Where is the evidence that chronic physical inactivity leads to raised muscle glycogen? Quite the contrary, endurance training leads to increased muscle glycogen content. For example, see the attached file. I am assuming you are not talking about very transient changes in muscle glycogen that might occur with the onset of physical inactivity.
Physical activity leads to an increase in muscle glycogen and a more efficiente utilization of the glucose. The opposite occurs with chronic physical inactivity