Reliability of Lingual Swallow Pressure Measurements in Healthy Older and Younger Adults

Background While maximum isometric pressure (MIP) is widely used in clinical and research settings, reduced lingual swallow pressure (LSP) has been observed in patients with dysphagia and in older healthy adults. However, limited evidence exists on the test–retest reliability of LSP across different bolus consistencies. Objective This study assessed the test–retest reliability of LSP measurements in both younger and older adults with healthy swallowing function to identify factors influencing oral swallowing pressure. Methods Participants 18–40 years (younger) and 60+ years (older) were assessed across four separate sessions. Bolus types included trials of saliva, thin, mildly thick and extremely thick water, randomised across study visits. Two‐way mixed effects models with absolute agreement were used to calculate intraclass correlation coefficients (ICCs) and evaluate test–retest reliability of LSP for each swallow type (regular or effortful) and bolus type. Linear mixed effects regression modelling was used to examine the factors influencing LSP. Results A total of 51 participants were included. Test–retest reliability for LSP ranged from good to excellent across both groups (ICC = 0.79–0.98). Reliability was non‐significantly higher in the older group (ICC = 0.96) and during effortful swallows (ICC = 0.94). Effort level significantly influenced LSP estimates, with effortful swallows producing about 1.83 times more lingual pressure than regular swallows. There were no significant effects of age, sex, or bolus type on LSP. Conclusion These findings suggest that LSP measurements are reliable across measurement time points in nondysphagic participants, regardless of age, effort level, or bolus type. Only swallow effort level significantly influenced LSP estimates.