Basic Kinematics

Basic Kinematics

Course Content • Introduction to the Course • Biomechanical Concepts Related to Human Movement • Anatomical Concepts Related to Human Movement • Applications in Human Movement

Biomechanical Concepts • Basic Kinematic Concepts • Vector Algebra • Basic Kinetic Concepts

Basic Kinematic Concepts • Variables for Describing Motion • Reference Systems for Describing Motion of the Human Body and Its Segments • Guidelines for Describing Motion of the Human Body and Its Segments

Rigid Body Mechanics

What is kinematics? • Spatial and temporal characteristics • Qualitative or quantitative • Linear & angular motion

Why use kinematics? • Practical: Provides a standard for us in performing, teaching, or evaluating a skill • Research: Once we describe, we can ask why? Problem with kinematics? • Practical: Proper kinematics does not always mean proper force application

Basic Kinematic Concepts • Variables for Describing Motion • Reference Systems for Describing Motion of the Human Body & Its Segments • Guidelines for Describing Motion of the Human Body & Its Segments

Kinematic Variables • Time • Position • Displacement & distance • Velocity & speed • Acceleration

WHEN? HOW OFTEN? IN WHAT ORDER? HOW LONG? Most basic analysis Examples: Cadence Stride time Temporal patterning Time – Temporal Analysis

Temporal Patterning

Stance Swing Temporal Patterning

Absolute vs. Relative Timing

Position • position - location in space relative to some reference point • Linear position (s) • x,y,z coordinates • Angular position () • Units WHERE?

Displacement (s, ) Final change in position Vector quantity Distance (p, ) Sum of all changes in position Scalar quantity Displacement & Distance HOW FAR? • Units (m, °)

Velocity (v, ) Vector quantity position  time Units (m.s-1, °.s-1) Acceleration (a, ) Vector quantity velocity  time Units (m.s-2, °.s-2) Insight into forces/torques Velocity & Acceleration HOW QUICKLY IS VELOCITY CHANGING? HOW FAST?

Basic Kinematic Concepts • Types of Motion • Variables for Describing Motion • Reference Systems for Describing Motion of the Human Body & Its Segments • Guidelines for Describing Motion of the Human Body & Its Segments

Reference Systems: Linear +y vertical horizontal -x +x Must define origin of reference system to quantify kinematics. horizontal +z -y

90° 180° 0° 270° Absolute Reference Systems: Angular /2 rad ¼ rev CCW + • rad ½ rev 2 rad 1 rev 3/2 rad ¾ rev

Relative Reference Systems: Angular

Relative Reference Systems • All Joints @ 0except • Ankle @ 90 • Forearm varies Fundamental Standing Position Anatomical Standing Position

Reference Systems for Measuring Joint Position & Displacement 90 140 140 0

0 40 90 0 90

Basic Kinematic Concepts • Types of Motion • Variables for Describing Motion • Reference Systems for Describing Motion of the Human Body & Its Segments • Guidelines for Describing Motion of the Human Body & Its Segments

1. Distinguish between motion & position of joints & segments. A B

2. Recognize that either segment can rotate about a joint.

3. Recognize that bones move linearly as well as angularly.

4. Understand that movement generally occurs in oblique planes around oblique axes.

5. When observing motion, look at the plane, down the axis.

Summary • Identify the system of interest • Identify the type(s) of motion of interest • Identify the reference system for the motion • Describe precisely the temporal & spatial characteristics of that motion using appropriate terminology for the situation • Time • Position • Displacement (ROM) • Velocity • Acceleration

For the next lecture day: • Lecture Topic #2 • Subtopic C – Vector Algebra

Basic Kinematics