This audio overview, titled "Under the Hood: Mapping Muscle Fiber Utilization to Training Zones" is a deep-dive overview where we explore the physiological anchors that define the QT2.0 training system. Rather than focusing on arbitrary percentages, we examine how Critical Power (CP) and Critical Speed (CS) serve as the definitive asymptote and boundary between physiological stability and instability. We break down the transition of energy systems from the steady-state recruitment of Type I (slow-twitch) muscle fibers in Z1 to the Type IIA Oxidative and Type IIA Glycolytic fiber recruitment that characterizes the move through Tempo (Z2) and Threshold (Z3). Finally, we look at what happens when you "raise the roof," moving into maximal aerobic intensities that recruit Type IIX fibers and draw from your finite anaerobic tank, known as W′ or D′. Discover how understanding these internal shifts allows you to move beyond "no-man's-land" training and toward a truly deliberate and intentional approach to performance. *This audio overview is AI-generated off of QT2 Systems' knowledge-base of source materials.