Assessment of Energy Expenditure

Question 1

state the 3 components of energy expenditure (and their relative percentages of TDEE)

Answer 1

1. Physical activity = 10-15 %
2. Diet induced thermogenesis (DIT) / thermic effect of food (TEF) = 10 %
3. basal metabolic rate (BMR) = 65-75 %

Question 2

state what it is meant by the key term - diet induced thermogenesis (DIT) / thermic effect of food (TEF)

Answer 2

the increase in metabolic rate after ingestion of a meal (everything from consuming to digestion to absorption)

Question 3

state what it is meant by the key term - basal metabolic rate (BMR)

Answer 3

Basal metabolic rate is the rate of energy expenditure per unit time by endothermic animals at rest

Question 4

how do you convert between a MJ and a Kcal

Answer 4

MJ = Kcal x 239

Question 5

how do yo convert between a Kj and a Kcal

Answer 5

KJ = Kcal x 4.2

Question 6

what is BMR dictated by ?

Answer 6

BMR is dictated by body size (Kg)

Question 7

state what it is meant by the key term - direct calorimetry

Answer 7

Direct calorimetry measures the heat production of an individual, in calories, when placed in an insulated chamber where the heat is transferred to surrounding water

Question 8

state 2/4 issues with the use of direct calorimetry

Answer 8

1. can’t measure rapid changes
2. the friction developed by an ergometer would contribute to the total heat produced during exercise
3. not all the heat produced during exercise ay be immediately liberated from the body
4. cannot determine which fuel is being utilised at one time so only measures metabolic rate

*therefore, not suitable for use during acute exercise

Question 9

state what it is meant by the key term - indirect calorimetry

Answer 9

indirect calorimetry calculates heat that living organisms produce by measuring either their production of carbon dioxide and nitrogen waste, or from their consumption of oxygen

Question 10

what is the usual piece of equipment used in the lab when doing indirect calorimetry

Answer 10

Douglas bag

Question 11

state what it is meant by the key term - Douglas bag

Answer 11

an inflatable bag used to collect expired air for the determination of oxygen consumption and basal metabolic rate

Question 12

what are the two main ways of predicting BMR with the use of age, height and weight ?

Answer 12

1. Schofield equations (UK)

2. Harris-Benedict equations (US)

Question 13

what is the Harris Benedict BMR equation for males ?

Answer 13

males = 66.47 + 13.5 (BW in Kg) + 5 (height, cm) - 6.76 (age)

Question 14

what is the Harris Benedict BMR equation for females ?

Answer 14

females = 65.1 + 9.56 (BW in Kg) + 1.85 (height, cm) - 4.68 (age)

Question 15

what is the Schofield equation for BMR in males aged 18-30 ?

Answer 15

(0.048 x Kg) + 3.653

Question 16

what is the Schofield equation for BMR in females aged 18-30 ?

Answer 16

(0.062 x Kg) + 2.036

Question 17

what is the Schofield equation for BMR in males aged 30-60 ?

Answer 17

(0.048 x Kg) + 3.653

Question 18

what is the Schofield equation for BMR in females aged 30-60 ?

Answer 18

(0.034 x Kg) + 3.538

Question 19

state 4 limitations of portable indirect calorimetry

Answer 19

1. expensive
2. inconvenient
3. alters behaviour
4. cannot be worn for extended periods

Question 20

state what it is meant by the key term - double labelled water (DLW)

Answer 20

doubly labeled water (DLW) can be used for a method to measure the average daily metabolic rate of an organism over a period of time

Question 21

what is the error of DLW relative to direct calorimetry

Answer 21

DLW has a 1-5 % error relative to direct calorimetry

Question 22

when was DLW first used in mice, and when was it first used in humans ?

Answer 22

1. mice - 1955

2. humans - 1980

Question 23

explain, in 4 steps, the theory behind the use of DLW

Answer 23

1. based upon use of stable heavy isotopes of H and O
2. when 2.H (deuterium) and 18.O are introduced into the body, they mix with the normal H and O in the body
3. the 18.O is lost more rapidly than 2.H as is lost in CO2 and H2O whereas 2H is only lost as H2O
4. the difference in the rates is used to calculate CO2 production

Question 24

state 3 disadvantages over the use of DLW

Answer 24

1. high cost of equipment and very specialised staff are required for analysis
2. assumed RER/RQ
3. no info on the components of energy expenditure

Question 25

explain (2 points) why assuming RER/RQ is a disadvantage of the use of DLW

Answer 25

1. assumes RQ of 0.8 or 0.85

2. could lead to error

Question 26

explain how the inability to gain info on the components of energy expenditure is a disadvantage over the use of DLW

Answer 26

total TDEE is the only thing measured - can combine with other measurements to obtain the other components (eg - BMR from indirect calorimetry)

Question 27

what is the issue with the use of DLW for physiologists ?

Answer 27

DLW provides no info on the pattern or intensity of physical activity

Question 28

state 4 facts about ‘activity diaries’ and ‘recall questionnaires’

Answer 28

1. mostly self reported, can be experimenter administered
2. usually utilise 10-15 min recording periods in the day
3. many, many different recall questionnaires
4. use either an activity score or a MET value for recorded activity to estimate EE

Question 29

who came up with, and when did they come up with, the ‘compendium of physical activity’ ?

Answer 29

Ainsworth et al, 1993, 2000, 2011

Question 30

why was the ‘compendium of physical activity’ designed ?

Answer 30

it was designed to increase the comparability of results from ‘reported PA’s’

Question 31

state 3 introductory facts about the ‘compendium of physical activity’

Answer 31

1. compromised from a variety of published an un-published sources
2. element of subjectivity in both the initial record of activity by the participant and the coder
3. uses averages of values for various activities

Question 32

state 2 facts about using the compendium

Answer 32

1. 1 MET= basal metabolic rate
2. therefore, the multination of a MET by time will estimate EE
3. eg) 1.5 Kcal/min (BMR) x 3 METs = 4.5 Kcal/min. ANS x 15 = 67.5 Kcals

Question 33

state 2 facts about Pedometers and Accelerometry (pro and con)

Answer 33

1. both very good at predicting energy EE during ambulatory activities (eg - running and walking)
2. doesn’t pick up data from non-ambulatory activities (eg - cycling)

Question 34

what is the purpose of the use of HR monitors in EE ?

Answer 34

HR monitors aim to pick up information that accelerometry may miss

Question 35

what is HR estimate of EE based off ? (2 points)

Answer 35

1. based off the linear relationship between HR and EE

2. linearity lost at low intensities, however

Question 36

state 2 additional facts about HR monitors and EE

Answer 36

1. required individual calibration

2. other factors can influence HR (eg - stress)

Question 37

state 2 types of ‘multi sensory physical activity monitors’

Answer 37

1. actiheart

2. sensewear armband

Question 38

state 2 facts about ‘actiheart’

Answer 38

1. actiheart tech uses a combination of HR and accelerometry data
2. as sources of error are different for the two methods, this should - theoretically - be more precise

Question 39

state 3 facts about ‘sensewear armband’

Answer 39

1. worn on the upper arm
2. has measures of heat flux, bi-axial accelerometer, skin temp, etc…
3. the calculation for measuring EE are proprietary

Question 40

what does it mean when it says the methods for calculating EE by ‘sensewear armbands’ are ‘proprietary’ ?

Answer 40

we don’t know how the algorithm works, we just trust the validity research