Physical Work and Effort is a collection of papers presented at the Proceedings of the First International Symposium held at Stockholm on December 2-4, 1975. This book deals with the investigations done on the clinical physiology of work and effort. This text discusses interdisciplinary measures conducted by psychologists and physiologists on both theoretical and clinical issues. Part 1 discusses basic theories; methods and results that can be found in studies relating to fatigue; visual perception; and stress that includes a simple method of rating these estimates of perceptions. Part 2 evaluates differential and developmental problems such as sex, heart rates, and the differences found in aerobic function related to childhood daily physical activities. Part 3 covers topics on clinical and applied studies such as ECG changes in asymptomatic men; perceived pain during tread-mill exercise; and changes in heart rate during work exertion or when driving under traffic conditions. Part 4 evaluates the psychophysiological intercorrelations from a series of experiments and concludes that two factors are present in the perception of exertion during physical work—the local factor and a central factor. The book also includes the use of a model to evaluate the perceived ratings of these two factors. Psychologists, physiologists, physical therapists, physiotherapists, and scientists involved in work improvement will find this book very valuable.