Comparison of Submental Muscle Activation and Tongue Pressure of Tongue Hold, Effortful Swallow and Mendelsohn Maneuvers in Different Gravitational Positions

This study aimed to investigate the effects of Tongue Hold Maneuver (THM), Mendelsohn Maneuver (MM), and Effortful Swallow Maneuver (ESM) performed under different gravitational positions (90° sitting, 45° sitting, supine, and lateral decubitus) on submental muscle activation (SMA) and oral pressure in healthy young adults. Thirty-three healthy volunteers aged 18-30 years participated. SMA was recorded using surface electromyography (sEMG), and oral pressure was measured with the Iowa Oral Performance Instrument (IOPI). Each maneuver was performed in four gravitational positions in a randomized order. SMA values were normalized with the maximum isometric voluntary contraction (MVC), and oral pressure was expressed in kilopascals. Repeated-measures ANOVA was used to compare submental muscle activation (%MVC) and tongue pressure (kPa) across swallowing maneuvers (THM, MM, ESM) and gravitational positions (90° sitting, 45° sitting, supine, lateral decubitus) within subjects. SMA varied significantly across positions and maneuvers (p < 0.05). The lowest activation was observed in the lateral decubitus position for all maneuvers, while ESM produced the highest activations.Oral pressure was significantly affected by maneuver type (p < 0.001), with ESM showing the highest and THM the lowest values. However, no significant effect of body position on oral pressure was found. Swallowing maneuvers showed different results of SMA and oral pressure under different gravitational conditions. Muscle activation decreased as gravity was eliminated, with the lowest values in lateral decubitus position, whereas oral pressure was influenced mainly by maneuver type. Using gravity-eliminated positions in rehabilitation may be considered as a starting point for patients with altered muscle strength and may facilitate gradual progression in rehabilitation. Accordingly, these findings should be interpreted within the limits of physiological measurements and not as indicators of clinical safety or therapeutic benefit.