Mandibular Stretching and 4-4-8 Breathing Exercises on Autonomic Nervous System Activity

The autonomic nervous system plays an important role in regulating physiological and psychological responses. Breathing techniques and mandibular stretching exercises are non-invasive approaches that may influence autonomic nervous system activity and muscle tone through neuromuscular and respiratory mechanisms. However, the combined or individual effects of these interventions on autonomic regulation and psychological outcomes remain insufficiently investigated.

This randomized controlled trial aims to examine the effects of mandibular stretching exercise and the 4-4-8 breathing exercise on autonomic nervous system activity, muscle tone, and psychological state in healthy university students. Participants will be randomly allocated to intervention groups according to the study protocol. Baseline and post-intervention measurements will be collected to evaluate changes in autonomic nervous system parameters, muscle tone, and psychological status.

The findings of this study may contribute to understanding the potential benefits of simple non-pharmacological interventions such as mandibular stretching and breathing exercises in improving physiological regulation and psychological well-being.

• Mandibular Stretching Exercise (Other): Participants perform mandibular stretching exercises according to the study protocol
• 4-4-8 Breathing Exercise (Other): Participants perform the 4-4-8 breathing exercise according to the study protocol.

Primary outcomes

• Autonomic Nervous System Activity [Baseline and 20, 40, 80, and 120 minutes after the intervention]: Autonomic nervous system activity will be assessed by measuring heart rate (beats per minute) using a digital pulse oximeter and blood pressure (mmHg) using an automatic blood pressure monitor. Measurements will be recorded at baseline and repeatedly after the intervention period (20, 40, 80, and 120 minutes).

Secondary outcomes

• Muscle Tone [Baseline and 20, 40, 80, and 120 minutes after the intervention]: Muscle activity of the temporalis and masseter muscles will be assessed using surface electromyography (EMG). EMG amplitude (microvolts, µV) will be recorded at baseline and repeatedly after the intervention period (20, 40, 80, and 120 minutes).
• Psychological State [Baseline and 20, 40, 80, and 120 minutes after the intervention]: Psychological state will be assessed using the State-Trait Anxiety Inventory (STAI) questionnaire. STAI scores (range 20-80 points) will be recorded at baseline and repeatedly after the intervention period (20, 40, 80, and 120 minutes).

Sex: All, ages: 18 Years to 30 Years, accepts healthy volunteers

Inclusion Criteria:

* Inclusion Criteria:
* Healthy university students
* Age between 18 and 30 years
* Voluntary participation in the study
* Ability to understand and perform mandibular stretching exercise and 4-4-8 breathing exercise

Exclusion Criteria:

* History of neurological disorders
* Musculoskeletal disorders affecting the jaw, neck, or respiratory system
* Respiratory diseases
* Use of medications that may affect the autonomic nervous system
* Inability to perform the exercises required in the study

• Neslihan Altuntaş YILMAZ, PhD, Principal investigator, Necmettin Erbakan University