Kris Stallenberg 60-min Z2 (Endurance) Medium #03 This workout features two descending Zone 2 blocks, starting with the longest effort first. This structure challenges you to hold a steady endurance pace while fresh, then repeat it for a shorter duration. This session is excellent for building the mental and physical stamina required for long rides. As defined by Coggan Power Zones, this sustained Z2 effort is key for developing your aerobic engine. bike