Kris Stallenberg 120-min Z2 (Endurance) Pushing #04 This session builds on a solid Z2 endurance base by incorporating short, 30-second surges into the Tempo zone (Z3). These 'spikes' simulate the effort needed to crest a small roller or make a brief acceleration in a group, improving your dynamic response without generating excessive fatigue. As per the Coggan Power Zones, the vast majority of the work remains aerobic, enhancing your ability to handle changes in pace during long events. bike