After deciding to join this study and signing the informed consent form, participants will undergo the following interventions:

All participants will receive a preoperative assessment (Tp) before surgery. Within five days after transferring from the ICU to the general ward, participants will receive a baseline assessment (T0). After completing seven sessions of myofascial release (MFR), a post-intervention assessment (T1) will be conducted.

Assessments include maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), pulmonary function tests, mid- and lower-thoracic mobility, surface electromyography (sEMG) to measure diaphragmatic and sternocleidomastoid muscle activity, and pain scores. Pulmonary function tests include forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC ratio, and maximum voluntary ventilation (MVV).

Participants will be randomly assigned to an intervention group or a control group. The intervention group will receive myofascial release therapy in addition to routine physical therapy in the general ward. Routine therapy includes daily physical therapy sessions such as out-of-bed activities, incentive spirometry training (Triflow), and functional exercises. The MFR intervention consists of three steps:

The therapist places both hands on the thoracic outlet, with the index and middle fingers above the clavicle.

One hand is placed on the anterior chest and the other hand parallel on the participant's back.

Both hands are placed on the anterolateral region of the thoracoabdominal diaphragm.

During each step, participants are instructed to take 10 slow, deep breaths and direct airflow toward the therapist's hands. Each session lasts approximately 15 minutes, once daily, for seven sessions.

The control group will receive only routine physical therapy (out-of-bed activities, incentive spirometry, and functional exercises) without additional myofascial release therapy.

Inclusion Criteria:

• Age ≥ 18 years
• Able to communicate verbally and follow instructions
• Diagnosed by a physician with coronary artery disease, valvular disease, or aortic disease
• Undergoing median sternotomy
• Able to provide informed consent

Exclusion Criteria:

• Presence of a cardiac pacemaker
• Presence of a ventricular assist device (VAD)
• Existing central nervous system disorders (e.g., hemorrhagic or ischemic stroke, spinal cord injury, traumatic brain injury)
• Cognitive impairment or inability to understand/follow instructions
• Diagnosed with chronic obstructive pulmonary disease (COPD)
• History of previous thoracic surgery
• ICU stay longer than 14 days