Surface Electrical Impedance Myography in Assessment of Morphofunctional Changes in Biological Tissues and Biofeedback Interfaces

Electrical impedance myography (EIM) is a noninvasive bioimpedance technique used to assess the structural and compositional properties of muscle tissue. It involves passing a low-intensity probing current between current electrodes and recording the resulting potential difference across measuring electrodes positioned over the muscle of interest. The complexity of signal interpretation lies in the mechanisms of its generation, which are based on dynamic morphofunctional changes in muscle tissue and the skin-fat layer during contraction, which remain incompletely understood. The aim of this review is to summarize current knowledge on the application of EIM in assessing morphofunctional changes in biological tissues for diagnostic, rehabilitation, and biofeedback purposes, taking into account the EIM signal generation mechanisms. Building upon current knowledge, the paper outlines promising avenues for future research in this area. This review includes research papers, review articles published in English from 2016 to 2025, in which EIM was used for diagnostic, rehabilitation, or biofeedback purposes. The selection criteria were experimental or clinical design involving humans or animals, the presence of quantitative data linking impedance parameters to physiological tissue properties, and the use of standard measurement techniques. The review included 51 papers selected from a search of the Scopus database covering 2016–2025 and conducted in accordance with the PRISMA-ScR criteria; a total of 458 records were identified, of which 51 studies were included in the final analysis after screening and full-text assessment. A small number of publications from 2026 are cited as supplementary background and were not part of the formal screening count. The conducted scoping review showed that EIM is a promising and informative tool for non-invasive assessment of the morphofunctional conditions of skeletal muscles, demonstrates a correlation with the muscle contraction force, and can be used as an independent or additional method for diagnostic and rehabilitation purposes. Despite the promise of the method, further detailed research signal generation mechanisms is needed. This includes the assessment and isolation of the contribution of various biological tissues to the recorded EIM signal, taking into account the determination of the electrode system location over the target muscle.