Kris Stallenberg 90-min Z2 (Endurance) Easy #08 This workout is designed to improve sustained endurance by progressively increasing the duration of the work intervals. This 'gradual build' structure challenges your mental focus and physical stamina. The entire session is centered in Z2 (Endurance) based on the Coggan Power Zones, ensuring the focus remains on aerobic development. As the blocks get longer, concentrate on maintaining consistent power and efficient pedaling. bike