Kris Stallenberg 90-min Z2 (Endurance) Medium #10 Welcome to 'The Grinder'. This session involves a very long, slow ramp up through the entirety of your endurance zone, followed by a long, slow ramp back down. It demands constant mental focus and precise power control, simulating the sustained effort of a massive, gradual climb and descent. This is a challenging Zone 2 workout, as defined by the Coggan Power Zones, that builds immense mental toughness and muscular endurance. bike