Dr. Iñigo San Millán is a professor at the University of Colorado School of Medicine, performing clinical and research work in cellular metabolism, especially in diabetes, cardiometabolic disease and cancer. He has been testing and coaching world-class endurance athletes for over 25 years. He is also the Head of Performance for the professional cycling team UAE, where he is the personal coach of two-time Tour de France champion Tadej Pogačar. San Millán's focus for his athletes is training the biochemical systems to empower the biomechanical systems. Using lactate and heart rate as the guiding biomarkers, he has developed protocols to train various energy systems for the best performance possible. Listen in as Dirk Friel asks for details on how these systems work, when a Zone 2 ride is no longer a Zone 2 ride and how to train effectively on only 10 hours per week.