Kris Stallenberg 60-min Z2 (Endurance) Pushing #09 This session features 'float downs,' where you start at the top of your Z2 (Endurance) zone and slowly decrease power over a long interval. This unique stimulus challenges your control and muscular endurance in a different way, forcing you to stay engaged as the effort eases. It's an excellent way to build fatigue resistance according to Coggan Power Zones principles. bike