Muscle elasticity variations in assessing age‐related changes in adults – A systematic review

Aim Muscle loss of strength, mass, and function is a natural process that occurs with aging. It is referred to as sarcopenia and represents a major cause of disability. The assessment and quantification of muscle have garnered considerable interest, leading to the recent introduction of shear wave elastography (SWE) as a noninvasive and accessible method for evaluating muscle. Considering this, our systematic review aimed to define the impact of aging on muscle using SWE. Methods We examined publications spanning the past decade, specifically focusing on muscle elasticity in the healthy older population. We finally included 15 cross‐sectional studies, which evaluated a great variety of anatomical regions using SWE. Results Although all studies compared muscle stiffness across age groups, the age cut‐offs varied widely. Findings revealed reduced or unchanged stiffness in relaxed muscles, decreased stiffness during contraction, and increased stiffness during passive stretching. Sex effects were inconsistent, with some studies reporting higher elasticity in males and others noting greater stiffness in females. SWE also showed a positive correlation with muscle function tests. Conclusions These insights highlight the importance of refining standardized SWE protocols to enhance the accuracy and reliability of future studies on muscle stiffness and aging. Owing to the substantial variability in methodologies, a meta‐analysis could not be conducted. © 2025 Japan Geriatrics Society. Geriatr Gerontol Int 2025; 25: 855–863 .