ABSTRACT
Estimation of body composition is a cornerstone of human nutrition assessment for health care providers, clinical researchers, and epidemiologists. This chapter outlines the fundamentals of the practical construct of body composition. An initial product of body composition research with physically active individuals was the characterization of body fatness by sport and gender. Overall, body fatness tended to be greater among female compared to male athletes and this trend continued within a specific sport. The 1940s and 1950s were the formative years of body composition research as related to physical activity. Fat-free mass is beneficial in physical activities that require development and application of force. Hydration is a complex physiological condition that includes total body water, its distribution, and the concentration of the major electrolytes. Epidemiological surveys reveal, and clinical research confirms, that body composition is related to risk of cardiometabolic and cardiovascular diseases. Environmental and behavioral factors can impact body size and composition, health, injury hazard, and performance.
