Energy balance, meals and hydration

Overview

Energy balance, total daily energy expenditure and basal metabolic rate, positive and negative balance for jockeys and boxers, meal timing and composition, eating after training, dehydration, and hypotonic, isotonic and hypertonic drinks.

What you need to know

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Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is meant by energy balance?

   Model answer

   Energy balance compares the energy taken in as food with the energy the body expends. Balance is neutral when intake equals expenditure.

2. 2

   What makes up a performer's total daily energy expenditure?

   Model answer

   Total expenditure is the basal metabolic rate plus the energy used digesting food. Total expenditure also includes the energy used in physical activity.

3. 3

   Define basal metabolic rate.

   Model answer

   Basal metabolic rate is the least energy needed at rest to maintain vital functions. Vital functions include breathing, circulation and cell repair.

4. 4

   What happens to body mass when a performer is in positive energy balance?

   Model answer

   Intake exceeds expenditure, so the surplus is stored mainly as fat. Body mass increases over time.

5. 5

   A rower eats 3,800 kcal in a day and expends 4,300 kcal. What is the energy balance?

   Model answer

   The energy balance is negative by 500 kcal. Intake minus expenditure is 3,800 kcal − 4,300 kcal = −500 kcal.

6. 6

   Why might a jockey or a boxer deliberately keep a negative energy balance?

   Model answer

   A negative balance reduces body mass so the performer can make a weight limit. Too great a deficit can cause fatigue, weakness and poor recovery.

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