1

Tony Leyland (778) 782-4338 leyland@sfu.ca http://www.sfu.ca/~leyland/

See website for more information

Definition of Biomechanics

The area of study wherein the knowledge and methods of mechanics are applied to the structure and function of the living human system.

Course Outline

  Lecture Schedule   Text Readings   Tutorial Attendance   Evaluation

 Assignments  Exams

My Website + Kin 201 Course Website

http://www.sfu.ca/~leyland/

Not all slides are on the

web.

Course Prerequisites   KIN 142 (a must, especially

functional anatomy)   PHYS 101 or 120 or 125 or 140

(a big help with most problems)   MATH 151 or 154 (essential

for some sections)   MATH 152 or 155 (can be taken

concurrently so less essential)

  The picture above shows KIN 201 student reviewing prerequisite information!

Strongly Recommended Course Text

Andy Kerr Introductory Biomechanics Churchill Livingstone Elsevier, Edinburgh, 2010.

Read Chapter 1 The text will be on library reserve as are many other biomechanics texts. I do not always follow the text sequentially which is why it is recommended not required.

2

Qualitative vs. Quantitative

good fifty revolutions poor three seconds long six meters heavy 25 kilograms flexed 45o angle

Course Text   The course text is the foundation of required

information presented in a qualitative format.   However, the course requires good

quantitative knowledge which you can learn from the lectures, tutorial and course website (and additional books on reserve if required).

  You cannot get all of the information via the text.

  This course has a large quantitative component.

Kelvin (1891) “I often say that when you can

measure what you are speaking about and express it in numbers, you know something about it: but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind”.

Oscar Wilde “Education is very admirable but

let us not forget that anything worth knowing cannot be taught”

in other words

you get out what you put in!!

e.g. If you don’t buy the text – or use a reserve text – you have to come to lecture!

Common Misconceptions

  If I don't lecture on the material it isn’t covered.

  If I do lecture on the material it is covered!

Problem Based Learning

  I believe that you don’t learn unless you do!   How would you learn to perform a jump

shot in basketball?   The same is true of biomechanical

concepts. You have to practice using them to fully learn them.

  http://www.sfu.ca/~leyland/Kin201%20Files/PBL.pdf

3

Downloads Required Soon

  http://www.sfu.ca/~leyland/Kin201%20Files/Outline.pdf   ………./PBL.pdf   ………../Freebody.pdf   ………./Equations.pdf   ………./Anthropometry.pdf

  These are located at the top of the Kin201 webpage.

Who Needs Biomechanics?

Ergonomists (postural strain, back injuries, repetitive

strain injuries, etc.)

Newtons “Rehabilitators”

(mechanical function of musculoskeletal system)

4

Musculoskeletal Injury   Many different disciplines have a role to play

in a comprehensive understanding of injury.   However, of all the scientific disciplines,

physics and its sub-discipline mechanics are arguably most central to the study of injury.

  The fundamental relation between mechanical energy and injury highlights biomechanics as the logical discipline to study the causes and effects of human musculoskeletal injury.

Whiting & Zernicke, 1998

Foot Pressure

Internal Forces Coaches & Physical Educators (optimal sports performance

and/or injury prevention)

Maximal foot / racquet velocity at contact?

2

21 mvrgyKineticEne =

5

Mechanics of Exercise Variable Resistance (leverage {force x distance})

Biomedical Engineers

Definitions

Kinematics study of motion (space/time)

Kinetics study of forces causing or resulting

from motion

6

Kinematics

Squats

Ground reaction force while performing squats

Kinetics

Muscle moments (torques) while performing squats

Human Movement Analysis

DisplacementVelocity

Acceleration

Linear

DisplacementVelocity

Acceleration

Angular

Kinematics

Force

Linear

Torque(Moment of Force)

Angular

Kinetics

Biomechanics

Functional Anatomy

Kinesiology

Definitions

Statics constant motion

Dynamics acceleration present

7

Anatomical Terms

Chapter 1

Movement Terminology Movement Description

  See text or web

8

Functional Anatomy http://www.exrx.net/

Axis of Rotation   pivot point for an angular motion

Direction Perpendicular to

sagittal axis (anteroposterior

axis)

horizontally from the front to

the back frontal plane

transverse axis (frontal axis or horizontal axis)

horizontally from side to side sagittal plane

vertical axis perpendicular to the ground transverse plane

Back to them prerequisites!

  Movement Analysis   List joint movement

and the main agonists for each action.

  State whether the muscle is working concentrically or eccentrically. Muscle moments (torques)

while performing squats

Text Activity 1.1

 Muscle Contraction   Concentric   Eccentric   Isometric

You want more?!

  Again for a down and up phase.   List joint movements and the main agonists

for each action.   State whether the muscle is working

concentrically or eccentrically.   List major stabilizers.

9

http://www.exrx.net/ Systems and

Free Body Diagrams

http://www.sfu.ca/~leyland/Kin201/Freebody.pdf

Systems

“A system is a body or group of bodies or objects whose motion is to be examined”

Ground reaction force

Body weight (minus weight of foot)

Muscle forces

mg

System   Once you have correctly

identified the system you can analyze what forces can cause the system to move.

  Although muscular force is required to move, it is not the actual force that propelled this goalkeeper into the air.

  What force did?

Internal & External Forces

System = windsurfer board and sail.

Internal forces Muscle forces, force of hands on boom, ?? External Forces Force of water on board, air resistance, gravity, ??

Reaction Forces

Although internally initiated movements of the segments are required to move the body (due to force of muscular contraction), to move a system an external force must be present.

10

“in other words....”

You have to push or pull against something to make your centre of gravity, or the CG of an object, move.

You can’t pull yourself up by your boot laces!

Free Body Diagrams

  Read the web pages on free body diagrams.

  This is a crucial skill in the analysis of human movement.

Draw all forces acting on runner What would the diagram look like if you drew a free body diagram of the foot and shank?

It is best not to draw stick figures for general FBDs

Cause and Effect   The cause of movement of a body or

segment is due to:   muscular force (torque)   gravitational force, or   another external force like an opponent

in a wrestling match   I often get students say things like “the

arm bends increasing the torque”.   Your muscles are your force generators.