Defining Run Economy

From My Tri Life

The point being: What we do know is that running economy tends to improve when we introduce the Progressive Overload Principle into our training. Why? Because progressive overload is what induces these adaptations.....No matter how you look at it, doing a lot of running at goal race pace, by itself, is not a factor in improving your running economy. It can only become a factor when the stimulus associated with training at goal race pace just so happens to be responsible for creating an overload and therefore eventually inducing an adaptation.