Distance is not the ultramarathon’s absolute challenge. Rather,the challenge lies in covering the distance within a limited time frame. Most everyone reading this column could complete 100 miles in several days without much issue; however, running 100 miles in less than 30 hours would be a much greater test. Add to this the component of competition, and the objective becomes even more demanding. In order to finish under cutoffs and race well against your peers, you must perfect your ability to run at a steady pace for a long period of time. Stamina-based workouts help you achieve this through lactate threshold (LT) improvement and learning to run by effort — two essential skills when racing on rough trails or hilly road courses.