KIN 4310 1st Edition Lecture 21Outline of Last Lecture I. Measurement of Health StatusII. Health StatusIII. Health Status (of a population)IV. ExamplesV. Health and FitnessOutline of Current Lecture I. Body CompositionII. Assessing Body CompositionIII. Direct TechniquesIV. Indirect TechniquesV. Aerobic FitnessVI. Metabolic Equivalents (METs)VII. Oxygen ConsumptionVIII. Aerobic FitnessIX. Field TestsX. Nonexercise EstimatesXI. Aerobic Fitness SummaryThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Current LectureI. Body Compositiona. Body Composition: The different components that make up the human bodyi. Fatii. Muscleiii. Boneiv. Important in assessing health status and disease riskb. Percent body fat (% BF): Weight of fat in the body relative to the person’s total weighti. Essential fat: Minimal amount of body fat needed for normal physiologicalfunctions; constitutes about 3-5% of total weight in men and 8-12% in womenii. Storage fat: Body fat in excess of essential fat; stored in adipose tissueiii. Note: this is better to evaluate versus using BMI. A person with a high BMI might have a lot of muscle mass and could be health, not obese.c. Lean body mass: Body weight without body fatII. Assessing Body Compositiona. Direct Techniques involve looking inside the body and measuring the different tissues by volume (or area)i. Dual energy X-ray absorptiometry (DXA)ii. Magnetic resonance imaging (MRI)iii. Computed tomography (CT)b. Indirect Techniques involve measurements outside or on the surface of the body to estimate what is inside:i. Hydrostatic weighingii. Air displacementiii. Skinfold thicknessiv. Bioelectrical impedancev. BMI, WC, WHRvi. Girth measurementsvii. Equation: BF% = (495/BD) – 450III. Direct Techniquesa. Dual energy X-ray absorptiometry (DXA)i. Most frequently used by research and medical facilitiesii. Considered the “gold standard technique” for body composition assessmentiii. Uses low-dose beams of X-ray energyiv. Measures fat mass, fat free mass, and bone densityv. Procedure is simple; takes only 15 minutes to administervi. Safe; no problems with radiation exposure, etc.b. Magnetic resonance imaging (MRI)i. Used primarily by research and medical facilitiesii. 2nd “gold standard” technique iii. Uses high powered magnets and imaging softwareiv. Measures total and regional adiposityv. Safe; no problems with radiation exposure, etc.vi. Procedure can be time consuming and is very expensivevii. Note: A lot more detailed that the DXA in terms of resolution but it is expensive compared to a DXA.c. Computed tomography (CT)i. Measures regional adiposity by imaging multiple cross-sectional slicesii. Measures fat layers within body cavity, limbs or organsiii. Sequential images are segmented into adipose and nonadipose tissue pixel values measured in Houndsield units (HU)iv. Uses higher-dose X-ray energyv. Radiation exposure can be a drawbackvi. Note: Would not normally use a CT scan for body fat percentage. Provideshighly accurate information but it is really expensive and you get a lot of radiation.IV. Indirect Techniquesa. Hydrostatic Weighingi. Underwater weighing ii. Most common technique used for decades iii. A person’s “land” weight is compared with underwater weightiv. Fat is more buoyant than lean tissuev. Most other indirect techniques have been validated against hydrostatic weighingvi. Note: Was the old gold standard, but now the DXA is.b. Hydrostatic Weighing Drawbacksi. Time consumingii. Not feasible to test large number of peopleiii. Requires measurement of residual lung volume unknown, can be estimatediv. Difficult to perform on the aquaphobicc. Air Displacementi. Individual sits inside small chamberii. Computerized pressure sensors determine the amount of air displaced by the personiii. Body volume is calculated by subtracting the air volume with the person inside the chamber the volume of the empty chamber (air in the lungs is taken into consideration)iv. Body density and percent body fat are then calculatedv. Less cumbersome administervi. Takes only about 5 minutesvii. Note: This takes care of the residual lung volume issue.d. Skinfold Thicknessi. Based on the principle that approximately half of the body’s fat tissue is directly beneath skinii. Reliable measurements can give a good indication of percent body fatiii. Skinfold test is done with pressure calipers iv. Several sites are measured and percent fat is estimated from the sum of the three sitesv. All measurements should be taken on the right side of the bodyvi. Skinfold thickness  %BF1. Femalesa. S = triceps + suprailium + thigh (in mm)b. BD = 1.099421 = (0.0009928 x S) + (0.00000023 x S2) – (0.0001382 x Age)c. Equation: %BF = (495/BD) – 450e. Bioelectrical Impedancei. Simple to administer, but accuracy is questionableii. Sensors are applied to the skin and a weak electrical current is run through the body to estimate body fat, lean body mass, and body wateriii. Based on the principle that fat tissue is a less-efficient conductor of an electrical currentiv. The easier the conductance, the leaner the individual v. Body weight scales with special sensors on the surface may also be used to perform this procedure vi. Hydration status can influence resultsvii. Note: Quite unreliable. If you are hydrated, it may underestimate the amount of fat you have. If you are dehydrated, you’ll have more impedance and it will elevate your score to where it seems like you have alot of fat.f. Body Mass Index (BMI)i. Most common measure of body compositionii. Incorporates height and weight to estimate critical fat values at which disease risk increases1. BMI = Body Mass / Stature22. Always expressed in metric units (kg/m2)g. Waist Circumferencei. Predicts disease risk according to region of adiposity (waist versus other areas)h. Waist-to-Hip Ratioi. Predicts disease risk according to distribution of adiposity)”apple” vs. “pear” shapei. Girth Measurementsi. Requires a standard measuring tapeii. Women: Upper arm, hip, and wrist measurements (cm)1. Look up constants based on measurements and determine body density and percent fat according to predicting equationsiii. Men: Waist and wrist measurements (inches)1. Use table for percent body fat estimateiv. Note: This is where they measured limbs. This was more prevalent around30 years ago, not so much