Chapter 6 Flashcards
(27 cards)
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
