Preface

Adipose tissue, once considered inert connective tissue, is an essential storage site for key substrates that are used as sources of energy. Adipocytes have numerous metabolic functions, the most important of which are the hydrolysis (lipolysis), uptake, and storage of triacylglycerol. The regulation of adipocyte lipid metabolism during periods of excess energy expenditure is critical for the maintenance of fuel homeostasis. For example, adipocytes adapt to acute and long-term increases in physical activity by enhancing their capacity to mobilize and replenish lipid, which is used for energy by exercising muscle. Furthermore, in recent years, cellular and molecular biologists have advanced the concept that adipocytes are not solely a cellular storage location for excess fuel. Rather, adipose tissue is an active secretory organ that synthesizes and releases a number of bioactive proteins, which influence energy and substrate metabolism throughout the body via endocrine, paracrine, and/or autocrine actions.

The exercise-induced adaptations in muscle metabolism are widely recognized and thoroughly studied across several disciplines. Yet, despite the important role of adipose tissue in providing fuel for exercise and its newly recognized role as an endocrine organ, exercise-induced adaptations in adipose tissue are far less familiar. This book is solely dedicated to providing exercise physiologists, nutritionists, medical professionals, and basic scientists with concise and current information regarding the effects of endurance exercise on adipose tissue metabolism, mass, and distribution. Each chapter is written by leading scientific researchers with specific expertise and firsthand knowledge of the subject of their chapters. Where appropriate, for each metabolic function, the necessary basic science is explained first, followed by a comprehensive review and interpretation of the scientific literature pertaining to the effects of endurance exercise on that metabolic function.

This book is designed to give the reader timely, current insight into the exercise-induced metabolic adaptations in adipose tissue metabolism and their clinical significance. The first few chapters focus on the effects of endurance exercise on the primary metabolic functions of adipocytes. Included are the effects of both a single exercise bout and endurance exercise training on adipose tissue lipolysis, lipoprotein lipase, and glucose uptake and insulin responsiveness. One chapter also summarizes the effects of endurance exercise on the endocrine/paracrine properties of adipose tissue, a newly devel- oping area of research. The book concludes with three chapters that examine the evolving research on the effects of endurance exercise on adipose tissue mass and body fat distribution. Although these topics have been historically presented in the context of the effects of exercise on body composition or obesity, the chapters written for this book highlight the unique capacity of endurance exercise to modify adipocyte size and the amount and location of adipose tissue in children and adults. The hope is that these chapters will provide an applied approach to the basic information presented on exercise and adipocyte metabolism and that this book will serve as a text and reference source for scientists and clinicians alike.

The preparation of this book required the hard work and dedication of each of the contributing authors and their assistants. They deserve gratitude and thanks for their willingness to contribute their expertise to this volume in such a creative, timely, and professional manner.