LAB6- Body Composition Assessment Flashcards
are fat free mass + lean mass the same
no
body composition in generic terms
refers to all the elements that make up the human body
in health + wellness, what does body composition refer to
a 2-compartment model of body copmosition
-the amount of fat-free tissue relative to fat-tissue
2-compartment model history
first theorized in 1940’s introduced by 2 research groups
-Siri, 1961
-Brozek, Grande, Anderson, + Keys, 1953
even though the 2-compartment model is the predominant method…
some methods of body copmosition may use other models
-BIA, DEXA, etc.
what is the predominant method of body composition
2-compartment model
body density is based off of
fat-free mass
body composition is based off
fat-free mass vs. fat mass
components of 2 compartment model
-fat-free mass
-fat mass
method for 2-compartment model
skinfold
components of 3-compartment model
-lean tissue mass
-bone mineral content
-fat mass
method for 3-compartment model
DXA
components of 4-compartment model
-protein
-total body water
-bone mineral content
-fat mass
2 methods for 4-compartment model
-DXA
-BIA
while lean mass + fat free mass are not the same..
they are often used interchangeably
lean mass is the sum of what
-body water
-total protein
-carbs
-non-fat lipids
-soft tissue mineral
what does fat-free mass include
everything that isn’t fat
in a true 2-compartment model, Siri + Brozek proposed that FFM had a density of ____ + FM had a density of ____ for all ages, genders, genetics, + training
FFM = 1.1 g/cm^3
FM = 0.9 g/cm^3
density of FFM
1.1 g/cm^3
density of FM
0.9 g/cm^3
how were the densities of FFM vs FM estimated
-estimated from 3 male cadavers ages 25, 35 and 46 years old
-since the creation of the 2-compartment model research has shown variation in those values depending on age, gender and genetics
where does a good amount of error in assessment techniques occur
in the variations that occur in FM + FFM densities
if you have 50/50 FM to FFM what is your density
(aka if you are about 50% fat)
1
what is the gold standard of body composition assessments
DXA
gold standard out of what we will do in class
bod pod
-considering we don’t have DXA
what 3 ways can body composition assessments be classified
-direct
-indirect
-doubly indirect
(don’t necessarily need to know)
body composition assessments ranked by validity
- DXA
- hydrostatic weighing
- air displacement plethysmography
- BIA
- skinfold
- ultrasound
(don’t necessarily need to know)
body composition assessments ranked by reliability
- DXA
- skinfold (if skilled technician)
- BIA
- hydrostatic weighing
- air displacement plethysmography
- ultrasound
(don’t necessarily need to know)
body composition assessments ranked by speed of measurement
- BIA
- 3D photonic scanning
- DXA
- ultrasound
- air displacement plethysmography
- skinfold
- hydrostatic weighing
(don’t necessarily need to know)
body composition assessments ranked by affordability
- skinfold
- BIA
- ultrasound
- 3D photonic scanning
- air displacement plethysmography
- hydrostatic weighing
- DXA
hydrostatic weighing measures
volume measured by water displacement
-volume is then used to calculate density
air displacement plethysmography measures
volume measured by changes in pressure using Boyle’s law
-volume is then used to calculate density
-then density is used to estimate body fat using the 2-compartment model
BIA measures what
total body water measured by current resistance in the body
-then regression equation is used to estimate body fat
ultrasound measures what
subcutaneous fat thickness measured by ultrasound
-then density is estimated from correlation of density to subcutaneous fat thickness
3D photonic scanning measures what
volume measured by 3-D imaging of the body
-volume is then used to calculate density and estimate body fat using the 2-compartment model
DXA measures what
density measured by high and low energy x-ray photons
-this allows the break-up of 3 and 4 compartment models
-but body fat can be estimated in traditional 2-compartment model
skinfold measures
subcutaneous fat thickness measured by skinfold measurement
-then body density is estimated from correlation of density to subcutaneous fat thickness
skinfold is direct/indirect/doubly indirect
doubly indirect
-because you must go through 2 layers of info
-subcutaneous fat at skinfold sites -> density -> body fat estimation
what are the 2 sites we go through for skinfold
-skinfold sites
-body density
what does skinfold testing measure
the amount of subcutaneous fat via thickness of skinfold and assumes a relationship between subcutaneous fat and total body fat
-measurement of skinfold -> sum of skinfolds -> estimation of body density -> estimation of body fat using 2-compartment model assumptions
who created the Lange calipers in 1957
Dr. Karl Lange
-they are the standard for skinfold testing (In the UK Harpenden (1958) calipers are often viewed as the standard)
is skinfold reliable
the technique must be thoroughly practiced before it becomes reliable
**what standard amount of force should the calipers be calibrated to deliver
10 g/mm^2
3 assumptions of skinfold
- skinfold is a good measure of subcutaneous fat
- the distribution of fat (subcutaneous vs. internal) is similar for all individuals within each sex (male vs female); roughly 1/2 of total body fat is subcutaneous fat
- there is a linear relationship between the sum of skinfolds + body density (linear relationship only for homogenous samples -> population-specific)
notes on skinfold assumptions
these assumptions don’t always hold true and can be a source of error
it is assumed that roughly ___ of total body fat is subcutaneous fat
1/3
interpersonal skills with skinfold
-make sure to fully describe the procedure to the client before any action is completed; in addition, make sure they know they are encouraged to asked questions throughout the procedure
-while interacting with the client try to be as relaxed and confident as possible
-before starting the procedure ask the client whether they would like you to explain the measurements while you’re taking them or discuss something else
-if the client wants you discuss them try to inform the client on the details of the procedure + why it’s important to follow a standard protocol
-the measurements should be taken in a private location (behind privacy screens are always a good option)
-before starting the measurements it’s always beneficial to demonstrate a measurement on yourself
-while taking the measurements refrain from making any verbal or facial reactions to the actual measurements
-if the client still feels uncomfortable you can always let them know having someone else (of the same sex as they are) performing the measurements is an option
standard protocol for skinfolds
- all measurements should be taken on the right side of the body, make sure the client’s skin is dry + free of lotions or any oils
- follow all standardized site identification on the following slides
- to lift the skinfold use your thumb + index or middle finger. bring the thumb + finger together + grab the skin as you do so. hold the skinfold firmly between these fingers approximately 1cm above the marked site where you will be placing the calipers. try + use the pads of your fingers to grip the skinfold + ensure your fingernails have been properly trimmed before performing skinfolds
- to ensure that you are grasping skin + fat only ask the client to contract the muscle under the skinfold afterwards reposition your grip on the skinfold
- position the jaws of the caliper perpendicular to the middle of the skinfold; do not let go of the skinfold while the calipers are in contact with the skin
- slowly release the jaws so that they are fully pressed against the skinfold; read the caliper measurement 2 seconds (note: ACSM states 1-2 seconds) after placement
- after taking the measurement open the calper jaws, remove from skin
- record the skinfold measurement on a data sheet to the nearest millimeter
- take a single measurement at each site + rotate through each site a minimum of 2x; if the 2 skinfold measurements are more than 2mm (ACSM states 1-2 mm + several publications state greater than 10% difference) different, then a 3rd measurement should be taken
- using the sum of the skinfolds estimate the body density using a body density estimation equation (most often Jackson and Pollock Equations)
- using the estimated body density estimate the body fat using a percent body fat estimation equation (Most often Siri or Brozek)