Is Susan Just a Freak of Nature?

So why is it that after those killer work outs that the other girls were sore and I wasn't? As little as only four years ago I used to get really sore just like anyone else. You know that "ooh-don't-touch-me-there-and-I-can't-barely-get-down-to-the-toilet-sore-muscles." It was normal, but not [...]