Abdominal Accesory Respiratory Muscles (rectus abdominis, transversus abdominis, and oblique muscles) and MIP(maximum inspiratory pressure) MEP(maximum expiratory pressure) values of the group with Parkinson's diagnosis and Hoehn Yahr Stage 1-2-3 will be measured, a 6-Minute Walk Test will be performed and the results will be noted.

Abdominal Accessory Respiratory Muscles (rectus abdominis, transversus abdominis, and oblique muscles) and MIP (maximum inspiratory muscles) MEP(maximum expiratory muscles) values of age and gender matched healthy values of age and gender matched healthy volunteers without any diagnosis of neuromuscular disease or chest diseases will be measured and the results will be noted.

MEP assesses the strength of abdominal and accessory expiratory muscles. During the maneuver, the patient is asked to blow forcefully into the mouthpiece for at least 1.5 seconds, as if inflating a balloon. The pressure generated during rapid expiration is measured by sensors, and after 1.5-2.0 seconds the shutter opens, ending the test. If multiple tests are conducted, the patient rests for at least 1 minute between trials, and a maximum of 3-5 trials are performed. Differences greater than 10 cmH₂O between trials are not accepted. The highest measurement is reported together with the predicted value. The MicroRPM Respiratory Pressure Meter (MicroDirect, USA) will be used.

MIP is used to assess the strength of inspiratory respiratory muscles. During the test, the patient is instructed to exhale down to residual volume. MIP is defined as the maximum negative pressure measured during a maximal inspiratory effort performed after reaching residual volume. Measurements will be taken using the MicroRPM Respiratory Pressure Meter (MicroDirect, USA).

Ultrasound measurements of the rectus abdominis, external oblique, internal oblique, and transversus abdominis muscles will be performed. Measurements will be taken in the supine position with the patient lying on their back, eyes facing upward, arms resting symmetrically beside the trunk, and lower extremities in full knee extension with an intermalleolar distance of 10 cm. Muscle thickness will be recorded at the end of normal expiration and at the end of forced expiration.

The 6MWT is performed in a corridor with a flat, firm surface that is at least 30 meters long and marked at 3-meter intervals. Turning points should be indicated with a colored object. Start and finish lines are designated. The patient is asked to walk the longest distance possible within 6 minutes. The distance walked is measured and recorded.