Understanding the human body's ability to metabolise carbohydrate and fat during exercise is crucial in enhancing sports performance and controlling lifestyle diseases such as obesity epidemic and type- 2 diabetes. The role of lactate and its measurement in exercise testing and prescription is equally important. This book is the first to jointly explain the metabolic responses of lactate, carbohydrate and fat utilisation by employing an interrelationship linking the measurements of indirect calorimetry with blood lactate concentration. Whether and how this interrelationship is affected by variations in exercise duration, mode and intensity has been investigated. Novel findings presented the evidence for the most appropriate protocol for jointly describing lactate, carbohydrate and fat utilisation during incremental exercise testing. The book presents a bridge between exercise physiology and biochemistry and provides a new approach in exercise testing. The book offers an exciting read for sport and exercise scientists, research students, and any sports, health and clinical practitioner.