Kris Stallenberg 75-min Z3/4 (Sweet Spot) Easy #08 This session builds a strong aerobic foundation with a long tempo block before sharpening the legs with sweet spot 'finishers'. By starting with sustained tempo, you pre-fatigue the muscles, forcing them to work harder during the higher-intensity intervals. This improves your ability to produce power late in a race or long ride when you're already tired. bike