Tongue Cleaning Enhances Activity of Suprahyoid Muscles During Exhalation in Healthy Young Adults: A Randomised Controlled Intervention Study.

Objective: Our previous study demonstrated that tongue cleaning can improve respiratory function, and this study seeks to understand the specific muscular mechanism for this improvement. The tongue and respiratory muscles are connected through the endothoracic fascia via the suprahyoid muscles. This study aimed to examine whether tongue cleaning activates suprahyoid muscle activity in healthy young adults, using surface electromyography (sEMG).

Methods: A 4-week randomised controlled trial was conducted with 30 participants aged 21-22. The participants were divided into two groups: an intervention group that practised tongue cleaning in addition to routine oral hygiene, and a control group that practised only routine oral hygiene. sEMG was used to assess the myoelectric activity of the suprahyoid muscles during various actions, including inhalation, exhalation, head lifting, tongue pressure and tongue cleaning. The sEMG data were presented as microvolt root mean squares (RMS). An examination was conducted at baseline and after the 4-week intervention period.

Results: The RMS of the suprahyoid muscles during various actions, except inhalation, had increased significantly by the end of the follow-up period in the intervention group but not in the control group. The degree of change to the RMS during exhalation in the intervention group was significantly larger than that in the control group [11.9 (-7.7 to 58.9) vs. 0 (-36.2 to 12.5), p = 0.013].

Conclusion: Practicing tongue cleaning for 4 weeks increased the activity of the suprahyoid muscles during exhalation in healthy young adults, and it could be used to improve respiratory function in individuals with weakened suprahyoid muscles.