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Body Composition. Body Composition. The amount of fat, and fat-free mass in the body Fat Fat-free mass Muscle Bone Body composition assessed in a variety of ways Advantages for each method Disadvantages for each method
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Body Composition • The amount of fat, and fat-free mass in the body • Fat • Fat-free mass • Muscle • Bone • Body composition assessed in a variety of ways • Advantages for each method • Disadvantages for each method • Cost, availability, complexity, user/equipment error, quality/quantity of information, accuracy
Scale Weight • Provides information on amount body mass • Advantages and disadvantages • Cost • Availability • Complexity • User/equipment error • Quality/quantity of information • Accuracy
Height and Weight Charts • Provides information based on person’s height, weight, frame size • Advantages & Disadvantages • Cost • Availability • Complexity • User/equipment error • Quality/quantity of information • Accuracy
Body Mass Index • Person’s weight divided by square of height • Provides information on disease risk • Advantages & Disadvantages • Cost • Availability • Complexity • User/equipment error • Quality/quantity of information • Accuracy
Circumferences • Specific areas on body are measured with measuring tape • Advantages & Disadvantages • Cost • Availability • Complexity • User/equipment error • Quality/quantity of information • Accuracy
Waist to Hip Ratio • Two circumferences: waist and hip • Measures provide CV disease risk information • Men: 0.90-1.0+ = “high risk” • Women: 0.75-0.85+ = “high risk”
Waist to Hip Ratio • Abdominal fat related to cardiovascular disease risk • Advantages & Disadvantages • Cost • Availability • Complexity • User/equipment error • Quality/quantity of information • Accuracy
Near Infrared Interactance • Method based on light absorption, reflectance • Probe is placed on body part, typically biceps • Probe emits infrared light, passing through tissue, reflected back into probe • Fat absorbs more infrared light than fat-free mass • The more light absorbed, the higher the fat mass
Near Infrared Interactance • Advantages & Disadvantages • Cost • Availability • Complexity • User/equipment error • Quality/quantity of information • Accuracy
Skinfolds • Specific instruments, “calipers” used to assess amount of fat under skin at specific sites on body • Since approximately 50% of body fat is located under skin, predictions can be made about total body fat
Skinfolds • Advantages & Disadvantages • Cost • Availability • Complexity • User/equipment error • Quality/quantity of information • Accuracy
Bioelectrical Impedance Analysis • A small, painless electrical current passes through body • Based on current difference between starting and ending points, percent fat can be estimated • Fat impedes/resists current more than fat-free mass • High impedance values will reflect higher fat mass
Bioelectrical Impedance Analysis • Advantages & Disadvantages • Cost • Availability • Complexity • User/equipment error • Quality/quantity of information • Accuracy
Hydrostatic Weighing • Person weighed in regular environment, and under water • Based on difference, can eventually estimate body volume • From volume, one calculates body density • From body density, fat percentage calculated • Higher density = leaner subject (bone, muscle are denser than fat)
Hydrostatic Weighing • Advantages & Disadvantages • Cost • Availability • Complexity • User/equipment error • Quality/quantity of information • Accuracy
Air Displacement • Similar to hydrostatic weighing • Device measures air displacement to determine body volume • From volume one can calculate body density • From body density, fat percentage is calculated
Air Displacement • Advantages & Disadvantages • Cost • Availability • Complexity • User/equipment error • Quality/quantity of information • Accuracy
Dual Energy X-Ray Apsorptiometry (DEXA) • Low-radiation dose of dual-energy x-ray beams pass over body • Based on attenuation of x-ray, measures of fat, bone and soft lean tissue can be made • Based on these measures, fat mass can be calculated
DEXA • Advantages & Disadvantages • Cost • Availability • Complexity • User/equipment error • Quality/quantity of information • Accuracy
What is Average? • Body Fat Ranges for Standard Adults (NIH/WHO BMI Guidelines) • Percent Body Fat Norms for Men and Women (American Council on Exercise)