Fast twitch muscle fibers are prone to degradation in skeletal muscle pathologies, such as sarcopenia and muscular dystrophies. We previously showed that the exercise-induced long noncoding RNA CYTOR promotes fast-twitch myogenesis. Here, we identify an independent functional element within human CYTOR, and optimize its RNA delivery. In human primary myoblasts exogenous CYTOR exon 2 recapitulates the effect of full-length CYTOR by boosting fast-twitch myogenic differentiation. Furthermore, chemically modified CYTOR