Assessment of Energy Expenditure

Question 1

• Direct measurement of heat liberated as a consequence of metabolism
• Organism put into chamber for period of time, temperature of air and water is measured

Answer 1

Direct calorimetry

Question 2

Problems with direct calorimetry

Answer 2

• Cannot monitor rapid changes
• Friction developed by ergometer would generate heat
• Not all heat produced in exercise is liberated immediately
• Cannot determine which fuel is being utilised

Question 3

• Collect expired air and analyse composition of expired air
• Energy expenditure can be estimated using equations based on O2 uptake and CO2 production
• Only works at steady state - at rest and when demands of exercise are met and are the same

Answer 3

Indirect calorimetry

Question 4

Problems with indirect calorimetry

Answer 4

• Expensive
• Inconvenient
• Alters behaviour
• Cannot be worn for extended periods

Question 5

• Based upon the use of stable heavy isotopes of hydrogen and oxygen
• Drink containing isotopes
• When 2H and 18O are introduced they mix with normal H and O in body
• The 18O is lost more rapidly than 2H as it is lost in CO2 and H2O, whereas 2H is only lost in H2O
• Difference in rates is used to calculated CO2 production

Answer 5

Doubly Labelled Water - DLW

Question 6

Limitations of Doubly Labelled Water

Answer 6

• High cost of equipment
• Very specialised staff needed
• Assumes RER of 0.8 or 0.85
• No information on components of energy expenditure
• No information on pattern or intensity of physical activity

Question 7

Activity Diaries and Recall Questionnaires

Answer 7

• Activity diaries generally utilise 10-15 mins recording periods throughout day
• They utilise an activity score or MET value for recorded activity to estimate EE

Question 8

• 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• Compiled from a variety of published and unpublished sources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 activities

Answer 8

Compendium of Physical Activities

Question 9

Issues with Activity Diaries and Recall Questionnaires

Answer 9

• A pain for everyone
• Social desirability
• Different impacts of exercise on different people
• People can forget what they did

Question 10

• May be used to try and capture activities that accelerometry miss
• Based upon fairly linear relationship between HR and EE
• Requires individual calibration

Answer 10

Heart rate monitors

Question 11

Multi-sensor physical activity monitors

Answer 11

• Actiheart

- Sensewear armband

Question 12

• Combination of HR and accelerometry data

- Should be theoretically more precise

Answer 12

Actiheart

Question 13

• Worn on upper arm
• Measures of heart flux, bioaxial accelerometer, galvanic skin response, skin temperature
• Equation for calculating EE are proprietary

Answer 13

Sensewear armband

Question 14

Pedometers and accelerometry

Answer 14

• Good at predicting EE during ambulatory activities

- Wll completely overlook activities like cycling