NCT02502942.

Study name	Effects of Upper Airway Muscle Training on Obstructive Sleep Apnea (OSA).
Methods	Parallel, RCT.
Participants	Inclusion criteria: 18 to 79 years old (adult, older Adult); prior diagnosis of OSA with AHI higher than 10 events/hour; PAP group: subjects who have been on PAP treatment for at least 3 months, with good compliance (at least 4 hours a day and use PAP for longer than 70% of the time). Untreated group: untreated subjects with generally mild OSA as defined by AHI lower than 20 events/hour and nadir SaO2 higher than 70%. Additionally, investigators will also recruit OSA subjects of all severities who have previously tried but are not currently using PAP. Oral appliance treatment group: subjects have residual AHI higher than 10 events/hour with oral appliance therapy. Exclusion Criteria: in those with untreated sleep apnoea, severe sleepiness with current ESS higher than 18 or history of motor vehicle accident due to obstructive sleep apnoea; taking medications classified as a muscle relaxant; pregnant women; psychiatric disorder, other than mild and controlled depression, e.g. schizophrenia, bipolar disorder, major depression, panic or anxiety disorders; current smokers, alcohol (higher than 3 oz/day) or use of illicit drugs. More than 10 cups of beverages with caffeine (coffee, tea, soda/pop) per day. Unstable cardiac disease (e.g. CHF). Pulmonary disease (apart from well‐controlled mild asthma and OSA). Systemic neuromuscular disease. Other systemic disease that affects breathing (e.g. stroke) or those with expected survival lower than 1 year. Poor oral condition, including: active periodontal disease, loose or broken teeth, lack of eight teeth in each arch, active TMJ dysfunction. Known allergy to oral appliance components.
Interventions	Intervention: Upper airway muscle exercise for six weeks. The exercises include 4 steps: step 1 is to put on an individualized fitted oral retainer device to guide the exercise; step 2 is to push the tongue towards the hard palate to press the movable part of the oral retainer device for 4 minutes; step 3 is to touch the hard palate using the middle part of the tongue, hold for 10 seconds and repeat it for 4 minutes; step 4 is to remove the retainer device and brush the tongue gently on both sides for 2 minute. The exercise will take 20 minutes a day (10 minutes in the morning and 10 minutes in the afternoon/evening). Comparator: Sham exercise.
Outcomes	Primary Outcome Measures: Apnea Hypopnea Index. Secondary Outcome Measures: Daytime sleepiness (ESS). Sleep quality (PSQI). Subjective quality of life (SF‐36). Neurocognitive function (PVT). Upper airway anatomy (acoustic pharyngostomy). Tongue strength and endurance (IOPI). Measurements: 6 weeks after treatment.
Starting date	Study Start Date: August 2015. Actual Study Completion Date: 24 June 2019
Contact information	Atul Malhotra, MD. University of California, San Diego.
Notes	Information from ClinicalTrials.gov.