Presentation Package for Concepts of Fitness and Wellness 6e

1
Presentation Package for Concepts of Fitness and
Wellness 6e

• Section V Concept 15
• Body Composition

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Trends in the Prevalence of Obesity in the U.S.
1991-98,
Click to see progression oftrends over time
Obese
Mokdad et al. JAMA 1999 2821519
Web15-1
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Health Risks Associated with Being Overweight

• Coronary heart disease
• Hypertension
• Hypercholesterolemia
• Diabetes

There are also health risks associated with
being too thin!
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Definitions of Overweight(Based on ht /wt
tables)

• Moderately Overweight
• 20 over desirable body weight
• Severely overweight
• 40 over desirable body weight

Burton, Foster, Hirsch, and Van Itallie, Health
implications of obesity An NIH consensus
development conference. Int J. Obesity, 9,
155-169, 1985.
Problem Ht/Wt tables do not take muscles mass
into account
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Definitions of Overweight (Based on BMI values)
Click for info on BMI

• BMI accounts for differences in frame size better
  than height weight tables. BMI Wt (kg) / Ht2
  (m)
• Standards
• Overweight 25
• Obesity 30
• Severe obesity 40

Problem BMI does not take muscles mass into
account
Web15-1 for moreinformation on standards
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Levels of Body Fatness
Click for calculations of ideal wt based on fat

• Men Women
• Essential fat 5 10
• Borderline 6-9 11-16
• Good fitness - health 10-20 17-28
• Marginal fitness 21-25 29-35
• Overfatness 25 35

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Regional Fat Deposition
Click for more info on fatdeposition

• Abdominal body fat poses greater health risks
  than fat stored in other areas
• Males store more fat centrally and have
  increased health risks associated with body
  fatness

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Body Composition Assessment Techniques

• Underwater weighing
• Technological assessments
• Skinfold technique
• Anthropometric measurements

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Underwater Weighing Technique
Click for more info


Body fat provides more bouyancy so a fatter
person weighs less (on a relative basis) than a
lean person


Web15-2 for info on underwater weighing
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Technological Assessments of Body Composition
Click to seemore info on all techniques

• Dual X-Ray Absorptiometry (DXA)
• Bioelectric impedance
• Infra-red spectroscopy
• Ultrasound
• Imaging techniques (DEXA, MRI)

Click individualtechnique to see more detail
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Skinfold Technique
Layers of subcutaneous fat are measured at
different sites of body to estimate total body
fat levels
Cross sectional view
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Benefits of Skinfold Technique

• Fairly accurate
• Easy to perform
• Inexpensive

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Common Skinfold Sites
Lab 15a info

• 7 site procedure
• Chest
• Axilla
• Tricep
• Subscapular
• Abdomen
• Supraillium
• Thigh

Jackson and Pollack Males Female Chest Triceps A
bdomen Supraillium Thigh Thigh
Alternative Sites (Males Females) Tricep Abdom
en Calf
Validation statistics on 3 site test - r .97
with 7 site procedure - R2 .80 with underwater
weighing
Web15-3
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Research Quality Skinfold Calipers
Lange Calipers
Harpenden Calipers
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Anthropometric Measurements
Lab 15binfo

• Body Mass Index (BMI)
• Waist to Hip Ratio (WHR)
• Circumference measures

More info
More info
More info
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Body Composition AssessmentImplications of
Results

• Values are estimates (/- 2-3 at best)
• Values are personal and confidential
• Proper uses of results
• - Serve as baseline data for repeated testing
• - Provide motivation for goal setting
• - Provide awareness about health risks

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Web Resources
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Supplemental Graphics

• Lab InformationDetail on BMI calculations
• Graphics on Obesity Trends

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Lab 15a InformationEvaluating Body Composition -
Skinfolds

• The purpose of this lab is to evaluate body
  composition with the skinfold assessment.
• Comparisons will be made between different
  procedures and testers to learn about the
  accuracy of the tests

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Lab 15a InformationSkinfold Technique
Return to presentation

• Measurement Technique
• Mark site with marker
• Pinch fold above and below mark with left and
  right hand
• Measure fold with caliper using the right hand
• Scoring Procedure
• Sum skinfolds from the 3 sites
• Look up percent body fat valuefrom chart in the
  book

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Lab 15b InformationEvaluating Body Composition -
Anthropometry

• The purpose of this lab is to evaluate body
  composition with some anthropometric assessments
• Body Mass Index
• Waist to Hip Ratio

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Lab 15b Information BMI Measurement Technique
Return to presentation

• Convert weight to kilograms (2.2 kg/lb.)
• Convert height to meters (.0254 m/in)
• Square the height in meters
• Divide the squared height value into the weight
  value

BMI Wt (kg) / Ht2 (m)
See Web15-05 for BMI calculators
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Lab 15b Information WHR Measurement Technique
Return to presentation

• Waist Measure at the "natural waist" (smallest
  circumference) or at the level of the umbilicus
• Hip Measure at the maximum circumference of the
  buttocks

Divide the hip measurement into the waist
measurement to obtain the WHR
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Sample BMI Values
Return to presentation
This chart reveals how BMI values change for a
hypothetical 6 foot tall person of different
body weights
See Web15-05 for BMI calculators
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Body Composition (2 compartment model)

• Fat
• Lean Body Mass (LBM) (bones, muscles, tissues,
  organs)

Sample calculation

• 70kg person with 20 body fat
• Lean tissue 70 kg x .80 56 kg
• Fat tissue 70 kg x .20 14 kg

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Calculating Desired Body Weight
See sample calculation


Current Lean weight
Wt. - (fat weight)
Desired Weight

Desired Lean
(1 - desired Fat)
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Calculating Desired Body Weight (Example)
Return to presentation
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Regional Fat DepositionVisceral Fat

• Visceral body fat poses greater health risks
  because this fat is more labile and has greater
  access to the circulation.
• The accumulation of visceral body fat is typical
  of the android (male) fat pattern
• males visceral accounts for 10-35 of total fat
• females visceral accounts for 8-13of total fat

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Abdominal Body FatRelationships with CHD Risks

• Abdominal obesity predicts CHD risk independent
  of BMI, smoking, cholesterol and
  hypertension(Kannel et al., J. Clin Epid., 44,
  183-190, 1991).
• Abdominal obesity predicts CHD risk independent
  of total body fatness. (Larsson et al.
  ,Appetite, 13, 37-44, 1989).
• Abdominal obesity statisticallly accounts for
  difference in CHD rates between men and women
  (Larsson et al., Am. J. Epi., 135 266-273, 1992).

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Abdominal Body FatRelationships with other risk
factors

• Abdominal obesity is strongly influenced by
  genetics - similar gain among twins (r.72).
  (Bouchard, NEJM, 322, 1477-1482, 1990).
• Abdominal obesity is greater in smokers than
  non-smokers due to the presence of androgens
  (Barrett-Conner, Ann. Int. Med. 111, 783-787,
  1989).
• Abdominal body fat is preferentially lost during
  a physical activity program(Kohrt, J.
  Gerontology, 47 M99-M105, 1992)

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Waist to Hip Ratio (WHR)
Return to presentation

• Waist to Hip Ratio is an effective way to examine
  regional fat distribution.

WOMEN
MEN
HEALTH RISK















































High Risk
1.0
.85
Moderate Risk
.90 -1.0
.80-.85
Low Risk


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Underwater WeighingMeasurement issues
Return to presentation

• Based on body density calculations
• Density of lean tissue 1.1 g/cc
• Density of fat tissue .9 g/cc
• Sources of error
• Residual lung volume
• Bone density varies by age, ethnicity and
  activity level
• General conclusions
• Gold standard measure (1-2 error)
• Impractical for most applications

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Dual X-Ray Absorptiometry (DXA)
Return to presentation

• The new criterion measure
• Visit the Hologic website for examples and
  details from one of the leading manufacturers of
  DXA devices.

Web15-2 for info on DXA
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Bioelectric Impedence(Measurement Issues)
Return to presentation

• Based on resistance to current flow
• Lean tissue has more water - less resistance
• Fat tissue has less water - more resistance
• Sources of error
• Temperature
• Hydration status
• General conclusions
• Overestimates lean / underestimates obese
• Practical, but expensive, measure for general
  population

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Infrared Spectroscopy(Measurement Issues)
Return to presentation

• Based on differential absorbance rates
• Lean tissue has a different energy absorption and
  reflectance pattern than fat tissue
• Sources of error
• Validity of absorbance readings is questionable!
• General findings
• NOT a valid measure!

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Ultrasound(Measurement Issues)
Return to presentation

• Based on reflection of sound
• Fat content increases the time is required for
  sound to reflect off of bone and muscle.
• Sources of error
• Representative sites for measurement
• Measurement error
• General conclusions
• Highly accurate measure of body fat - especially
  for obese
• Expensive and not practical for most applications

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Imaging Techniques(Measurement Issues)
Return to presentation

• Based on imaging of body tissues
• Based on cross sectional area measures
  calculated at different levels of the body
• Sources of error
• Representative sites for measurement
• Measurement error
• General conclusions
• Very precise measure of body composition
• Expensive and not practical measure for most uses

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Circumferences (Measurement Technique)
Return to presentation

• Based on circumference measures
• sample prediction equation fat - 47.372
  (.579 x abdomen) (.252 x hip) (.214 x iliac)
  (.356 x BW)
• Sources of error
• Location of sites
• Inability to distinguish fat and muscle
• General conclusions
• Provides reasonable estimate of body fat
• Not as accurate as skinfold and takes same time

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Obesity Trends Among U.S. Adults Proportion of
Obese Adults by StateBRFSS
(BMI ? 30, or 30 lbs overweight for 54 woman)
Slides from the CDC
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Obesity Trends Among U.S. AdultsBRFSS, 1990
(BMI ? 30, or 30 lbs overweight for 54 woman)
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Obesity Trends Among U.S. AdultsBRFSS, 1991
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Obesity Trends Among U.S. AdultsBRFSS, 1992
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Obesity Trends Among U.S. AdultsBRFSS, 1993
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Obesity Trends Among U.S. AdultsBRFSS, 1994
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Obesity Trends Among U.S. AdultsBRFSS, 1995
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Obesity Trends Among U.S. AdultsBRFSS, 1996
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Obesity Trends Among U.S. AdultsBRFSS, 1997
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Obesity Trends Among U.S. AdultsBRFSS, 1998
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Obesity Trends Among U.S. AdultsBRFSS, 1999
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Obesity Trends Among U.S. AdultsBRFSS, 2000
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Obesity Trends Among U.S. Adults BRFSS, 1991,
1995 and 2000
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
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Latest data (2003 BRFSS)
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Web Links

• Behavioral Risk Factor Surveillance System
  (BRFSS) Interactive Web Page
• http//www.cdc.gov/brfss/