Adolescent idiopathic scoliosis result in deterioration of core muscles and respiratory system. Core muscles provide trunk stabilization as well as responsible for respiratory system. Especially tr. abdominis, rectus abdominis, external oblic and internal oblic muscle, which are core muscles, highly active during forced expiration while diaphragm muscle also active during inspiration. Thus, expiratory muscle strength training has effect not only respiratory muscle strength but also trunk stabilization. While, effects of expiratory muscle strength training in adolesecent idiopathic scoliosis is a topic that needs to be investigated, this topic has not been investigated until today. Hence, this current study aimed to investigate the effects of expiratory muscle strength training on cobb angle, respiratory muscle strength, core stabilization, functional exercise capacity and quality of life.

A convenience of children with adolescent idiopathic scoliosis, 10-19 years, is going to recruited from Gazi University, Faculty of Health Sciences, Department of Physiotherapy and Rehabilitation. Patients will randomly allocate to either a treatment group or control group. The treatments group will receive expiratory muscle strength training at 50% maximal expiratory presssure while, the control group will receive sham expiratory muscle strength training without physiological load. Groups are going to train for a total of 25 breathe/day, 5 days/week, for 6 weeks. Before and after treatment, all of patients progression of scoliosis will be evaluated by calculating cobb angle, respiratory muscle strength using with electronic mouth pressure device, core stability using with Mc-Gill endurance test and the stabilizer biofeedback unit, functional exercise capacity using with six minute walk test (6MWT) and six minute pegboard and ring test (6MPBRT), quality of life using with scoliosis research society -22 questionnare (SRS-22) and daily living activity of upper extremity using with quick-DASH questionnare.

Inclusion Criteria:

• Individuals diagnosed with idiopathic scoliosis,
• aged between 10 and 19 years,
• with a Cobb angle ranging from 10 to 45 degrees.

Exclusion Criteria:

• Individuals who have undergone spinal surgery,
• who have received conservative or surgical treatment for scoliosis,
• individuals with neurological, neuromuscular, systemic, rheumatological, or musculoskeletal disorders, or conditions affecting balance and walking,
• individuals with a history of cardiac or pulmonary diseases that could affect respiratory function and exercise capacity.