Table 4.

Interventions in treatment and control groups.

Study	Intervention Therapy	Details	Duration	Frequency	Control Therapy
Diaferia et al, 201325	Myofunctional therapy	Exercises of localized muscle resistance in the oropharyngeal area (soft palate, pharyngeal constrictor muscles, suprahyoid muscles, tip and root of the tongue, cheeks, and lips)	3 mo	20 minutes, 3 times per day. Exercise daily diary (new exercises every week)	Sham speech/myofunctional therapy (head movements without any therapeutic function)
Diaferia et al, 201722	Myofunctional therapy	a. Soft palate exercises	3 mo	a. 3 minutes, 3 times per day	Sham speech/myofunctional therapy (head movements without any therapeutic function)
		b. Tongue brushing		b. 5 times, 3 times per day
		c. Tongue pushing and sucking		c. 20 times, 3 times per day
		d. Tongue rotation		d. 10 times on each side, 3 times per day
		e. Facial exercises
		e1. Pressing the buccinators muscle outward		e1. 10 times on each side, 3 times per day
		e2. Sucking air from a syringe		e2. 5 times, 3 times per day
		f. Stomatognathic functions
		f1. Breathing and speech including forced nasal inspiration and oral expiration in conjunction with phonation of open vowels		f1. During sitting
		f2. Balloon inflation with prolonged nasal inspiration and then forced blowing		f2. 5 times per day
		f3. Swallowing and chewing		f3. During eating
Guimaraes et al, 200914	Oropharyngeal exercises	a. Soft palate and tongue exercises	3 mo	a. 3 minutes per day	Supervised session (30 min per week of deep breathing + nasal lavage with 10 ml of saline in each nostril 3 times per day.
		b. Tongue brushing (superior and lateral surface)		b. Each movement 5 times, 3 times per day
		c. Closing the orbicularis oris		c. 30 seconds
		d. Mouth angle elevation		d. 10 intermittent elevations, 3 times per day
		e. Stomatognathic functions		e. Similar to Diaferia et al22
Ieto et al, 201521	Nasal lavage three times a day followed by oropharyngeal exercises.	Oropharyngeal exercises:	3 mo	8-min set of exercises (20 times), 3 times a day for therapy and control	Nasal washing/lavage 3 × day + deep breathing exercises while sitting)
		a. Pushing the tip of the tongue against the hard palate and slide the tongue backward
		b. Sucking the tongue upward against the palate, pressing the entire tongue against the palate
		c. Forcing the back of the tongue against the floor of the mouth
		d. Elevation of the soft palate and uvula
		e. Pressing the buccinators outward
		f. Alternate bilateral chewing and deglutition during eating
Kuo et al, 201716	Expiratory muscle training Resistance pressure at 75% of each participant’s PE max	Inhalation and exhalation with an interval of 30–60 s with 2-min break after each breathing cycle	5 weeks	5 days per week, 25 breaths per day, 5 breaths per cycle, 5 cycles per day	Expiratory muscle training (resistance pressure at 0% of each participant’s PE max)
Puhan et al, 200627	Playing Didgeridoo and daily practice at home with standardized instruments	a. Week 1: Lip technique to produce and hold the keynote for 20–30 seconds.	4 mo.	At least 20 minutes and at least 5 days per week	Waiting list (no treatment)
		b. Week 2 and 3: Circular breathing technique
		c. Week 4: Optimization of the complex interaction between the lips, the vocal tract, and circular breathing
		d. 8 weeks later: Repetition of techniques and corrections
Villa et al, 201526 and Villa et al, 201724	Oropharyngeal exercises	a. Nasal breathing rehabilitation	2 mo.	10–20 repetitions, 3 times per day	Nasal washing/lavage 2 times per day
		b. Labial seal and lip tone exercises
		c. Tongue posture exercises
Vranish & Bailey, 201628	Inspiratory muscle strength training (75% of PI max)	Inspiratory muscle strength training	6 weeks	30 breaths per day	Inspiratory muscle strength training (15% of PI max)

PE max = expiratory pressure, PI max = inspiratory pressure.