KIN 4310 1st Edition Lecture 21 Outline of Last Lecture I Measurement of Health Status II Health Status III Health Status of a population IV Examples V Health and Fitness Outline of Current Lecture I Body Composition II Assessing Body Composition III Direct Techniques IV Indirect Techniques V Aerobic Fitness VI Metabolic Equivalents METs VII Oxygen Consumption VIII Aerobic Fitness IX Field Tests X Nonexercise Estimates XI Aerobic Fitness Summary These 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 Lecture I Body Composition a Body Composition The different components that make up the human body i Fat ii Muscle iii Bone iv Important in assessing health status and disease risk b Percent body fat BF Weight of fat in the body relative to the person s total weight i Essential fat Minimal amount of body fat needed for normal physiological functions constitutes about 3 5 of total weight in men and 8 12 in women ii Storage fat Body fat in excess of essential fat stored in adipose tissue iii 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 fat II Assessing Body Composition a 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 weighing ii Air displacement iii Skinfold thickness iv Bioelectrical impedance v BMI WC WHR vi Girth measurements vii Equation BF 495 BD 450 III Direct Techniques a Dual energy X ray absorptiometry DXA i Most frequently used by research and medical facilities ii Considered the gold standard technique for body composition assessment iii Uses low dose beams of X ray energy iv Measures fat mass fat free mass and bone density v Procedure is simple takes only 15 minutes to administer vi Safe no problems with radiation exposure etc b Magnetic resonance imaging MRI i Used primarily by research and medical facilities ii 2nd gold standard technique iii Uses high powered magnets and imaging software iv Measures total and regional adiposity v Safe no problems with radiation exposure etc vi Procedure can be time consuming and is very expensive vii 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 slices ii Measures fat layers within body cavity limbs or organs iii Sequential images are segmented into adipose and nonadipose tissue pixel values measured in Houndsield units HU iv Uses higher dose X ray energy v Radiation exposure can be a drawback vi Note Would not normally use a CT scan for body fat percentage Provides highly accurate information but it is really expensive and you get a lot of radiation IV Indirect Techniques a Hydrostatic Weighing i Underwater weighing ii Most common technique used for decades iii A person s land weight is compared with underwater weight iv Fat is more buoyant than lean tissue v Most other indirect techniques have been validated against hydrostatic weighing vi Note Was the old gold standard but now the DXA is b Hydrostatic Weighing Drawbacks i Time consuming ii Not feasible to test large number of people iii Requires measurement of residual lung volume unknown can be estimated iv Difficult to perform on the aquaphobic c Air Displacement i Individual sits inside small chamber ii Computerized pressure sensors determine the amount of air displaced by the person iii 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 d e f g h iv Body density and percent body fat are then calculated v Less cumbersome administer vi Takes only about 5 minutes vii Note This takes care of the residual lung volume issue Skinfold Thickness i Based on the principle that approximately half of the body s fat tissue is directly beneath skin ii Reliable measurements can give a good indication of percent body fat iii Skinfold test is done with pressure calipers iv Several sites are measured and percent fat is estimated from the sum of the three sites v All measurements should be taken on the right side of the body vi Skinfold thickness BF 1 Females a S triceps suprailium thigh in mm b BD 1 099421 0 0009928 x S 0 00000023 x S 2 0 0001382 x Age c Equation BF 495 BD 450 Bioelectrical Impedance i Simple to administer but accuracy is questionable ii 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 water iii Based on the principle that fat tissue is a less efficient conductor of an electrical current iv 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 results vii 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 a lot of fat Body Mass Index BMI i Most common measure of body composition ii Incorporates height and weight to estimate critical fat values at which disease risk increases 1 BMI Body Mass Stature2 2 Always expressed in metric units kg m2 Waist Circumference i Predicts disease risk according to region of adiposity waist versus other areas Waist to Hip Ratio i V VI i Predicts disease risk according to distribution of adiposity apple vs pear shape Girth Measurements i Requires a standard measuring tape ii 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 equations iii Men Waist and wrist measurements inches 1 Use table for percent body fat estimate iv Note This is where they measured limbs This was more prevalent around 30 years ago not so much anymore Aerobic Fitness a The ability of the heart lungs and blood vessels to supply oxygen to the working muscles b The ability of the muscles to use the available oxygen c A major component of fitness d Note This