I recently spoke with someone in biotechnology who was doing a deep dive on "exercise pills". she told me that it would only be approved if it treated a specific disease, like muscular dystrophy, because the FDA views any potential negative side effect as too risky to approve for healthy people. Long term negative side effects are tolerable in Duchenne muscular dystrophy because those people are going to die without intervention. Once people with DMD show the safety profile it can be evaluated for more conditions.