The Skinny On Muscles

What's happening to our bodies before, during, and after exercise.
We all know exercise is good for us. We remind ourselves of it whenever we’re tempted to sleep in instead of work out or go home after work instead of to the gym. But what’s actually happening to our bodies during exercise? Does it really give us more energy or is that all in our heads? And does carbo-loading actually do anything for my workouts?