Tongue pressure waveform analysis for ascertaining the influence of tongue muscle composition on articulation.

Background: Rate force development is associated with performance and muscle composition in whole-body muscle. Although rate force development on tongue muscle can be examined using tongue pressure waveform, there have been only few investigations on this topic.

Objectives: This study's main purpose was to investigate the reliability of tongue pressure waveform analysis and its relationship with articulation and tongue muscle composition. In addition, we also investigated the association between tongue muscle composition and articulation.

Methods: Forty-five community-dwelling individuals aged >20 years participated. We analysed tongue pressure waveform, including maximum tongue pressure (MTP), time to peak, mean rate of tongue force development and peak rate of tongue force development (PRTFD). We also assessed oral diadochokinesis. Magnetic resonance imaging of the tongue provided data on tongue muscle composition, including tongue volume, fat mass, lean muscle mass and fat percentage. We evaluated the reliability of tongue pressure waveform analysis. Moreover, we examined the coefficients between tongue pressure waveform analysis, oral diadochokinesis and tongue composition.

Results: We detected a high reliability of MTP and PRTFD. MTP and PRTFD were significantly correlated with tongue muscle composition. MTP was not significantly correlated with oral diadochokinesis. PRTFD was significantly positively correlated with oral diadochokinesis. Tongue fat mass and fat percentage were negatively correlated with oral diadochokinesis of /ta/ and /ka/.

Conclusions: Peak rate of tongue force development is a highly reliable method for tongue pressure analysis and is useful for elucidating the functional importance of tongue muscle function on articulation. We speculated that fatty infiltration of the tongue adversely affects articulation.