Physical therapy vs. athletic training?

I am a junior in high school. I actually go to a career center for Exercise Science/Sports Medicine and I have no doubt that this is the field I want to be in. I have wanted to be a physical therapist since middle school, but now I'm thinking I might want to be an athletic trainer. I know I can, in theory, succeed in anything I choose... But the problem is that I don't really understand sports. (I know, it sounds lame...) I've always been more into books than athletics. Don't get me wrong, I am all about sports injuries and sports med, but I don't understand all the rules and regulations of the games themselves. I'm a great student and I know it... I've got a 4.5 GPA, I'm taking Pre-calculus, Chemistry, and Anatomy. I know I'm talented and I know I'm smart. How much will the whole not-understanding-sports set me back? Should I not even try to get into this career?