With the growing aging population, interest in age-related declines in muscle mass and strength has increased. While sarcopenia has traditionally been defined by the loss of appendicular skeletal muscle, the concept has recently expanded to include respiratory muscles, leading to the emerging term respiratory sarcopenia. Respiratory sarcopenia is recognized as a potential contributor to dyspnea, reduced exercise tolerance, and secondary health deterioration in older adults. This review summarizes the evolution of diagnostic criteria for sarcopenia and explores their application to respiratory muscles. In particular, we synthesize findings from studies conducted in Korean populations that investigated respiratory muscle strength, primarily maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP), and reported reference values and cut off points for clinical screening. Evidence shows significant associations between MIP and MEP and common sarcopenia indicators such as hand grip strength and skeletal muscle mass, suggesting that respiratory muscle strength can serve as a practical surrogate marker in settings where limb measurements are not feasible. Furthermore, inspiratory muscle training (IMT) has demonstrated positive effects not only on MIP and MEP but also on cough capacity and functional performance, underscoring the clinical importance of early assessment and intervention. Although consensus definitions and standardized protocols for respiratory sarcopenia remain under development, integrating respiratory muscle assessment into routine evaluations may enhance early detection and guide tailored rehabilitation strategies. Future large scale studies are warranted to refine diagnostic algorithms and establish evidence based guidelines for managing respiratory sarcopenia in diverse populations.
Lee et al. (Mon,) studied this question.