Kris Stallenberg 60-min Z2 (Endurance) Pushing #05 This workout features descending interval lengths. You'll start with shorter, sharper efforts at the top of Z2 (Endurance) and progress to a long, sustained block in the middle of the zone. This structure challenges your focus early on and finishes with a test of pure aerobic stamina, consistent with the goals of training using Coggan Power Zones. bike