Effects of Upper Airway Muscle Training on OSA

Obstructive sleep apnea (OSA) is a common disorder characterized by recurrent collapse of the upper airway during sleep, which leads to recurrent arousal and subsequent daytime sleepiness. The most commonly accepted reason for the initiation of obstructive respiratory events in OSA is that patients have a small upper airway that is kept patent during wakefulness by a compensatory increase in upper airway dilator muscle (e.g. genioglossus) activity. At sleep onset this compensation is reduced or lost, resulting in upper airway narrowing or collapse. Upper airway (UA) muscle training appears to have some benefit in OSA with improvement in the AHI, although the current data shows variable results, particularly when publication bias is taken into account. Many remain skeptical about these data based on clinical experience and prior negative studies (which remain largely unpublished). Moreover, previous positive studies involved exercises that are usually impractical to be continued in the long-term. Therefore, investigators will undertake a rigorous assessment of a practical UA muscle training on OSA. Investigators will recruit patients with OSA that are wither unable/unwilling to use CPAP, as well as those who are already on treatment with PAP or oral appliances. 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). Investigators will study the effect of upper airway (UA) muscle training on OSA severity, muscle strengh and endurance. Investigators aim to determine the characteristics of OSA patients most likely to benefit from UA muscle training and the association between changes in muscle function and OSA severity.