Exercise Physiology Chapter 16 - Body Composition, Obesity, and Weight Control

What is "Archimedes principle" and how does it relate in determining body density?

*-An object's loss of weight in water equals the weight of the volume of water it displaces. -A body immersed in water is buoyed up with a force equal to the weight of the water displaced - the apparent loss in mass between the body mass-in-air and the body mass-in-water is equal to the mass (or weight) of the water displaced. -Once the mass of the water is displaced is known, the volume of the water can be determined by dividing the mass of the water by the density of the water- this volume of water is assumed to be equal to body volume.

How is BMI related to mortality?

-BMI is used for categorizing persons with respect to their degree of obesity and risks of chronic disease and death. -A high BMI is related to an increased risk of chronic diseases and conditions, including hypertension, diabetes, metabolic syndrome, & coronary heart disease.

List 2 factors that affect BIA results

-Hydration Level -Skin Temperature

What four lung volumes make up "total lung capacity"?

-Inspiratory reserve volume (IRV) -Tidal volume (TV) -Expiratory reserve volume (ERV) -Residual volume (RV)

What percent of body fat range defines the "optimal fitness" category in men & women?

-Men: 12-18% -Women 16-25%

Which girth measurements are used in assessing body composition in men&women?

-Men: 2 girth & waist-to-hip ratio 2 girth: neck girth and midabdominal girth W:H: upper abdominal & hip girth -Women: 3-girth & W:H 3 girth: neck girth, upper abdominal, hip W:H: upper abdominal, hip

What waist girth in men and women is related to an increased obesity-associated risk of disease (in inches)?

-Men: >40in. -Women: >35in.

What is "vital capacity" defined functionally? What volumes make up VC (vital capacity)?

-Sum of 3 volumes: IRV, TV, ERV -VC test-blow as large as breath as possible into a spirometer -Provides an indication of size of lungs -the greatest volume of air that can be expelled from the lungs after taking the deepest possible breath.

What is the rationale for using girths to estimate body composition?

-The body is compartmentalized into fat and fat-free divisions that may be estimated by the linear measurement from girths. -Higher % fat occurs in women of same height but greater hip girths. -The greater the sum of the neck girth & height for a given hip and/or abdominal girth, the lower the percent fat likely will be.

How is the "ventilatory equivalent" identified and to what physiological response does it relate?

-The ventilatory equivalent for oxygen (VE/VO2) reflects the ventilation needed for each liter of oxygen consumed, or the metabolic cost of breathing (VE/VO2)=VE(Lxmin^-1) / VO2(Lxmin^-1) -the ratio of ventilation to oxygen consumption, or to carbon dioxide output

What is a range of a "normal" BMI?

18.5-24.9

How many electrodes are used in the BIA method?

4

Compute the percentage of body fat for a person with a body density of 1.0399 g/ml

495/1.0399-450=26.0%

Calculate the desired body weight in pounds for a 24 year old female who weighs 75kg with a percentage of fat of 32 and would like to have a 15% fat count. How much will she need to lose in terms of pounds?

75kg x 2.2 lbs / 1kg = 165 lbs. 165 lbs. x .32 = 52.8 lbs. FM 165 lbs. - 52.8 lbs. = 112.2 lbs. FFM Ideal: 112/(1.00-.15)= 112/0.85 = 131.8 lbs. 165-131.8 = 33. 2 lbs to lose

Compute the BMI for a male 75kg and 176.5 cm tall

75kg/1.765m^2 = 24.12

densitometry

Archimedes' principle of water displacement to estimate whole-body density; other terms include hydrostatic weighing, hydrodensiometry, and underwater weighing

Know relationship among temperature and density in water

As temperature of water increases, density of water decreases

How is BMI calculated?

BMI=body mass(kg) / height (m^2)

reference man and reference woman

Behnke's reference standards for men and women that partition body mass into lean body mass, muscle, and bone, with fat subdivided into storage and essential fat; standards for body dimensions developed from military and anthropometric surveys

How are bradycardia & tachycardia defined in terms of bpm?

Bradycardia: resting HR < 60 Tachycardia: resting HR > 100

In terms of body composition analysis, what do CT scans measure?

Detailed cross-sectional, two-dimensional radiographic images of body segments when an x-ray beam of ionizing radiation passes through tissues of different densities

Explain why there are different "Fat free density of the body" for different populations.

Each estimate of the FFDB uses slightly different values for the proportions of the body's protein, mineral, & water content.

goal body weight

FFM divided by (1.00-%fat desired)

Give another name for underwater weighing.

Hydrostatic weighing

What is the rationale for using skinfold thickness to estimate percent body fat?

In some cases, the regression equation is transformed into a table or nomogram based upon 2 or more skinfolds (or their sum), which is then used to find the corresponding percent body fat.

What is an "MET", what is its equivalent in kg x ml x min-1

MET- metabolic equivalent One MET is equivalent to resting metabolic rate (VO2=3.5ml x kg-1 x min-1

What does "ST segment" depression indicate on EKG?

Myocardial ischemia (lack of blood flow) and hypoxia (lack of oxygen)

How well do percent body fats estimated by skinfolds correlate with those measured hydrostatically?

Numerous skinfold sites may be measured originally, with the combination of sites best predicting body density and/or body fat being chosen for the regression equation. (Regression equations for predicting percent body fat and/or body density are based upon correlations between anthropometric measures (e.g. skinfolds) and hydrostatic measures of body density. -Body fat for an individual usually ranges between 3% and 5% body fat units computed from body density with hydrostatic weighing.

How is skinfold thickness affected by aging?

Older persons store a greater proportion of body fat internally, especially in the visceral area. They also demonstrate a decrease in skin thickness, an increase in skinfold compressibility & a loss of bone density. So, the %bf of older adults is corrected statistically and their values are higher than younger adults at the same skinfold sum.

What electrical events in the heart are represented by the following EKG waves: P QRS complex T QT Interval

P: atrial depolarization QRS complex: ventricular depolarization T: ventricular repolarization QT interval: length of time required for ventricles to repolarize

What is the SBP (systolic) & DBP (diastolic) criteria end - points for an exercise stress test?

SBP: > or = 250mmHg DBP: > or = 115 mmHg

State the difference between density & specific gravity.

SG= (body weight in air)/[body weight in air-body weight in water)] -an object's "heaviness" related to its volume Density=body weight/body volume -weight per volume *The temperature effect distinguishes density from specific gravity

Describe difference between essential & storage fat.

Storage fat: fat or triacylglycerol packed primarily in adipose tissue; visceral fatty tissues that protect thoracic & abdominal cavity internal organs from trauma; similar proportional distribution in men & women Essential fat: fat in the heart, lungs, liver, spleen, kidneys, intestines, muscles, & lipid-rich tissues of the CNS & bone marrow; normal physiologic function requires this fat; in women, additional essnetial fat serves biologically important functions related to childbearing & other hormonal functions; 4x percentage in women

What is meant with the term "ventilatory equivalent"? (VE/VO2)

The ratio of pulmonary ventilation (VE) to oxygen consumption (VO2)

In terms of body composition analysis, what does ultra-sound measure?

Thickness of fat and muscle and image deeper tissues

What is the most common use for Dual-Energy Xray Assessment (DEXA)?

To assess spinal osteoporosis for bone mineral density in osteoporosis screening

How is BMI used by epidemiologists?

To determine the degree to which that person is overweight or obese.

How is VE (pulmonary ventilation) determined in formula form?

VE(L x min^-1) = BR (br x min^-1) x TV (L x br^-1) BR=breathing rate TV= tidal volume

What is the effect of temperature on water density?

Water that is cooler and harder (due to increased mineral content) is denser and therefore increase the buoyancy of the participant.

How long after taking skinfold should you wait before you read the caliper dial?

Within 2 seconds after applying the full force of the caliper

Compute the percentage of body fat for the following subpopulations:

a.) Hispanic female with a Db=1.0417g/ml 4.87/1.0417-4.41= 26.5% b.) American male with a Db=1.0611g/ml 4.95/1.0611-4.50= 16.5% c.) 15 year old boy with Db=1.0444g/ml 5.07/1.0444-4.64= 21.5%

subcutaneous fat

adipose tissue located beneath the skin

Visceral adipose tissue (VAT)

adipose tissue within and surrounding thoracic (e.g. heart, liver, lungs) and abdominal (e.g. liver, kidneys, intestines) cavities

fat mass (FM)

all extractable lipids from adipose and other body tissues

set point theory

all persons have a well-regulated internal control mechanism similar to a thermostat located deep within the brain's lateral hypothalamus; this neural modulating center maintains a preset level of body weight, body fat, or both within a tight range; the weight that a person would assume when not counting intake calories

fat-free body mass (FFM)

all residual lipid-free chemicals and tissues, including water, muscle, bone, connective tissue, and internal organs

activities of daily living (ADL)

basic and routine everyday life tasks

near-infrared interactance (NIR)

body fat measurement that applies technology originally developed by the U.S. Department of Agriculture to assess the body composition of livestock and the lipid content of various grains

body density (Db)

body mass expressed per unit body volume (Db= body mass/body volume)

specific gravity

body mass in air divided by loss of weight in water (body mass/[body mass - body weight in water])

minimal body mass

body mass plus essential body fat (includes sex-specific essential fat); 48.5kg for the reference woman; computed from bone diameters, stature, and other constants

leptin

body weight-regulating hormone produced by adipose cells and released into the bloodstream that acts on the hypothalamus; impacts the neurochemistry of appetite and metabolism

ketone bodies

byproducts of incomplete fat breakdown; often from inadequate carbohydrate catabolism

dual-energy x-ray absorptiometry (DXA)

clinical device which emits two distinct low-energy x-ray beams with short exposure and low radiation dosage that penetrate bone and soft tissue areas; quantifies fat and nonbone regional LBM, including the mineral content of the body's deeper bony structures

obese syndrome

constellation of nine comorbidities- glucose intolerance, insulin resistance, dyslipidemia, type 2 diabetes, hypertension, elevated plasma leptin concentrations, increased visceral adipose tissue, increased risk of coronary heart, and some cancers

Bioelectrical impedance analysis (BIA)

device that injects (via surface electrodes) an electric current that penetrate the body's water to detect impedance to current flow, calculated by measuring current and voltage using Ohm's law; these relationships quantify the volume of water within the body, and from this, percentage body fat and FFM

ketogenic diets

diet form that emphasizes carbohydrate restriction while generally ignoring total calories and the diet's cholesterol and saturated fat content

first law of thermodynamics

energy transfers from one system to another in many forms but cannot be created or destroyed; also known as the law of conservation of energy

overweight

excess body weight relative to other individuals of the same age or height despite the absence of accompanying body fat measures

overfat

excess fat above a predefined limit based on age and gender

gynoid-type obesity

excess fat in the gluteal and femoral regions

essential fat

fat accumulated in the heart, lungs, liver, spleen, kidneys, intestines, muscles, and lipid-rich tissues of the central nervous system and bone marrow (fat required for normal physiologic functioning)

sex-specific essential fat

fat in females, mainly in breast and tissues related to childbearing and selected hormonal functions

relative body fat (%bf)

fat mass expressed as a percentage of total body mass

fat cell hypertrophy

filling of existing fat cell with more fat

obesity

for young men, body fat content greater than 20%; in older men, body fat content exceeding 30%. in young women, body fat content greater than 30%; in older women body fat content exceeding 30%

stature

height expressed in metric units; for example, 72 in. =182.88cm =1.829m

energy availability hyopthesis

inadequate energy reserve to sustain pregnancy that induces ovulation cessation

storage fat

includes fat or triacylglycerol packed primarily in adipose tissue; contains appoximately 83% pure fat, 2% protein, and 15% water within its supporting structures; includes the visceral fatty tissues that protect thoracic and abdominal cavity internal organs from trauma

fat cell hyperplasia

increase total number of fat cells

gastric banding surgey

inflatable silicone device surgically implanted around the top portion of the stomach to create a small pouch that can hold only a small amount of food; controls how quickly food passes from the pouch to the lower part of the stomach and entry to the small intestine for digestion

total adipocyte number

mass of body fat/fat content per cell

spot reduction

notion that an increase in a muscle's metabolic activity via selective exercise stimulates relatively greater fat mobilization from the adipose tissue in proximity to the active muscle

android-type obesity

obese condition with increased health risk from excessive fat deposition in the abdominal region

fat patterning

pattern of distribution of trunk and extremity body fat

mutant gene

permanent alteration in a gene's DNA sequence

air plethysmography (BOD POD)

plethysmographic device to assess body volume and its changes; body volume is determined by measuring the initial volume of the empty chamber and then the volume with the person inside

Archimede's principle

principle developed by the greek mathematician Archimedes who determined that an object's loss of weight in water equals the weight of the volume of water it displaces

exercise stress hypothesis

prolonged levels of chronic physical stress can disrupt the hypothalamic-pituitary-adrenal axis and gonadotropin-releasing hormone output to produce irregular menstruation

FTO gene

protein-coding gene affecting a person's risks of becoming obese

body mass index (BMI)

ratio of body mass to stature squared (body mass, kg/stature m^2)

liposuction

removing large amounts of fat by surgically excising fat deposits at selected body sites

brown adipose tissue (BAT)

site of non-shivering thermogenesis

kidney stones

small, solid deposits consisting of mineral (calcium) and acid salts (urinary oxalate) formed inside the kidneys

anthropometry

standardized techniques (e.g. calipers, tapes) to quantify (or predict) body size, proportion, and shape

abdominal fat

subcutaneous and visceral fat in the abdominal region

Bariatric surgery

surgical treatment to reduce fat mass, usually in morbidly obese patients

ultrasound

technology that converts electrical energy through a probe into high-frequency pulsed sound waves that penetrate the skin surface into the underlying tissues; the sound w aves pass through adipose tissue and penetrate the muscle layer; the waves then reflect against the bone to the fat-muscle interface to produce an echo, which returns to a receiver within the probe to provide an image of underlying tissues

computer tomography (CT)

technology that uses an array of x-ray emitters and detectors to generate detailed cross-sectional, two-dimensional radiographic images of body segments when an x-ray beam of ionizing radiation passed through tissues of different densities; scan produces pictorial and quantitative information about total tissue area, total fat and muscle area, and thickness and volume of tissues within an organ

magnetic resonance imaging (MRI)

technology where electromagnetic radiation in a strong magnetic field excites the hydrogen nuclei of the body's water and lipid molecules, where the molecules are more concentrated in fat, less so in water and blood, and least i bone; the nuclei then project a detectable signal that rearranges under computer software to quantify total and subcutaneous adipose tissue in individuals of varying body fatness, and other tissues structures

skinfolds

the double layer of skin plus subcutaneous fat just below the skin surface at selected anatomic sites (e.g., triceps, subscapula, iliac, abdomen, thigh)

lean body mass (LBM)

theoretical entity; fat-free body mass plus essential body fat

very low-calorie diet (VLCD)

therapeutic fast providing between 400 and 800 kcal daily as high-quality protein foods or liquid meal replacements

residual lung volume (RLV)

volume of air remaining in the lungs after a forced maximal exhalation

adipose-tissue free weight (ATFW)

whole-body mass minus the mass of all dissectible adipose tissue that contains about 83% pure fat

skinfold calipers

works on the same principle as a micrometer to measure the distance between two points, in this case, skinfolds at selected anatomic regions; pincer jaws exert a constant tension of 10 g/mm-^2 at the point of contact with the double layer of skin plus subcutaneous fat