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)
all skinfold measurements are taken on what side of body
right
can client wear lotions or oil
no, we want dry skin
how 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
how 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
does order matter for skinfold
yes
-once you go through entire thing once, you do it all over again
-not 2 of each site at one time
how do you position the jaws of the caliper
perpendicular to the middle of the skinfold
how fast should you read calipers after placements
2 seconds after
-ACSM says 1-2 seconds
skinfold measurement is written to the nearest ____
mm
when should a third measurement be taken
when more than 2mm apart
triceps- anatomic description of triceps location
on the posterior midline of the upper arm, halfway between the acromion and olecranon processes, with the arm held freely by to the side of the body
triceps- direction of the fold
vertical
triceps- instructions for taking measurement
-with the elbow flexed at 90 degrees, measure and mark the halfway point between the acromion process of the scapula + the bottom of the olecranon process (elbow) on the lateral side of the arm
-using the tape measure, visualize a line from this point and around to the midline on the posterior side of the arm
-mark this site, ask the client to extend their elbow into a relaxed position, + take the skinfold measurement here.
subscapular- anatomic description of subscapular location
diagonal fold (at a 45-degree angle)
-1-2 cm below the inferior border/angle of the scapula
subscapular- direction of the fold
diagonal
subscapular- instructions for taking measurement
-palpate the inferior angle of the scapula + measure 2cm below this reference point + mark
-the fold is lifted in a diagonal orientation along the natural tension of the skin
chest- anatomic description of chest location
MEN- 1/2 the distance between the anterior axillary line + the nipple
WOMEN- 1/3 of the distance between the anterior axillary line + the nipple
chest- direction of the fold
diagonal
chest- instructions for taking measurement
-measure diagonally from the anterior axillary line (armpit) fold + the nipple
-for men, the skinfold is marked + measured halfway along this distance
-for women, the skinfold is marked + measured in the first 1/3 of this distance
-the fold is lifted in a diagonal orientation along this line
suprailiac- anatomic description of suprailiac lcoarion
in line with the natural angle of the iliac crest taken in the anterior axillary line immediately superior to the iliac crest
suprailiac- direction of the fold
diagonal
suprailiac- instructions for taking measurement
-identify the anterior axillary fold + using a tape measure, visualize a line from this position to the iliac crest of the pelvis
-mark the site along this line (anterior axillary line) + slightly superior to the iliac crest
-the fold is lifted in a diagonal orientation along with the line of the iliac crest + natural tension of the skin
abdominal- anatomic description of abdomen location
2cm to the right of the umbilicus
abdominal- direction of the fold
vertical
abdominal- instructions for taking measurement
-mark + measure exactly 2cm to the side + at the level of the umbilicus
-the fold is lifted in a vertical orientation
-the calipers should be on either side of the fold + not contacting the inside edge of the umbilicus
midaxillary- anatomic description of midaxillary location
on the midaxillary line at the level of the xiphoid process of the sternum
midaxillary- direction of the fold
vertical
midaxillary- instructions for taking measurement
-instruct the client to abduct their arm to 90 degrees to start
-palpate the xiphoid process + identify the midaxillary line (the vertical line that divides the armpit in half)
-using the tape measure, visualize a line across from + at the level of the xiphoid process to the midaxillary line + mark this site
-the fold is lifted in a vertical orientation along the midaxillary line
thigh- anatomic description of thigh location
on the anterior midline of the thigh, midway between the proximal border of the patella + the inguinal crease (hip)
thigh- direction of the fold
vertical
thigh- instructions for taking measurement
-with the hip and knee flexed at 90 degrees (the client should hold on to a stable support (e.g. table or chair) + place their foot on a stable surface for good balance + safety
-measure along the midline of the thigh + mark the halfway point between the inguinal crease (the junction point between the hip + leg created with the hip flexed) + the superior border of the patella
-once the site is marked, the client should return their leg to a standing but relaxed position
-the fold is lifted in a vertical orientation
types of calipers
-lange metal calipers
-harpenden calipers
-accu-measure calipers
-slimguide calipers
lange metal calipers
-gold-standard of skinfold measurements in the US
-developed by Dr. Karl O. Lange at the University of Kentucky in the Aeronautical Research Laboratory in 1953
-standard Pressure exerted of 10gm/mm2
-have a range of 60mm
harpenden calipers
-gold-standard of skinfold measurements internationally
-released in 1958
-can measure to the tenth of a millimeter
-have a range of 90mm
accu-measure calipers
-very simple and inexpensive
-released in 1992
-not recommended for clinical use
-have a range of 60mm
slimguide calipers
-some studies have shown similar validity + reliability to Lange + Harpenden
-released in 1976
-have a range of 95mm
waist-to-hip ratio (WHR)
-circumference measures can be used to determine body fat distribution
-specifically, with the waist + hip measurements it can be determined whether a client has a gynoid or android shape
WHR- android
known as central adiposity
-larger amounts of fat are stored around the waist + are associated with higher risk of metabolic disorders
WHR- gynoid
larger amounts of fat are distributed around the thighs + hips instead of the waist
WHR- waist anatomic locations based on CDC + NIH
just above the hipbones
WHR- waist anatomic locations based on WHO
made at the midpoint between the lower margin of the last palpable rib + the top of iliac crest
WHR- waist anatomic locations based on ACSM
height of the iliac crest, usually at the level of the umbilicus
-ACSM resources for the EP- made at the narrowest part of the torso above the umbilicus + below the xiphoid process
WHR- waist anatomic locations for THIS CLASS
right above iliac crest
WHR- hip anatomic locations based on CDC, NIH, WHO, ACSM guidelines/resources for the EP
made at the maximum circumference of the buttocks
waist to hip protocol
- inform the client what you will be measuring + how you’ll be measuring
- locate the waist measurement site; measurement should be made against the skin + bring the tape to the right side of the body to read the measurement
- the accuracy of waist measurements depends on the tightness + levelness of tape; so, make sure that the tape is tight but not constricting the client + at a level parallel to the floor
- record your waist measurement to the nearest millimeter.
- locate the hip measurement site. unlike waist measurement, the hip measurement will be made with clothing on. however, make sure the clothing is as tight to the skin as possible before making measurement
- remember to bring the tape to the right side of the body to read the measurement
- the accuracy of hip measurements depends on the tightness + levelness of tape. so, make sure that the tape is tight but not constricting the client + at a level parallel to the floor
- each site should be measured twice in a rotational order. if the two measurements are greater than 5mm apart a third measurement should be made. an average of the two measures is used to represent the circumference value
- take the waist value + divide it by the hip value this will yield the waist to hip ratio
closer to 1 on WHR is good/bad
bad
body mass index (BMI)
originally created by Aldophe Quetelet in 1835 + wasn’t used in relation to body composition until 1972 when Ancel Keys published a paper indicating it could be used to estimate population obesity levels
units for BMI
kg/m^2
(weight/height)
does BMI measure or estimate body composition
NO
what is BMI
a ratio of weight to height
-that ratio has a correlation with body fat at the population level, but not for the individual
multiple research studies have shown that BMI is…
incorrectly labeled the body composition of up to 40% of individuals
whenn calculating BMI, how do we convert lbs to kg
divide lb / 2.2
when calcualting BMI, how do we convert inches to cm
inches x 2.54
muscle/fat weighs more
muscle
-this is why BMI is not a good representation of body comp
BIA
a measurement of body composition where a weak electric current flows through the body at a certain frequency + the voltage is measured in order to calculate the impedance of the body
what is impedance
the frequency dependent opposition of a conductor to the flow of an alternating current
BIA- what is the main measure that is derived from the impedance level
total body water (TBW)
BIA- high TBW =
good current flow
-low impedance
BIA- low TBW =
poor current flow
-high impedance
fat is composed of ____% water
10%
muscle is composed of ____% water
70-80%
BIA- lower impedance =
high lean mass
BIA- high impedance =
high fat mass
compare BIA to skinfolds
like skinfolds there is an inherent error in BIA that assumes there is no variability in water composition of fat free mass across age, gender, genetics + situation
-the value is assumed to be 73%
-this value was based off of 6 cadavers
-hydration levels of fat-free mass have been shown to vary from 70-80%
there are multiple types of BIA based on what
-how many electrodes a device has
-how many frequencies they send
multi-frequency BIA
these devices send out multiple frequencies in order to get a better assessment of total body water
-they’re also known as bioelectrical spectroscopy (BIS) devices.
hand-held BIA
electrodes mounted on handgrips
foot-to-foot BIA
electrodes mounted on a foot-plate
hand-to-foot BIA
electrodes mounted on a foot-plate + hand grips
BIA- eating/drinking protocol
no eating/drinking within 4 hours of test
BIA- exercise protocol
no moderate-vigorous exercise within 12 hours of test
BIA- bladder protocol
void bladder 30 min prior to test
BIA- alcohol consumption protocol
no alcohol consumption 48 hours prior to test
BIA- diuretics protocol
no diuretics (including coffee) prior to test
BIA- female client protocol
do not test female clients if they perceive they are retaining water
