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
- 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
- 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
- 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.