Effects of respiratory muscle training (RMT) in patients with mild to moderate obstructive sleep apnea (OSA).
Different forms of training focusing on the muscles of the upper airways showed limited effects on obstructive sleep apnea (OSA) and/or snoring. We investigated the effect of generalized respiratory muscle training (RMT) in lean patients with mild to moderate OSA. Nine male subjects (52.0 ± 10.8 years, BMI 29.1 ± 2.1 kg/m2) with obstructive sleep apnea (apnea-hypopnea index (AHI) 9-29) participated in an open, single-arm pilot study. After a 1-week build-up phase, patients underwent 4 weeks of normocapnic hyperpnea RMT five times a week for 30 min each. The initial and final measurements comprised polysomnography, pulmonary function tests, Epworth sleepiness scale (ESS), and SF-36 questionnaire (quality of life (QoL) self-assessment). The investigational site was a university-affiliated hospital for pulmonary diseases and sleep medicine, Solingen/Germany. Patients trained effectively, seen by a significant (p < 0.01) increase of breathing frequency (23.3 ± 1.5 /min vs. 30.6 ± 2.9 /min) and minute volume (81.2 ± 13.7 L vs. 109.1 ± 21.9 L). AHI, snoring and ESS remained unchanged after training. QoL as measured by SF-36 significantly (p < 0.05) improved after the training in the subscales "bodily pain" (79 ± 21 vs. 90 ± 12) and "change of health" (3.1 ± 0.3 vs. 2.4 ± 0.5). There is no evidence that AHI, pulmonary function or daytime sleepiness are affected by 5 weeks of RMT. Nevertheless, there is an improvement of parameters of quality of life. ClinicalTrials.gov , register no. NCT 00936286.