MYH(myosin heavy chain) is a critical component of the sarcomeric thick filaments in heart muscle fibers, playing a central role in muscle contraction by interacting with actin filaments to generate force. Myosin is a hexameric protein composed of a pair of myosin heavy chains (MYH) and two pairs of nonidentical light chains. Myosin heavy chains are encoded by a multigene family. In mammals at least 10 different myosin heavy chain (MYH) isoforms have been described from striated, smooth, and nonmuscle cells. These isoforms show expression that is spatially and temporally regulated during development. Post-translational modifications of the myosin heavy chain, such as phosphorylation, glycation, and oxidative modifications, can alter cardiac muscle contractility and responsiveness to physiological stimuli. Dysregulation of these modifications has been implicated in cardiac diseases such as cardiomyopathies and heart failure.