Week 2 - Anthropometry and Body Composition

Body Composition

• Comprised of many type of elements like Oxygen, Carbon, Hydrogen, Nitrogen.

• Made up of Muscle, Bone, Fat

• Each component depends on sex, genetics, age, lifestyle

What are the main four tissue types

• Nervous

• Epithelial

• Muscle

• Connective

Nervous tissue

• Brain

• Spinal cord

• Nerves

Epithelial tissue

• Lining of GI tract organs and other hollow organs

• Skin surface (epidermis)

Muscle tissue

• Cardiac muscle

• Smooth muscle

• Skeletal muscle

Connective tissue

• Fat and other soft padding tissue

• Bone

• Tendon

Two component model

• The amount of Fat and Fat-Free Mass of which the body is composed

• Fat free mass is primarily composed of bone, muscle, water, vital organs, and connective tissue

• Body mass = Fat mass + Lean body mass

Chemical Four Component model

• Fat

• Fat Free

  • Protein

  • Mineral

  • Water

Anthropometry

• Quantitative measurement of body size and proportions to understand human physical variation and body comp

  • Skin fold thicknesses

  • Circumferences

  • Bony widths and lengths

  • Height

  • Body weight

Why assess body composition?

• Monitor changes in body composition associated with growth, maturation and aging to distinguish normal from disease states

• Establish optimal ranges for health and performance of athletes in various sports

• Track goals for weight management or strength training

• Suitable body composition is important for health

Eating disorders

• A disturbance in eating behaviour that jeopardizes a person’s physical or psychological health

Types of Eating disorders

• Anorexia nervosa

• Bulimia nervosa

• Binge eating disorder

• Female athlete triad

Essential fat

• Fat that is required for normal physiological functioning

  • structural components of cell membranes

  • Synthesis of certain hormones

  • Transport of fat-soluble vitamins

Storage fat

• Fat that is stored in adipose tissue for energy supply purposes

  • Located underneath the skin (subcutaneous), in the abdominal cavity, and around certain organs

Males vs Females

• Average male is taller, heavier, has a large muscle mass, and a lower total body fat content.

• Females have sex specific fat depots in the breasts, pelvic and thigh regions, and probably other areas

Apple Shape

• Male type patterning (Android)

  • Upper torso

  • Abdomen

Pear Shape

• Female type patterning (Gynoid)

  • Thighs

  • Hips

  • Buttocks

• After menopause females begin depositing more fat in the abdominal area

Obesity

• BMI > 30

• Body fat % > 20% (men) or 30% (women)

Causes of Obesity Epidemic

• Caloric intake exceeds caloric expenditure

• Decreased physical activity

• Increased consumption of calories

• Social environment

• Biology - epigenetic

Epigenetics

• Changes in a chromosome that affect gene activity and expression

• Any heritable phenotype change that doesn’t involve genetic modification

Body Composition and Aging

• Increased fat mass

• Decreased muscle mass - sarcopenia

• Decreased bone mass

• These changes can be slowed down by a regular exercise program and proper dietary habits

Direct Methods

chemical analysis of human cadavers

Indirect Methods

Noninvasive techniques used on living persons

Types of Indirect methods for assessing body composition

• Weight tables

• Body Density and Volume Measurements

• Height Indices

• Waist Circumference

• Skinfold Measurements

• CSEP-PATH Body Composition Assessment

• O-Scale System

• Bioelectrical Impedance Analysis

• Other procedures

Weight Tables

Desirable weight with regard to the lowest death rates is predicted from tables that have been developed by insurance actuaries

Criticisms of Weight Tables

• These tables don’t consider body composition. They estimate health risk

• Data comes from white, middle-class, US adults age 25-29

• No accepted method has been devised for determining frame size

Body Density and Volume Measurements

• Greater proportion of fat → lower body density

• Use underwater weighing or volumetry to measure body volume

Air-Displacement plethysmorgraphy (BOD POD method)

• Subject is immersed not in water but in a closed air-filled chamber

• Measure the volume of air displaced inside the closed chamber

Siri Equation used to determine body fat

% fat = (4.95-4.5) / (Body Density) x 100

• Human body has two compartments - fat and nonfat

• Each of these compartments has densities which are known constants

  • Fat density = 0.9 g/mL

  • Nonfat density = 1.1 g/mL

Problems with nonfat compartment measurements

• Cadaver studies shown that the density of the nonfat compartment varies as a function of age, sex and racial group

• nonfat density of 1.1 g/mL is not universally applicable

• Concluding that densitometry should not be used to predict percent fat

Four Component Models

• Preferred more over two compartment models for equations

• Total Body Mass: Fat Mass + Fat-Free Mass

  • Fat Mass: Fat

  • Fat-Free Mass: Water, Protein, Minerals

Height indices

Use BMI (kg/m²) as a indicator of obesity

• BMI less than 18.5 = underweight

• BMI of 25 - 29.9 = overweight

• BMI of 30 or higher = obese

What does BMI not consider?

• Body composition

• Fat Distribution

• Amount of visceral fat

  • Criticism - Does not differentiate body composition

Waist Circumference

• Excellent correlation with abdominal imaging (CT and MRI)

• High association with CVD risk and mortality

• Waist circumference and/or waist to hip ratio may be a better predictor of obesity related health risks than BMI

Skinfold measurements

• A relationship exists between the fat located in the depots directly beneath the skin and internal body fat and body density

Two ways to use fat folds

• Use the sum of a number of skinfolds as an indication of relative fatness among individuals. Compare before and after

• Use the fat folds in conjunction with equations or tables to predict percent body fat

• Use skinfold calliper formulae to predict percent fat

Assumptions in using skinfold measurement to predict percent fat

• Constant densities in a two-compartment model

• Proper identification of measurement site and proper measurement technique

• Constant compressibility of the skinfold

• Fixed adipose tissue patterning

• Fixed proportion of internal to external fat

Two types of body composition prediction equations

• Population specific

• Generalized

Population specific equations

• Yuhasz

  • Developed from small, homogenous (age, sex, state of training, fatness) samples

  • Their application is limited to that subsample

Generalized equations

• Jackson and Pollock, Durnin & Womersley, Peterson, Wang

  • Developed from large, heterogenous samples

  • Wider application in terms of age and fatness

Skin fold SEE

3-4% error

O-Scale System

• Requires eight skin fold, ten girths, four skinfold-corrected girths and two bone breadths

• Provides: Adiposity rating, Proportional weight rating

• Uses stanine scale

Bioelectrical Impedance Analysis

• Used to measure the resistance to the flow of electricity in the body

• Impedance is greater in adipose tissue (14-22% water) than in bone and muscle (71-75% water)

• The higher the electrical impedance, the fatter the subject → subject less conductive

• Error approx 3-5% body fat

Dual Energy X-Ray Absorptiometry (DEXA)

Widely used for performing bone mineral density measurements. It can also reliably and accurately quantify fat and regional lean body mass

Other Procedures

• CT - Computerized tomography

• MRI - Magnetic Resonance Imaging

• Total body water - hydrometry

• Ultrasound

• Total body potassium

• NIR - Near-infrared Interactance