Why do I want to have a long run?

The purpose of a long run is to deplete your glycogen levels close to empty. What is glycogen level? Glycogen is like your backup fuel. It releases glucose into the bloodstream when the body needs a quick energy boost or when a person's blood glucose level drops.

But why would you want to do that? The answer to that is, for the recovery process. While you are recovering, your glycogen levels are now being restored. With training, over time your glycogen levels will restore in time for your next run the following day. Which indicates that your body has now adapted to recovering from a long run. This is important because when your body is able to effectively perform the “LONG RUN” this way, your body is able to recover from all your runs in the following weeks. In other words the long run sets your GLYCOGEN BASE, which all other runs will feed off of.

GLYCOGEN IS MUSCLE FUEL

While running, your muscle fuel is GLYCOGEN, and through out your long run the goal is to almost deplete almost all glycogen stores that you currently hold. During your long run you need to make sure to give your body the proper sources for energy and fuel.

It is impossible to fuel glycogen and energy stores completely while running because your burning 100+ calories a mile, and also with anaerobic muscle strain continuing over time, the processes are too numerous to keep from happening.