Kris Stallenberg 30-min Z2 (Endurance) Pushing #09 This is a pure strength-endurance session. The goal is to hold a power level at the very top of your Z2 (Endurance) zone for three solid blocks, building muscular resilience and aerobic capacity. This 'grinder' workout is a classic application of the Coggan Power Zones' Level 2 for developing the ability to push a big gear for a long time. bike