Is dynamometry able to infer the risk of muscle mass loss in patients with COPD?

Introduction: Sarcopenia is characterized by a progressive and generalized decrease of strength and muscle mass. Muscle mass loss is prevalent in patients with chronic obstructive pulmonary disease (COPD) as a result of both the disease and aging. Some methods have been proposed to assess body composition (and therefore identify muscle mass loss) in this population. Despite the high accuracy of some methods, they require sophisticated and costly equipment. Aim: The purpose of this study was to infer the occurrence of muscle mass loss measured by a sophisticated method (dual energy X-ray absorptiometry [ DEXA]) using a more simple and affordable equipment (dynamometer). Methods: Fifty-seven stable subjects with COPD were evaluated for anthropometric characteristics, lung function, functional exercise capacity, body composition, and peripheral muscle strength. A binary logistic regression model verified whether knee-extension strength (measured by dynamometry) could infer muscle mass loss (from DEXA). Results: Patients with decreased knee-extension strength were 5.93 times more likely to have muscle mass loss, regardless of sex, disease stage, and functional exercise capacity (P=0.045). Conclusion: Knee-extension dynamometry was able to infer muscle mass loss in patients with COPD.