# Effects of Tongue Training Tasks on Intramuscular Activity Distribution: Evaluation Using Muscle Functional Magnetic Resonance Imaging

## TL;DR

Different tongue training exercises activate different parts of the tongue muscle, which could help improve rehabilitation programs.

## Contribution

The study reveals how tongue resistance training direction affects muscle activity patterns in the tongue using mfMRI.

## Key findings

- Elevation training activates the anterior tongue and genioglossus origin.
- Lateral training activates a wider area extending to the tongue root.
- Elevation training improves maximal elevation tongue pressure and oral diadochokinesis more effectively.

## Abstract

From the perspective of site specificity, inducing muscle activity across a large area of the tongue through diversified tongue resistance training (TRT) may be an effective approach to improve tongue pressure (TP) and function. However, the distribution of muscle activity within the tongue during different TRT exercises remains unclear.

To examine the hypothesis that muscle activity distribution within the tongue varies with TRT direction using muscle functional magnetic resonance imaging (mfMRI), and to clarify the relationship between these distributions and functional outcomes.

Twenty young volunteers were randomly assigned to either an elevation or a lateral 4 week TRT group. We performed mfMRI before (at rest) and immediately following each training task, before and after 4 weeks of TRT, and we measured maximal elevation, lateral TP, and oral diadochokinesis (ODK). A linear mixed‐effects model was used to analyse the functional outcomes.

After TRT, mfMRI revealed that elevation exercise activated the anterior tongue, including the origin of the genioglossus. Conversely, lateral exercise induced significant activity across a wider area extending to the tongue root. Post‐training maximal elevation TP and overall ODK values were significantly higher in the elevation training group. No significant differences between groups were observed in post‐training lateral TP.

TRT direction changes the pattern of muscle activity in the tongue. This finding reveals qualitative aspects of TRT that cannot be evaluated by post‐training TP alone, offering a new perspective for designing more effective rehabilitation programs.

ClinicalTrials.gov identifier: UMIN000047658

Patterns of muscle activity within the tongue vary by tongue resistance training direction. This finding will aid in designing more effective rehabilitation programs.