Advancing sarcopenia assessment with wearable and app-based technology: a scoping review.

Sarcopenia, a condition characterized by loss of skeletal muscle mass (SMM) and strength, contributes to frailty, disability, and increased healthcare burden, yet remains underdiagnosed due to limitations of conventional assessment methods. Wearable and mobile technologies have emerged as potential tools for SMM evaluation, offering the advantages of portability, low participant burden, and the ability to monitor dynamic changes over time. This scoping review aims to evaluate the current scientific and clinical evidence on wearable and mobile technologies for SMM assessment and to examine their potential application for sarcopenia evaluation in home and non-research clinical settings. Literature searches were conducted across PubMed, Scopus, and Google Scholar in accordance with PRISMA-ScR guidelines. Inclusion criteria comprised original studies reporting SMM as a primary outcome using wearable devices or smartphone-based applications. Review articles and studies without original SMM data were excluded. A total of six studies were included, consisting of three wearable-based investigations and three smartphone application-based studies. Included studies primarily examined apparently healthy or physically active adults, with one study including individuals with type 1 diabetes and overweight or obesity. Sample sizes ranged from 53 to 568 participants, comprising a total of 1,235 individuals across all studies. Overall, studies demonstrated that consumer-grade wearable and smartphone technologies had constant error values (i.e., mean differences) ranging from -0.01 to 4.3 kg, correlation coefficients >0.80, and 95% limits of agreement <±4.0 kg. Criterion measures for comparisons included dual energy X-ray absorptiometry and clinical-grade bioimpedance analysis devices. Altogether, wearable and mobile technologies show emerging potential as accessible tools for SMM assessment and sarcopenia-related monitoring. However, limited study volume, restricted clinical validation, and methodological heterogeneity currently constrain clinical adoption of digital SMM tools, which should be considered adjunctive monitoring instruments rather than diagnostic replacements until rigorously validated across diverse populations.