Harvard Medical School - Beth Israel Deaconess Medical Center 1 article published in JoVE Biology Performing In Vivo and Ex Vivo Electrical Impedance Myography in Rodents Marie Mortreux1, Janice A. Nagy1, Haowen Zhong1, Dong-Min Sung1, Holly A. Concepcion1, Melanie Leitner2, Laura Dalle Pazze3, Seward B. Rutkove1 1Department of Neurology, Harvard Medical School - Beth Israel Deaconess Medical Center, 2Accelerating NeuroVentures, 3 This article details how to perform in vivo (using surface and needle electrode arrays) and ex vivo (using a dielectric cell) electrical impedance myography on the rodent gastrocnemius muscle. It will demonstrate the technique in both mice and rats and detail the modifications available, (i.e., obese animals, pups).