I can't speak to fast or slow twitch muscle fibers--that confuses me, too. But I can tell you that if you are looking for a "body builders body" you need to lift HEAVY. Even when doing more of an endurance tape like ME, you want to lift as heavy as you can with good form. You want to be careful not to lift so heavy that the "speed" that Cathe is working at puts you at risk for injury. How do you know whent hat is? I feel like I'm moving too fast, like it's just not there. I drop my barbell weight to 5 or 8 lbs less than I started if I feel like that.
I have been working out for 3 years, consistently. I didn't start seeing real muscle changes until I quit being afraid of the burn & started lifting heavy. Now in 4 months I've actually got a bicep & am starting to build delts. I still don't have the definition I want but my arms are looking pretty darn good, if I do say so myself. My legs for whatever reason build muscle pretty easily & except for the upper portions of them, have looked pretty good for while. But with adding weight to my bar (I can almost lift as much as Cathe), I am seeing great things happen to my legs.
Also, keep in mind to get definition in your body you will need to eat a very clean, higher protein diet. DON'T ever deprive yourself. Even Cathe eats an occassional piece of cheesecake. I read that somewhere here & it stuck with me because someday I'm going to look like her. Ok, maybe not but a girl can dream, right? LOL Anyway, I've been playing with my meals & have actually had great strength gains & body fat loss with really watching my fat intake & increasing my protein. I AM NOT A NUTRITIONIST (my little disclaimer), so I don't know what would work for you.
Finally, I'm reading in a few places that cutting down on cardio is actually good for you. Doing 2 or 3 sessions a week at 30 minutes in your target heart range (180-your age + or 1 5 points) is what some people are saying is optimal for fat burning. A few girls here have posted results if you want to do a search on "reduced cardio" or "cutting cardio" I think you'll find that. Other people are cardio lovers & say you can't reduce body fat without hours of cardio. I actually stopped doing cardio for 2 months & have not gained weight at all & have built more muscle. So, it's all an experiment for your body.
Hope this information is helpful to you.
