Chapter 6 Flashcards
Body composition?
Describes the amount and relative proportions of fat
mass (FM) and fat-free mass (FFM) in the human body
Body composition provides information regarding?
– Percent body fat (PBF)
– Fat distribution
– Body segment girth
– Bone density
Body composition used for?
– Reducing health risks associated with disease
– Designing safe and effective training programs
– Optimizing athletic performance
There are many benefits for measuring body composition in
all populations, such as?
- PBF estimation provides information regarding health
and fitness. - Detection of adiposity-based chronic disease (ABCD)
– Excess BF is associated with several diseases. - Malnutrition and some weight-controlled sports can cause
severe dehydration and BF levels. - Estimation of FFM and bone mineral density (BMD)
- Assesses for risk of sarcopenia and osteopenia
- Assesses for sarcopenic obesity
– Low FFM and high FM - Individualization of exercise prescription and
evaluation of an exercise program
Body composition methods can be classified as ____, ____, or ____ ____.
Body composition methods can be classified as direct,
indirect, or doubly indirect
Direct method?
- In vitro: cadaver dissection and chemical analysis
- In vivo: MRI, CT scans, and DXA scan
Indirect method?
Indirect method: measure one parameter to
estimate another
* E.g. Hydrostatic weighing (HW)
– Measures body volume
– Predicts PBF based on assumed FM and FFM densities
Different models have been proposed for characterizing
human body composition by discrete compartments?
- Sum of compartments equal the individual’s body mass
- Two-compartment model (2C): partitions body mass
into FM and FFM - Widest application to body composition analysis
- Limited by assumptions
- Multicompartment models: partition body into more
than two compartments, which provides more accurate
results - Three-compartment model (3C): FM, dry FFM, and total body
water (TBW) - Four-compartment model (4C): FM, TBW, BMD, and dry FFM
Describe anthropometry?
Measurement of the human body using simple
physical techniques
- Height
- Assess with a stadiometer.
- Standard procedures include:
– No shoes, heels together, erect posture, head level, and, after a
deep inhalation, holding breath
- Body mass
- Assess on a calibrated scale.
- Standard procedures include:
– Participant wearing minimal clothing and assess at a standard time
Describe BMI?
- Body mass index (BMI)
- Assesses an individual’s mass relative to height
- BMI = body mass (kg)/ height (m)2
- Primary advantages
- Easy measure to obtain
- Easily classifies large populations as overweight or obese
- Can be used to estimate ideal body weight
- Primary disadvantages
- BMI is a poor predictor of PBF.
- Provides inaccurate classifications for certain populations
– Muscular individuals
Describe circumference measurement use?
Circumference measures: estimate body composition
and provide specific reference to BF distribution
* BF distribution is an important indicator of
obesity-related health risks.
Android obesity related to? Advantages? Measurement accuracy?
- Android obesity increases the risk of:
– Hypertension
– Metabolic syndrome
– Type 2 diabetes
– Dyslipidemia
– Coronary artery disease
– Premature death - Primary advantages
- Easy to learn, quick to complete, and inexpensive
- Measurement accuracy ranges from 2.5% to 4%.
Describe waist circumference?
Represents subcutaneous adipose tissue (SAT) and visceral
adipose tissue (VAT)
BF ____ is considered a bigger risk of CVD than ____ ____ BF.
BF distribution is considered a bigger risk of CVD than excess total BF.
Most effective to use ____ and ____ to assess cardiometabolic risk
Most effective to use WC and BMI to assess cardiometabolic risk
Hip circumference is
Inversely related to ____, ____, and ____ ____?
Hip circumference
Inversely related to CVD, diabetes, and early mortality
What does waist to hip ratio indicate?
Ratio measure of waist circumference to hip circumference
* Indicator of BF distribution
* High WHR may indicate visceral obesity
What is RFM?
Relative fat mass (RFM)
* 64 − (20 × height/waist circumference) + (12 × sex); sex = 0 for men and 1 for
women; measurements expressed in meters; used for adults 20 or older
Key findings:
* RFM-defined obesity prevalence is higher than when using
BMI
* Prevalence increased by 13.9 points and 12.0 points among
women and men respectively over the last 20 years
* Prevalence: 64.7% for women and 45.8% for men
Hydrodensitometry?
Hydrodensitometry is a direct method for determining
body volume but an indirect method for predicting PBF.
* Also known as underwater/hydrostatic weighing
What is hydrodensitometry based on?
Based on the Archimedes principle
* Body immersed in water is subject to a buoyant force
that results in the loss of weight equal to the weight of
the water displaced.
* Assumed density of BF is less than water, whereas FFM
density exceeds the density of water.
* Body density (BD) is then converted to PBF using a 2C
model equation.
– BD is inversely related to PBF
Describe BIA?
Bioelectrical impedance (BIA)
* Small electrical current is sent through the body, and
the impedance to that current is measured.
* Lean tissue is a good electrical conductor, whereas fat is a poor
electrical conductor and impedes the electrical current.
* BIA estimates TBW and uses hydration levels to predict PBF.
* Noninvasive and easy to administer
Potential disadvantages
* Some devices cannot distinguish between intracellular and
extracellular fluid.
* Highly influenced by hydration levels
* Athletes must abstain from exercise 12-24 hours prior to
measurement to ensure accurate results.
ADP?
Air displacement plethysmography (ADP)
* Measures body volume via changes in air pressure
using Boyle’s law
* Quick, noninvasive, comfortable assessment that
accommodates a wide range of populations
Potential disadvantages
* Expensive equipment
* Assumptions associated with equations
* Many potential sources of technical error
DXA?
Gold Standard!
DXA is based on the attenuation of x-rays at two
energies as they pass through the body.
* 3C model including total body mineral stores, FM,
and FFM
* Generates information for the total body and specific
body regions
Potential advantages
* Easy to administer
* Higher comfort level for subjects
* Safe, fast, and accurate
Potential disadvantages
* Tall or overweight subjects may have to maintain a
cramped position, which could effect results.
* High cost and lack of portability
Describe how to assess body composition in children?
Due to the effects of growth/maturation on FM, FFM,
and hydration state, body composition is difficult to
measure in children and adolescents.
- BMI
- Easy to obtain and used frequently in clinical settings
- Does not distinguish between FM and FFM
- Skinfold
- Commonly used; accuracy is questionable
- ADP
- Accurate and modifiable for this population
- BIA
- Practical method but susceptible to measurement error
Interpretation of PBF is complicated by three factors?
1) Lack of established/accepted universal standards
2) All measurements are indirect, so error should be
considered.
3) No universally accepted criterion measurement
* However, 12%–23% for men and 17%–26% for
women span the “good” category across a wide
age spectrum.
Why is assessing body composition essential?
Assessing body composition is essential for determining
and tracking health status and aids in optimizing
physical performance.
What body composition assessments are routinely used?
When more specific information is needed, ____, ____, ____. ____ should be used.
Skinfold measurements, hydrostatic weighing, BIA, and
ADP are routinely used.
When more specific information is needed, DXA, CT,
ultrasound, or MRI should be used.
