Kris Stallenberg 120-min Z2 (Endurance) Medium #04 This workout builds endurance with short 'surges' into the Tempo zone (Zone 3). The majority of the time is spent in Zone 2, adhering to the principles of aerobic development from the Coggan Power Zones. These brief, one-minute pushes into a higher intensity mimic the effort needed for small hills or slight pace increases in a group, improving your ability to recover while still working. This makes your endurance more robust and road-ready. bike