Chronic obstructive pulmonary disease (COPD) is a significant, preventable, and treatable public health problem and a growing cause of chronic morbidity and mortality worldwide. Frailty is a biological syndrome resulting from a progressive decrease in the reserve capacity of multiple physiological systems. COPD and frailty are closely associated with common risk factors such as aging, tobacco use, impaired neuroendocrine function, immune system dysfunction, and chronic inflammation.

Cardiopulmonary exercise testing (CPET) is a valuable tool for assessing exercise capacity, evaluating the severity of limitations, and identifying their causes. CPET provides an objective measurement of exercise capacity with direct applications in risk stratification. It also guides rehabilitation practices, including the planning and prescription of exercise training.

COPD is associated with a systemic inflammatory process that can lead to progressive loss of muscle mass and function and sarcopenia. The prevalence of COPD in sarcopenic patients varies between 4.4% and 86.55% due to the variability of various diagnostic tools, different reference values, and threshold values presented in the literature Further research is needed in the literature regarding the role of sarcopenia and factors that may affect sarcopenia, such as cardiorespiratory exercise capacity, in a specific lung disease like COPD.

The primary aim of this study was to examine the differences in respiratory function, respiratory muscle strength, cardiopulmonary exercise capacity, rectus femoris muscle thickness, activities of daily living, balance, and frailty parameters among patients with possible sarcopenic, sarcopenic, and severe sarcopenic COPD.

The secondary aim of this study was to identify the factors affecting sarcopenia in COPD patients.

Chronic obstructive pulmonary disease (COPD) is a significant, preventable, and treatable public health problem and a growing cause of chronic morbidity and mortality worldwide. Currently, COPD is among the top three causes of death globally. Very often, the combination of impaired lung function and comorbidities leads to frailty and physical weakness. Estimates of frailty among individuals with COPD range widely; for example, 10% for a Dutch study, 11% for a Japanese study, approximately 25% for two UK studies, and 18% and 58% for US populations. Frailty is a biological syndrome resulting from a progressive decrease in the reserve capacity of multiple physiological systems . COPD and frailty are closely associated with common risk factors such as aging, tobacco use, impaired neuroendocrine function, immune system dysfunction, and chronic inflammation.

Dyspnea and exercise intolerance are common symptoms of COPD. COPD patients exhibit decreased exercise tolerance due to critical inspiratory restriction of possible tidal volume (Vt) expansion during exercise, decreased oxygen availability, and gas exchange abnormalities. Cardiopulmonary exercise testing (CPET) is a valuable tool for assessing exercise capacity, evaluating the severity of limitations, and identifying their causes. COPD is a heterogeneous condition in which physical function can be impaired through multiple mechanisms. CPET provides an objective measurement of exercise capacity with direct applications in risk stratification. It also guides rehabilitation practices, including the planning and prescription of exercise training.

Sarcopenia is a disorder that defines age-related loss of muscle mass and decreased muscle strength, and it develops due to several factors, including inflammation and chronic disease. COPD is associated with a systemic inflammatory process that can lead to progressive loss of muscle mass and function and sarcopenia. Layton et al. showed that frail lung transplant candidates have reduced exercise capacity disproportionate to the severity of their lung disease. They assessed exercise capacity with CPET. The prevalence of COPD in sarcopenic patients varies between 4.4% and 86.55% due to the variability of various diagnostic tools, different reference values, and threshold values presented in the literature. Although knowing the prevalence and diagnostic methods of COPD and sarcopenia is crucial for researching effective prevention and intervention strategies, further research is still needed in this area.

In one study, the prevalence of sarcopenia in COPD patients was found to be 24.6%. Sarcopenia was associated with decreased muscle strength and mass, walking speed, and decreased body mass index in COPD patients. Further research is needed in the literature regarding the role of sarcopenia and factors that may affect sarcopenia, such as cardiorespiratory exercise capacity, in a specific lung disease like COPD.

The primary aim of this study was to examine the differences in respiratory function, respiratory muscle strength, cardiopulmonary exercise capacity, rectus femoris muscle thickness, activities of daily living, balance, and frailty parameters among patients with possible sarcopenic, sarcopenic, and severe sarcopenic COPD.

The secondary aim of this study was to identify the factors affecting sarcopenia in COPD patients.

Inclusion Criteria:

• Individuals who were clinically stable for the past month and not using antibiotics,
• 40 years of age and older, cooperative, able to ambulate without support or assistive devices,
• diagnosed with and followed up at the Chest Diseases Outpatient Clinic of Bursa City Hospital,
• evaluated for sarcopenia by an internal medicine and geriatrics specialist,

and volunteered to participate in the study were included.

Exclusion Criteria:

• Individuals with any additional neuromuscular, musculoskeletal, cardiac, rheumatological, neurological, psychiatric or orthopedic disease,
• other chronic diseases that may affect balance and walking,
• cognitive impairment (Mini Mental Test score <24) (13) were not included in the study.

This study will be conducted with COPD patients referred to the Physical Therapy and Rehabilitation Department of Bursa City Hospital for cardiopulmonary rehabilitation. For sample size analysis, the study by Tsekoura et al., which examined the prevalence of sarcopenia and factors affecting sarcopenia among COPD patients, was used. Sample size analysis was performed using the SCALEX SP program (Heinrich Heine University, Düsseldorf, Germany). Based on the frailty prevalence (24.6%) in the study by Tsekoura et al., and considering the 20% patient mortality rate, at least 41 COPD patients need to be included in the study to reach the required significance level of 0.05.