Since its origin in 2011, The Preseason Project has been a powerful triathlon training research environment and a catalyst for continuous improvement and innovation. The participating athletes themselves have made this possible. Training data and direct feedback from more than 15,000 triathletes has driven significant measurable improvements over industry norms in training efficiency, race results, and overall athlete experience. This has fundamentally changed how athletes train and how coaches coach. Today we look back on the history of the Preseason Project and the milestone findings, results, and events that have defined its continuing influence on the triathlon industry.