Presentation Package for Concepts of Physical Fitness 12e

Presentation Package for Concepts of Physical Fitness 12e
McGraw Hill - Presentation Package for Concepts of Physical Fitness 12e Section V: Concept 15: Body Composition This lecture will cover the subject of body composition. Students will learn about the different assessment techniques and how body composition influences health. Created by: Gregory J. Welk Iowa State University Concept 15 2

Trends in the Prevalence of Obesity in the U.S. 1991-98,
Concepts of Physical Fitness 12e McGraw Hill - Trends in the Prevalence of Obesity in the U.S , Click to see progression of trends over time % Obese This slide shows the increasing prevalence of obesity. Click on the Play button to see the CDC slides showing the progression across different states. Mokdad et al. JAMA 1999; 282:1519 Web15-1 Concepts of Physical Fitness 12e Concept 15

Health Risks Associated with Being Overweight
Concepts of Physical Fitness 12e McGraw Hill - Health Risks Associated with Being Overweight Coronary heart disease Hypertension Hypercholesterolemia Diabetes Many health problems are associated with excess levels of body fatness Obesity is considered to be a secondary risk factor for coronary heart disease mainly because the effect of body fatness is manifested in other risk factors. These data show the relative risk of other risks if you are overfat (data from NHANES II data cited in VanIttallie (1992): Hypertension (RR = 2.9x) Hypercholesterolemia (RR = 1.5x Diabetes (RR = 2.9x) VanIttallie, T. B. (1992) Body Weight, Morbidity, and Longevity. IN: Bjorntorp, P. & Brodoff, B.N. (Eds.) Obesity. Lippincott Co.., Philadelphia. There are also health risks associated with being too thin! Concepts of Physical Fitness 12e Concept 15 5

Definitions of Overweight: (Based on ht /wt tables)
Concepts of Physical Fitness 12e McGraw Hill - 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, , 1985. The standard definition of being overweight is if you are more than 20% over “desirable body weight” for your height. Problem: Ht/Wt tables do not take muscles mass into account Concepts of Physical Fitness 12e Concept 15

Definitions of Overweight (Based on BMI values)
Concepts of Physical Fitness 12e Click for info on BMI McGraw Hill - Definitions of Overweight (Based on BMI values) 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 BMI is an alternative procedure to identify overweight conditions based on height and weight. BMI provides a slightly more accurate assessment of body composition than simple height/weight charts but the same bias is present. People with a large LBM will have a high BMI value even if their body fat level is low. Review procedure for the calculation of BMI Web15-1 for more information on standards Concepts of Physical Fitness 12e Concept 15 15

Concepts of Physical Fitness 12e
Click for calculations of ideal wt based on % fat McGraw Hill - Levels of Body Fatness Men Women Essential fat % % Borderline % % Good fitness - health % 17-28% Marginal fitness % 29-35% Overfatness > 25% > 35% These are the health-related criterion referenced standards for body fatness. Essential fat is the minimal amount of fat needed by the body for good health. Fat is needed for energy, insulation, shock absorption and synthesizing hormones. Values less than the essential levels are unhealthy because the body does not have enough fat to perform these functions. The Performance zone is primarily for athletes and shouldn't be the goal for most people. The Health Zone is attainable for most people doing reasonable amounts of exercise. The range for men is 13-20% and for women it is 18-25%. The Marginal and Overfat zones suggest that the person could have health problems due to too much body fat. Note that it is normal for women to have higher percentages of body fat than men. Concepts of Physical Fitness 12e Concept 15 8

Regional Fat Deposition
Concepts of Physical Fitness 12e Click for more info on fat deposition McGraw Hill - Regional Fat Deposition 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 Higher health risk Lower health risk Male (apple) Female (pear) The site of fat deposition is also an important consideration for health. Fat stored in the abdominal region presents more risk than fat stored in the lower or upper extremities Concepts of Physical Fitness 12e Concept 15 9

Body Composition Assessment Techniques
Concepts of Physical Fitness 12e McGraw Hill - Body Composition Assessment Techniques Underwater weighing Technological assessments Skinfold technique Anthropometric measurements A variety of techniques have been developed to measure body composition. Each will be discussed in greater detail so use the slide as a general introduction to the area. Concepts of Physical Fitness 12e Concept 15 3

Underwater Weighing Technique
Concepts of Physical Fitness 12e Click for more info McGraw Hill - Underwater Weighing Technique Body fat provides more bouyancy so a fatter person weighs less (on a relative basis) than a lean person The gold standard measurement for body composition assessment is currently underwater weighing. It is based on the fact that muscle is more dense than fat - muscle is like a rock (it sinks) - fat is like styrofoam (it floats) By weighing a person underwater you can estimate body density. The procedure is based on Archimedes Principle which states that the buoyant force is equal to the weight of the volume of water that is displaced. Fat because it is less dense occupies a larger volume which gives it a larger buoyant force NOTE: The story of Archimedes and the gold crown is effective for explanation (muscle = gold and fat = silver) Web15-2 for info on underwater weighing Concepts of Physical Fitness 12e Concept 15 4

Technological Assessments of Body Composition
Concepts of Physical Fitness 12e McGraw Hill - Technological Assessments of Body Composition Click to see more info on all techniques Dual X-Ray Impedance Analysis (DXA) Bioelectric impedance Infra-red spectroscopy Ultrasound Imaging techniques (DEXA, MRI) Click individual technique to see more detail Other body fat assessment techniques are available. Bioelectric Impedance: Electrical conduction is different in different tissues. Muscle has water and is a good conduction. Fat has less water and is a poor conductor. It tends to overestimate %fat in lean people and underestimate %fat in fat people. Infra Red Absorption of light is different in different tissues. Ultrasound Sound absorbence is different in different tissues (muscle: sounds bounces off; fat: sounds pass through) Imaging Techniques (DEXA, MRI) Considered to be highly accurate but expensive Chemical measures (3 methyl histidine - waste product of muscle - corr with LBM Web15-2 for info on DXA Concepts of Physical Fitness 12e Concept 15 5

McGraw Hill - Skinfold Technique Layers of subcutaneous fat are measured at different sites of body to estimate total body fat levels The technique is called skinfold because a fold of skin is picked up and measured. Underneath the skin the body stores subcutaneous fat so when the skin is lifted the fat layer can be measured. Body fat is stored in people in different places and the measurement of fat in one place is not always an accurate measure of total body fat. Also, the thicknesses must be converted into a meaningful measure (% body fat). This is done using a statistical procedure called multiple regression. Discuss procedure (optional): Body fat is measured with a very accurate technique and then the various skinfold sites are used to predict the overall percent body fat as assessed by the criterion measure.. Cross sectional view Concepts of Physical Fitness 12e Concept 15 6

Benefits of Skinfold Technique
Concepts of Physical Fitness 12e McGraw Hill - Benefits of Skinfold Technique Fairly accurate Easy to perform Inexpensive Skinfold Technique is the most common way to assess body fat. It has the following advantages: - fairly accurate - easy to perform - inexpensive Concepts of Physical Fitness 12e Concept 15 7

McGraw Hill - Lab 15a info Common Skinfold Sites 7 site procedure Chest Axilla Tricep Subscapular Abdomen Supraillium Thigh Jackson and Pollack Males Female Chest Triceps Abdomen Supraillium Thigh Thigh Alternative Sites (Males & Females) Tricep Abdomen Calf 7 site procedure was originally developed and different weights were put on different sites for men and women Separate equations were developed for men and women but they both used the same sites. (1978) The authors later provided evidence that similar validity could be obtained by only using 3 sites and these were different for men and women. (1985). Correlations with 7 site procedure were very high (.97) and it was a very strong predictor of body fat measurements from underwater weighing. Now, if any of you have ever done testing you know that there are certain sites that are more difficult than others. What is toughes site for women? men? They have also provided alternative 3 site procedures for both men and women men: subscapular substituted for abdomen women: abdomen substituted for thigh For children, we use a 2 site procedure that includes the calf and the tricep. This is from the Fitnessgram program ( Validation statistics on 3 site test: - r = .97 with 7 site procedure - R2 = .80 with underwater weighing Web15-3 Concepts of Physical Fitness 12e Concept 15 8

Anthropometric Measurements
Concepts of Physical Fitness 12e Lab 15b info McGraw Hill - Anthropometric Measurements Body Mass Index (BMI) Waist to Hip Ratio (WHR) Circumference measures More info More info More info It is difficult to get body fat measures on all people so in many occasions anthropometric measures are still effective ways to obtain information about body composition. Concepts of Physical Fitness 12e Concept 15 12

Body Composition Assessment Implications of Results
Concepts of Physical Fitness 12e McGraw Hill - Body Composition Assessment Implications 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 Body Fat estimates from calipers must be interpreted correctly. It is important to keep the following factors in mind: 1. The estimates have 2-3% error so the value that results is not "exact". It is more important to look at trends over time. 2.Values serve as baseline for goal setting. You need to know where you are to set objective goals. Book has a chart to calculate desired weight based on current level and desired level (formula available from instructor). 3. Values are individual. People should not compare values with other people or be embarrassed about their numbers. Each person is different and it may not be possible for all people to achieve the ideal percent body fat. Concepts of Physical Fitness 12e Concept 15 11

McGraw Hill - Web Resources “On the Web” pages for Concept Online Learning Center This page provides active hyperlinks if the computer is connected to the Internet. Concepts of Physical Fitness 12e Concept 15

Supplemental Graphics
Concepts of Physical Fitness 12e Concepts of Physical Fitness 12e McGraw Hill - McGraw Hill - Supplemental Graphics Lab Information Detail on BMI calculations Graphics on Obesity Trends Supplemental graphics follow this slide. Concept 15 Concept 15 17

Lab 15a Information Evaluating Body Composition - Skinfolds
Concepts of Physical Fitness 12e McGraw Hill - Lab 15a Information Evaluating 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 Lab information Concepts of Physical Fitness 12e Concept 15

Lab 15a Information Skinfold Technique
Concepts of Physical Fitness 12e McGraw Hill - Lab 15a Information Skinfold 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 value from chart in the book This diagram shows the technique that is used in skinfold analysis. Go through steps. It takes a lot of practice to get very good at the technique but it can be done in class so students get an idea of how the technique is performed. If time is limited ask for a volunteer to serve as a subject for a class demonstration. Concepts of Physical Fitness 12e Concept 15 9

Lab 15b Information Evaluating Body Composition - Anthropometry
Concepts of Physical Fitness 12e McGraw Hill - Lab 15b Information Evaluating Body Composition - Anthropometry The purpose of this lab is to evaluate body composition with some anthropometric assessments Body Mass Index Waist to Hip Ratio Lab information Concepts of Physical Fitness 12e Concept 15

Lab 15b Information BMI Measurement Technique
Concepts of Physical Fitness 12e McGraw Hill - 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 Review procedure for the calculation of BMI BMI = Wt (kg) / Ht2 (m) See Web15-05 for BMI calculators Concepts of Physical Fitness 12e Concept 15 15

Lab 15b Information WHR Measurement Technique
Concepts of Physical Fitness 12e McGraw Hill - 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 Explain the calculation of WHR Divide the hip measurement into the waist measurement to obtain the WHR Concepts of Physical Fitness 12e Concept 15 13

McGraw Hill - Sample BMI Values Return to presentation This chart reveals how BMI values change for a hypothetical 6 foot tall person of different body weights HT (in.) WT (lb.) BMI See Web15-05 for BMI calculators Figure shows sample BMI values for a hypothetical 6 foot person of different body weights. This helps students see how the values change for people of different sizes. Concepts of Physical Fitness 12e Concept 15 16

Body Composition (2 compartment model)
Concepts of Physical Fitness 12e McGraw Hill - Body Composition (2 compartment model) Fat Lean Body Mass (LBM): (bones, muscles, tissues, organs) Sample calculation: Discuss the 2 compartment model of body composition. Fat Mass (FM) Lean Body Mass (LBM) or Fat Free Mass (FFM) 70kg person with 20% body fat: Lean tissue: 70 kg x .80 = 56 kg Fat tissue: 70 kg x .20 = 14 kg Concepts of Physical Fitness 12e Concept 15 6

Calculating Desired Body Weight
Concepts of Physical Fitness 12e See sample calculation McGraw Hill - Calculating Desired Body Weight Current Lean weight Wt. - (fat weight) Desired Weight = = Desired Lean % (1 - desired %Fat) Desired Weight = Wt. - (Wt. x %Fat / 100) (1 - desired %Fat) After finding out percent body fat, it is possible to calculate a desirable body weight based on a desired body fat percentage. This can provide guidelines for individuals interested in losing (or gaining) body weight. This calculation assumes that lean body mass remains constant. This may or may not be true depending on the type of training that is performed. Ideally, another test of body fat could be performed so that the relative changes in fat and lean weights following training can be determined. Concepts of Physical Fitness 12e Concept 15 18

Calculating Desired Body Weight (Example)
Concepts of Physical Fitness 12e McGraw Hill - Calculating Desired Body Weight (Example) Return to presentation Current weight = 200 Current body fat% = 20% Desired body fat% = 15% Desired Weight = (200 x .20) ( ) (.85) = 160 .85 = 188 This slide shows the calculations used to calculate desired body weight based on current body fat percentage and desired body fat percentage A chart in the book simplifies this calculation Concepts of Physical Fitness 12e Concept 15 19

Regional Fat Deposition Visceral Fat
Concepts of Physical Fitness 12e McGraw Hill - Regional Fat Deposition Visceral 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 8-13%of total fat The site of fat deposition is also an important consideration for health. Fat stored in the abdominal region presents more risk than fat stored in the lower or upper extremities Concepts of Physical Fitness 12e Concept 15 9

Abdominal Body Fat Relationships with CHD Risks
Concepts of Physical Fitness 12e McGraw Hill - Abdominal Body Fat Relationships with CHD Risks Abdominal obesity predicts CHD risk independent of BMI, smoking, cholesterol and hypertension (Kannel et al., J. Clin Epid., 44, , 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: , 1992). There are many studies that document the health risks associated with abdominal obesity. Concepts of Physical Fitness 12e Concept 15

Abdominal Body Fat Relationships with other risk factors
Concepts of Physical Fitness 12e McGraw Hill - Abdominal Body Fat Relationships with other risk factors Abdominal obesity is strongly influenced by genetics - similar gain among twins (r=.72). (Bouchard, NEJM, 322, , 1990). Abdominal obesity is greater in smokers than non-smokers due to the presence of androgens (Barrett-Conner, Ann. Int. Med. 111, , 1989). Abdominal body fat is preferentially lost during a physical activity program (Kohrt, J. Gerontology, 47: M99-M105, 1992) These are some additional studies that document the health risks of abdominal obesity Concepts of Physical Fitness 12e Concept 15

Waist to Hip Ratio (WHR)
Concepts of Physical Fitness 12e McGraw Hill - Waist to Hip Ratio (WHR) Return to presentation Waist to Hip Ratio is an effective way to examine regional fat distribution. HEALTH RISK MEN WOMEN High Risk > 1.0 > .85 Review health consequences associated with abdominal body fat Moderate Risk Low Risk < .90 < .80 Concepts of Physical Fitness 12e Concept 15 14

Underwater Weighing Measurement issues
Concepts of Physical Fitness 12e McGraw Hill - Underwater Weighing Measurement 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 Underwater weighing is based on body density calculations. The density of lean tissue is greater than the density of fat tissue. Underwater weighing, while it is considered to be the gold standard, does have considerable measurement error and still must be classified as an estimate. Residual lung volume is a major source of error. For an accurate assessment a person must exhale all of their air and remain still enough for a person to accurately read the value. Some people cannot hold their breath under water or get claustrophobic and come up too soon. Even if you exhale all of your air there is still some residual volume of air in your lungs that you cannot remove. This has to be measured in an additional test that has its own levels of errors. When estimates of residual volume are made then the tests have still higher errors. Body density values vary by age, ethnicity, and activity level. Most calculations do not take those variables into account which can lead to erroneous values. Blacks have higher bone density - underprediction (2% unreal) children have lower bone density - overprediction A difference of .015 g/cc in density estimate can lead to a 4-5% error in % fat Concepts of Physical Fitness 12e Concept 15

Bioelectric Impedence (Measurement Issues)
Concepts of Physical Fitness 12e McGraw Hill - 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 Bioelectric impedence is based on differential resistance to current flow Because it is actually providing an estimate of total body water which is then used to predict body fatness the test is very sensitive to hydration status. The test will generally overestimate lean people and underestimate obese people So the relationship with measured percent body fat is really curvilinear rather than linear Concepts of Physical Fitness 12e Concept 15

Infrared Spectroscopy (Measurement Issues)
Concepts of Physical Fitness 12e McGraw Hill - 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! Infrared spectroscopy is a fairly new procedure that you will see in many health clubs. It looks great and they have good marketing for the product but when you come right down to it the procedure really doesn’t work - at least in the way that they claim. The procedure was originated in the agriculture field where they would use it to determine the quality of different cuts of meats. They take a little light gun and shine and infrared light beam into your biceps and measure the amount of light reflected back to the sensor after it has been somewhat absorbed by the body. Show the overhead of the faulty readings Concepts of Physical Fitness 12e Concept 15

Ultrasound (Measurement Issues)
Concepts of Physical Fitness 12e McGraw Hill - 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 Ultrasound is a highly accurate technique but it is typically only used in hospital or clinical settings. Concepts of Physical Fitness 12e Concept 15

Imaging Techniques (Measurement Issues)
Concepts of Physical Fitness 12e McGraw Hill - 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 Imaging techniques provide a valid assessment but are very expensive. This is typically only done in laboratory or clinical settings. Concepts of Physical Fitness 12e Concept 15

Circumferences (Measurement Technique)
Concepts of Physical Fitness 12e McGraw Hill - Circumferences (Measurement Technique) Return to presentation Based on circumference measures sample prediction equation: % fat = (.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 Circumferences have commonly been used. I included a reference for a circumference procedure that you might be interested but in my opinion they are not as accurate as skinfolds and take just as much time so there is really no advantage. Some people will want to measure circumferences to monitor changes in muscle size but skinfolds are certainly a better way to assess b ody fatness. Concepts of Physical Fitness 12e Concept 15

Obesity Trends. Among U. S
Obesity Trends* Among U.S. Adults Proportion of Obese Adults by State BRFSS (*BMI  30, or ~ 30 lbs overweight for 5’4” woman) Slides from the CDC Concepts of Physical Fitness 12e

Obesity Trends* Among U.S. Adults BRFSS, 1990
No Data <10% %-14% % 20% Source: Mokdad AH. (*BMI  30, or ~ 30 lbs overweight for 5’4” woman) Concepts of Physical Fitness 12e

(*BMI  30, or ~ 30 lbs overweight for 5’4” woman) No Data <10% %-14% % 20% Source: Mokdad AH. Concepts of Physical Fitness 12e

Obesity Trends* Among U.S. Adults BRFSS, 1991, 1995 and 2000 1991 1995 2000 Source: Mokdad A H, et al. J Am Med Assoc 1999;28216, 2001;286:10. Concepts of Physical Fitness 12e

Web Links BRFSS Interactive Web Page Concepts of Physical Fitness 12e

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