Join Dr. Kathy Vidlock as she takes you deep inside the human body to explore the remarkable—and sometimes perilous—physiology of endurance sports. From ultra-marathons to long-distance triathlons, discover how the heart, lungs, muscles, and metabolism adapt under extreme stress, and what happens when the limits are pushed too far. Through real-world athlete stories and cutting-edge science, Dr. Vidlock unpacks the physical feats, hidden dangers, and recovery strategies that define performance at the edge of human capability.