The moment you think of martial arts you think of one thing first: insanely fast punches and kicks. Certainly that is part of it. Repetition of techniques, over time, builds up speed in execution. But that is only part of it. Good fighters are fast not because they can react fast but because they can predict what their opponents are going to do and then move to counter it. Sometimes, the very best fighters, can precipitate an opponent’s move by adequately reading them from the start and controlling their movements through an action/reaction plan. But even those who cannot are usually pretty good in seeing what’s coming long before it does. It takes a little time and some experience but it’s not magic. From any given physical position there are only a limited number of moves that are available and they can be telegraphed in advance by the posture of the fighter. It takes a little practice.