Purpose: The aim of this study was to evaluate the effectiveness of inspiratory muscle training (IMT) on sleep and functional capacity to exercise in subjects with obstructive sleep apnea (OSA).
Methods: This is a controlled, randomized, double-blind study conducted in 16 OSA patients divided into two groups: training (IMT: n = 8) and placebo-IMT (P-IMT: n = 8). IMT was conducted during 12 weeks with a moderate load (50-60% of maximal inspiratory pressure-MIP), while P-IMT used a load < 20% of MPI. Total daily IMT time for both groups was 30 min, 7 days per week, twice a day.
Results: There was no difference comparing IMT to P-IMT group after training for lung function (p > 0.05) and respiratory muscle strength (p > 0.05). Maximal oxygen uptake (VO2Max) was not significantly different between IMT and P-IMT group (mean difference - 1.76, confidence interval (CI) - 7.93 to 4.41, p = 0.71). The same was observed for the other ventilatory and cardiometabolic variables measured (p > 0.05). A significant improvement in sleep quality was found when Pittsburgh Sleep Quality Index (PSQI) values of IMT and P-IMT group after training were compared (mean difference: 3.7, confidence interval 95% (CI95%) 0.6 to 6.9, p = 0.02) but no significant changes were seen in daytime sleepiness between both groups after the intervention (mean difference: 3.4, CI 95%: - 3.3 to 10.0; p = 0.29).
Conclusion: According to these results, 12 weeks of moderate load IMT resulted in improved sleep quality, but there were no significant repercussions on functional capacity to exercise or excessive daytime sleepiness.
Keywords: Functional capacity to exercise; Inspiratory muscle training; Obstructive sleep apnea; Sleep.