I am most definately not an expert, but I believe that by definition almost all D1 wide receivers, dbacks, running backs and most linebackers would be blessed with what would be termed fast twitch muscles, and everything else. To me it is a reflection of their quickness, reaction time, speed, etc. For example most point guards in the SEC I would classify as fast twitchers although I am going to defer to the more qualified, i.e. doctors, trainers, players to give a more detailed explanation. I don't know if you can quantify it but I would think that anyone who runs a 4.7 fourty or faster is so blessed. Curious to hear from someone more knowledgable than I.