section 6: body composition - western...

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Section 6:Body Composition

Section 6:Body Composition

ACSM Guidelines: Chapter 4 (pp. 62‐72)

ACSM Manual: Chapters 4

ACSM Guidelines: Chapter 4 (pp. 62‐72)

ACSM Manual: Chapters 4

HPHE 4450

Dr. Cheatham

HPHE 4450

Dr. Cheatham

OutlineOutline

• 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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IntroductionIntroduction

• 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)

– Non–insulin‐dependent diabetes mellitus (NIDDM)

– Hypertension (HTN)

– Certain cancers

– Hyperlipidemia (high blood cholesterol)

Why do we measure BC?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 PrinciplesBasic Principles

Basic PrinciplesBasic Principles

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TerminologyTerminology

• 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

BC TechniquesBC Techniques

• Definition: Measurement of the human body

• Categories 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 individual’s target, desirable, or optimal weight

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Anthropometry ‐ Body Mass Index (BMI)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 and mortality 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 fat determined by hydrostatic weight


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Anthropometry ‐ CircumferencesAnthropometry ‐ Circumferences

• Uses:– Pre‐post changes in body measurements

• Useful for weight management programs/motivation for clients/patients

– Waist circumference used along with BMI can be used as an estimate of disease risk (ACSM Manual, Table 4.2)

– 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

Anthropometry ‐Waist CircumferenceAnthropometry ‐Waist Circumference

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Anthropometry ‐ Circumferences ‐ SitesAnthropometry ‐ Circumferences ‐ Sites

Anthropometry ‐ Circumferences ‐ SitesAnthropometry ‐ Circumferences ‐ Sites

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Anthropometry ‐ Circumferences ‐ ProceduresAnthropometry ‐ Circumferences ‐ Procedures

Anthropometry ‐Waist‐to‐Hip RatioAnthropometry ‐Waist‐to‐Hip Ratio

• Definition– Comparison between the circumference of the waist and hips, representing the person’s distribution 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 fat distribution 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


ACSM Box 4.1 (Waist)

ACSM Box 4.1 (Buttocks/Hips)

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Waist Measurement

Hip Measurement

Anthropometry ‐ Skinfold AssessmentAnthropometry ‐ Skinfold Assessment

• Principle

– ~33% of our total body fat lies directly beneath the skin (subcutaneous)

– Therefore, by measuring skinfold thickness we can estimate body density and % body fat

• Accuracy (± 4‐5%)

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Anthropometry ‐ Skinfold Assessment ‐ SitesAnthropometry ‐ Skinfold Assessment ‐ Sites


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Anthropometry ‐ Skinfold – Sites (Chest)Anthropometry ‐ Skinfold – Sites (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 ‐ Skinfold – Sites (Abdomen)Anthropometry ‐ Skinfold – Sites (Abdomen)

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

Correct locationWRONG orientation

Anthropometry ‐ Skinfold – Sites (Thigh)Anthropometry ‐ Skinfold – Sites (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 ‐ Skinfold – Sites (Tricep)Anthropometry ‐ Skinfold – Sites (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

Anthropometry ‐ Skinfold – Sites (Suprailiac)Anthropometry ‐ Skinfold – Sites (Suprailiac)

Diagonal fold; in line with the natural angle of the iliac crest taken in the anterior

axillary line immediately superior to the iliac crest

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Anthropometry ‐ Skinfold – Sites (Midaxillary)Anthropometry ‐ Skinfold – Sites (Midaxillary)

Vertical fold; on the midaxillary line at the level of the xiphoid process of the

sternum.

Correct locationWRONG orientation

Anthropometry ‐ Skinfold – Sites (Subscapular)Anthropometry ‐ Skinfold – Sites (Subscapular)

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

scapula

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Anthropometry ‐ Skinfold – Sites (Calf)Anthropometry ‐ Skinfold – Sites (Calf)

Vertical fold; at the maximum circumference of the calf on the midline

of its medial border

Anthropometry ‐ Skinfolds Assessment ‐ ProceduresAnthropometry ‐ Skinfolds Assessment ‐ Procedures

• Technique:– Firmly grasp all subcutaneous fat (without muscle)

– Use two fingers (thumb and index) about 8 cm apart, perpendicular to long axis of site 1 cm above the site to be measured

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

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

– Use the average of each skinfold site for use in the regression formula

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


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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Hydrostatic WeighingHydrostatic Weighing

• Measurement of Density– Density = mass/volume

• Mass = The bodyweight we measure in air on the 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 completely immersed in water, the apparent loss in weight will be equal to the weight of the displaced liquid.“

• By knowing the density of water, it is easy to go from weight to volume.


• Considered the “Gold Standard” (Sort of)

• 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%)

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More Muscle More FatSame Weight


Body Density =BWAIR

BWAIR – (BWUWW – Tare)

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

BWAIR = Bodyweight in air in gramsBWUW = Bodyweight underwater in gramsTare = Chair weight (and any other apparatus) in gramsH2O Density = Density of water at specific temperatureRV = Residual volume in mL

Residual Volume (males) = (0.027 * Ht) + (0.017 * age) - 3.45Residual Volume (females) = (0.032 * Ht) + (0.009 * age) - 3.90Residual Volume (both) = 0.24 x FVC

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

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Air Displacement PlethysmographyAir Displacement Plethysmography

Bioelectrical Impedance AnalysisBioelectrical 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 poor electrical conductor

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

• Accuracy is highly variable

– Greatly affected by caffeine, alcohol, fluid intake

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BIA ProceduresBIA 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


• 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 lie down 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

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Other MethodsOther Methods

• Magnetic Resonance Imaging (MRI) and Computed Tomography (CT)

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Other MethodsOther Methods

• Dual‐Energy X‐Ray Absorptiometry

Summary of MethodsSummary of Methods

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Interpretation of DataInterpretation of Data

• Based on BMI:


• Based on Circumferences:

– Pre‐ to Post‐Changes

– Waist Circumference

– Waist‐to‐Hip Ratio

WHR

WaistCircumference

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• Based on Skinfolds, BIA, any technique that provides 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%


• 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 (cont’d)

– How do you pick a desired %BF?

• Use population norm charts

• Based on attainable or incremental goals

• Based on %BF considered satisfactory for health

Practice ProblemPractice Problem

19 21

20 20

14 18 16

19 24 21

25 27

30 30

22 25 22

45Male #1

90.9

5

JP‐7, Brozek

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Practice ProblemPractice Problem

• Calculate the following:

– Body Density

– % Body Fat

– Fat‐Weight (kg)

– Fat‐Free Weight (kg)

– Ideal Body Weight

• Use a % desired body fat of 18%

section 6: body composition - western...

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