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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
• 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
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)
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
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
• 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
• 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)