Skinfold Flashcards
3 anthropometric methods
Body mass index
circumferences
skinfold measurements
2 densitometry methods
Hydrodensitometry (underwatering) weighing
Plethysmography
4 other body comp techniques
dual energy x-ray absorptiometry
total body electrical conductivity
bioelectrical impedance analysis
near-infared interactance
overweight BMI
25-29.9 kg/m2
obese BMI
greater than or equal to 30 kg/m2
What is an important indicator of health and prognosis?
pattern of body fat distriubution
Android obesity
characterized by more fat on the trunk (abdominal fat) increases the risk of HTN, Metabolic syndrome, DM2, dylipidemia, CVD, and premature death compared to indiciuals who demonstrate gynoid or gynecoid obesity (fat distributed in the hip and thigh).
android fat is common in ?
men
gynoid fat is common in?
women
android is what fruit shpae
apple
gynoid is what fruit shape
pear
What makes waist circumferneces accurate?
A cloth tape measure with a spring loaded handle (gulick tape) reduces skin compression and improves consistency of measurement
how is circumferences taken?
duplicate measurements recommended for each site and a rotational manner of consecutive order for circumference
What measurement is used for circum?
Average of the two measures is used provided they dont differ by more than 5 mm
How is abd circumerfence taken?
With the subject standing upright and relaxed, a horizontal measure taken at the height of iliac crest, usually at the level of the umbilicus
Arm circumference taken where?
With subject standing erect and arms hanging freelu at the sides with hands facing the thigh, a horizontal measure midway btwn the acromion and olecranon process
Buttocks and Hip circumf
With the subject standing erect and feet together, a horizontal measure is taken at the maximal circumfernce of buttokcs, and this measure is used for the hip measure in a waist/hip measure
Calf circumference
With the subject standing erect (feet apart approx 20 cm), a horizontal measure taken at level of the maximum circumference btween the knee and ankle, perpendicular to the long axis
Forearm C
With the subject standing, arms hanging downward but slightly away from the trunk and palms facing anteriorly, a measure is taken perpendicular to the long axis at the maximal C
Hips/Thigh C
With the subject standing, legs slightly apart (~ 10 cm), a horizontal measure is taken at the maximal circumference if the hip/proximal thigh, just below the gluteal fold
Mid-thigh C
W/ the subj standing and one foot on a bench so the knee is flexed @ 90 degs, a measure taken midway btw the inguinal crease and the proximal border of the patella, perpendicular to the long axis
Waist C
With the subject standing, arms at the sides, feet together, and abdomen relaxed, a horizontal measure is taken at the narrowest part of the torso (above the umbilicus and below the xiphoid process). The National Obesity Task Force (NOTF) suggests obtaining a horizontal measure directly above the iliac crest as a method to enhance standardization. Unfortunately, current formulae are not predicated on the NOTF suggested site.
box 4.1 standardized description of C sites and procedures
All measurements should be made with a flexible yet inelastic tape measure.
The tape should be placed on the skin surface without compressing the subcutaneous adipose tissue.
If a Gulick spring-loaded handle is used, the handle should be extended to the same marking with each trial.
Take duplicate measures at each site and retest if duplicate measurements are not within 5 mm.
Rotate through measurement sites or allow time for skin to regain normal texture.
Waist to Hip Ratio (WHR)
The waist-to-hip ratio is the circumference of the waist (above the iliac crest) divided by the circumference of the hips (buttocks/hips measure) and has traditionally been used as a simple method for assessing body fat distribution and identifying individuals with higher and more detrimental amounts of abdominal fat.
Health risks does what with WHR? and standrads
Health risk increases as WHR increases, and the standards for risk vary with age and sex.
WAIST measurement for WHR
the smallest waist circumference usually above the umbilicus or navel
HIP measurement for WHR
Largest circumference around the buttock, above the gluteal fold.
Health risk is very high for young men when WHR is
> 0.95 and for young women when WHR is >0.86.
For individuals aged 60–69 yr, the WHR cutoff values are
> 1.03 for men and >0.90 for women for the same high-risk classification as young adults.
The waist circumference can be used alone
as an indicator of health risk because abdominal obesity is the primary issue.
The Expert Panel on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults provides
a classification of disease risk based on both BMI and waist circumference as shown in Table 4.1.
A newer risk stratification scheme for adults based on .
waist circumference has been proposed (see Table 4.3)
Evidence indicates that all currently available waist circumference measurement techniques
are equally reliable and effective in identifying individuals at increased health risk.
Measurement of waist circumference immediately above
the iliac crest, as proposed by National Institutes of Health guidelines, may be the preferable circumference method to assess health risk given the ease by which this anatomical landmark is identified
Body composition determined from and is determined by?
skinfold thickness measurements correlates well (r = 0.70–0.90) with body composition determined by hydrodensitometry.
The principle behind skinfold measurements is
that the amount of subcutaneous fat is proportional to the total amount of body fat.
It is assumed that close to one-third of the total fat (SKINF)
is located subcutaneously.
The exact proportion of subcutaneous to total fat varies with (SKIN FOLD)
sex, age, and race.
Regression equations used to
convert sum of skinfolds to percent body fat should consider these variables for greatest accuracy.
Abd skinfold site
Vertical fold; 2 cm to the right side of the umbilicus
Triceps: skinfold
Vertical fold; on the posterior midline of the upper arm, halfway between the acromion and olecranon processes, with the arm held freely to the side of the body
Biceps skinfold
Biceps: Vertical fold; on the anterior aspect of the arm over the belly of the biceps muscle, 1 cm above the level used to mark the triceps site
Chest/pec skinf
Chest/Pectoral: Diagonal fold; one-half the distance between the anterior axillary line and the nipple (men), or one-third of the distance between the anterior axillary line and the nipple (women)
Medial Calf skinF
Medial calf: Vertical fold; at the maximum circumference of the calf on the midline of its medial border
Midaxillary skinf
: Vertical fold; on the midaxillary line at the level of the xiphoid process of the sternum. An alternate method is a horizontal fold taken at the level of the xiphoid/sternal border in the midaxillary line
Subscapular: SKF
Diagonal fold (at a 45-degree angle); 1–2 cm below the inferior angle of the scapula
Suprailiac: SKF
Diagonal fold; in line with the natural angle of the iliac crest taken in the anterior axillary line immediately superior to the iliac crest
Thigh skf
: Vertical fold; on the anterior midline of the thigh, midway between the proximal border of the patella and the inguinal crease (hip)
Skinfold Procedures
Box 4.2 Standardized Description of Skinfold Sites and Procedures (cont.)
All measurements should be made on the right side of the body with the subject standing upright
Caliper should be placed directly on the skin surface, 1 cm away from the thumb and finger, perpendicular to the skinfold, and halfway between the crest and the base of the fold
Pinch should be maintained while reading the caliper
Wait 1–2 s (not longer) before reading caliper
Take duplicate measures at each site and retest if duplicate measurements are not within 1–2 mm
Rotate through measurement sites or allow time for skin to regain normal texture and thickness
Factors that may contribute to measurement error within skinfold assessment include:
Poor technique
An inexperienced evaluator
An extremely obese or extremely lean subject
An improperly calibrated caliper (tension should be set at ~12 g · mm−2) (constant tension)
Skinfold Determination
Record the reading in 1-2 second (NO LONGER) WHY??
Measure the skinfold to the nearest 0.5 mm. If not within 1 or 2 mm retest!
Measure the skinfold sites twice and make sure to ROTATE. WHY??
Sum the averages of each skinfold site to determine percent body fat with the SPECIFIC SKINFOLD FORMULA!
Different formulas use different skinfold sites.
Record the reading in 1-2 second WHY??
caliper time get deeper into skin making number smaller
Measure the skinfold to the nearest
0.5 mm. If not within 1 or 2 mm retest!
Measure the skinfold sites twice and make sure to ROTATE. WHY??
allows tissue to go back to normal position
Sum the averages of each skinfold site to determine
percent body fat with the SPECIFIC SKINFOLD FORMULA!
Different formulas use
different skinfold sites.
Things to remember for skinfold procedures:
All measurements are taken on the right side of the body
Caliper should be placed 1 cm from the thumb and index finger
Pinch should be maintained while reading the caliper
Wait 1-2 s before reading the caliper
Duplicate measurements at each site
Rotate through the sites
Although limited in the ability to provide highly precise estimates of percent body fat, anthropometric measurements (i.e., BMI, WHR, waist circumference, and skinfolds) provide
valuable information on general health and risk stratification. As such, inclusion of these easily obtainable variables during a comprehensive health/fitness assessment is beneficial.
Densitometry
Whole-body density using the ratio of body mass to body volume
Densitometry has been used as a reference or criterion standard for assessing body composition for many years.
The limiting factor in the measurement of body density is the accuracy of the body volume measurement because body mass is measured simply as body weight.
Hydrodensitometry (underwater) weighing Based on
Archimedes’ principle:
Archimedes’ principle:
When a body is immersed in water, it is buoyed by a counterforce equal to the weight of the water displaced.
Bone and muscle tissue are
denser than water, whereas fat tissue is less dense.
Therefore, an individual with more fat-free mass (FFM) for the same total body mass weighs
more in water and has a higher body density and lower percentage of body fat
The density of a material is a function of the density of its components.
For example, the human body can be divided into two compartments: fat and fat-free. Each of the two compartments has its own density, with fat-free tissue being more dense than fat tissue.
Measurement of %fat by densitometry relies on certain assumptions:
The proportions of body compartments other than fat (i.e. those that make up fat-free mass as shown in the image on the right) are relatively constant from person to person.
Subjects being measured differ from the reference standards for body composition only in their amounts of body fat.
In actuality, there are certain factors that can affect fat-free mass composition and density. These include growth and maturation, physical training, aging, race, and sex. Some or all of these factors need to be taken into account when using densitometry for body composition assessment.
Density=
Mass/volume
Underwater weighing =
gold standard for body composition analysis (2.5% error).
(UWW)The density can then be converted to percent body fat using one of the two following equations:
siri and brozek
Siri Equation:
% body fat = 4.95/BD – 4.50 x 100
Brozek Equation:
% body fat = 4.57/BD – 4.142 x 100
During this method the body is divided into two components:
Fat mass (FM) Fat-free mass (FFM)
Several variables must be known for the UWW method:
Mass in the air Vital capacity Mass in water Tare weight Water temperature Water density
Hydrostatic Weighing must obtain what first an how? What is the tool used? Formula?
Spirometer
Vital capacity is used to estimate lung volume
RV (ml)BTPS=VCATPS * (.24 m or .28 f) * 1.063 * 1000
Water Temperature impacts
density of water.
Water density is reported in
grams/milliliter or g/cc
Water density at varies
water temp
BTPS
Body Temperature, pressure saturated with water vapor
ATPS
Ambient temp, pressure saturated with water vapor
density has how many sig figs?
3
Water 4 degs C has a density of what?
1.000 g/mm
cold water is what?
more dense than hot water
fat tissue density is =
.900 g/mm
lean tissue density =
1.100 g/mm
what is the range you are looking for?
.9-1.100 g/mm
Plethysmography def
measured by air rather than water displacement
Plethysmography uses a dual-chamber
Plethysmograph that measures body volume by changes in pressure in a closed chamber
Plethysmography technology is now well
established and generally reduces the anxiety associated with the technique of hydrodensitometry
