Alex shares the science and the mysteries of endurance, a subject near and dear to all runners. From short sprints to ultra-marathons, endurance plays a crucial role and today we find out what it is and how to extend it. Alex covered Nike’s Breaking 2 project in 2017 where elite marathoner Eliud Kipchoge attempted a sub-2 hour marathon, albeit in fabricated and controlled conditions. Kipchoge came up just short, but in so doing, showed us how close the human body actually is to breaking this wall.