Kris Stallenberg 60-min Z2 (Endurance) Pushing #04 Enhance your endurance with Z2 'spin-ups'. This session builds on a solid Z2 (Endurance) foundation, punctuated by brief accelerations into the Tempo zone. The goal is to improve your ability to respond to changes in pace while quickly settling back into an efficient aerobic rhythm. This aligns with Coggan Power Zones by stressing aerobic pathways with slight variations. bike