This study aims to develop a muscle-specific multimodal artificial intelligence (AI) model for the diagnosis of sarcopenia and to investigate the effects of rehabilitation training on muscle aging. Clinical, functional, and imaging data will be collected from participants with muscle function decline. Multimodal data, including muscle function measurements and clinical assessments, will be integrated to develop and validate an AI-based diagnostic model for sarcopenia. In addition, the effects of rehabilitation training on muscle function and muscle aging-related outcomes will be evaluated. The results of this study are expected to contribute to the development of digital biomarkers and precision rehabilitation strategies for sarcopenia.