Kris Stallenberg 60-min Z2 (Endurance) Pushing #01 This workout focuses on building a strong aerobic base with two substantial, sustained intervals at the upper end of your endurance zone. The goal is to improve muscular endurance and fat oxidation efficiency, key components of the Z2 (Endurance) range as defined by Coggan Power Zones. Maintaining a steady output for these long durations is the primary challenge. bike