Eccentric Chin Closure Exercise

Swallowing is a set of functions that start with the acceptance of food and end with its delivery to the stomach. One of the most important problems associated with swallowing disorders is insufficient airway closure and the risk of aspiration. It is due to the inadequacy of laryngeal elevation that should occur during swallowing. Suprahyoid muscles are the most basic structures responsible for laryngeal elevation. Insufficient activation of the suprahyoid muscles causes insufficient laryngeal elevation.

The suprahyoid muscles consist of a group of muscles located in the anterior region of the neck between the hyoid bone and the mandible. The muscles which forming SH muscles m. digastricus, m. stylohyoideus, m. mylohyoideus and m. geniohyoideus muscles work as a group. SH muscles play a primary role in controlling hyoid bone movement during swallowing due to their relationship with the hyoid bone. It has been reported that the muscle with the highest potential to move the hyoid anteriorly is the geniohyoid muscle, and the mylohyoid muscle has the highest potential to move the hyoid in the superior direction. In addition, in another study, it was stated that since the geniohyoid and mylohyoid muscles have greater structural potential than other SH muscles for anterior and superior displacement of the hyoid, respectively. By understanding the potential for hyoid excursion arising from the structural properties of these muscles, therapists can target specific muscles with exercises designed to promote hyolaryngeal elevation.

Exercises such as Shaker exercise and resistance chin tuck in the literature either directly involve concentric training of the suprahyoid muscles or indirectly aim to gain strength by strengthening the neck flexors. In the light of the available evidence in the literature, eccentric training is also a viable method in swallowing rehabilitation. In eccentric training, the muscle is positioned by shortening its length. Eccentric training can be done by applying resistance to the jaw while the mouth is open and asking the mouth to be closed in a controlled manner against the resistance. In addition, swallowing exercise can be planned by adjusting the mouth opening and placing the SH muscles at the most appropriate angle to generate force. The aim of this study is to compare the effects of these three different exercises on suprahyoid muscle activation, muscle strength, dysphagia limit and perceived exertion level.

Swallowing is a set of functions that start with the acceptance of food and end with its delivery to the stomach. The oral preparation consists of 4 phases, namely the oral, pharyngeal and esophageal phase. Swallowing disorder (dysphagia) is defined as problems occurring in at least one of the swallowing phases. One of the most important problems associated with swallowing disorders is insufficient airway closure and the risk of aspiration. It is due to the inadequacy of laryngeal elevation that should occur during swallowing. Suprahyoid muscles are the most basic structures responsible for laryngeal elevation. Insufficient activation of the suprahyoid muscles causes insufficient laryngeal elevation.

The suprahyoid (SH) muscles consist of a group of muscles located in the anterior region of the neck between the hyoid bone and the mandible. The muscles which forming SH muscles m. digastricus, m. stylohyoideus, m. mylohyoideus and m. geniohyoideus muscles work as a group. SH muscles play a primary role in controlling hyoid bone movement during swallowing due to their relationship with the hyoid bone. It has been reported that the muscle with the highest potential to move the hyoid anteriorly is the geniohyoid muscle, and the mylohyoid muscle has the highest potential to move the hyoid in the superior direction. In addition, in another study, it was stated that since the geniohyoid and mylohyoid muscles have greater structural potential than other SH muscles for anterior and superior displacement of the hyoid, respectively, these two muscles can be targeted for neuromuscular stimulation preferably. Studies have also shown that exercise can increase motor unit involvement for certain functions. By understanding the potential for hyoid excursion arising from the structural properties of these muscles, therapists can target specific muscles with exercises designed to promote hyolaryngeal elevation.

Interventions to protect the airway in case of swallowing disorder are aimed at increasing the hyolaryngeal elevation. SH muscles provide elevation of the hyolaryngeal complex and also support the opening of the upper esophageal sphincter (UES). The cricopharyngeal muscle, which opens the UES, is opened by the contraction of the SH muscles and the anterior-superior traction of the hyoid and larynx. Insufficient elevation of the hyoid and larynx causes insufficient opening of the UES, resulting in an increase in the amount of pharyngeal residue and the risk of aspiration. Superior hyolaryngeal excursion during swallowing is thought to contribute to airway protection, preventing aspiration. Anterior hyalaryngeal excursion is thought to be associated with the patency of the UES. Exercises such as Shaker exercise and resistance chin tuck in the literature either directly involve concentric training of the suprahyoid muscles or indirectly aim to gain strength by strengthening the neck flexors.

Shaker Exercises were the first exercise developed to increase suprahyoid muscle activation. This exercise, which is characterized by raising the patient's head in the supine position, has been accepted as one of the most basic exercises in dysphagia rehabilitation for many years. In the following years, the Chin Tuck Against Resistance (CTAR) exercise was developed due to the challenging protocol and positional discomfort of the Shaker exercise. In the CTAR exercise, the patient is asked to press a standard size and inflatable ball, which he puts under his chin, towards his sternum. CTAR has become the most commonly used exercise in dysphagia rehabilitation. In the light of the available evidence in the literature, eccentric training is also a viable method in swallowing rehabilitation. In eccentric training, the muscle is positioned by shortening its length. Eccentric training can be done by applying resistance to the jaw while the mouth is open and asking the mouth to be closed in a controlled manner against the resistance. In addition, swallowing exercise can be planned by adjusting the mouth opening and placing the SH muscles at the most appropriate angle to generate force. The aim of this study is to compare the effects of these three different exercises on suprahyoid muscle activation, muscle strength, dysphagia limit and perceived exertion level.

H0 Hypothesis: There is no difference between CTAR, Shaker and Eccentric Chin Closure exercises in terms of suprahyoid muscle activation, suprahyoid muscle strength, dysphagia limit and perceived exertion level in healthy individuals.

H1 Hypothesis: There is a difference between CTAR, Shaker and Eccentric Chin Closure exercises in terms of suprahyoid muscle activation, suprahyoid muscle strength, dysphagia limit and perceived exertion level in healthy individuals.

Eligibility Criteria:
Inclusion Criteria:

* Being between the ages of 18 - 35,
* Volunteering to participate in the study,
* Getting less than 3 points from the T-EAT-10 (Turkish Eating Assessment Test).

Exclusion Criteria:

* Having disc herniation, mechanical neck pain or any pathology in the cervical region.
* Having a temporamandibular joint problem that may affect joint biomechanics and muscle functions.
* Having any neurological or systemic disease,
* Having undergone head and neck surgery or received radiotherapy.

Dischart Criteria

* Individuals who accepted the study and then stopped participating in the study
* Individuals who did not attend the assessments
* Individuals missing 5 days from the weekly follow-up of exercise sessions.