# Measuring Energy Expenditure Flashcards

1
Q

calorimetry measures

A

heat energy liberated in metabolic processes

2
Q

basic unit of heat

A

calorie

3
Q

function of a calorie

A

raise 1 gram of water by 1 degree

4
Q

1kcal= how many kj?

A

4.186

5
Q

Total daily energy expenditure includes (3)

A

basal/resting metabolic rate
thermogenesis
exercise/activity energy expenditure

6
Q

basal metabolic rate

A

sleeping - energy required for body’s vital functions

7
Q

resting metabolic rate

A

energy expended while resting quietly (supine)

8
Q

total daily energy expenditure is proportional to

A

work done and heat produced

9
Q

Macronutrients + O2 =

A

ATP for mechanical work and heat

10
Q

thermogenesis

A

thermal effect of food - heat through metabolization of the food

11
Q

body heat production can be measured with

A

whole body calorimeters

12
Q

Heat production + work completed in calorimeter =

A

TEE

13
Q

limitations of whole body calorimeters

A

expensive
error due to
- heat produced by ergometer
- thermoregulation - body can act as a reservoir of heat, which can be affected by body composition/ind variability

14
Q

Atwater and Rosa used a whole body calorimeter to establish that

A

oxygen consumption is proportional to energy expenditure

15
Q

experimental findings and therefore?

A

direct heat measurement - 2723 kcal
gas analysis - 2717 kcal
difference of 0.2%
we can measure oxygen consumed we can indirectly determine energy expenditure (from both muscular work and heat production)

16
Q

every litre of oxygen consumed is equal to

A

5kcal burned, precise number depends on the specific type of macronutrient

17
Q

food +o2 =

A

co2 and h2o and energy

18
Q

how do you know what you’re burning?

A

Respiratory quotient - ratio of amount of CO2 produced divided by the amount of oxygen consumed at the cellular level

19
Q

C6H12O6 needs ___ to produce _____

A

6 O2 to get 6 CO2 and 6 H2O

20
Q

RQ of glucose

A

6CO2/6O2 = 1

21
Q

amount of O2 required and CO2 produced for the oxidation of carbs

A

equivalent

22
Q

RQ for fat

A

a molecule of fat is less oxidized (higher ratio of carbon to oxygen) - more oxygen is required to oxidize fat RQ<1

23
Q

Palmitic FA RQ

A

C16H32O2+ 24O2=16CO2 +16H2O

16/24=0.67

24
Q

What is not a major source of energy during rest and submax exercise

A

proteins

25
Q

proteins are catabolized into

A

AA

26
Q

Average RQ of AA is

A

0.85

27
Q

what is RQ for protein largely ignored by exercise physiologists

A

little protein is used as a source of energy during exercise

28
Q

RER

A

respiratory exchange ratio

- CO2/O2at mouth

29
Q

RQ vs RER

A

same at rest and during steady state submaximal exercise

30
Q

RER depends on and ranges from

A

intensity of exercise, 0.7 (all fat) -1.0 (all carbs, greater than 1, hydrogen buffering

31
Q

RER lvls have an assigned

A

caloric equivalent value

32
Q

hydrogen buffering

A

lactate and hydrate needed bicarbonate to get rid of it, production of more co2 which can mess with things to affect the ratio and slightly anaerobic

33
Q

how do we measure oxygen consumed and CO2 produced

A
```spirometry - indirect calorimetry method for estimating heat production in which expired air is measured and analyzed for the amount of O2 consumed and CO2 produced
Closed system (air out of a tank, not usually) and open circuit spirometry (breath in room air and analyze the composition and volume of air that you breathed out)```
34
Q

composition of atmosphere air

A

oxygen -21%
CO2 - .03%
N2 - 79%

35
Q

open circuit indirect calorimetry/spirometry uses _____ to measure

A

computerized metabolic(metabolic cart) for

• volume of air expired
• % of O2 and CO2 in expired air
36
Q

how to determinate oxygen consumption with open circuit indirect calorimetry/spirometry

A

it is the amt of oxygen taken up, transported and used at the cellular level
VO2 = volume inspiredfraction O2-volume expiredfraction O2 volume

37
Q

how to determine CO2 produced

A

amt of CO2 generated during metabolism

VCO2 = volume expiredfraction CO2-volume inspiredfraction CO2

38
Q

how do we determine volume inspired

A

volume of air inspired vs expired are slightly diff
- haldane transformation (VFIN2-VFEN2)
because N2 is not used in metabolism (inert gas) so we can use the ratio of nitrogen inspired /expired to obtain original volume

39
Q

gas volume as affected by barometric pressure, temp, and water vapour

A

increase pressure - decreased volume (boyles law)
increased temperture - increased air volume (charles law)
increased humidity - increased air volume

40
Q

why standardize spirometry?

A

permit VO2 results in different settings - normalize VE to STPD - standard temperature pressure dry
273 kelvin or 0 degrees, 700mmhg, normalized effects of humidity

41
Q

we measure CO2 and O2 to

A

see their kcals

42
Q

prior to using the metabolic cart the machine must be

A

calibrated

• O2 and CO2 sensors calibrated with standardized gas mix
• known gas volume used to calibrate volume of air so accurate VE measures are obtained (large syringe)
43
Q

portable metabolic carts for

A

running, swimming, animals

44
Q

douglas bags

A

breathing tubes with valves to analyze air flow out of lungs

45
Q

How does RER increase and what does it mean?

A

increase of intensity to increase Carb utilization

46
Q

low intensity and RER

A

low RER and high utilization of fat

47
Q

liver glycogen is high during (2)

A

high intensity short and moderate duration

48
Q

RER and RQ are equal when?

A

under rest and sub max exercise

49
Q

3 situations when

A

1- bicarbonate buffering during high intensity exercise - elevated CO2 production RER bigger than 1

1. anticipatory response to exercise - hyperventilation results in increased VCO2 increasing RER
2. Recovery - decrease in ventilation (hypoventilation) and restoration of blood bicarbonate conc. resulting in decreased VCO2 relative to VO2, decreased RER
50
Q

MET

A

metabolic equivalent
- amt of energy used for resting metabolism
1MET = 3.5mlO2 /(min*kg)
no additional stress or activity factors for normal body weight of 25-30BMI

51
Q

activities and MET

A

multiples of MET - asses someone’s energy expenditure

52
Q

double labeled water

A

12-17 day period objective measure of energy expenditure -
deuterium and O18 to indirectly measure energy expenditure
H leaves as water whereas O leaves as water and CO2, difference in the loss of O and H lets you calculate the CO2 produces