Isometric exercises of the abdominal muscles in the supine, prone, and squatting positions; isotonic exercises in the supine, prone, squatting, and side-lying positions; isotonic exercises in coordination with the extremity movements in the supine, prone, and crawling positions; and trunk rotation exercises in the sitting position will be performed. The Swiss ball will be used for dynamic exercises. It will include isometric and isotonic exercises of the abdominal muscles. Exercises will start with 3 sets of 20 repetitions, gradually increase in intensity on static and dynamic surfaces, and progress towards difficulty. Each exercise will be performed in coordination with breathing control.Breathing control will be coordinated with every exercise.

Since no training will be given to the control group during the study, we consider it ethically necessary to provide the same training to the control group if it proves effective after the study is over.

Isometric exercises of the abdominal muscles in the supine, prone, and squatting positions; isotonic exercises in the supine, prone, squatting, and side-lying positions; isotonic exercises in coordination with the extremity movements in the supine, prone, and crawling positions; and trunk rotation exercises in the sitting position will be performed. The Swiss ball will be used for dynamic exercises. It will include isometric and isotonic exercises of the abdominal muscles. Exercises will start with 3 sets of 20 repetitions, gradually increase in intensity on static and dynamic surfaces, and progress towards difficulty. Each exercise will be performed in coordination with breathing control. Breathing control will be coordinated with every exercise.

Chest wall expansion will be measured with a standard measuring tape at three different levels. While the child is in an upright position, with his feet shoulder-width apart and his arms relaxed at his side, measurements will be taken from three areas: at the axilla level (upper level), at the xiphoid level (middle level) and at the subcostal level (lower level).

The physical therapist standing in front of the child will initially ask the child to breathe normally to determine the tidal volume, after placing the tape measure around the chest. The child will be asked to exhale maximally and then inhale maximally. The difference between the two scales (inhalation - exhalation) will be determined as thoracic expansion (chest expansion). Participants will be instructed to perform three maneuvers and the obtained values will be averaged and recorded. Data will be measured by the same physiotherapist to minimize possible errors due to heterogeneity.

The 6-minute walk test (6MWT) is a commonly used submaximal exercise test to assess functional capacity. This test, used to measure cardiovascular endurance, is a clinical indicator of functional capacity and helps measure the ability to perform activities of daily living. The 6MWT will be performed in accordance with The American Thoracic Society guidelines. The participant will be instructed to walk as fast as possible on a 30 m path for 6 minutes, but not to run. The child will sit in a chair close to the starting position and vital values (heart rate and respiratory rate) will be recorded before administering the test. At the end of the test, the distance walked for 6 minutes will be recorded as 6 minutes walking distance (6MWD). After completion of the test, heart rate, respiratory rate will be measured and the child will be asked about the maximum fatigue level after completing the test using the Borg scale.