Chapter 2: Kinematic Concepts for Analyzing Human Motion

Chapter 2:
Kinematic Concepts for
Analyzing Human Motion
Basic Biomechanics, 4 th edition
Susan J. Hall
Presentation Created by
TK Koesterer, Ph.D., ATC
Humboldt State University

Objectives
• Identify & describe reference positions,
planes, and axes associated with the human
body
• Provide examples of linear, angular, &
general forms of motion
• Define & appropriately use directional terms &
joint movement terminology
• Explain how to plan & conduct an effective
qualitative human movement analysis
• Identify & describe uses of available
instrumentation for measuring kinematics

Forms of Motion
• Most human movement is general motion
– A complex combination of
• Linear and
• Angular motion components

Forms of Motion
• Linear Motion
– May also be thought of as motion along a
line that may be straight or curved, with all
parts of the body moving in the same
direction at the same speed, also known as
translatory motion, or translation.
• Rectilinear – along a straight line
• Curvilinear – along a curved line

Forms of Motion
• Angular motion – involving rotation around a
central line or point
• Axis of rotation – imaginary line perpendicular
to the plane of rotation and passing through
the center of rotation

General Motion
• A combination of translation and
rotation
• Most human movement activities are
categorized as general motion

2-2

Mechanical Systems
• Before determining the nature of a
movement, the mechanical system of
interest must be defined.
• System – a body or group of bodies
whose motion is being analyzed

Standard Reference Terminology
Anatomical Reference Position
• Erect standing position with all body
parts, including the palms of the hands,
facing forward; considered the starting
position for body segment movements

Standard Reference Terminology
Directional Terms
• Superior
• Inferior
• Anterior
• Posterior
• Medial
• Lateral
• Proximal
• Distal
• Superficial
• Deep

Standard Reference Terminology
Anatomical Reference Planes
• Cardinal planes – 3 imaginary perpendicular
reference planes that divide the body in half
by mass
– Sagittal plane
– Frontal plane
– Transverse plane

Standard Reference Terminology
Anatomical Reference Axes
• An imaginary axis of rotation that passes
through a joint to which it is attached
– Mediolateral or frontal axis
– Anterioposterior or sagittal axis
– Longitudinal axis

2-5

Joint Movement Terminology
• In anatomical position, all body segments are
considered to be positioned at zero degrees.
– Sagittal Plane Movements
– Frontal Plane Movements
– Transverse Plane Movements
• Other Movements

2-6
Sagittal plane movements

2-8
Frontal Plane Movements

2-13
Transverse Plane Movements

2-16
Other Movements

2-19

Spatial Reference Systems
• Used to standardize the measurements taken
Cartesian Coordinate system
• Movements primarily in a single direction, or
planar, can be analyzed using a twodimensional
Cartesian
– X (horizontal) direction
– Y (vertical) direction
• 3-dimensional by adding a z-axis

Cartesian Coordinate System

Qualitative Analysis
of Human Movement
• Requires knowledge of the specific
biomechanical purpose of the movement and
the ability to detect the causes of errors
• Qualitative refers to a description of quality
without the use of numbers.

Prerequisite Knowledge
for a Qualitative Analysis
• Kinematics
• Performance outcome
Analysts should be able to distinguish the cause
of a problem from symptoms of the problem
or an unrelated movement idiosyncrasy
Experience in performing a motor skill does not
necessarily translate to proficiency in
analyzing the skill.

Planning a Qualitative Analysis
1. What are major questions to be answered
2. Determine the optimal perspective(s)
3. Analyst’s viewing distance
4. Number trial or executions
5. Performer’s attire
6. Nature of surrounding equipment
7. Visual observation or video camera

Conducting a Qualitative Analysis
• Continuous process of;
– formulating an analysis
– collecting additional observations
– formulating an updated analysis
• Detecting biomechanical errors
• Characteristics of the performer
• Other factors that can affect performance
• Auditory information
• Feedback from the Performer
• Observation skill

2-21

Tools for Measuring
Kinematic Quantities
• Cinematography & Videography
– Standard video 30 pictures per second
– Higher rates available
– Clarity of images
– Number of cameras to capture information
– Computer-linked equipment – digitizing

Measuring Kinematic
Quantities
• Other Movement Monitoring Systems
– Real-time tracking of LEDs
– Computer-linked cameras track targets
• Other Assessment Tools
– Goniometer or Electrogoniometer
– Photocells, light beams, and timers
– Accelerometer

Summary
• Teachers of physical activities, clinicians &
coaches all routinely perform qualitative
analyses to assess, correct, or improve
human movements
• Both knowledge of the specific biomechanical
purpose of the movement and careful
preplanning are necessary for an effective
qualitative analysis

The End