In Chronic Obstructive Pulmonary Disease (COPD), a mismatch develops between the respiratory system's demand and the functional capacity of respiratory muscles due to the combination of local and systemic factors increasing the respiratory workload. This results in impaired coordination of muscle groups, leading to muscle dysfunction. Respiratory muscle dysfunction is a significant determinant of life expectancy in COPD. Additionally, respiratory muscles unable to cope with increased workloads lead to impaired respiratory functions and reduced exercise capacity.

It is widely accepted that appropriate training of respiratory muscles can increase their strength, endurance, and their close relationship with lung volume capacities. Besides their role in respiration, respiratory muscles also contribute to postural function and core stabilization. Studies on respiratory muscle training in COPD have primarily focused on inspiratory muscle strength training, neglecting the core stabilization function of respiratory muscles. However, optimal gains in a muscle can only be achieved with training tailored to its functional characteristics. Therefore, a comprehensive training program should be developed considering the multifunctional nature of respiratory muscles. Studies published in healthy individuals and different patient populations demonstrate that core training can improve lung functions. The aim of this study is to compare the effects of inspiratory muscle training and core stabilization training on diaphragm activation, inspiratory muscle strength, functional capacity, respiratory functions, physical activity, and quality of life in individuals with COPD.

Inclusion Criteria:

• Being over 18 years old
• Having a diagnosis of COPD according to the GOLD criteria and being at stage 3 or lower
• Not being in an acute exacerbation period and having at least one month since the last exacerbation
• Being able to walk independently
• Having sufficient mental capacity to understand the tasks in the study (Mini-Mental Test >24)
• Being willing to participate in the study

Exclusion Criteria:

• Being a stage 4 COPD patient according to the GOLD criteria
• Having a diagnosis of lung cancer, pulmonary hypertension, and heart failure
• Being in a COPD exacerbation period
• Scoring below 24 on the Mini-Mental Test
• Having any other disease that affects respiratory functions
• Having undergone pulmonary surgery