The increase in the elderly population worldwide necessitates further research on age-related physiological changes and health problems related to these changes in geriatric individuals. One of these problems, sarcopenia, is a syndrome characterized by a decrease in muscle mass, muscle strength, and physical performance due to aging. Sarcopenia affects not only the extremity muscles but also the respiratory muscles, significantly reducing the individual's functional capacity and quality of life. Sarcopenia is a progressive and widespread loss of skeletal muscles, characterized by a decrease in muscle strength, muscle mass, and physical performance. Although it is usually seen in older individuals, it can also occur in people with certain diseases or who lead a sedentary lifestyle. The European Working Group on Sarcopenia in Older People (EWGSOP) has developed a guideline for the diagnosis of sarcopenia and determination of its severity. In line with this guideline, the EWGSOP considers sarcopenia in three basic stages: pre-sarcopenia, sarcopenia, and severe sarcopenia. Pre-sarcopenia is the stage in which muscle mass is low but muscle strength or physical performance is not yet affected. Sarcopenia is the stage in which low muscle mass is accompanied by decreased muscle strength or low physical performance. Severe sarcopenia is defined as the most advanced stage in which all these criteria are met. Respiratory muscle sarcopenia is defined as muscle fiber atrophy and weakness in the respiratory muscles. The Japanese Respiratory Sarcopenia Study Group defines this condition as whole-body sarcopenia with low respiratory muscle mass, decreased respiratory muscle strength, and/or respiratory dysfunction. Kera et al. (2019) evaluated respiratory muscle sarcopenia according to the peak expiratory flow rate value. However, whole-body sarcopenia and respiratory muscle strength are considered important parameters in the definition and diagnosis of respiratory muscle sarcopenia. It is reported that the rate of respiratory muscle sarcopenia is higher in the presence of sarcopenia. Sarcopenic respiratory failure is diagnosed in the presence of sarcopenia accompanied by functional disability, while individuals without functional disability but at risk for respiratory muscle sarcopenia are considered "at risk of sarcopenic respiratory failure". Sarcopenia is thought to be associated with insulin resistance and oxidative stress, leading to decreased muscle strength and muscle mass, as well as muscle atrophy. Respiratory muscles may also be affected in a similar way. Thus, weakening of respiratory muscles may lead to decreased respiratory function and decreased quality of life. In the current literature, studies examining the effects of aging on respiratory muscles are limited. Therefore, determining the potential effects of aging on respiratory muscles and evaluating respiratory muscle sarcopenia in this context may provide an important contribution to the development of new approaches and the literature.
