This study was designed to investigate and compare the effects of standard diaphragmatic breathing and physiotherapy exercises versus 360-degree expandable diaphragmatic breathing and physiotherapy exercises on respiratory functions, respiratory muscle strength, clinical course of the disease (such as thoracic mobility, flexibility), and functional status in individuals with Ankylosing Spondylitis (AS).

One of the primary problems in Ankylosing Spondylitis (AS) is decreased thoracic expansion. For this reason, breathing exercises, especially thorax expansion, should be included. Moreover, according to Pascal's principle, the pressure applied to a closed fluid must be transmitted to every part of the fluid and to the walls of the space in which it is located, without decreasing (13). For this reason, it is thought that the disrupted breathing pattern cannot be adequately corrected by standard diaphragm exercises, in which the patient's hand is placed on the abdomen and the anterior abdominal wall is pushed forward/outward, and the diaphragm descent to the caudal level during inspiration with 360-degree expansion of the thoraco-abdominal cavity may not be sufficient (14). The aims of this study are as follows:

1. To examine and compare the effects of standard diaphragmatic breathing and physiotherapy exercises and 360-degree expanded diaphragm exercises and physiotherapy exercises on respiratory function in individuals with AS.
2. To examine and compare the effects of standard diaphragmatic breathing and physiotherapy exercises, 360-degree expanded diaphragm exercises and physiotherapy exercises on inspiratory and expiratory muscle strength in individuals with AS.
3. To examine and compare the effects of standard diaphragmatic breathing and physiotherapy exercises, 360-degree expanded diaphragm exercises and physiotherapy exercises on spinal mobility and the clinical course of the disease in individuals with AS.

Inclusion Criteria:

• Age between 20-60 years
• Diagnosis according to the 1988 Modified New York criteria
• Voluntary participation
• BASDAI score of 3 or 4
• No mental problems that could hinder cooperation and understanding

Exclusion Criteria:

• Presence of a neurological disease
• Other respiratory system diseases that could affect chest expansion (COPD, asthma, etc.)
• Regular exercise within the last 3 months Additionally, individuals who miss four consecutive exercise sessions or require a change in treatment will be excluded from the study.