TABLE OF CONTENTS - StudentVIP

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WEEK 1: BIOMECHANICS BASICS

WHAT IS BIOMECHANICS?

● Biomechanics: application of mechanical principles (laws of physics) to the human body

○ A measurement science using physics and maths to evaluate human movement

■ Statics + dynamics

■ Movement + forces

○ The study of internal and external forces on the body and the effects produced by these forces

● Many different applications of biomechanics:

○ E.g. sports biomechanics, occupational biomechanics, orthopaedic biomechanics

SPORT BIOMECHANICS

● Sports biomechanics: the study of forces as they relate to humans in exercise and sport

○ E.g. high jumper

■ Have to adjust the centre of gravity; angular momentum

● The Athlete (Raw Talent) +

The Coach (Develops Talent) +

Biomechanics – Technique Physiology – Fitness Psychology – Mental State S&C – Physical State Sports Med/Biomech/S&C – Injury prevention/Mgmt

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OPTIMAL PERFORMANCE

APPROACHES OF STUDYING MOVEMENT

● Quantitative approach:

○ Describe movement in numerical terms

○ Measurements using instrumentation

○ Objective description

○ Equipment often expensive

○ May not be time efficient

○ May not be transportable to the field?

● Qualitative approach

○ Describe movement in non-numerical terms

○ Based on ability to recognize critical features of a skill

○ Predominant in teaching and coaching

○ Can use video or photography

■ E.g. smartphones

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AREAS OF BIOMECHANICS

● Only looking at statics

○ Kinematics and kinetics

ELECTROMYOGRAPHY (EMG)

● An electrical signal associated with a muscle contraction is called an electromyogram or EMG

● The study of EMG is called electromyography provides information about:

○ control signal of each muscle

○ which muscle(s)

○ recruitment of different muscle fibers

○ fatigue state

VIDEO ANALYSIS

● 2D and 3D video used to analyse performance and technique using high speed video

FOOT PRESSURE/PLATES

● Sensor array measures pressure on shoe insole

● Pressure = Force/Area

○ so Force can be derived

● Useful for real time viewing of gait

SIMULATION AND MODELING

● Mathematical modeling of anatomical characteristics of a living body

● Simulation allows for the prediction of performance and development of new techniques

● Experimental data collected with:

○ video, emg, electrogoniometry, accelerometry

TIMING GATES

● Timing Gates: time, velocity, acceleration

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WEEK 2: KEY BIOMECHANICAL CONCEPTS

REFERENCE PLANES

● Sagittal (anteroposterior- AP)

○ Vertical left and right halves

● Frontal (mediolateral; coronal- C)

○ Front and back halves

● Transverse (inferior/superior- T)

○ Top and bottom halves

REFERENCES AXES

● Frontal axis- (medio-lateral): passes horizontally from side to side or left to right

○ Perpendicular to sagittal plane

● Sagittal axis- (antero-posterior): passing horizontally from front to back

○ Perpendicular to the frontal plane

● Longitudinal axis: passing right angles to the ground

○ Perpendicular to the transverse plane

FORMS OF MOTION

● Movement: 2 forms

○ Linear (straight line) or angular (rotational)

● Forms of motion

○ Translation (or linear motion)

○ Rectilinear translation

○ Curvilinear translation

○ Rotation (or angular motion)

○ General motion (translation and rotation combined)

DIMENSIONS

● A picture/image that has or appears to have height, width, and depth is 3D

● A picture that has height and width but no depth is 2D

● The 4th dimension (4D) refers to time

UNITS OF MEASUREMENT

● SI UNITS

○ Length - meters (m)

○ Time - seconds (s0

○ Mass - kilogram (kg)

○ Velocity - m/s

○ Acceleration - m/s2

○ Force - kg/m2 = Newton (N)

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○ Work - N.m = Joule (J)

○ Energy - Joule (J)

○ Power - J/s = Watt (W)

WHAT IS A FORCE?

● Forces are defined as a pull or push

● Used to:

○ Get objects moving

○ Stop objects moving

○ Change the direction of a moving object

○ Change the speed of a moving object

○ Balance another force to keep an object still

● Force is measured in Newtons (N)

○ Weight = mass x gravity (W=mg) (g=9.8m/s)

○ E.g. a mass of 5kg has a weight of 49N

● Forces may be external

○ Gravity

○ Friction

○ Air resistance

○ Water resistance

● Forces can also be internal

○ Actions of muscles and tendons on the skeletal system

■ (air and water are both "fluids")

NEWTON'S LAWS OF MOTION

● 1st law of motion: the Law of Inertia

○ "every body continues in its state of rest, or uniform motion in a straight line unless it is acted upon by an external force"

■ The greater an object's inertia, the greater the force required to initiate its movement or change its state of motion

○ Is directly proportional to an object's mass

● 2nd law of motion: the Law of Acceleration

○ "the change in motion of an object is proportional to the force impressed; and is made in the direction of the straight line in which it is impressed

■ ΣF = ma

■ ΣF = net external force (N)

■ m = mass (kg)

■ a = acceleration (m/s2)

■ "net force causes acceleration"

● 3rd law of motion: the Law of Action and Reaction

○ "to every action there is an equal and opposite reaction"

■ If object A exerts a force on object B, then object B exerts the same force on the object A but in the opposite direction

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BIOMECHANICS TOOL BOX

1. BASICS OF EQUIPMENT

● The transducer converts the mechanical entity (force, temperature, load, humidity, flow, etc.) into a measurable form (electricity)

● The amplifier increases the magnitude of the signal to facilitate recording and processing

● The recording equipment (computer) represents the signal

● Force platforms:

○ 1D plates are for vertical force only

■ Vertical force difference between left and right leg is 104 N (p < .05)

■ Horizontal force difference between left and right leg is 134 N (p < .05)

■ Power output difference between left and right leg is 742 W (p < .05)

■ These differences exist in every quarter

○ 3D plates are more common (though more expensive) and measures x, y, and z forces as well as movements and center of force