It seems like to me that NFL Athletes have access to resources similar to some pro Xtreme Athletes.

Take Pro Motorbike Trick Athletes for example some of them are be able to build massive foam pits to practice over and over whatever trick they want to show off to a crowd without having to worry about getting injured.

I think something similar could be said about NFL Athletes. I would imagine that they are able to practice and train in a way that allows them to push their limits daily without injuring themselves in the process.