After going through several dozen Stack Exchange betas so far, if there's one thing I've learned, is that nothing hurts a young Stack Exchange more than appearing to be a place for those who only have a superficial level of knowledge in the subject.
What do I mean by that?
The purpose of this seven-day private beta is to stock up the site with a bunch of on-topic, expert questions and answers about fitness and nutrition, so that when the site opens to the public, it's already pre-populated with a bunch of the kind of content that will attract other fitness experts.
It's tempting to start with broad, subjective questions, like "What is the best exercise?" or "What is the perfect diet for … ?" or "Does system [X] actually work?"
Those are not good questions for the private beta, because ultimately, they don't reflect the actual content that we want this site to contain, and are not representative of it. Once the site gets going and accumulates some quality content, come back and ask those canonical, basic questions. But hold off on them for now; they are only hurting the long-term prospects for the site. Please read: Asking the First Questions.
If you're a fitness expert and stumble into this site, if you see the an actual, intriguing question faced by professionals, you might think, "wow, yeah, this is a site for people like ME."
If you see a question about what blogs to read you'll think "Oh boy, just another site for gym-rats and overweight people looking for a quick-fix diets."