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Chapter 5 Summary

  • Energy balance is represented by the difference between energy intake and energy expenditure, and imbalance manifests itself as a change in body mass and/or composition.
  • Political, social, economic, perceptual and scientific influences have all had a role to play in general dietary/nutritional patterns and those in sport and exercise over the last 150 years.
  • Body composition can be considered at a number of levels, from chemical to tissue to organ and these all have a role to play in the compartment modelling of human body composition, of which 3 and 4 compartment models are becoming ‘gold standards’.
  • There are few available direct methods of measuring body composition, and most techniques for estimating body composition are therefore based on indirect or doubly-indirect anthropometric/physiological/imaging measurements with varying assumptions.
  • Energy intake can be estimated, for example, at population, disease and individual level.
  • It is often important in sport and exercise to gauge energy intake that will sustain ‘economically and socially desirable physical activity’, and of importance for health is the estimation of energy intake that will prevent over-consumption.
  • Energy expenditure has three primary components, including BMR, physical activity, and several determinants such as body size, body composition, gender, psychological status.
  • Much of the measurement of energy expenditure in sport, exercise and health is dependent on indirect calorimetry, assessed by measuring oxygen consumption in the laboratory or in the field.
  • Most exercise efforts lasting more than 5 minutes are highly dependent on carbohydrate as a substrate source, which is stored as glycogen in muscle and the liver and its storage can be manipulated by diet and exercise.
  • There is a need to develop better methodology for the study of energy balance in free-living subjects, that would be of benefit in sport, exercise, health and disease.
  • Hydration and rehydration in sport and exercise has received greater attention in recent years and is important in reducing the deleterious physiological effects that affect performance and health of the athlete.