Abstract
PURPOSE: Swallowing safety and efficiency are influenced by the timing of swallowing events, such as laryngeal vestibule closure (LVC) and upper esophageal sphincter opening (UESO). Although age-related changes in these parameters are well documented, whether bolus location at swallow onset (BLSO) influences timing measures is less understood. This study investigated the effects of BLSO and age on timing measures of swallowing in a healthy older adult sample. METHOD: This single-center, cross-sectional, retrospective study included 26 community-dwelling healthy participants (21 women, five men; aged 56-77 years) who underwent a videofluoroscopic swallowing study involving three thin liquid swallows: two 5-ml swallows (Bolus 1 [B1], Bolus 2 [B2]) and one cup sip (Bolus 3 [B3]). BLSO was classified as high (at/above the valleculae) or low (beyond the valleculae). Three timing measures were analyzed: swallow reaction time (SRT), hyoidburst-to-UESO (HYB-to-UESO) interval, and time to LVC (TTLVC). Statistical analyses (α = .05) included univariate analyses of variance, Spearman correlations, and mixed models exploring BLSO and age interactions. RESULTS: BLSO was not correlated with age and varied within participants across boluses, necessitating separate analyses by bolus (B1, B2, B3) rather than repeated-measures analysis. In univariate analyses, lower BLSO was associated with prolonged SRT across all three boluses and shorter HYB-to-UESO interval for B1. Older age was correlated (ρ > .3) with a longer SRT (B1, B3), a shorter HYB-to-UESO interval (B1), and a shorter TTLVC (B1, B2). No significant main effects or interactions were observed in the combined models. CONCLUSIONS: Lower BLSO was associated with prolonged SRT. Inconsistent age-related differences in timing measures were observed in this sample across different liquid bolus presentations.