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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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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
Anthropometry ‐ Body Mass Index (BMI)Anthropometry ‐ Body Mass Index (BMI)
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Anthropometry ‐ Body Mass Index (BMI)Anthropometry ‐ Body Mass Index (BMI)
Anthropometry ‐ Body Mass Index (BMI)Anthropometry ‐ Body Mass Index (BMI)
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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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Anthropometry ‐Waist‐to‐Hip RatioAnthropometry ‐Waist‐to‐Hip Ratio
• 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
Anthropometry ‐Waist‐to‐Hip RatioAnthropometry ‐Waist‐to‐Hip Ratio
ACSM Box 4.1 (Waist)
ACSM Box 4.1 (Buttocks/Hips)
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Anthropometry ‐Waist‐to‐Hip RatioAnthropometry ‐Waist‐to‐Hip Ratio
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 Assessment ‐ SitesAnthropometry ‐ Skinfold Assessment ‐ Sites
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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Anthropometry ‐ Skinfolds Assessment ‐ ProceduresAnthropometry ‐ Skinfolds Assessment ‐ Procedures
Anthropometry ‐ Skinfolds Assessment ‐ ProceduresAnthropometry ‐ Skinfolds Assessment ‐ Procedures
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Anthropometry ‐ Skinfolds Assessment ‐ ProceduresAnthropometry ‐ Skinfolds Assessment ‐ Procedures
Note: Make sure to carry body density out to three decimal places.
Anthropometry ‐ Skinfolds Assessment ‐ ProceduresAnthropometry ‐ Skinfolds Assessment ‐ Procedures
Note: Make sure to carry body density out to three decimal places.
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Anthropometry ‐ Skinfolds Assessment ‐ ProceduresAnthropometry ‐ Skinfolds Assessment ‐ Procedures
• Converting Body Density to % Body Fat
– Generalized Equations:
• % Fat = (457 / Body Density) – 414.2 (Brozek)
• % Fat = (495 / Body Density) – 450 (Siri)
Anthropometry ‐ Skinfolds Assessment ‐ ProceduresAnthropometry ‐ Skinfolds Assessment ‐ Procedures
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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.
Hydrostatic WeighingHydrostatic Weighing
• 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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Hydrostatic WeighingHydrostatic Weighing
More Muscle More FatSame Weight
Hydrostatic WeighingHydrostatic Weighing
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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Bioelectrical Impedance AnalysisBioelectrical Impedance Analysis
Bioelectrical Impedance AnalysisBioelectrical Impedance Analysis
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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
BIA ProceduresBIA 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 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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BIA ProceduresBIA Procedures
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:
Interpretation of DataInterpretation of Data
• Based on Circumferences:
– Pre‐ to Post‐Changes
– Waist Circumference
– Waist‐to‐Hip Ratio
WHR
WaistCircumference
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Interpretation of DataInterpretation of Data
• 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
Interpretation of DataInterpretation of Data
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Interpretation of DataInterpretation of Data
• % BF Population Norms
– See previous slide
– % BF considered satisfactory for health:
• Men: 10 to 22%
• Women: 20 to 32%
Interpretation of DataInterpretation of Data
• 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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Interpretation of DataInterpretation of Data
• 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