1. Kinetic Concepts for
Analyzing Human Motion
Presentation Created by
Dr. Hazrat Bilal Malakandi. PT
DPT (IPM&R, KMU)

2. Objectives
• Identify common units of measurement for mass,
force, weight, pressure, volume, density, specific
weight, torque, and impulse
• Identify and describe the different types of mechanical
loads that act on the human body
• Identify and describe the available instrumentation for
measuring kinetic quantities
• Solve quantitative problem involving vector quantities
using both graphic and trigonometric procedures

3. Basic Concepts
Related to Kinetics
• Inertia
• Mass
• Force
• Center of Gravity
• Weight
• Pressure
• Volume
• Density
• Specific weight
• Torque
• Impulse

4. Common Units for
Kinetic Quantities
Quantity Symbol Metric Unit English Unit
Mass m kg slug
Force F N lb
Pressure P Pa psi
Volume (solids) V m3
ft3
(liquids) liter gallon
Density ρ kg/m3
lb/ft3
Specific weight γ N/m3
lb/ft3
Torque T N-m ft-lb
Impulse N • s lb • s

5. Mechanical Loads on
the Human Body
• Compression
• Tension
• Shear
• Stress
• Torsion
• Bending
• Combined loading

6. The Effects of Loading
• Deformation
When an external force is applied to the human
body, several factors influence whether an
injury occurs
– Magnitude and direction of force
– Area over which force is distributed
– Load-deformation curve
– Yield point (elastic limit)
– Failure

7. Repetitive vs. Acute Loads
• Repetitive loading
• Acute loading
• Macrotrauma
• Microtrauma

8. Tools for Measuring
Kinetic Quantities
• Electromyography (EMG)
– To study neuromuscular function
• Dynamography
– Primarily employed in gait research
– Starts, takeoffs, landings, baseball & golf
swings, and balance

9. Vector Algebra
• Vector
• Kinetic vector quantities
– force weight, pressure, specific weight &
torque
• Kinematic vector quantities
– Displacement, velocity & acceleration
• Scalar quantities
– Mass, volume, length & speed

10. Vector Resolution
Vertical
Horizontal
Example: A ball is thrown into the air