Effects of laryngeal restriction on pharyngeal peristalsis and biomechanics: Clinical implications

To date, rehabilitative exercises aimed at strengthening the pharyngeal muscles have not been developed due to the inability to successfully overload and fatigue these muscles during their contraction, a necessary requirement for strength training. The purpose of this study was to test the hypothesis that applying resistance against anterosuperior movement of the hyolaryngeal complex will overload the pharyngeal muscles and by repetitive swallowing will result in their fatigue manifested by a reduction in pharyngeal peristaltic amplitude. Studies were done in two groups. In group 1 studies 15 healthy subjects (age: 42 ± 14 yr, 11 females) were studied to determine whether imposing resistance to swallowing using a handmade device can affect the swallow-induced hyolaryngeal excursion and related upper esophageal sphincter (UES) opening. In group 2, an additional 15 healthy subjects (age 56 ± 25 yr, 7 females) were studied to determine whether imposing resistance to the anterosuperior excursion of the hyolaryngeal complex induces fatigue manifested as reduction in pharyngeal contractile pressure during repeated swallowing. Analysis of the video recordings showed significant decrease in maximum deglutitive superior laryngeal excursion and UES opening diameter (P < 0.01) due to resistive load. Consecutive swallows against the resistive load showed significant decrease in pharyngeal contractile integral (PhCI) values (P < 0.01). Correlation analysis showed a significant negative correlation between PhCI and successive swallows, suggesting "fatigue" (P < 0.001). In conclusion, repeated swallows against a resistive load induced by restricting the anterosuperior excursion of the larynx safely induces fatigue in pharyngeal peristalsis and thus has the potential to strengthen the pharyngeal contractile function.