Applied Exercise Physiology Exam IV Study Guide Exam date April 24 2014 Chapters 28 body composition Chapter 30 exercise and weight control 1 Know and understand the principle of Archimedes and how it applies to the procedure of human body volume measurements pg 740 743 Archimedes principle an object s loss of weight in the water equals the weight of the volume of water that it displaces The object submerged or floating becomes buoyed up by a counterforce that equals the weight of the volume it displaces Therefore the object loses weight in water Specific gravity weight in air loss of weight in water o Ex If a person weighed 50 kg in air and 45 kg in water or 5 kg less the specific gravity would be 50 kg 5 kg 10 In simpler terms specific gravity is an object s heaviness related to its volume density o This is used in hydrostatic weighing computes body volume as the difference between body mass measured in air Ma and body weight measured during water submersion Ww In hydrostatic weighing you must take residual lung volume and water temperature into account normally is measured right before submersion underwater Using these calculations you can determine body density body fat and percentage body fat Body density Db Ma Ma Ww Dw RLV residual lung volume Siri equation determines percent body fat BF 495 Density 450 o Fat weight fat 100 body weight o Lean body weight Body weight Fat weight General densities Water 1 00 g cc fat 0 90 g cc and muscle 1 10 g cc Hydrostatic weighing is known as the gold standard for indirect measurements 2 Understand the differences and usefulness of different body composition and anthropometric assessment procedures discussed in the text and class What are the general assumptions used by indirect measures o Hydrostatic weighing discussed in question 1 o Bod Pod uses air pressure displacement to determine body fat Determines body volume by measuring the initial volume of the empty chapter and then the volume with the person inside Breathes several times to assess pulmonary lung volume while in the Bod Pod pg 743 744 o Skinfold and girth measurements good method to measure adipose tissue directly under the skin internal fat and whole body density Principle is that the amount of subcutaneous fat is proportional to the total body fat Provides meaningful information about body fat and its distribution pg 745 747 These are anthropometric measurements o Caliper used at thigh iliac subscapular abdomen chest triceps and biceps o Sum of these skinfolds measures relative fatness o Sex specific method 3 sites and 7 site method Men bicep chest abdomen Women triceps thigh and iliac o With advancing age more fat deposits internally visceral than subcutaneously Have to use age adjusted generalized equations to predict body fat in older men and women o Girth measurements are done at right biceps right forearm abdomen buttocks right thigh and right calf There are equations to then determine body fat from girth but don t apply well to those overly thin overly obese or high in endurance training o Bioelectrical Impedance electrode passes through hydrated fat free body tissues than fat or bone tissues pg 748 749 o Hyperhydration gives a higher body fat measurement and hypohydration gives a lower body fat measurement Overpredicts in lean people o Assesses total body water well o Each electrode can be placed on 2 hands or hand and foot depending on preference o DXA dual energy x ray absorptiometry quantifies fat and nonbone regional lean body mass including the mineral content of the body s deeper bony structures Low energy X ray beam penetrate bone and soft tissue areas and produce an image of underlying tissues and quantifies bone mineral content total fat mass and FFM Strength of prediction decreases for older and fatter subjects pg 756 3 What are the body composition differences between males and females pg 736 737 o Average essential fat in women 12 average essential fat in men 3 o The large difference in these values is due to sex specific essential fat Women have sex specific fat in the breast and genitals lower body subcutaneous and intramuscular fat This is most likely due to the biologically important functions for child bearing and other hormone related functions o Storage fat in women 15 storage fat in men 12 o Total fat in women average 25 27 total fat in men average 15 4 Understand the difference between essential and storage fat and the difference between FFM and LBM pg 736 o Esssential fat fat in heart lungs liver spleen kidneys intestines muscles and lipid rich tissues of the central nervous system and bone marrow Normal physiologic functioning requires this fat o Storage fat fat primarily in adipose tissue Adipose energy reserve is about 83 pure fat 2 protein and 15 water Includes visceral fatty tissues that protect the organs in thoracic and abdominal cavities from trauma and larger adipose tissue underneath the skin s surface o Fat Free Body Mass FFM represents the body mass devoid of all extractable fat body mass o Lean Body Mass LBM contains the small percentage of non sex specific essential fat equivalent to about 3 of body mass o FFM and LBM normally differ only in essential fat component fat mass 5 How does energy balance and weight loss affect body composition pg 802 o By first law of thermodynamics weight loss occurs whenever energy output exceeds energy intake regardless of the diet s macronutrient mixture o Most common weight loss method is to make sure energy input is 500 1000 kcal below energy expenditure daily o Ex if doing a daily deficit of 1000 kcal there will be a weekly deficit of 7000 kcal which is equivalent to 0 9 kg of body fat 6 Understand the potential impact of diet and exercise on obesity e g what are the differences of dieting alone as compared to dieting and exercise combined pg 812 o Excess weight gain often parallels reduced physical activity rather than increased caloric intake o Physical activity increases energy output and decreases risk of disease o For long term weight loss emphasizing diet alone will not effectively keep the weight off o A negative energy balance induced by increased caloric expenditure unbalances the energy equation for weight loss improves physical fitness and the health risk profile and favorably alters body composition and body fat distribution for children and adults o Recommended to do 30 minutes of exercise 4x per week at least 7 Understand the concept of the energy balance equations pg 801 802 o 1
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