Detailed Study Notes on Anthropometry and the Musculoskeletal System

Anatomical Bases of Human Movement

Unit 2: Basic Concepts of Anthropometry (Chapter 4)

Learning Concepts

  • Overview and scope of anthropometry

  • Standards for evaluating body composition

  • Equipment and theories for estimating body fat

  • Shorthand methods for describing physique

Anthropometry

  • Definition: Science focusing on the measurement of size, proportions, and composition of the human body.

  • Subfield: Kinanthropometry - anthropometry as it applies specifically to kinesiology.

  • Assessments focus on body composition, distinguishing between fat mass (FM) and fat-free mass (FFM).

Measurement Types

  • Direct Measurement: Involves precise methods such as:

    • Chemical analysis: Breaks down the body into fat and fat-free components.

    • Physical dissection: Assessing fat, fat-free tissue, muscle, and bone.

  • Indirect Measurement: Estimates body composition using non-invasive methods.

Body Composition Elements

  1. Size - Dimensions of the body.

    • Examples include:

      • Height

      • Length

      • Mass

      • Volume

      • Surface area

  2. Structure - Refers to the shape and form:

    • Examples include:

      • Head breadth/head length

      • Shoulder width/hip width

      • Sitting height/standing height

      • Thigh length/leg length

      • Neck circumference/neck length

  3. Composition - Quantitative makeup:

    • Examples include:

      • Percent body fat

      • Lean body mass

      • Water content

      • Calcified tissue

Body Composition Standards

  • Reference standards help evaluate ‘normal’ body composition:

    • Reference Individual (Age: 20-24 years)

    • Male: 70 kg (1.74 m or 68.5 in)

    • Female: 56.7 kg (1.64 m or 64.5 in)

Fat Types

  1. Storage Fat

    • Subcutaneous fat: Located under the skin.

    • Visceral fat: Surrounds organs; higher health risks as it affects organ function.

  2. Essential Fat: Necessary for physiological functions, located in:

    • Central nervous system (CNS)

    • Bone marrow

    • Cell membranes

Individual Variability

  • Differences exist in fat distribution and health risk:

    • Visceral fat poses a greater health risk compared to subcutaneous fat.

    • Subcutaneous fat is of lower health concern but may be aesthetically displeasing.

Healthy Body Fat Composition Standards

  • Lack of consensus on what constitutes normal or healthy levels of body fat:

    • General Guidelines for Body Fat Percentages:

    • Men

      • Above Average: >20%

      • Average: 10-15%

      • Below Average: <10%

      • Obese: >25%

      • Moderately Overfat: 21-25%

      • Healthy: 10-20%

      • Lean (High Performance): 5-9%

      • Excessively Lean: <5%

      • Overweight: >25%

      • Acceptable: 18-24%

      • Fitness: 14-17%

      • Athlete: 6-13%

    • Women

      • Above Average: >25%

      • Average: 15-25%

      • Below Average: <15%

      • Obese: >32%

      • Moderately Overfat: 26-32%

      • Healthy: 18-25%

      • Lean (High Performance): 8-17%

      • Excessively Lean: <8%

      • Overweight: >32%

      • Acceptable: 25-31%

      • Fitness: 21-24%

      • Athlete: 14-20%

Body Composition Assessment Models

  • Various models estimate body composition based on compartment models, accounting for biological variability:

    • Whole Body 2-C Model

    • Chemical Model: 4 compartments

    • Fluid Metabolic Model

    • Anatomic Model: 4 compartments

    • Compartment breakdown includes: fat, fat-free body, water, protein, minerals.

Densiometry (Hydrostatic Weighing)

  • Traditional gold standard method for body composition analysis.

  • Assess body density to estimate % body fat (BF):

    • Relies on water displacement under Archimedes’ principle.

    • Density () is calculated using the formula: extDensity=racextmassextvolumeext{Density} = rac{ ext{mass} }{ ext{volume} }

    • Example: Determining total body volume from water displaced.

Hydrostatic Weighing Methodology

  • Process: Measure weight on land, then measure weight underwater to calculate density.

  • Assumptions:

    • Density of fat and FFB: Fat density = 0.9 g/ml, FFB density = 1.1 g/ml.

    • Variation in FFB composition based on factors such as race and gender.

Siri Equation for Body Fat Calculation

  • Formula: ext{%Fat} = rac{495}{D_b} - 450.0

  • Example calculations:

    • Brozek Equation: %BF = rac457Db−414.2rac{457}{D_b} - 414.2

Data Variability and Impact of Assumptions

  • Variability can arise from:

    • Race and ethnicity differences affect density assumptions, leading to biased %BF estimates.

    • Age-related changes can influence accuracy.

    • Disease states and physical activity influence muscle and bone density.

Refinement of FFM Density

  • Multi-component models provide improved accuracy in assessing body fat.

  • 3-compartment model formula: %BF = rac(2.118)Db−0.78W−1.354rac{(2.118)}{D_b} - 0.78W - 1.354

  • 4-compartment model formula: %BF = rac(2.747)Db−0.714W+1.146B−2.053rac{(2.747)}{D_b} - 0.714W + 1.146B - 2.053

  • Where:

    • BW = body weight (kg)

    • W = total body water (l) / BW (kg)

    • B = bone mineral (kg) / BW (kg)

Dual Energy X-Ray Absorptiometry (DXA)

  • Measures fat mass, fat-free mass, and bone mineral without assumptions of constant biological composition.

  • Utilizes x-ray energies for assessment.

  • Recognized as a new gold standard; however, high costs and resource needs are limitations.

Skinfold Measurements

  • Method for estimating subcutaneous fat across multiple sites to evaluate whole body fat content.

  • Common issues include accuracy and dependence on equation origins and site selection.

Bioelectrical Impedance (Bioimpedance)

  • Sends low-voltage current through the body to measure total body water, thereby estimating FFM and %BF.

  • Conditions affecting accuracy: hydration status and body temperature. It tends to overestimate lean individuals and underestimate obese individuals.

Near Infrared Interactance

  • Uses infrared spectroscopy to estimate body fat based on light reflection per individual characteristics.

  • Limitations include validity issues and measurement restrictions.

Other Body Composition Methods

  • Computed Tomography (CT): Generates 2-D images for total tissue analysis.

  • Magnetic Resonance Imaging (MRI): Uses electromagnetic radiation for fat assessment.

  • Air Displacement Plethysmography (Bod Pod): Air-volume assessment method taking only minutes and correlates well with hydrostatic weighing.

Body Mass Index (BMI)

  • Calculated as: extBMI=racextWeight(kg)extHeight2(extm)ext{BMI} = rac{ ext{Weight (kg)} }{ ext{Height}^2 ( ext{m})}

    • E.g. if weight = 70 kg and height = 1.64 m, then BMI = 26.

  • BMI does not differentiate between fat mass and lean mass.

Morbidity Outcomes Associated with BMI

  • Hazard ratios for various conditions according to BMI classifications in older individuals:

    • Myocardial infarction: 1.00 (BMI < 20) to 1.16 (BMI > 30)

    • Stroke: 1.00 (BMI < 20) to 1.11 (BMI > 30)

    • Type 2 diabetes risks escalate significantly with increasing BMI.

Waist-to-Hip Ratio (W:H)

  • Formula: W:H=racextWaistCircumferenceextHipCircumferenceW:H = rac{ ext{Waist Circumference} }{ ext{Hip Circumference} }

  • Indicates fat distribution with higher ratios correlating to health risks.

  • Ideal W:H ratios:

    • Women: <0.80; Men: <0.90

    • Higher risk with values exceeding 1.0.

Somatotyping and Body Build Classification

  • Originated by psychologist William Sheldon in the 1940s for quick identification:

    • Ectomorph: Slim build, long limbs, low muscle mass.

    • Mesomorph: Muscular and strong, oval-shaped body.

    • Endomorph: Higher fat storage, wide waist, and larger bone structure.

Unit 1: Basic Concepts of the Musculoskeletal System (Chapter 3)

Learning Concepts

  • Key aspects of bone formation and classifications

  • Characteristics of joints

  • Directional and movement terminology relevant to cardinal planes

  • Structural and neural influences on muscular strength

  • Biological processes involved in muscle contraction

  • Factors contributing to muscle fatigue

Bone Development (Osteogenesis)

  • Processes of bone formation:

    • Intramembranous Ossification: Bone develops from membrane.

    • Endochondral Ossification: Bone develops from cartilage.

  • Bone Cells: Types include:

    • Osteoblast: Immature cell that builds bone.

    • Osteocyte: Mature bone cell.

    • Osteoclast: Cell that destroys the bone matrix.

  • Development overview:

    • Early embryonic stages lead to the development of three germ layers, ultimately forming bone cells.

Intramembranous Ossification Steps

  1. Ossification centers appear in the fibrous connective tissue membrane.

  2. Calcification occurs: deposition of calcium and minerals hardens the matrix.

  3. Formation of woven bone and periosteum occurs.

  4. Vascularized mesenchyme condenses around external surfaces.

Endochondral Ossification Overview

  • Process: Cartilage model grows, then undergoes transformation as primary ossification centers develop.

  • Secondary ossification centers appear after birth in epiphyses.

  • Formation of articular cartilage from hyaline cartilage.

  • Growth plates facilitate longitudinal growth.

Bone Growth Throughout Lifespan

  • Longitudinal growth is completed with the closure of growth plates.

  • Appositional growth continues throughout life.

Histology of Bone

  • Bone Structure: Comprised of dense and spongy bone with distinct functionalities.

  • Components include:

    • Compact Bone: Provides strength.

    • Trabecular (Spongy) Bone: Lightweight support and storage.

    • Features like trabecular structure allow for communication and nutrients supply between bone cells.

Classification of the Skeletal System

  • Location: Axial and Appendicular Skeleton

  • Axial consists of:

    • Skull, vertebrae, ribs, sternum.

  • Appendicular includes upper and lower limbs:

    • Clavicle, scapula, humerus, femur, and others.

Classification by Shape

  • Long, short, flat, irregular, and sesamoid bones categorized based on structure and function:

    • Provide protection, serve as levers, and maintain stability.

Functions of the Skeletal System

  • Mechanical Functions: Protection, support, leverage for movement.

  • Physiological Functions: Mineral storage (calcium and phosphate), blood cell production (hematopoiesis).

The Articular System

  • Arthrology: Study of joints.

  • Joint classifications based on movement capabilities or materials uniting bones:

    • Fibrous, Cartilaginous, Synovial.

Fibrous Joints

  • Description: Bones are in close contact or separated by fibrous tissues.

  • Examples include skull sutures, teeth in sockets.

Cartilaginous Joints

  • Description: Bones united by cartilage.

  • Examples include hip bones and spinal vertebrae articulations.

Synovial Joints

  • Joint capsule provides stability and limits range of motion, often reinforced by ligaments.

  • Synovial membrane produces synovial fluid, lubricating cartilage and aiding in movement.

Synovial Joint Movement Capabilities

  • Classification based on movements:

    • Linear (Gliding): E.g. wrist bones.

    • Angular: Including pivots and hinges for specific movement types.

Range of Movements Allowed by Synovial Joints

  • Describing joint mobility in terms of flexibility and range of motion based on structural design.

  • Joint stability reflects resistance to movement, directly influenced by morphological and physiological factors.

Description of Movement

  • Cardinal planes divide body movement:

    • Sagittal Plane: Right and left.

    • Frontal Plane: Front and back.

    • Transverse Plane: Upper and lower segments.

Special Movement Terminology

  • Foot movements clarified:

    • Inversion and Eversion: Pertaining to foot positioning.

    • Circumduction: Describing joint movements involving multiple planes.