Speed work built on a weak aerobic base produces rapid plateaus and predictable injuries. TC 31-5 covers the physiology behind Zone 2 training — mitochondrial density, lactate threshold, cardiac efficiency, and why these adaptations take the time they take. Includes the five-zone heart rate model, four methods for measuring Zone 2, the 8-week base protocol with adaptation signals by week, strength and mobility integration, and the full 24-week arc from base to SFAS-ready performance. The companion program with session-level prescription is TC 31-15.
Speed work built on a weak aerobic base produces rapid plateaus and predictable injuries. TC 31-5 covers the physiology behind Zone 2 training — mitochondrial density, lactate threshold, cardiac efficiency, and why these adaptations take the time they take. Includes the five-zone heart rate model, four methods for measuring Zone 2, the 8-week base protocol with adaptation signals by week, strength and mobility integration, and the full 24-week arc from base to SFAS-ready performance. The companion program with session-level prescription is TC 31-15.
