2 Gross Composition of Human Body Body composition analysis often focuses on the tissue and whole body levels of multi-component model.
3 Behnke’s Reference Man 12% storage, 3% essential for menStorage fat averages ___% of body mass for young men.Essential fat averages ___% of body mass for young men.
4 Reference Woman Storage fat averages ___% for young adult women. 15% storage and 12% essential for womenStorage fat averages ___% for young adult women.Essential fat averages ___% for young adult women.Four times greater essential fat for females relates to child-bearing.
5 Gross Composition of Body Essential fat: fat in organs, muscle, CNS, bone marrow. Also includes sex-specific essential fat necessary for survival.Storage fat: energy reserve includes visceral adipose tissue & larger subcutaneous depots.Fat Free Body Mass and Lean Body MassIn vivo (within a living organism), it isn’t possible to differentiate between essential and non-essential fat.LBM =FFM (bone, muscle, organs, connective tissue) + essential fat. LBM is an in vivo entity.Density of human fat is .901 g/cm3. FFM varies.Essential fat amount of fat necessary for survival
6 Gross Composition of Body Density of FFM lower in children than adults.Female density of FFM is lower at each age than male.Percentage of FFM that is composed of water is higher in children.
7 Gross Composition of Body Minimal body massWhat is suggested “healthy” lower level % fat in ? 3%In females, includes 3% essential fat (same as ) + 9% sex-specific essential fat = 12%.Optimal range of body fat should be established for each sport.Elite female athletes in ballet, gymnastics, rowing, skating, track running events, triathlon body fat 8-15%Underweight ≠ thin; appearance may average 18.2% body fat.
8 Leanness, Exercise, and Menstrual Irregularity Lean:fat ratio may play role normal menstrual function.Peripheral fat’s role in angrogens to estrogenProduction of leptin in adipose tissueFactors associated with menstrual irregularityHigh levels chronic physical stress causes hormone cascadeNutritional inadequacy to sustain pregnancyToo little fat triggers metabolic disturbancesRegional fat deposition
9 Methods of Body Composition Direct AssessmentChemical dissolution: dissolves body into fat and fat-free componentsPhysical dissection: extensive dissection of cadavers.
11 Hydrostatic WeighingHow is Archimedes principle of water displacement used to evaluate body composition?Loss of weight in water equals weight of water displaced which yields volume of water any temperature.Example: 50 kg FF = 48,000 cm350 kg ÷ 48,000 cm3 = g/cm3
12 Hydrostatic Weighing Body Density = Mass ÷ Volume Computing % body fat using population specific equation.Limitations and Errors.Air compartments in body.Densities of FFM vary due to race, age, and athletic experience.
13 Air Displacement Air displaced = Body Volume Body density = mass ÷ volumeHigh validity compared to hydrostatic weighing
14 Skinfolds Common field method Relationships among selected skinfold sites and body densityCaliper exerts constant tension of 10 g/mm2Sum of skinfolds indicates relative fatness of individual
15 Girth Measurements Uses 3 sites: see Appendix F Men: right forearm, abdomen, right upper arm (<27) or buttocks (27+)Women: abdomen, right thigh, right forearm (<27) or right calf (27+)Pattern of fat distributionPredicting Body Fat
16 Bioelectrical Impedance Hydrated, fat-free body tissues and extracellular water facilitate electrical flow compared to fat tissue because of greater electrolyte content of fat-free component.
17 Dual Energy X-Ray Absorptiometry Two distinct x-ray energies penetrate into bone & soft tissue areas to depth of 30 cm. Computer software reconstructs an image of underlying tissue.Quantifies bone mineral content, total fat mass, and FFM.
18 Body Mass IndexImportance of this easy to obtain index is its curvilinear relationship to all-cause mortality.
19 Near-Infrared Interactance Uses technology developed by U.S. Dept. Agriculture to assess body composition of livestock and lipid content of grains.Does not accurately predict human body fat across broad range of body fat levels.
20 Ultrasound Measures: Assess thickness of different tissues Obtain image of deeper tissues, e.g. muscle’s cross sectional areaIt works by converting electrical energy through a probe into high frequency pulsed sound waves that penetrate the skin surface to fat-muscle interface.
21 Computed TomographyGenerates detailed cross-sectional, 2 dimensional radiographic images.Passes x-ray beam through tissues of different densities.Provides quantitative information on:Total tissue areaTotal fat and muscle areaThickness and volume of tissues w/i organ
22 Magnetic Resonance Imaging Electromagnetic radiation, not ionizing radiation, in strong magnetic field excites hydrogen nuclei of body’s water and lipid molecules. Nuclei then project detectable signal to visually represent various body tissues.Provides quantitative information on total and subcutaneous adipose tissue.
23 Average Values for Body Composition Average young male possesses between __ and __% fat.Average young female possesses between ___ and ___ % fat.Men = 12-15%Women = 25-28%
24 Goal WeightGoal weight should be based on body composition not stature.Goal Weight = Fat Free Body ÷ (100 -% Desired Body Fat)Desirable Fat Loss = Present body weight – Goal body weight
25 Percentage of Body Fat Ballet dancers: 13-20 Body builders: 10-15 Triathlon: 10-15Jumpers: 10-18
26 Illustration References McArdle, William D., Frank I. Katch, and Victor L. Katch Essentials of Exercise Physiology 2nd ed. Image Collection. Lippincott Williams & Wilkins.Plowman, Sharon A. and Denise L. Smith Digital Image Archive for Exercise Physiology. Allyn & Bacon.