Kris Stallenberg 75-min Z2 (Endurance) Pushing #02 This session builds endurance with a twist. The majority of the work is in Zone 2, but short, one-minute surges into Zone 3 (Tempo) will challenge your body's ability to clear lactate while still under aerobic stress. This mimics the variable power demands of rolling terrain. As defined by Coggan Power Zones, the goal is to enhance your aerobic engine while improving your ability to handle changes in pace. Focus on returning to a smooth Z2 rhythm immediately after each surge. bike