I hear of many piano players that do "warm up" excercises (and by that, they mean that they play on the piano a bit, for example Hanon, or things like that). I myself have also made the experience that after some minutes of playing, my playing gets smother, and the likelyhood I "miss" a key (miss in the sense that the force applied to the key actually is too small, which results in the key remaining silent) shrinks. I especially observe the same effect (stronger keystrokes, basically) when I exaggerated the movements before, and pressed the keys way stronger than they usually should be pressed.
An explanation I have read once (don't know anymore where I have read that) is that those kind of "warm-up-exercises" result in a (temporarely) higher tonus of the muscles, which results in a temporarely perceived higher ability to press keys. Is this explanation valid?
Are the observations that I have made all linked to "warming up" helping my playing? What exactly does warming up do to my muscles and my tendons, that leads to a higher ability of playing smooth runs on the piano?
Edit: To be honest I'm rather unhappy with the question having been migrated to this page, because a) it is common to do "warming up'" on the piano (In the way I described), b) it doesn't have that mutch to do with the warm ups in sports (stretching and such), and c) I would have hoped for opinions of pianoplayers and there experiences with "warming up". I haven't been asked wether I want this question to be migrated either.