Electrical impedance myography, or EIM, is a non-invasive technique for the assessment of muscle health that is based on the measurement of the electrical impedance characteristics of individual muscles or groups of muscles. The technique has been used for the purpose of evaluating neuromuscular diseases both for their diagnosis and for their ongoing assessment of progression or with therapeutic intervention. Muscle composition and microscopic structure change with disease, and EIM measures alterations in impedance that occur as a result of disease pathology. EIM has been specifically recognized for its potential as an ALS biomarker (also known as a biological correlate or surrogate endpoint) by Prize4Life, a 501(c)(3) nonprofit organization dedicated to accelerating the discovery of treat