Slide 6 - Air Displacement Flashcards
Air displacement is what type of model
Two component model of body compositon
What is the equation for body density
Mass / volume
How is volume determined
By air displacement
What does the BodPod have to determine the amount of air displaced by the person
Pressure sensors
What law is the relationship between pressure and volume
Boyles Law
What does Boyles Law estimate
Body volume
Boyles Law states
Equation
What do we have to assume
Volume and Pressure are inversely related
P1V1 = P2V2
or
P1/P2 = V2/V1
Isothermal conditions
What is the methodology behind the air displacement
Isothermal conditions = Temp of air remains constant as its volume changes
Majority of the air in the enclosed bod pos is under Adiabtic conditions
What is adiabatic conditions
Temp of air does NOT remain constant as volume changes
Thus it will compress or expand as the temo changes within the chamber
What is the Poissons Law equation
What does it state
P1/ P2 = (V2/V1) v
The ratio of the specific heat of the gas at constant pressure to that of constant volume
What is the Body volume equation
Body volume (L) = Body volume (raw) - surface area artifact + 40% TGV
What does TGV stand for
Where is it measured
Thoracic gas volume
In the BodPod
What is the equation for body density
What equation do we use to estimate body fat %
Body mass / body volume
Siri equation
How do we minimise isothermal effect
Wear minimal clothing
Men:
Speedo etc
Women:
Form fitting clothing
Wear swim cap
Near skin surface
How long does it take for the BodPod to calibrate
30 min warm up for electronics
What does the BodPod have to go through in order to have good quality control
Analyze hardware
Calibrate scale
Autorun
Volume check - calibration cylinder
2 point calibration before each client
What are the pre test measures of BodPod
No exercise, food or drink 3 hours before
Use restroom before test
Measure body mass 1 time
Measure body volume 2-3 times
Select daily activity level
Measure/predict TGV
How do you work out TGV
FRC + 1/2 TV
What errors may occur with BodPod
Airway pressure - high if puff too forcefully
Merit - high if air leaks
When assessing body composition of each client in the Bod Pod, a 2-point calibration is performed by measuring the empty chamber of Bod Pod and the chamber with a 50 L calibration volume cylinder (and breathing tube) placed inside
True
Like hydrostatic weighing, the Air Displacement Plethysmography using Bod Pod assesses body composition by determining the density of the body
True
When using Bod Pod, correct height and weight measurements are needed to calculate body surface area
True
Exhaling to maximal expiration is necessary to obtain an accurate measure of body fat when using the Air displacement plethysmography
False
The air inside the chamber expands or is compressed as the temperature in the chamber changes describes isothermal conditions
False
How does the Air Displacement Plethysmography assess body composition
By measuring changes in pressure within an enclosed chamber
Air displacement plethysmography measures ______ component(s) model of body composition
2
You are a 30 year old woman with body weight of 85.6kg and height 167.2cm. % body fat was determined using Bod Pod and it was 35%. Your current lean body mass is
85.6 x 0.65 = 55.64 Kg
You are a 30 year old woman with body weight of 85.6kg and height 167.2cm. % body fat was determined using Bod Pod and it was 35%. If you want to reduce body fat to 28%, what is your target weight
- 6 x 0.65 = 55.64
55. 64 / 0.72 % = 77.3 kg
Your result from Bodpod showed that your % body fat was 10.5% while DXA result showed 10.6%. This indicates that _____ regarding measurement concept
Air displacement plethysmorgraphy is a VALID technique to ASSESS body composition
Air displacement plethysmography using Bodpod follows Boyle’s law because of the isothermal condition that the body creates in the chamber
False
Air displacement plethysmography using Bodpod follows Poisson’s law because of the adiabatic condition that the body creates in the chamber
True
Using Bodpod, body volume can be underestimated if your thoracic gas volume is higher than what it is
False
