ESS 345 (Chapter Five) Questions and Answers plus summaries
Direct Calorimetry **** Most accurate method for directly quantifying energy
expenditure
Very expensive to construct and operate
Scarcity of available human direct calorimeters
Subject confinement required during period of measurement
Must account for heat produced by ergometers
Indirect Calorimetry **** Advantages:
Accurate and Noninvasive
Provides Information of metabolic substrates being used for energy
Portable devices allow the assessment of energy expenditure in the field environment
Disadvantages:
Relatively high cost, including instrumentation
Calibration and upkeep of instrumentation
Usually performed in well-controlled laboratory or clinical settings (although portable
devices are available)
Trained personnel needed to ensure accuracy and reliability
Isotope Measurements **** Advantages:
Highly accurate
Gold standard for measurement in free living conditions
Allows freedom of activity for participants
Disadvantages:
High cost (including the high price of isotopes and expensive equipment for analysis)
Advanced expertise required
Does not provide any specific details on physical activity
Heart Rate Monitoring **** Advantages:
Objective tool for estimating energy expenditure
Relatively low cost
Noninvasive and versatile
Can be used both in controlled settings and free living conditions
Disadvantages:
Inaccurate at rest and during low-intensity activities
Possible electrical or magnetic interference from common electrical devices
Relation between heart rate and energy expenditure valid only within an individual
Pedometry and accelerometry **** Relatively inexpensive and noninvasive
Used to assess step counts and energy associated w common activities
Can increase or maintain physical activity
, Disadvantages:
May be limited to measuring only certain types of activities such as walking or running
(pedometry)
Less accurate for assessing the distance covered and the energy expended
Self-report Methods **** Advantages:
Low cost (large sample sizes)
Low burden on subjects
Provides info on physical activity patterns
Disadvantages:
Low accuracy and reliability
Dependent on the participant's memory and perception of activity
Less valid and reliable for some study populations (e.g., young children)
How much of energy in metabolism makes ATP? **** 40%
How much energy is converted to heat in metabolism? **** 60%
Direct Calorimetry **** "Measuring Heat"
Good for measuring resting metabolism and prolonged steady-state aerobic exercise
What are the main substrates of aerobic exercise? **** fat and glucose
What does aerobic exercise use and produce? **** Use: O2
Produces: CO2
How is energy expenditure measured via indirect calorimetry? **** Measuring the
respiratory exchange of O2 and CO2
What is indirect calorimetry limited to? **** Steady-state aerobic activities
Respiratory gas exchange **** Determined by measurement of volume of O2 and
CO2 that enters and leaves lungs
Does the body have limited O2 storage? **** yes
Does the amount of O2 taken up by the lungs accurately reflect the body's use of O2?
**** yes
VO2 **** Actual volume of oxygen consumed
VCO2 **** Volume of CO2 produced
RER **** Respiratory Exchange Ratio
RER = VCO2/VO2
Direct Calorimetry **** Most accurate method for directly quantifying energy
expenditure
Very expensive to construct and operate
Scarcity of available human direct calorimeters
Subject confinement required during period of measurement
Must account for heat produced by ergometers
Indirect Calorimetry **** Advantages:
Accurate and Noninvasive
Provides Information of metabolic substrates being used for energy
Portable devices allow the assessment of energy expenditure in the field environment
Disadvantages:
Relatively high cost, including instrumentation
Calibration and upkeep of instrumentation
Usually performed in well-controlled laboratory or clinical settings (although portable
devices are available)
Trained personnel needed to ensure accuracy and reliability
Isotope Measurements **** Advantages:
Highly accurate
Gold standard for measurement in free living conditions
Allows freedom of activity for participants
Disadvantages:
High cost (including the high price of isotopes and expensive equipment for analysis)
Advanced expertise required
Does not provide any specific details on physical activity
Heart Rate Monitoring **** Advantages:
Objective tool for estimating energy expenditure
Relatively low cost
Noninvasive and versatile
Can be used both in controlled settings and free living conditions
Disadvantages:
Inaccurate at rest and during low-intensity activities
Possible electrical or magnetic interference from common electrical devices
Relation between heart rate and energy expenditure valid only within an individual
Pedometry and accelerometry **** Relatively inexpensive and noninvasive
Used to assess step counts and energy associated w common activities
Can increase or maintain physical activity
, Disadvantages:
May be limited to measuring only certain types of activities such as walking or running
(pedometry)
Less accurate for assessing the distance covered and the energy expended
Self-report Methods **** Advantages:
Low cost (large sample sizes)
Low burden on subjects
Provides info on physical activity patterns
Disadvantages:
Low accuracy and reliability
Dependent on the participant's memory and perception of activity
Less valid and reliable for some study populations (e.g., young children)
How much of energy in metabolism makes ATP? **** 40%
How much energy is converted to heat in metabolism? **** 60%
Direct Calorimetry **** "Measuring Heat"
Good for measuring resting metabolism and prolonged steady-state aerobic exercise
What are the main substrates of aerobic exercise? **** fat and glucose
What does aerobic exercise use and produce? **** Use: O2
Produces: CO2
How is energy expenditure measured via indirect calorimetry? **** Measuring the
respiratory exchange of O2 and CO2
What is indirect calorimetry limited to? **** Steady-state aerobic activities
Respiratory gas exchange **** Determined by measurement of volume of O2 and
CO2 that enters and leaves lungs
Does the body have limited O2 storage? **** yes
Does the amount of O2 taken up by the lungs accurately reflect the body's use of O2?
**** yes
VO2 **** Actual volume of oxygen consumed
VCO2 **** Volume of CO2 produced
RER **** Respiratory Exchange Ratio
RER = VCO2/VO2
