In this episode of Fast Physiology on the Critical Oxygen podcast, Dave Schell and I discuss the nuances and importance of zone two training. We start with a quick introduction of our new series - Fast Physiology, which is designed to dispel the myths surrounding training trends. We define zone two training as the intensity necessary to build volume over time and emphasize the importance of perceived effort for practical application. We highlight the role of zone two training in supporting high-intensity work and recovery, as well as its contribution to endurance performance. They also address the misconceptions and limitations of zone two training and stress the significance of consistency in training.