Measurements of energy expenditure

What are the 4 measurements of energy expenditure

• Indirect calorimetry

• Lactate sampling

• VO2 max test

• Respiratory exchange ratio (RER)

Define indirect calorimetry

A method of estimating energy expenditure by measuring the amount of oxygen consumed and carbon dioxide produced during exercise and comparing it to at rest.

What is the purpose of indirect calorimetry in sport? 2

• Determines how much energy an athlete uses during different intensities of exercise.

• Helps design nutrition and training plans for endurance athletes.

What are the key limitations of indirect calorimetry? 2

• Requires expensive equipment and controlled lab conditions.

• Accuracy can be affected if measurements are not taken correctly.

Define lactate sampling

A process of taking blood samples during or after exercise to measure lactate concentration.

What is the purpose of lactate sampling in sport? 2

• Identifies the lactate threshold, which indicates when the body shifts from aerobic to anaerobic energy systems.

• Useful for setting training zones for endurance athletes- gives us an idea of fitness levels, allowing coaches to monitor improvements, allowing correct intensity traning.

What are the key limitations of lactate sampling? 2

• Invasive- requires blood samples.

• Needs trained personnel and specialised equipment.

Define VO2 max test

A test that measures the maximum amount of oxygen an athlete can utilise during intense exercise.

What is the purpose of the VO2 max test in sport? 2

• Indicates aerobic capacity and endurance potential.

• Used to monitor progress and compare fitness levels.

What are key limitations of the VO2 max test? 2

• Requires specialised lab equipment and trained staff.

• Can be physically demanding and unsuitable for beginners.

Define the respiratory exchange ratio

The ratio of carbon dioxide produced compared to oxygen consumed during metabolism (CO2 / O2).

What is the purpose of the RER in sport? 2

• Indicates whether carbohydrates or fats are the primary fuel source during exercise. This calculates the energy expenditure.

• Helps athletes optimise diet and training for endurance or fat utilisation. This tells us if the athlete is working aerobically or anaerobically.

How is RER measured?

• RER close to 1 means the performer is using carbohydrates

• RER close to 0.7 means the performer is using fats (aerobic)

• RER greater than 1 means anaerobic respiration as more CO2 is produced than O2 consumed

What are the key limitations of RER?

• Only accurate under steady-state conditions

• Requires precise gas analysis equipment