Magnetomyography for skeletal muscle function assessment: prospective applications in sarcopenia

Sarcopenia is a progressive and generalized skeletal muscle disorder characterized by loss of muscle strength, reduced muscle quantity or quality, and impaired physical performance. It is associated with adverse outcomes including falls, fractures, physical disability, and mortality, and represents a growing global health concern. However, currently available clinical assessments provide limited information on the electrophysiological and neuromuscular alterations that may precede overt functional decline. Magnetomyography (MMG)—here defined as the non-invasive detection of biomagnetic fields generated by skeletal muscle electrical activity and distinguished from mechanomyography—offers a contactless approach to characterizing muscle electrophysiology. Recent advances in optically pumped magnetometers, portable magnetic shielding, and signal-processing methods have expanded the feasibility of MMG for detecting muscle action potentials, motor-unit activity, fatigue-related changes, and training adaptations. In this perspective review, we summarize the principles and technological development of MMG, critically evaluate current evidence for skeletal muscle assessment, and discuss its potential relevance to sarcopenia. In particular, we propose a conceptual framework in which MMG could complement established assessments by characterizing neuromuscular integrity, investigating potential neural and muscular contributions to functional decline, and monitoring responses to intervention. Importantly, direct evidence in individuals with sarcopenia is currently lacking, and MMG remains an experimental rather than clinically validated diagnostic approach.