Abstract
OBJECTIVE: This study aimed to determine whether tongue-hold swallow (THS) training affects laryngeal elevation in healthy older men during swallowing and whether THS induces muscle activity comparable to that of the Mendelsohn maneuver (MM), which is known to improve laryngeal elevation. METHODS: In study 1, 10 healthy older men were trained (two sets/day, five days/week for six weeks) with THS. They visited the clinic four times to evaluate the training effect with the maximum tongue pressure as well as the distance and peak velocity of laryngeal elevation. Laryngeal elevation was measured in a total of four conditions, two bolus conditions (saliva and water) and two swallowing methods (normal swallow (NS) and effortful swallow (ES)), using a noninvasive laryngeal elevation measurement device. In study 2, surface electromyography was performed on the same participants as in study 1 to measure integrated electromyography (iEMG) and iEMG/s during NS, THS, and MM by placing the surface electrodes on the submental muscle region and the thyrohyoid muscle region. RESULTS: In study 1, the maximum tongue pressure was significantly different between the first and other three evaluation visits and between the second and fourth visits, increasing gradually. Regarding the laryngeal elevation, only the distance showed a statistically significant increase between the first and fourth visits in the saliva/ES condition. In study 2, the iEMG/s of the submental muscles was greater in THS than in NS, while the iEMG value was greater in THS and MM than in NS. The iEMG value of the thyrohyoid muscle region was greater in MM than in NS and also in MM than in THS. CONCLUSIONS: The maximum tongue pressure and laryngeal elevation distance in the saliva/ES condition were greater after the training. THS and MM showed similar levels of muscle activity in the submental muscles but not in the thyrohyoid muscle region. Therefore, the combination of THS with other training is recommended in strengthening the laryngeal elevation. THS may contribute not only to an increase of the posterior pharyngeal wall constriction and tongue retraction but also to an enhancement of the laryngeal elevation.