Non invasive techniques for muscle quality functional domain monitoring in older adults: a scoping review
Abstract
Background: The EWGSOP update emphasizes the importance of assessing muscle quality (MQ) as a key indicator of skeletal muscle function. MQ defined by functional domains, reflects how effectively a muscle generates force relative to its size, often quantified through muscle quality index. Age-related declines in MQ typically precede loss of muscle mass, highlighting its potential as a more sensitive functional marker. This review focuses on indirect non-invasive techniques for assessing the functional domain of MQ, which are practical, accessible, and widely applicable in older populations. Therefore, the aim is to map and synthesise current evidence on non-invasive tools to assess functional MQ in older adults as well as to promote the adoption of accessible and simple methods in community settings. Results: A total of 79 studies were included. The definitions align with indirect measures of muscle function relative to muscle mass (strength per unit of muscle mass). For strength assessment, key tools included handheld dynamometers, isokinetic dynamometers, leg power tests, RM testing, and combined strength measures. For muscle mass, methods included dual energy X-ray absorptiometry (DXA), ultrasound, bioelectrical impedance analysis (BIA), magnetic resonance imaging (MRI), and computed tomography (CT). Conclusions: This review highlights the heterogeneity in MQ, particularly in the methods used to assess muscle strength and mass. A variety of non-invasive tools are available for assessing MQ, with handheld dynamometers and 1RM tests being practical for community use, while isokinetic dynamometers and power assessments are more specialized. For muscle mass, MRI, DXA, and CT are widely used to assess structural and compositional aspects of muscle but costly, whereas BIA and ultrasound offer more accessible and cost-effective alternatives for community settings.
Keywords: Muscle quality, funional domain, non invasive techniques, older adults, assessment methodss