What we're talking about today is stamina. Stamina is your ability to maintain a pace for a long time. Stamina comprises endurance and economy. Endurance is your ability to cover a distance or to persist for a time. Economy is a traditionally quantified as the steady state oxygen consumption at a given running velocity. For our purposes, economy of running is the energy required to run at a given pace. Today's episode is meant to introduce the key concepts and functional goals of improving endurance and economy so that you can improve stamina. Today, we also explain endurance as a capacity and how to increase endurance within the context of consistency for sufficient and relative weekly volumes. We also outline how to progress training volume of easy running and how to test your bioenergetic and physiological capacity profile with an easy run test. Then we added strides as a salvo into developing economy. Economy will be the next topic in the series on training your body for ultra-marathons.