Myotonic dystrophy type 1 (DM1) is a multisystem trinucleotide repeat expansion disorder characterized by the misregulated alternative splicing of critical mRNAs. Previous work in a transgenic mouse model indicated that aerobic exercise effectively improves splicing regulation and function in skeletal muscle. In this issue of the JCI, Mikhail et al. describe the safety and benefits of applying this approach in individuals affected by DM1. A 12-week aerobic exercise program improved aerobic capacity and mobility, but not by the mechanism observed in transgenic mice. Here, we consider the possible reasons for this disparity and review other salient findings of the study in the context of evolving DM1 research.