Okay I admit it Im a little confused why does cardio have to be done 8 hours before weight training

counter productive i guess. Your body needs simple carbs and protein straight after for muscle rebuilding, and adding cardio straight after might inhibit it.

(not sure, let someone else confirm or not).

counter productive i guess. Your body needs simple carbs and protein straight after for muscle rebuilding, and adding cardio straight after might inhibit it.

(not sure, let someone else confirm or not).
Thank you for your first response what about before you weight train I would do a mile just to break a sweat and looseing up??????????

Before you lift isn't great, because if you're tired from running, you won't be able to lift as well, and you won't gain as much.

Before a weight training session I'll usually do about a 5-10 minute very moderate cardio session. Actually I wouldn't even call it a cardio session. It's just a warmup to get blood warm and what-not.

I wouldn't recommend a full out cardio session before the weights personally because, from my experience and with me anyway, it sucks the energy out and I don't lift with as high of an intensity level.

To add what the others have said, if you do cardio right before weights you deplete the glycogen and ATP stores of the muscles leading to a poor weights workout (no energy). If you do cardio right after weights you inhibit the ability of your muscles to recover. This is putting it in simple terms, Im sure some of the more knowledgable members on the boards could give you a more technical explaination.

Take note though, doing cardio before or after weights doesnt make either workout pointless, it just reduces the effectiveness of the workouts. Sometimes when I'm having a busy day, I'll have to compromise and do them together, but usually I try and seperate them by the usual 8 hours.

I'm not sure what study the 8 hours comes from but it is the generally accepted time (well, I don't know how accepted it is) it takes to replenish glycogen stores after areobic activity. And eating more afterwards won't speed that up.