Kris Stallenberg 30-min Z2 (Endurance) Pushing #07 This session consists of two long, gradual ramps that span the entire Z2 (Endurance) range. The slow, steady increase in effort challenges your muscular control and aerobic system. It's a test of patience and endurance, reinforcing the base-building principles of the Coggan Power Zones by spending significant time across the entire Level 2 spectrum. bike