety and hemodynamic, cardiac autonomic and inflammatory responses to a single session of inspiratory muscle training in obstructive sleep apnea.

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.

Construct validity and reproducibility of the six-minute step test in subjects with obstructive sleep apnea treated with continuous positive airway pressure.

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.

Construct validity and reproducibility of the six-minute step test in subjects with obstructive sleep apnea treated with continuous positive airway pressure / Validação de constructo e reprodutibilidade do teste de degrau de seis minutos em indivíduos com apneia obstrutiva do sono tratados com pressão positiva contínua nas vias aéreas

ABSTRACT 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.

RESUMO Objetivo: Avaliar a validade do constructo e a reprodutibilidade do teste de degrau de seis minutos (TD6) em indivíduos com apneia obstrutiva do sono (AOS) tratados com continuous positive airway pressure (CPAP, pressão positiva contínua nas vias aéreas). Métodos: Foram avaliados 48 voluntários com diagnóstico de AOS e tratados com CPAP há, no mínimo, dois meses. Os voluntários foram submetidos ao teste de caminhada de seis minutos (TC6) e ao TD6, em ordem aleatória e em dias diferentes, com um intervalo de, no máximo, sete dias entre os dois testes. Resultados: Foi observada uma correlação positiva moderada entre a distância percorrida no TC6 e o número de subidas no TD6, (r = 0,520; p < 0,001). Não foram encontradas diferenças significativas no número de subidas entre os dois TD6 (121,7 ± 27,1 vs. 123,6 ± 26,7 degraus). A reprodutibilidade para o desempenho no TD6 e para as variáveis cardiovasculares foi considerada excelente (coeficiente de correlação intraclasse > 0,8). Com relação às respostas cardiovasculares, quando comparado ao TC6, o TD6 apresentou maiores valores em relação a FC no sexto minuto, percentual do predito da FC máxima, fadiga de membros inferiores no sexto minuto e pressão arterial sistólica no sexto minuto e no primeiro minuto da fase de recuperação. Conclusões: O TD6 é válido, reprodutível e causa maior estresse cardiovascular quando comparado ao TC6. No entanto, o TD6 também se caracteriza como um teste submáximo para a avaliação da tolerância ao esforço em indivíduos com AOS tratados com CPAP.