The empire hates cheating and manipulation of honest trades or sports. There is an explosion of sports and athletic events and all that. So. They are very popular.
Sports in general include stuff like: racing on foot or on horses, gladiatorial style games, handball, other ball related sports, rowing, martial arts like our MMA or boxing...etc.
To that end at some point an office was made titled: The office of anti sports cheating and dishonest practices.
This means that they investigate stuff like betting and match fixing but also the medical aspect of the equation which I'm focusing on. I'm only interested in the medical aspect here but giving this for context
There is also another organization which is the doctors guild which would work as you expect. The purpose of mentioning this is to provide you with that fact that the setting has a great deal of standardization and scientific practices across the whole empire. This again should help you the limitation of the solution.
But the problem is that so far we are dealing with 1500-1550 technology.
That leads me to ask: Is there a scientific way for doctors of the time to detect the usage of drugs or similar substances that enhance athletes giving the effect of what we now call steroids...etc in athletes?
Please note I'm only asking for a possible, if it is possible, way for doctors to figure that out. Do not worry about the cost of testing, I will try to figure out the implantation of that into my world. It's like saying to a bunch of scientists make me a cure for this disease and let me worry about the costs. The world building elements for context and overall limitations
If that is not possible what is the next best scientific solution?