Our study aims to investigate changes in serum calprotectin levels in patients with axial spondyloarthritis enrolled in a pulmonary rehabilitation programme and to examine the relationship between serum calprotectin levels and NLR (neutrophil-lymphocyte ratio), PLR (platelet-lymphocyte ratio), SIRI (systemic inflammation response index), SII (systemic immune-inflammation index) values, pulmonary function tests, disease activity scores, and quality of life. It will be conducted between 2 April 2025 and 1 April 2026. Patients diagnosed with axial SpA who were enrolled in the pulmonary rehabilitation programme at the Cardiopulmonary Rehabilitation Unit of the Department of Physical Medicine and Rehabilitation at Giresun University Training and Research Hospital between 21 August 2025 - 24 February 2026, patients diagnosed with axial SpA who are enrolled in the pulmonary rehabilitation programme will be evaluated according to inclusion and exclusion criteria, and 30 suitable patients will be included in the study. The following data will be recorded for these patients: age, gender, occupation, duration of diagnosis, medications used, presence of additional diseases, anthropometric measurements (chest expansion test, occipital wall, tragus wall, finger span), BMI, and history of smoking and alcohol consumption. For patient follow-up, the results of routine haematological tests, acute phase reactants, and spirometry examinations performed before and after the rehabilitation programme will be recorded. Data obtained from haematological test results will be used to calculate NLR, PLR, SIRI, and SII values. Additionally, serum calprotectin levels will be measured from the blood sample taken for CRP. The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), Ankylosing Spondylitis Disease Activity Score-C Reactive Protein (ASDAS-CRP), Maastricht Ankylosing Spondylitis Enthesitis Score (MASES), the Nottingham Health Profile (NHP), the Health Assessment Questionnaire (HAQ), the St George's Quality of Life Questionnaire (SGRQ), the Modified Borg Scale, and the 6-Minute Walk Test will be evaluated. The outcome measures recorded at the start of treatment will be repeated after a four-week rehabilitation programme.