This is a very interesting article. It explains very well the confusion with the breaking down of glycogen, the storing of glucose in the liver and the carrying of hydrogen by lactic acid out of the muscle cells to impede it from accumulating and in that way allow the hard working muscle to continue to exercise with intensity. That is why, we cyclists, have to learn how to breath properly to be able to bring more oxygen into our body when we bike with intensity to avoid the accumulation of hydrogen in the muscles.
http://www.ultrafit.com/newsletter/october04.html#Joe