glycogen needs to be broken down into a usable sugar. we break it down into glucose - 6 - phosphate, we can use this to re-synthesis ATP. The break down process if called glycolosis. we break down this glucose to get a product called pyruvic acid. in the break down to pyruvic acid, we generate two ATP, so we are able to re-synthesis 2 ATP from this process. it takes 2 ATP to do the break down so are net gain is 2 ATP.