Effects of multi directional chin tuck against resistance exercise on tongue pressure and thickness and suprahyoid muscle activity

The chin tuck against resistance (CTAR) exercise is a therapeutic method developed to activate and strengthen the oropharyngeal muscles related to swallowing in patients experiencing post-stroke dysphagia. However, existing CTAR exercises could be improved by considering the complex characteristics of the suprahyoid muscles. To investigate the efficacy of multidirectional (md-) CTAR on tongue pressure and suprahyoid muscle activity in older adults. Thirty-four older adults were enrolled and randomly assigned to two groups (n = 17/group). Group 1 performed md-CTAR exercises in the left and right diagonal and vertical directions, using the prototype device developed for this study. In contrast, group 2 performed only the vertical-directional (vd-) CTAR exercise using the same device as group 1. Both groups performed the same exercise for 5 days over 6 weeks. Outcome measures were tongue pressure, tongue thickness, and suprahyoid muscle activity, which were evaluated using the Iowa Oral Performance Instrument, ultrasound, and surface electromyography, respectively. As a results, group 1 exhibited significantly higher maximal tongue pressure, tongue thickness, and suprahyoid muscle activity during swallowing than group 2 (p < .05). In conclusion, This study demonstrated that the md-CTAR exercise was more effective than the vd-CTAR exercise in activating the suprahyoid muscles while promoting greater maximal tongue pressure and thickness in older adults.