Kris Stallenberg 120-min Z2 (Endurance) Pushing #01 This workout focuses on sustained endurance efforts, a cornerstone of building aerobic base. The main set consists of three long, 30-minute intervals at the upper end of your Z2 (Endurance) zone, based on Coggan Power Zones. The short recoveries are active, keeping the pressure on and simulating the demands of a long, steady ride. This session is designed to improve fat metabolism and muscular endurance. bike