OpenSim is a biomechanical physics environment for musculoskeletal simulations. Biomechanical community designed a range of musculoskeletal models compatible with this environment. These models can be, for example, fit to clinical data to understand underlying causes of injuries using inverse kinematics and inverse dynamics. For many of these models there are controllers designed for forward simulations of movement, however they are often finely tuned for the model and data. Advancements in reinforcement learning may allow building more robust controllers which can in turn provide another tool for validating the models.