6701529 introduction to bio mechanics

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Biomechanics 2015

Section 1:1

An Introduction to Biomechanics

Dr. Moira McPherson,

School of Kinesiology



AN INTRODUCTION TO THE STUDY AND

ANALYSIS OF HUMAN MOVEMENT

During the past decade the term

BIOMECHANICS has emerged as an area of inquiry in the sport science domain.Biomechanics is based on NEWTON'S LAWS and

involves the study of the motion of bodies andthe interrelationships among the forces actingon these bodies.



INTRODUCTION TO THE STUDY AND ANALYSISOF HUMAN MOVEMENT

BIOMECHANICS: BIO = LIVING

MECHANICS = FORCES & EFFECTS

The application of mechanics to the living organism

Involves the principles of anatomy and physics in thedescriptions and analysis of movement.

Has many diverse applications to all biological systems

The study of biological structures, processes andfunctions by applying the methods and principles of mechanics



HAY, 1995

THE SCIENCE THAT EXAMINES THEINTERNAL AND EXTERNAL FORCES

ACTING ON THE BODY AND THE EFFECTSPRODUCED BY THESE FORCES

KINEMATICS & KINETICS



Why learn about Biomechanics?



AREAS OF STUDY, RESEARCH

AND PRACTICE Sport and Exercise Science

Coaching

Ergonomics

Equipment Design

Gait & Locomotion

Orthopedics - Rehabilitation -Physiotherapy, OccupationalTherapy

Prosthetics and Orthotics

Motor Control

Computer Simulation



Videotape Analysis: A

Functional Capacity Lift



Graphical Analysis



MECHANICS

Rigid body mechanics are based on theassumption that a solid body is considered

to be a rigid body if the distance betweenthe particles remains fixed when a force isapplied.



Figure 2. Force



SEGMENTAL ANALYSIS

We often make the assumptionthat the human skeleton canbe represented as a series of

links. Researchers have usedeverything from cones tospheres to form the linkswhich best approximated thecomplexity of the human body.However, by far the most

widely adopted and simplestlink system representation isthe stick man.



The stick man uses straight sticks to represent each of the links. In any case, regardless of the shapes which

are used we also make the assumption that the human

link system is a system of rigid bodies connected at the joints



Figure 3.

Rigid Body Mechanics

kinematics kinetics

linear curvilinear statics dynamics

angular parabolic



KINETICS

examines the causes of motion, theinternal and external forces that cause

motion or cause a body to remain at rest,and the interactions between these forces.There are two branches of kinetics;

STATICS and DYNAMICS



KINEMATICS Describes the motion

of a body without

reference to theforces causing it.Kinematics examineshow, when, and

where a body moves.



For example, variables such as thedisplacement of a ball, the velocity of a

skater, and the acceleration of the free legall describe motion, and are kinematicvariables.



We classify the kinematic motionaccording to the pathway it takes.Movement may be LINEAR,CURVILINEAR, or a combination of the two. Curvilinear motion can befurther specified as ANGULAR orPARABOLIC.



LINEAR MOTION

Linear motion is the

movement of a body in astraight line or along astraight pathway. Linearmotion is also produced

when external forces areapplied directly through thecentre of mass of an body.



CURVILINEAR : Motion along a curvedpath



ANGULAR : Angular motion takes place

when a body moves along a circularpath about some AXIS in space. Thisaxis is known as the axis of rotation.

Angular motion is produced whenforces are applied away from the axis of rotation of a body.



Our body limbs are able to rotate aboutthe joints because all of our muscles are

attached at some distance from the centreof the joints.



PARABOLIC: Bodieswhich are projected

into the air willassume aPARABOLIC PATH and are governed by

the laws of projectilemotion.



STATICS: Statics refers to situations

where the body or object remains at rest,or is moving at a constant speed in a stateof equilibrium. Equilibrium is a balancedstate in which there is no acceleration.



DYNAMICS: Dynamics deals with thechanges in motion brought on by

unbalanced forces.



QUANTITATIVE VS QUALITATIVE

Both kinematics and kinetics can be analyzedusing a quantitative or qualitative approach

A quantitative analysis requires a numericalevaluation of an individual’s movement

Qualitative analysis involves a systematic

analysis of movement based on biomechanicalconcepts but without actual measurement



METHODS OF ACQUIRINGDATA

1. VIDEO ACQUISITION 2 D or 3D

Points are digitized manually or by attaching

reflective markers and digi auto 2. 3 D OPTICAL ACQUISITION

3D in controlled environment

Marker only system that uses 2 – 12 cameras and

infra red lights to collect 3D coordinates 3. ANALOG ACQUISITON

analog sampling from force platforms, EMG orother devices.

Can be integrated with video or 3D optical



VIDEOGRAPHY



Fax



SOME QUESTIONS that may

require quantitative videoanalysis?

1. An objective of prescribing anorthosis is usually to improve thefunction of the patient. How can wedetermine if the use of a foot orthotic is

correcting for the severe pronationexhibited by a patient?

Video tape, digi and compare jointangular displacement throughout stride



Hydro workers

Hydro workers are required to lean out of a lift to repair the lines. The action of

leaning and working from a distance putsdangerous loads on the lower back – injury.

How can the lift be modified to reduce therisk of injury?



EMG

BASED ON RELATIONSHIP BETWEENFORCE AND THE ELECTRICAL ACTIVITY

ACROSS THE MUSCLE MEMBRANE EXAMPLE: Which exercise is best for

rehabilitation of a particular muscle?



ELECTROMYOGRAPHY-EMGRaw EMG

Full wave

Rectify

Linear

Envelope

Integrate over

contraction



http://www.mie-uk.com/mt8/FullScreen/screen1.htm



Fy Fz

FORCE ANALYSIS

FX

How much force is applied in the

Horizontal direction?



JOINTREACTIONFORCES



QUALITATIVE ANALYSIS

Qualitative analysis involves a systematicanalysis of movement based on

biomechanical concepts but without actualmeasurement



What does the QA process

include? Is there a technique error?

What are the mechanical concepts that

govern specific parts of the skill? What the critical features of the

performance?

What is the best observation strategy? How do you detect errors in performance

and remediate?



Sally, a powerful outside hitter on a highschool volleyball team, has been out for

two weeks with mild shoulder bursitis, buthas recently received her physiciansclearance to return to practice. The coach

notices that Sally’s spikes are traveling ata slow speed and are being easily handledby the defensive players?????



TEXT BOOK

Page28-61

6701529 introduction to bio mechanics

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