Energy Expenditure

Question 1

What is a calorie?

Answer 1

The amount of energy needed to raise one gram of water by 1 degree celcius

Question 2

How does a calorimeter calculate the calories in food?

Answer 2

• Put a sample of the food in a ‘bomb cell’ surrounded by a water bath
• They oxidise (burn) the food sample and calculate the temperature change in the water due to this

Question 3

What reasons do we need to measure energy expenditure?

Answer 3

• Assess metabolic needs
• Fuel utilisation
• Thermic effects of foods
• Nutritional interventions for performance and recovery
• Assessment of economy

Question 4

How can we estimate EE?

Indirect Calorimetry

Answer 4

Expired air gas analysis, the amount of oxygen consumed and the amount of CO2 produced.

Question 5

How can we do direct calorimetry with a human?

Answer 5

• Measure all the heat that’s given off by them during exercise
• The heat is picked up by the water system in the room and therefore can work out the change in temperature

Question 6

What are the Pros and Cons of direct calorimetry?

Answer 6

Pros: Direct measure of heat & Accurate for steady state measures
Cons: Expensive, Slow to generate results, Few in operation & Accurate for exercise?

Question 7

What is the Respiratory Exchange Ratio?

RER

Answer 7

Production of CO2 : Uptake of O2

Question 8

What would an RER of 0.7 indicate?

Answer 8

Fat burning

Question 9

What would an RER of 1.0 indicate?

Answer 9

Carbohydrate burning

Question 10

What are the advantages of indirect calorimetry?

Gas analysis

Answer 10

• Can detect changes during exercise with breath by breath systems
• No longer affected by the heat of equipment
• Easy to administer
• Fairly accurate for aerobic measures
• Direct assessments of gas exchange

Question 11

Which fuel substrate gives us the most energy per gram?

Answer 11

Fat, around 9 Kcal vs 4 Kcal for carbs

Question 12

Which fuel substrate costs the most oxygen per kilocalorie?

Answer 12

Fat, about 5 Kcal per litre of oxygen consumed so we get slightly more energy per litre of oxygen from the carbohydrates

Question 13

What are limitations of Indirect Calorimetry?

Answer 13

• Assumes the body’s O2 content is constant but the body has O2 stores that isn’t directly reflected in pulmonary measures
• CO2 exchange in the lungs is proportional to release from cells

Question 14

What RER will someone reach at their VO2max?

Answer 14

1.15

Question 15

What is Basal Metabolic Rate?

Answer 15

The energy cost for someone at rest

Question 16

Why does BMR decrease 2-3% per decade?

Answer 16

• Decrease in fat free mass
• Depression of metabolic activity of lean tissues
• Altered by change in body composition and physical activity

Question 17

What is the difference between BMR and RMR?

Resting Metabolic Rate

Answer 17

BMR is a less tightly controlled version and is more accessible

Question 18

What does MET stand for?

Answer 18

Metabolic Equivalent of Task

Question 19

What does MET tell us?

Answer 19

For each activity you carry out, how many multiples of RMR is that activity worth?

Question 20

What is 1 MET equal to?

Answer 20

3.5ml/kg/min

Question 21

How many MET are required for running at a moderate high pace (70% of VO2max) for a man whose VO2max is 60ml/kg/min?

Answer 21

0.7 x 60 = 42
42 / 3.5 = 12
Therefore this is a 12 MET activity

Question 22

What is Fat Max?

Answer 22

A description of the intensity at which maximum rate of fat utilisation occurs

Question 23

What benefit does having a higher Fat Max give us?

Answer 23

Allows us to increase the intensity we can go to before relying on carbohydrates as a fuel

Question 24

What is Mechanical Efficiency?

Answer 24

External work accomplished / energy expenditure