Energy Expenditure

Question 1

What is the definition of a calorie?

Answer 1

Amount of energy required to raise 1g of water by 1 degree celsius.

Question 2

Describe indirect calorimetry

Answer 2

Caloric expenditure measured via respiratory gases.
Aerobic exercise with expired air captured in Douglas bags. Use of the Haldane transformation and other formulas to calculate RER.

Question 3

Why do fat give off more energy than CHO

Answer 3

Fats cost the most oxygen per kcal.
This is because they need an additional 2 oxygen atoms per carbon atom, whereas CHO only needs 1.

Question 4

What is the advantages of indirect calorimetry.

Answer 4

Detects changes with breath-by-breath systems.
Not affected by equipment heat.
Easy to administer.
Accurate aerobic measure.
Direct assessment of gas exchange.

Question 5

What two assumptions is indirect calorimetry based upon?

Answer 5

1. Assumes body’s oxygen content remains constant and CO2 exchange in lungs is proportional to release from cells.
   This is not true as some oxygen remains bound to haemoglobin and in tissues.
2. Use of RER ignores protein oxidation for energy.
   This again is not true as protein oxidation contributes to up to 5% of our total energy.

Question 6

What is the limitation regarding RER for indirect calorimetry?

Answer 6

RER outside the range of 0.7 - 1 is inappropriate for energy estimations.
RER > 1 = anaerobic metabolism
RER < 0.7 = gluconeogenesis

Question 7

How much energy in direct calorimetry is converted to heat?

Answer 7

60%

Question 8

What is indirect calorimetry?

Answer 8

Participant exercises in an air tight chamber surrounded with water-filled copper pipes.
Exercise and heat given off warms the water in the pipes.
Before and after water temperature is recorded.

Question 9

State the advantages of direct calorimetry.

Answer 9

Direct measure of heat via water.
Accurate for steady state measures.

Question 10

State the disadvantages of direct calorimetry.

Answer 10

Expensive
Slow to generate results
Results are not dynamic (heat given out is averaged)
Few chambers available
Machine gives off heat
Some heat is retained as body temperature rises

Question 11

What is BMR

Answer 11

Basal metabolic rate.
How much energy is used at rest in supine position.

Question 12

Which of these requires a lab to obtain value: BMR or RMR

Answer 12

BMR

Question 13

What is a MET?

Answer 13

Metabolic equivalent of task = 3.5ml/kg/min

Question 14

After fat max peak, what can be observed regarding FFAs?

Answer 14

Lower availability of plasma FFAs.

Reduced entry of FFAs into the mitochondria, predominant fuel source shifts to CHO oxidation.

Question 15

What is the fast portion of the EPOC curve?

Answer 15

Rapid decline in oxygen uptake.

Represents oxygen required to resynthesise ATP and PCr.
Oxygen levels are restored by myoglobin and haemoglobin.
Shows the thermogenic effects of hormones.

Question 16

What is the slow portion of the EPOC curve.

Answer 16

Represents recovery post-exercise.

Curve shallows as lactate is removed from the tissues and either converted to glycogen or oxidised to give rise to CO2.
Increased ventilation to expel CO2.
Shows thermogenic effects of elevated core temperature.