Topic 04: Anthropometry and Body Composition Measurementhomepages.wmich.edu/~ccheatha/hphe6720/files/HPHE6720-Topic04-… · 8/30/2013 1 Topic 04: Anthropometry and Body Composition

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Topic 04:Anthropometry and Body Composition Measurement

Topic 04:Anthropometry and Body Composition Measurement

Laboratory Manual Section 04Laboratory Manual Section 04

HPHE 6720

Dr. Cheatham

HPHE 6720

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

Body Composition TechniquesBody 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 individual’s target, desirable, or optimal weight

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Anthropometry ‐ Height and WeightAnthropometry ‐ Height and Weight

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 4‐3)

– 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

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)

Health risks are very high for the young when:

•Males > 0.95

•Females > 0.86

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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

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)

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

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

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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)

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

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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

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

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

sternum.

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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

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

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

of its medial border

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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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Densitometry ‐ Hydrostatic WeighingDensitometry ‐ Hydrostatic 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.


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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%)


More Muscle More FatSame Weight

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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)

Densitometry ‐ Air Displacement PlethysmographyDensitometry ‐ Air Displacement Plethysmography

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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


• 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 material’s ability to slow an electrical current.

– Therefore, the equation for Impedance is:

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• Principle (cont’d):

– 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 and amount 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 or impedance. Muscle has a very high water content (~75%) and thus has a low level of resistance or impedance.


• Principle (cont’d):

– Essentially, BIA measures an individual’s total body water based on the principle of the following equation:

• Volume = p x L2 / Z

• Where:– p = a constant representing a material’s ability to impede an electrical current at a given temperatureL = Length (or in the case of humans, height)Z = Impedance

– Finally, since the approximate water content of adipose tissue 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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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

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• 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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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

Laboratory ExerciseLaboratory 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 for these same variables?

Documents

Topic 04: Anthropometry and Body Composition Measurementhomepages.wmich.edu/~ccheatha/hphe6720/files/HPHE6720-Topic04-… · 8/30/2013 1 Topic 04: Anthropometry and Body Composition