Kris Stallenberg 90-min Z2 (Endurance) Easy #01 This workout focuses on building a strong aerobic base with a sustained, uninterrupted effort in your endurance zone. Based on the Coggan Power Zones, this session targets Z2 (Endurance) to improve mitochondrial density and fat oxidation efficiency, all while keeping physiological stress low. The goal is to maintain a steady, conversational pace throughout the main set. Focus on smooth, consistent pedaling. bike