Tongue cleaning improves respiratory function by activating the suprahyoid muscles. [Mayu Izumi, Lecturer, Department of Oral Health]

Research Projects

We have previously reported that tongue cleaning maintains and improves respiratory function in older adults. In this study, we focused on the relationship between respiratory-related muscle groups and suprahyoid muscles and investigated the effect of tongue cleaning on the suprahyoid muscles. A 6-week randomized controlled trial was conducted with 50 older adults aged 65 years and older, including residents and day-care participants of an elderly care facility in Kitakyushu City. Participants were randomly assigned to either an intervention group (tongue cleaning and standard oral hygiene) or a control group (standard oral hygiene only). Surface electromyography (sEMG) was used to evaluate the electromyographic activity of the suprahyoid muscles during inspiration, expiration, and forced vital capacity (FVC), and evaluations were performed at baseline and at the end of the follow-up period. 36 participants were included in the analysis. Compared to breathing, tongue elevation, and swallowing, tongue cleaning most activated the electromyographic activity of the suprahyoid muscles. In the intervention group, the root mean square (RMS) of expiratory sEMG at the end of the follow-up period was significantly increased compared to baseline [48.7 (18.0–177.5) vs. 64.9 (21.6–163.0), p = 0.001], while no significant change was observed in the control group. A generalized linear model showed that the rate of change in FVC was associated with the change in RMS of sEMG of the suprahyoid muscles during expiratory. These findings confirm that tongue cleaning enhances the electromyographic activity of the suprahyoid muscles.

This research was published in the "Journal of Oral Rehabilitation" in December 2016 and July 2021, and in "Scientific Reports" in September 2024.

Glossary

The suprahyoid muscles are a group of small muscles located at the bottom of the mouth. When these muscles function properly, smooth chewing, swallowing, and speaking are possible.
Surface electromyography (SEM) is a method of measuring electrical signals generated when muscles move, by examining the skin. When muscles contract, weak electrical signals are generated. These signals are captured by electrodes attached to the skin, recording muscle movement and strength.
Root mean square: This value is used when analyzing electromyograms (EMGs) and indicates the average strength of how actively a muscle is working.

Comments from researchers

Tongue cleaning has been shown to not only improve the oral environment but also activate the electromyographic activity of the suprahyoid muscles, thereby improving respiratory function. While a decline in respiratory and swallowing function is known as a phenomenon of aging, this study can be considered a paper that scientifically proves the importance of oral health management as a preventative measure. Because tongue cleaning can be easily performed on a daily basis, we believe it will be effective even for elderly people with dementia or those who are bedridden, for whom respiratory function rehabilitation has previously had to be abandoned.

Paper/researcher information

PubMed: 
https://pubmed.ncbi.nlm.nih.gov/27748575/
https://pubmed.ncbi.nlm.nih.gov/33687734/
ORCID: https://orcid.org/0000-0001-7325-9708
researchmap: https://researchmap.jp/izumi_maya