There is no doubt training put in. They are professionals competing at the peak of their chosen sports at the end of the day. However, humans have a limit. And to say that training techniques can evolve and deliver improvements, though incremental, on an ongoing basis whilst delivering these to expecting fans is highly unlikely.
Even your weekend warriors are juiced up to the gills thesedays. With social media and smartphones, you can see off-season bodies on the built athletes. The endurance types are a little trickier to see, but look at Lance Armstrong and what his crew did for many many years. This is just the tip of the iceberg. Running would also be in the same boat I am sure.
A well trained natural athlete will still beat out an enhanced semi-pro athlete by the way. Just like I am stronger and faster than someone who wants to only look good and compete topless in races. However, I would get smoked by someone who is even remotely serious about results who takes performance enhancing drugs. It is what it is.