Correlation between Body Composition and Cardiopulmonary Exercise Capacity in Patients with Chronic Obstructive Pulmonary Disease

Background Cardiopulmonary exercise testing (CPET) is essential for assessing the maximal exercise capacity of patients with chronic obstructive pulmonary disease (COPD) and for developing rehabilitation prescriptions. Body composition has been shown to be associated with CPET results, which is complex, time-consuming, contraindicated, and risky, and cannot be performed in some COPD patients, whereas body composition analysis is simple and fast. Objective This paper focuses on the correlation between body composition and CPET in patients with COPD, and provides a basis for predicting maximal exercise capacity, formulating rehabilitation prescriptions, and rational nutritional support for patients with COPD who are unable to complete cardiopulmonary exercise testing. Methods Stable COPD patients were enrolled in the outpatient respiratory clinic of China-Japan Friendship Hospital between July 2021 and March 2022, and were sequentially subjected to body composition measurements and CPET with continuous incremental loading, and the test results were analyzed to assess the relationship between body composition and CPET results, and to analyze the value of the body composition indexes in predicting the results of CPET. Results Seventy-seven eligible patients with stable COPD completed body composition measurement and exercise cardiopulmonary exercise testing. Correlation analysis showed that body fat percentage (BFP) was negatively correlated with peak metabolic equivalents (peakMETs) (P<0.01) ; skeletal muscle mass index (SMI) was positively correlated with peak oxygen uptake (peakVO2), peak load, peak ventilation volume (peakVE), maximum heart rate (peakHR), peak oxygen pulse (peakO2pulse), and oxygen uptake efficiency slope (OUES) at the highest exercise state were positively correlated (P<0.01) ; and the fat free mass index (FFMI) was positively correlated with peakVO2, peakLoad, peakVE, peakO2pulse, and OUES (P<0.01). The results of multivariable linear regression analysis showed that SMI and FFMI were independently and positively correlated with peakLoad, peakVE, peakO2pulse, and OUES in patients with COPD (P<0.05). BFP was independently and negatively correlated with peakMETs in patients with COPD (P<0.05). SMI had better predictive ability than FFMI for the results of the CPET trial in COPD patients peakLoad, peakVE, peakO2pulse, and OUES. Conclusion Muscle content is positively correlated with the exercise capacity of COPD patients, and the results of body composition measurement can be used as an important criterion for predicting the exercise capacity of COPD patients, guiding the rehabilitation exercise and rational nutritional support therapy.