Well, you don't really get to the Olympian athlete or Mega-mind levels in the game. You just train to an "exceptionally good shape" and a "top student in your grade". Which are both very possible within a span of a year if you put your mind to it. The fact that you can get from 5 to a 100 withing a couple of months, and do all five skills within a year, well, that we'll have to write off as magical intervention =D
As for Elizabeth's sports outfit, well, I guess you'll have to wait for this one. As she is not in the same grade as you, and you have very few chances to see her in her sports outfit (unlike Gwen), she will have a very low priority there. Nonetheless, she does have a few new outfits planned for her. At least one of which should be pretty saucy =)