I have a concern regarding cardio vs. weight training. I'm currently exercising to gain muscle mass, sculpt my body, and my weight is not a concern at all. However I've also been doing some cardio work. It is counter-productive do both weights and cardio? I normally go to the gym and spend 15-20 on an x-trainer or stationary bike, or I ride my bike to the gym, then I lift weights. When I do cardio work it's not just a light ordeal, I put a lot of effort into it. I realize that you need to get the blood flowing before you can lift, but am I spending too much time doing cardio before hand? and burning muscle beforehand.