Lecture 15 - Assessment of Energy Expenditure

Question 1

What did Brody do to prove Body mass dictates BMR

Answer 1

Direct calorimetry

The total heat loss is equal to the rate of energy utilization when
body temperature is constant

Question 2

What is the Snellen Calorimeter

Answer 2

Only direct calorimeter for humans

Question 3

What are the issues with direct calorimetry

Answer 3

Cannot monitor rapid changes
– Not all the heat produced during exercise may be
immediately liberated from the body
* Representative behaviours?
* Accounting for friction? (ergometer would contribute
to the total heat produced during exercise)
* Cannot determine which fuel is being utilised at any
one time – only determine metabolic rate

Question 4

What is an alternative to direct calorimetry

Answer 4

Douglas bag technique

Substrates + oxygen–> Heat + CO2 + H2O

Question 5

What are the BMR that can be predicted

Answer 5

Schofield
Harris-Benedict

Question 6

What is the Harris-Benedict equation

Answer 6

BMR = 66.47 +13.75 x BW(kg) + 5 x Ht(cm) -6.76 x age

Question 7

What is the Schofield equation for men between 18 and 30

Answer 7

Males = (0.063 x BW(kg)) + 2.896 = BMR in MJ

Question 8

What is room calorimetry

Answer 8

slide 26

Question 9

What is DLW

Answer 9

Doubly labelled water

Considered the “gold standard”
in assessment of free living
* Based upon the use of stable heavy isotopes of Hydrogen and Oxygen discovered in 1920’s and 1930’s.
energy expenditure. 1-5% error
* When 2H (Deuterium) and 18O are introduced into the
relative to room calorimetry.
body they mix with the normal Hydrogen and Oxygen in the body.
* First effectively used in mice in
1955.
* The 18O is lost more rapidly than the 2H as it is lost in
expired CO2 and H2O, whereas the 2H is only lost in
H2O.
* First use in humans was 1980.

Question 10

What is the theory of DLW

Answer 10

Based upon the use of stable heavy isotopes of Hydrogen and Oxygen discovered in 1920’s and 1930’s.
energy expenditure. 1-5% error
* When 2H (Deuterium) and 18O are introduced into the
relative to room calorimetry.
body they mix with the normal Hydrogen and Oxygen in the body.
* First effectively used in mice in
1955.
* The 18O is lost more rapidly than the 2H as it is lost in
expired CO2 and H2O, whereas the 2H is only lost in
H2O.
* First use in humans was 1980.
* The difference in these rates is used to calculate CO2
production

Question 11

What are the limitations of DLW

Answer 11

High cost of equipment and very
specialised staff required for analysis.
* Assumed RER/RQ….
– Assumes RQ of 0.8 or 0.85
* This could lead to error…
* No information on components of energy
expenditure

Question 12

What is MET

Answer 12

Normal metabolic rate

Question 13

What is the compendium of physical activities

Answer 13

Designed to increase the comparability of results from self reported PA.
* Compiled from a variety of published and unpublished sources.
* Element of subjectivity in both initial record of activity by participant and by coder.
* Uses averages of values for various

Slides 40-42

Question 14

Issues with self-reported physical activity

Answer 14

memory loss
Lying
varying intensity

Question 15

Issues with HR monitors

Answer 15

Heart rate monitors may be used to
try and capture activities that
accelerometry may miss.
* Based upon the fairly linear
relationship between HR and EE.
– Requires individual calibration
– Linearity is lost at low intensities
* Other factors can influence HR i.e
Stress

Question 16

what is actiheart

Answer 16

Actiheart technology uses combination of HR
and accelerometry data.
* As sources of error are different for two
methods should be theoretically more precise.