Kris Stallenberg 45-min Z2 (Endurance) Medium #09 This session features a large pyramid structure, slowly ramping up to the top of your Zone 2, holding it, and then slowly ramping back down. This sustained, controlled effort is fantastic for building aerobic capacity and muscular endurance, key tenets of the Coggan Power Zones philosophy. The long, gradual changes in power keep the work engaging and highly effective for building your base fitness. bike