Fatigue is a condition spanning the breadth of human functioning in health and disease and is a central concern in sport and exercise. Even so we are yet to fully understand its causes. One reason for this lack of understanding is that we seldom consider fatigue from an evolutionary perspective - as an adaptation that provided reproductive success. This ground-breaking book outlines the evidence that fatigue is a result of adaptations distinctive to humans. It argues that humans developed adaptations which led to enhanced fatigue resistance compared with other mammals and discusses the implications in the context of exercise, health and performance. Highly illustrated throughout, it covers topics such as defining and measuring fatigue, the emotional aspect of fatigue, how thermoregulation affects the human capacity to resist fatigue, and fatigue in disease. Human Fatigue is essential reading for all exercise scientists as well as graduate and undergraduate students in the broad field of physiology and exercise physiology.