This randomized crossover study aims to address an important gap in manual therapy by examining the acute physiological effects of different Graston Technique application speeds (60 BPM vs. 120 BPM) on the dominant upper trapezius muscle in patients with bruxism. Although the Graston Technique is widely used, the specific impact of application speed on parameters such as muscle stiffness, muscle oxygenation, pressure pain threshold, and pain intensity remains under-investigated. By utilizing a crossover design with a 1-week washout period, this study allows for a precise within-subject comparison of the two speeds. The findings will clarify the optimal application frequency, providing objective data to guide the development of more effective, evidence-based manual therapy protocols for bruxism management.

Background and Rationale: Bruxism is a condition characterized by repetitive jaw muscle activity, which frequently leads to secondary musculoskeletal symptoms in the cervical region, particularly increasing muscle stiffness and pain in the upper trapezius muscle. While Instrument-Assisted Soft Tissue Mobilization (IASTM), specifically the Graston Technique, is a widely utilized intervention for managing myofascial restrictions, the optimal application parameters remain unclear. Specifically, the physiological impact of the application speed (frequency) on tissue properties and hemodynamics has not been systematically investigated in this population.

Study Design and Protocol: This study utilizes a prospective, randomized, crossover design to evaluate the acute effects of two different Graston Technique application speeds. A total of 36 participants diagnosed with bruxism will be included. Using a block randomization method, participants will be assigned to one of two intervention sequences (AB or BA) to ensure a balanced distribution.

Intervention Protocol: The study targets the dominant upper trapezius muscle. Each participant will complete two sessions separated by a 1-week washout period to prevent carry-over effects. The interventions are as follows:

Slow Speed Application (60 BPM): The Graston technique will be applied at a frequency of 60 beats per minute (1 Hz).

Fast Speed Application (120 BPM): The Graston technique will be applied at a frequency of 120 beats per minute (2 Hz).

For both conditions, the application speed will be standardized and controlled using a metronome. The duration of the intervention is set to 5 minutes per session. The application pressure will be kept consistent by the same physiotherapist throughout the study.

Outcome Measures: Assessments will be performed immediately before (pre-intervention) and immediately after (post-intervention) each session to measure acute changes. The following parameters will be evaluated:

Muscle Stiffness and Tone: Evaluated objectively using an ultrasound shear wave elastography to assess viscoelastic properties.

Muscle Oxygenation: Hemodynamic changes (tissue oxygenation index) will be monitored using Near-Infrared Spectroscopy (NIRS).

Pressure Pain Threshold (PPT): Assessed using an algometer to quantify mechanical pain sensitivity.

Pain Intensity: Subjective pain levels will be rated by participants using a Visual Analog Scale (VAS).

This study aims to determine whether a specific application speed provides superior physiological benefits, thereby contributing to the development of evidence-based manual therapy protocols for patients with bruxism.

Inclusion Criteria:

• Diagnosed with bruxism.
• Aged 18-55 years.
• Presence of trigger points in the trapezius muscle, according to the criteria defined by Travell and Simons.

Exclusion Criteria:

• Acute tears, tendon ruptures, or severe muscle injuries.
• Conditions that prevent the application of the Graston Technique (e.g., skin lesions, open wounds, infections).
• Having received botox injections in the temporomandibular joint (TMJ) region within the last 6 months.
• Psychological disorders that may affect participation or measurements.