The Dynamics of Pharyngeal Shortening in Healthy Swallowing: Effects of Sex, Age, Bolus Volume and Consistency

Background Pharyngeal shortening is thought to facilitate bolus clearance through the pharynx and upper oesophageal sphincter (UES) in swallowing. However, little information is available regarding pharyngeal shortening in healthy swallowing. Objective(s) We characterised the timing and extent of pharyngeal shortening by tracking the height of the UES across key time points in healthy swallowing. Additionally, we identified variations in pharyngeal shortening attributable to participant (sex, age) and bolus factors (consistency, volume). Methods Videofluoroscopy data for (1) sips of thin liquid and (2) teaspoons of mildly thick liquid were analysed from 80 healthy adults (40 males, 40 females), distributed across four age groups: 18–35, 36–53, 54–72, 73–90 years. UES height was tracked relative to the cervical spine on the frames of UES opening (UESO), maximum UES height (UESMaxHeight) and swallow rest (SR) using a 20‐point ordinal scale. Statistical analyses explored effects of sex, age‐group, and task on: (1) latency‐to‐UESMaxHeight, (2) UES height at UESO and SR, and (3) the degree of pharyngeal shortening at UESMaxHeight relative to UESO and SR. Results Maximum UES height occurred between the events of UES opening and closure, in close proximity to other biomechanically linked events. UES height was lower in males. Greater pharyngeal shortening was seen in males and on thin liquid tasks. Conclusion These findings refine our understanding of healthy swallowing dynamics and highlight the influence of sex‐linked differences in height on UES position relative to the cervical spine. Trial Registration ClinicalTrials.gov : NCT05497219