Aging is often accompanied by a decline in bodily functions, including the swallowing process. Tongue-strengthening exercises have been shown to improve tongue strength and thickness in healthy adults and the elderly, thereby supporting swallowing function. Consistent exercise is key to preventing muscle weakness and preserving their ability to swallow. However, there is limited research on the effects of tongue-strengthening exercises that explores varying intensities and repetitions in elderly with impaired tongue pressure. Consequently, the objective of this study is to investigate the effect of biofeedback tongue strengthening program on tongue pressure and swallowing performance in elderly with abnormal tongue pressure. The results will serve as valuable data for selecting effective interventions to improve tongue strength and swallowing.

Sample size calculation: A sample size of 52 participants was determined for this study, accounting for a 20% dropout rate. The calculation was performed using G*Power software (version 3.1.7), based on an effect size of 0.87. This value was derived from a previous study by Van den Steen et al. (21), which measured the difference in mean tongue pressure strength between training and control groups. With an effect size of 0.87, considered a large effect, a minimum of 44 participants was required to achieve 80% statistical power at a significance level of 0.05. Statistical analysis: IBM SPSS Statistics will be used for all data analysis. A chi-squared test and Mann-Whitney U test will be performed to compare the baseline characteristics of participants between the two groups. A two-way ANOVA will be used to analyze differences between the two groups (strengthening training and endurance training) across the three time points (Baseline, Post-test after one day, and Post-test after one month). Subsequently, a Wilcoxon signed-rank test will be used to identify significant changes within each group at each time point.

Inclusion Criteria:

• Aged 60 years or older.
• No cognitive impairment, as screened by the Mini-Mental State Examination (MMSE) with a score of 24 or higher.
• Elderly with abnormal tongue pressure have an anterior maximum isometric tongue pressure (MIP) average of less than 30 kilopascals.

Exclusion Criteria:

• Diagnosed with head and neck cancers, a neurological disorder, or other conditions that affect the tongue muscle strength and training.

We will share IPD when we receive the consent from participants.

This research is a double-blind study, in which both participants and the assessor are blinded to the group assignments.