Kris Stallenberg 30-min Z2 (Endurance) Pushing #03 This workout builds intensity progressively, starting in mid-Z2 and finishing at the top of your endurance range. This negative-split approach teaches pacing and improves stamina under increasing fatigue. It's a great way to explore the full spectrum of your Z2 (Endurance) zone as outlined by the Coggan Power Zones. bike