[Hayden Giuliani recently finished her Master's degree at the University of North Carolina Chapel Hill, where she now works as a research coordinator. She is currently in the Coaching Mentorship Program at Athletic Lab.] It seems like the best way to improve running long distances would be to run long distances. Endurance breeds endurance. Just like the best way to get better at a particular sport would be to play that sport. Over the years, coaches and researchers alike have begun to take a different perspective on that thought. Can doing a seemingly contradictory form of training actually improve endurance performance? If we sort through the research, it seems the answer is yes. In the article, I will break down the characteristics of endurance athletes, the types and descriptions of sprint training, and the implementation of sprint work into endurance training. Endurance athletes are well-conditioned individuals that perform long events, such as running, cycling, or triathlons. Endurance-trained persons typically exhibit certain characteristics, including, but not limited to, high maximal oxygen intake (VO2 max), efficient running economy, a high proportion of type I fibers, and leaner body composition. This simply means they can perform at a high capacity for a long period of time, yet they also tend to be less proficient at strength and power tasks. The typical training program for endurance athletes, which includes runners, cyclists, or triathletes to name a few, would include multiple longer bouts throughout a week's time. When individuals think of aerobic training, it tends to be very compartmentalized. For instance, there is the immediate energy resource of creatine phosphate, in contrast to lipids which are used over prolonged periods of time. This compartmentalization isn't necessary; the systems are always [...]