Just a simple anecdote recently Meb Keflezighi posted a photo of his watch from his last long run before a marathon . He completed it at 637 pace . That ' s a man that can run ~ 500 mile for 26 miles running a shorter run at more than 90 secondsmile slower . It might end up being A LOT slower than race pace . Two tests to determine easy pace 1 . 4 steps for every breath in , 4 steps for every breath out . Works best if you are at a more typical cadence 160180 but applies for most . 2 . The talk test . This is done best with a training partner otherwise you might sound crazy but it is how you should be able to speak for 23 sentences without feeling out of breath while working at your current intensity . These are very much feel tests . They might change day to day based on your previous workout , level of sleep , nutrition , and stress . Adapting each day is a good thing though and being vigilant of the need to change is essential to run healthy .