Book excerpt: The popularity of high-intensity interval training (HIIT), which consists primarily of repeated bursts of high-intensity exercise, continues to soar because its effectiveness and efficiency have been proven in use by both elite athletes and general fitness enthusiasts. Surprisingly, few resources have attempted to explain both the science behind the HIIT movement and its sport-specific application to athlete training. That’s why Science and Application of High-Intensity Interval Training is a must-have resource for sport coaches, strength and conditioning professionals, personal trainers, and exercise physiologists, as well as for researchers and sport scientists who study high-intensity interval training.