Assessment of energy expenditure Flashcards
(14 cards)
What are the 3 components of energy expenditure?
Physical activity
DIT/TEF
BMR
Physical activity component of energy expenditure?
15-30%
energy expended through movement
DIT component of energy expenditure?
10%
dietry induced thermogenesis
amount of energy needed to put in to digest food
BMR component of energy expenditure?
65-75%
basal metabolic rate
energy requirement at rest
problems with direct calorimetry
cannot monitor rapid changes
limited in how representative it is (small chambers)
friction not accounted for (ergometer)
cannot determine which fuel is being used at any given time; can only measure metabolic rate
direct calorimetry
total heat loss is equal to the rate of energy utilization when body temperature is constant
indirect calorimetry
douglas bag technique
indirect calorimetry and exercise
measure oxygen uptake during steady state
doubly labelled water
assessment of free living energy expenditure
use of stable heavy isotopes of hydrogen and oxygen
deuterium and 18O provided in a drink and mix with bodily hydrogen and oxygen
18O is lost quicker than deuterium as it is also expired in CO2 (both lost in water)
difference in rates used to calculate CO2 production
limitations of doubly labelled water
high cost of equipment
highly specialised staff needed for analysis
assumes RER
no info on components of energy expenditure (total only)
1 MET=
resting metabolic rate
multiplication on METs by time estimates energy expenditure
pedometers and accelerometery pro and con
predict energy expenditure during ambulatory exercises
overlook other activities
heart rate monitors
fairly linear relationship between heart rate and energy expenditure but lost at low intensities and needs calibration
other factors can influence heart rate
Actiheart
combination of HR and accelerometry data
based on branch equation model
low intensity>accel
high intensity>HR
shows pattern over prolonged period of time
