HPHE 6720 - Topic 4

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Topic 04:

Anthropometry and BodyComposition Measurement

Laboratory Manual Section 04

HPHE 6720

Dr. Cheatham

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Outline

Importance of Body Composition

General Principles Basic principles

Anthropometric Methods Body Mass Index (BMI)

Circumferences / Waist to Hip Ratio

Skinfold Measurements

Densitometry Methods Hydrostatic (Underwater) Weighing

Plethysmography (Air Displacement)

Other Methods Bioelectrical Impedance Analysis (BIA)

Dual Energy X-Ray Absorptiometry (DEXA)

Interpretation of Results

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Introduction

Definition: Relative proportion of fat and fat-free tissue in the body.

Clinical significance: Obesity is correlated to an

increased risk of: Coronary artery disease (CAD)

Noninsulin-dependent diabetes mellitus (NIDDM)

Hypertension (HTN) Certain cancers

Hyperlipidemia (high blood cholesterol)

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Why Do We Measure BC?

Excess body fat is associated with: Hypertension, Type 2 Diabetes, Stroke, CAD, Hyperlipidemia

To assess the decrease in body fat weight that occurs

in response to a weight management program.

To help athletes determine the best body composition

for performance.

To monitor fat and fat-free weight in patients with

disease.

To track long-term changes that occur in body fat and

fat-free mass with aging.

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Basic Principles

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Basic Principles

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Terminology

Percent Body Fat (%BF)

The percentage of the bodyweight that is adipose tissue

Fat Weight (FW)

The total weight of the adipose tissue

Fat-Free Weight (FFW)

The total weight of everything that is not fat Lean Body Mass (LBW)

More so refers to the weight of muscle

Overweight

Deviation in body weight from some standard or ideal weight in relation to

height

Overfat

Undesirable percent body fat (difference males vs. females)

Obesity

Surplus of adipose tissue resulting from excessive energy intake relative to

energy expenditure

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Body Composition Techniques

Definition: Measurement of the human body

Techniques include:

Height and weight (body mass index [BMI], waist-to-hip

ratio [WHR])

Circumferences and girths

Skinfolds

Bioelectrical impedance analysis

Hydrostatic weighing

Purpose: To evaluate body weight and composition

in the health and fitness field, often to establish an

individuals target, desirable, or optimal weight

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Anthropometry - Height and Weight

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Anthropometry - Body Mass Index (BMI)

Body mass index = __Weight in kg__(Height in meters)2

Statistics: For most people, obesity-related health problems

increase beyond a BMI of 25.0

In increased risk of hypertension, TC/HDL ratio, CAD andmortality rate are associated with a BMI 30

Limitations: It is difficult for clients to interpret weight loss and gain

There is no differentiation between fat weight and fat-free weight

There is only a modest correlation with percent body fatdetermined by hydrostatic weight

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Anthropometry - Circumferences

Uses: Pre-post changes in body measurements

Useful for weight management programs/motivation forclients/patients

Waist circumference used along with BMI can be used

as an estimate of disease risk (ACSM Manual, Table 4-3) Estimate % BF (limited accuracy)

Calculate Waist-to-Hip Ratio

Advantages: Easily learned Quickly administered

Quantifies changes in muscle with specific training(muscle girth size)

Easy to document changes in body size

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Anthropometry - Waist Circumference

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Anthropometry - Circumferences - Sites

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Anthropometry - Circumferences - Sites

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Anthropometry - Circumferences - Procedures

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Anthropometry - Waist-to-Hip Ratio

Definition Comparison between the circumference of the

waist and hips, representing the personsdistribution of body fat

WHR = Waist circumference (cm)

Hip circumference (cm)

Waist circumference alone may be used as an

indicator of health risk Truncal adiposity increases the risk of chronic

disease

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The pattern of body fatdistribution is an important

predictor of the health risks

of obesity.

Android (male pattern)

Trunk/abdominal fat

Increased risk for hypertension,

diabetes, dyslipidemia, CAD,

premature death Gynoid (female pattern

Hip and thigh

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ACSM Box 4-1 (Waist)

ACSM Box 4-1 (Buttocks/Hips)

Health risks are very high forthe young when:

Males > 0.95

Females > 0.86

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Waist Measurement

Hip Measurement

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Anthropometry - Skinfold Assessment

Principle ~33% of our total body

fat lies directlybeneath the skin

(subcutaneous)

Therefore, bymeasuring skinfold

thickness we canestimate body densityand % body fat

Accuracy ( 4-5%)

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Anthropometry - Skinfold Assessment - Sites

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Anthropometry - Skinfold Assessment - Sites

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Anthropometry - SkinfoldSites (Chest)

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)

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Anthropometry - SkinfoldSites (Abdomen)

Vertical fold; 2 cm to the right side of the umbilicus

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Anthropometry - SkinfoldSites (Thigh)

Vertical fold; on the anterior midline of the thigh, mid-way between the proximal

border of the patella and the inguinal crease (hip)

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Anthropometry - SkinfoldSites (Tricep)

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

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Anthropometry - SkinfoldSites (Suprailiac)

Diagonal fold; in line with the natural

angle of the iliac crest taken in the anterioraxillary line immediately superior to the

iliac crest

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Anthropometry - SkinfoldSites (Midaxillary)

Vertical fold; on the midaxillary line at

the level of the xiphoid process of the

sternum.

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Anthropometry - SkinfoldSites (Subscapular)

Diagonal fold (at a 45 degree angle); 1to 2 cm below the inferior angle of the

scapula

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Anthropometry - SkinfoldSites (Calf)

Vertical fold; at the maximumcircumference of the calf on the midline

of its medial border

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Anthropometry - Skinfolds Assessment - Procedures

Technique: Firmly grasp all subcutaneous fat (without muscle)

Use two fingers (thumb and index) about 8 cmapart, perpendicular to long axis of site 1 cm above

the site to be measured

Release the scissor grip of the caliper but supportits weight while measuring no longer than 1 to 2seconds to the nearest 0.5 mm

Measure each site at least two times, rotatingthrough the sites (should be within 1 to 2 mm)

Use the average of each skinfold site for use in theregression formula

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Note: Make sure to carry body density out to three decimal places.

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Note: Make sure to carry body density out to three decimal places.

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Converting Body Density to % Body Fat Generalized Equations:

% Fat = (457 / Body Density) 414.2 (Brozek)

% Fat = (495 / Body Density) 450 (Siri)

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Densitometry - Hydrostatic Weighing

Measurement of Density Density = mass/volume

Mass = The bodyweight we measure in air onthe scale

Volume = Why we are doing hydrostatic

weighing Use of hydrostatic weighing to measure

volume Based on Archimedes Principle:

"When a solid body is partially or completelyimmersed in water, the apparent loss in weightwill be equal to the weight of the displacedliquid.

By knowing the density of water, it is easy to gofrom weight to volume.

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d h

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Considered the Gold Standard Measurement of Body Density

Underwater, muscle and bone is more dense than

fat Therefore, the more muscle/bone, the more the

subject will weigh underwater or vice versa

By weighing the subject in the air AND underwater,

we can measure BODY DENSITY

From body density, % body fat is calculated

Accuracy ( 3%)

i d i i hi

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More Muscle More FatSame Weight

D i H d i W i hi

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Body Density =

BWAIR

BWAIR (BWUWW Tare)

H2O Density- (RV +100)( )( )

BWAIR = Bodyweight in air in gramsBWUW = Bodyweight underwater in grams

Tare = Chair weight (and any other apparatus) in grams

H2O Density = Density of water at specific temperature

RV = Residual volume in mL

Residual Volume (males) = (0.027 * Ht) + (0.017 * age) - 3.45

Residual Volume (females) = (0.032 * Ht) + (0.009 * age) - 3.90

Residual Volume (both) = 0.24 x FVC

% Body Fat = (457 body density) 414.2 (Brozek)

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Densitometry - Air Displacement Plethysmography

Bi l t i l I d A l i

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Bioelectrical Impedance Analysis

Premise: The volume of fat-free tissue is proportional to the

electrical conductivity of the body

Fat (tissue with little water: 14% to 22%) is a poorelectrical conductor

Lean tissue (mostly water: >90%) is a good electrical

conductor

Accuracy is highly variable

Greatly affected by caffeine, alcohol, fluid intake

Bi l t i l I d A l i22

XcRZ 22

XcRZ

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Principle:

Impedance (Z): A measure of how an electrical current is

slowed or stopped as it passes through a material.

Impedance has two components: Resistance (R) and

Reactance (Xc). Approximately 95% of impedance is

determined by resistance.

Resistance (R): A measure of the amount of electrical

current a substance will stop.

Reactance (Xc): A measure of a materials ability to slow an

electrical current.

Therefore, the equation for Impedance is:

22XcRZ


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Principle (contd):

A BIA analyzer sends a weak electrical current via two

electrodes through the body. That current is then detected

by two other electrodes. The extent to which the electrical

current is impeded or resisted is related to the type andamount of tissue through which it passes.

Water is a very good conductor of electricity and has a very

low level of resistance. Adipose tissue has a very low water

content (~20%) and thus has a high level of resistance orimpedance. Muscle has a very high water content (~75%)

and thus has a low level of resistance or impedance.


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Principle (contd):

Essentially, BIA measures an individuals total body water

based on the principle of the following equation:

Volume = p x L2 / Z

Where:

p = a constant representing a materials ability to impede an

electrical current at a given temperature

L = Length (or in the case of humans, height)

Z = Impedance

Finally, since the approximate water content of adiposetissue and fat-free mass (muscle, bone, fluid, etc.) are

known, the measurement of total body water can be

converted to fat-free mass and then fat-mass and % body fat

can be calculated.


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Bioelectrical Impedance Anal sis

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BIA Procedures

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BIA Procedures

Conditions: No eating or drinking within 4 hours of the test

No exercise within 12 hours of the test

Urinate completely within 30 minutes of the test No alcohol consumption in the previous 48 hours

No diuretics in the previous 7 days

Limited use of diuretic agents before the test

BIA Procedures

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BIA Procedures

Pre-Test Procedures: Record age, gender, height, weight, activity level, frame

size

Performing the test: Calibrate the instrument

Prepare the subject for the test by having them liedown on the table Have subject remove all jewelry, right sock and shoe

Arms and legs should not touch each other

Clean electrode sites with alcohol pad, allow to dry Attach electrodes and wires

Allow values to stabilize (~30 seconds)

Enter information into BIA software

BIA Procedures

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BIA Procedures

BIA Procedures

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BIA Procedures

Summary of Methods

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Summary of Methods

Interpretation of Data

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Based on BMI:


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Based on Circumferences:

Pre- to Post-Changes

Waist Circumference

Waist-to-Hip Ratio

WHR

Waist

Circumference


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Based on Skinfolds, BIA, any technique thatprovides a calculation of %BF

Pre- to Post-Changes

Population Norms Calculations of Fat-Weight, Fat-Free Weight, Ideal

Body Weight


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% BF Population Norms See previous slide

% BF considered satisfactory for health:

Men: 10 to 22% Women: 20 to 32%


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Fat Weight: FW = BW x % BF

% BF needs to be in decimal form (i.e. 25% = 0.25)

Fat-Free Weight: FFW = BW x (1-%BF)

OR FFW = BW - FW

% BF needs to be in decimal form Ideal Body Weight:

IBW = FFW / (1 Desired %BF)

Desired %BF must be in decimal form


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Ideal Body Weight (contd) How do you pick a desired %BF?

Use population norm charts

Based on attainable or incremental goals

Based on %BF considered satisfactory for health

Laboratory Exercise

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Laboratory Exercise

Procedures: Each student will collect the following data on him or

herself using the following procedures: BMI, Skinfolds, Circumferences, BIA

At least six students (hopefully more) will undergo

underwater weighing Research Question

Is there a statistically significant difference in %BF, FW,FFW between the three methods:

UWW vs. Skinfolds UWW vs. BIA

Skinfolds vs. BIA

What is the correlation between the three methods forthese same variables?

HPHE 6720 - Topic 4

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