Kinesiology and Biomechanics

Kinesiology & Biomechanics

Kinesiology is the study of human movement, combining multiple subfields:

  • Anatomy (structure)

  • Physiology (function)

  • Biomechanics (forces affecting movement)

  • Psychology (how movement is learned & controlled)

  • Metrology (measurement of movement)

Biomechanics applies mechanics to human movement. It focuses on:

  • Kinetics – forces causing movement

  • Kinematics – description of movement

🔹 Why do we move?

  • To survive

  • To get things done

  • To stay in shape

🔹 Types of movement

  1. Mobility – moving body freely

  2. Activities of Daily Living (ADLs) – essential tasks (walking, dressing, eating)

  3. Occupation – work-related movement

  4. Leisure – recreational movement

  5. Communication – gestures, sign language

Biomechanics Breakdown

⚡ Statics vs. Dynamics

  • Statics – No movement, stable, balanced

  • Dynamics – Movement, unbalanced forces

🔹 Types of Motion

  • Linear – Moving in a straight line

  • Angular – Rotating around a point (all body movements are angular due to joints)

🔹 Goals of Biomechanics

  1. Optimize performance

  2. Prevent injuries

  3. Restore function (clinical use)

Optimized Performance (SEE):

  • Safety

  • Effectiveness

  • Efficiency

How We Study Biomechanics

  1. Quantitative – Uses numbers, measurements

  2. Qualitative – Observational analysis

Steps in Analyzing Movement:

  1. Describe – Purpose, phases, movement patterns

  2. Identify – Movement phases, how forces interact

  3. Analyze – Anatomical & mechanical breakdown

  4. Prescribe – Identify problems, suggest improvements

Kinematics vs. Kinetics

  • Kinematics – Describes movement (speed, velocity, acceleration)

  • Kinetics – Forces causing movement (gravity, friction, muscles)

Basic Forces in Kinetics:

  • Gravity – Affects movement & posture

  • Muscle force – Generates movement

  • External resistance – Ex: weights, bands

  • Friction – Helps movement (ex: walking)

Anatomy & Movement

Anatomical Position – Standard body position for describing movements:
✔ Body upright, facing forward
✔ Feet parallel
✔ Arms at sides, palms facing forward

Directional Terms:

  • Medial – Closer to the midline

  • Lateral – Further from midline

  • Anterior (ventral) – Front

  • Posterior (dorsal) – Back

  • Proximal – Closer to the trunk

  • Distal – Further from trunk

Planes of Motion & Movements

  1. Frontal (coronal) – Front & back halves (side-to-side movements)

    • Abduction/adduction (hips, shoulders)

    • Lateral flexion (neck, trunk)

  2. Sagittal – Right & left halves (forward/backward movements)

    • Flexion/extension (knees, arms, neck)

    • Dorsiflexion/plantar flexion (ankle)

  3. Transverse (horizontal) – Upper & lower halves (rotational movements)

    • Rotation (hip, spine)

    • Pronation/supination (forearm)

Other Movements:

  • Elevation & Depression (scapula, jaw)

  • Protraction & Retraction (scapula)

  • Circumduction (circular movement of limbs)

Forces & Their Effects on the Body

  1. Compression – Squeezing force (ex: gravity pressing on spine)

  2. Tension – Pulling force (ex: muscles pulling on bones)

  3. Shear – Sliding forces (ex: knee impact in long jump)

  4. Torsion – Twisting force (ex: forearm pronation/supination)

Levers in the Human Body

Levers help the body move by magnifying force. They consist of:

  • Axis (A) – Joint (pivot point)

  • Effort (E) – Force applied by muscles

  • Resistance (R) – Object/body weight

🔹 Types of Levers

  1. First-class (EAR) – Effort & resistance on opposite sides (ex: seesaw)

  2. Second-class (ERA) – Resistance between effort & axis (ex: plantar flexion)

  3. Third-class (REA) – Effort between resistance & axis (ex: bicep curl) – most common in the body

Key Equations

✔ Force (F) = mass × acceleration (F = ma)
✔ Weight (Wt) = mass × gravity (Wt = mg)
✔ Torque (T) = Force × perpendicular distance
✔ Density (p) = mass/volume