Radiant floor heat is a great choice for bathrooms, but NOT for gyms or fitness rooms. Most newer fitness floors are stacked or layered rubber, like Ecore Rally. This has more give, vibration resistance, and sound absorption than older hard rubber floors. But it also has a high 'R' rating, so the heat won't transfer, and many fitness floors can expand or contract based after an install with radiant floor heat.
Further, depending on the type of adhesive, there could be offgassing from the glue or breakdown of the glue.
Almost no fitness floor works well with radiant heat, and I've had a number of unhappy clients recently that already had radiant floor heat set up before their gym was designed. Having their best choices pulled from the table makes everyone look bad.
If you have any questions, please feel free to reach out.