KIN 222 - Midterm 1

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Biomechanics

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Tags and Description

Biology

113 Terms

1

Biomechanics

study of structure and function of biological system by means of the methods of mechanics

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2

Kinematics

study of motion WITHOUT regard to the forces that cause it

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3

Kinetics

study of forces

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4

Quantitative analysis definition and example

  • numerical evaluation of motion based on measurement

  • hip flexes X degrees, knee flexes Y degrees

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5

pros/cons of quantitative analysis

pros: objective, accurate, specific cons: expensive, difficult to get data (special training and equipment required), difficult to apply, need norms

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6

Qualitative analysis definition and example

  • non-numerical evaluation of motion based on observation

  • hip flexes, knees flex

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7

pros/cons on qualitative analysis

pros: cheaper, time efficient cons: subjective, general, less accurate, experience changes results

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8

statics is the evaluation of objects in a state of ...

evaluation of objects in a state of equilibrium - at rest or constant velocity

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9

dynamics is the evaluation of objects ...

evaluation of objects that are not in a state of equilibrium - acceleration

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10

Evaluating a runner at the start position would be static or dynamic?

static

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11

Evaluating a runner after the start position would be static or dynamic?

dynamic

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12

Scalar definition and examples

  • can be described by magnitude

  • distance, speed, mass, volume, energy

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13

Vector definition and examples

  • can be described by magnitude and direction

  • displacement, velocity, acceleration, force

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14

linear motion definition and example

  • straight or curved motion where all parts move the same distance in an equal amount of time

  • ball travelling after a throw

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15

Angular motion definition and example

  • motion about an axis of rotation where regions do not move the same distance in an equal amount of time

  • a rotating sprinkler

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16

Gait definition. What are the two primary gait patterns?

  • particular pattern of footfalls that are used in locomotion

  • walk and run

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17

Describe the gait cycle events

Stance Phase (60% of the stride): Heel #1 makes contact with ground in frontward position (double support). All weight transfers to #1 (single support) as hip extends. Heel #2 makes contact with ground (double support).

Swing Phase (40% of the stride): All weight transfers to leg #2(single support). Leg #1 swings from hip extension to flexion

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18

Step

process of moving one limb forward

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19

stride

porcess of making one step with each foot

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20

stride time

time it takes to complete one stride

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21

stride length

distance between heel strikes of the same foot

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22

stride velocity

  • vector so includes changes in direction

  • stride length/stride time

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23

walking speed

  • scalar

  • distance/time

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24

stride cadence (this is a frequency)

1/stride time

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25

If time decreases what happens to stride velocity and walking speed?

increases

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26

What is the relationship between stride velocity and stride length, and stride velocity and cadence? What does this relationship show?

There is a linear relationship (increase stride length = increase stride velocity, increase cadence = increase stride velocity). This shows the preferred speed-step length relationship where the pace chosen is the pace with the least metabolic cost

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27

What happens to stride length and cadence as velocity increases during running?

The linear relationship held at walking speed does not continue. Stride length plateaus and cadence increases

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28

What is the difference between a walk and a run?

Walk:

  • always one foot in contact with ground

  • contact pattern: 1, 2,1

Run:

  • an airborne phase between single supports

  • contact pattern: 1, 0, 1

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29

What is considered to be a functional vital sign?

Walking speed. It is used to identify health issues and can predict adverse health outcomes

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30

displacement

  • change in an objects position from initial to final location

  • vector = final position - initial position

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31

velocity

  • rate of change of an objects displacement over a particular time interval

  • vector = displacement/time or (final position- initial position)/ (final time - initial time)

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32

when velocity = 0

object not moving or object changing direction

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33

Distance

  • total length travelled

  • scalar

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34

when distance = displacement

object moves in straight line

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35

Displacement is always _____ than or _____ to distance

less than or equal

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36

speed

  • distance travelled over time or rate of distance travelled over time

  • scalar = distance/time

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37

average velocity

average change in displacement over a time interval

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38

instantaneous velocity

rate of change of displacement at a particular instant in time

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39

what happens to displacement when velocity increases and time is constant?

displacement increases

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40

What happens to displacement when time increases and velocity is constant

displacement increases

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41

On a displacement over time graph, what represents velocity? A positive velocity is indicated by? A negative velocity is indicated by? What point on a graph would indicate that the object is changing direction? The greater the slope = ? Lesser?

  • slope

  • positive slope (line going upward)

  • negative slope (line going downward)

  • when slope changes from pos to neg or neg/pos. This indicates velocity = 0

  • greater velocity

  • lesser velocity

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42

How do you calculate velocity on a displacement over time graph?

slope = rise/run

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43

What motion is each segment represent?

  1. Accelerating walking in positive direction (speeding up)

  2. decelerating walking in positive direction (slowing down)

  3. y = 0 stop or change in direction

  4. Accelerating in negative direction

  5. Decelerating in negative direction

  6. stop

<ol><li><p>Accelerating walking in positive direction (speeding up)</p></li><li><p>decelerating walking in positive direction (slowing down)</p></li><li><p>y = 0 stop or change in direction</p></li><li><p>Accelerating in negative direction</p></li><li><p>Decelerating in negative direction</p></li><li><p>stop</p></li></ol>
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44

How is displacement calculated on a velocity vs time graph?

By taking the area of the graph and subtracting positive and negative displacements. Calculate area of a triangle = 0.5 x base x height

<p>By taking the area of the graph and subtracting positive and negative displacements. Calculate area of a triangle = 0.5 x base x height</p>
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45

Describe the motion that each velocity vs time graph illustrates

A: slow acceleration , fast acceleration , fast deceleration, slower deceleration B: deceleration + direction, change direction, acceleration in - direction C: constant deceleration to a stop D: moving at a constant velocity

<p>A: slow acceleration , fast acceleration , fast deceleration, slower deceleration B: deceleration + direction, change direction, acceleration in - direction C: constant deceleration to a stop D: moving at a constant velocity</p>
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46

Acceleration

  • measure of the rate of change of velocity with respect to time

  • vector quantity

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47

True or False. A change in velocity does not always indicate there is acceleration?

False. If there is a change in velocity (either magnitude or direction) then there is acceleration

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48

If acceleration and velocity are in the same direction

velocity will increase

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49

If acceleration and velocity are in opposite directions

velocity will decrease until the object stops or changes direction

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50

What type of path do projectiles follow?

Parabolic

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51

What are the vertical and horizontal accelerations of projectiles

  • vertical -9.81 m/s^2

  • horizontal 0, remains constant

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52

If you kick a ball upwards at 0, 45, and 90 degrees, which will have the greatest vertical and horizontal displacement?

0

  • no vertical displacement

  • horizontal displacement but slows down from surface friction

45

  • less vertical displacement than kicking upwards at 90

  • greatest horizontal displacement

90

  • greatest vertical displacement

  • no horizontal displacement

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53

Describe the time and horizontal displacement of a projectile with equal launch and landing height

  • time from launch to apex is equal to time from apex to landing

  • horizontal displacement equal from launch to apex and apex to landing

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54

Describe the time and horizontal displacement of a projectile with a higher launch point than landing point

  • time from launch to apex will be shorter than apex to landing

  • horizontal displacement will be shorter from launch to apex than apex to land

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55

Describe the time and horizontal displacement of a projectile with a lower launch point than landing point

  • time from launch to apex will be longer than apex to land

  • horizontal displacement from launch to apex will be longer than apex to land

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56

When are velocity formulas inaccurate?

when the object is undergoing acceleration

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57

If a person is not undergoing acceleration, what formula can be used and will be accurate

average velocity formulas can be used

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58

frontal plane

anterior and posterior halves

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59

transverse plane

inferior and superior portions

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60

saggital plane

left and right sides

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61

Anteroposterior axis

  • goes through the body from front to back

  • associated with frontal plane

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62

Longitudinal axis

  • runs from top to bottom

  • associated with the transverse plane

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63

Mediolateral axis

  • side to side

  • associated with sagittal plane

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64

what are degrees of freedom? What is the max degrees of freedom? How many degrees of freedom do joints have?

  • number of independent movements an object can perform

  • max 6 degrees of freedom (3 rotations, 3 translations)

  • joints have 1-3 however, translation also occurs at many joints, increasing their degrees of freedom

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65

Shoulder joint (Glenohumeral) - what type of joint and how many degrees of freedom?

  • ball and socket

  • 3 df

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66

Name the glenohumeral joint movements and what plane/axis they occur in

Flexion/extension

  • saggital and mediolateral

Abduction/abduction

  • frontal and anteroposterior

Medial and lateral rotation

  • transverse plane longitudinal axis

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67

Superior and inferior radioulnar joints - what type of joint and how many degrees of freedom

  • pivot joint

  • 1 df

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68

ulnarhumeral and radiohumeral joint - what type of joint and how many degrees of freedom

  • hinge

  • 1 df

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69

Acetabulofemoral - what type of joint and how many df?

  • ball and socket

  • 3 df

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70

Describe the movements of the hip joint and what plane/axis they occur in

Flexion/extension

  • sagital

  • mediolateral

Adduction/abduction

  • frontal

  • anteroposterior

medial/lateral rotation

  • transverse

  • longitudinal

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71

Knee (Tibiofemoral) joint - what type of joint and how many df?

  • double condyloid (modified hinge)

  • 2 df

  • significant translation accompanies knee joint motion

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72

Name the movements of the knee joint and what plane/axis they occur in

Flexion/extension

  • sagital

  • mediolateral

Medial/lateral rotation

  • transverse

  • longitudinal axis

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73

Ankle (talocrural) joint - what type of joint and how many df?

  • hinge

  • 1 df

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74

ankle joint movements and plane/axis

dorsi/plantar flexion

  • sagital

  • mediolateral

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75

What symbols are used for angular kinematics?

  • theta: angular displacement

  • omega: angular velocity

  • alpha: angular acceleration

<ul><li><p>theta: angular displacement</p></li><li><p>omega: angular velocity</p></li><li><p>alpha: angular acceleration</p></li></ul>
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76

Counter clockwise rotations are? Clockwise?

  • positive

  • negative

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77

Angular displacement definition. Vector/scalar? Formula

  • differences between the initial and final orientation of a rotating object

  • vector = final orientation - initial orientation

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78

Angular distance definition. Vector/scalar?

  • total of all angular changes measured following a rotating segments exact path

  • scalar

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79

Angular displacement cannot be greater than _____, angular distance can be ______

  • 360 degrees

  • any value

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80

Angular velocity definition. What is it analogous to? Formula.

  • rate of change of angular displacement over time

  • analogous to linear velocity

  • w = (theta final - initial)/time

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81

The steepness of an angle vs time graph determines the? The direction of the slope determines the?

  • magnitude of angular velocity

  • direction of angular velocity

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82

On an angle vs time graph, a change in the direction of the slope indicates a?

a change in the direction of movement

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83

on an angular velocity vs time graph, a change in the sign of angular velocity indicates

a change in direction of movement

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84

Angular motion definition

  • evaluation of an objects motion around a fixed axis

  • all parts move through the same angle, but do not have equal linear distance

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85

Name 3 techniques used to measure angular motion

  • Video: camera captures frames/sec

  • Motion capture: uses specific dots/points on body, then is input into computer

  • goniometry: measures the joint angle with specific instruments ex. the bendy wire

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86

local reference system

axes are aligned with a segment and intersect at the joint center

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87

global reference system

axes are aligned with the vertical and horizontal relative to the environment (lab)

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88

How are absolute segment angles calculated?

  • use the trigonometric relationship of tangent

  • the distal end coordinate values are subtracted from the proximal end coordinate values

  • theta = [(y prox - y dist)/ (x prox - x dist)]

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89

What is a relative joint angle? What reference system is used? Where is the vertex located?

  • the angle between the longitudinal axis of two segments. Defined as the angle of one segment relative to another segment

  • local reference system

  • at joint

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90

Relative (joint) angle conventions - a system of lower limb conventions has been proposed for two dimensional sagittal plane rotation of the _____, _______, and ______ joints.

This system uses the _______ angles of the trunk, thigh, leg, and foot to calculate relative joint angles

With this system, it is assumed that the _____ side of the body is captured

  • hip, knee, and ankle

  • absolute

  • right

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91

The relative hip angle is based on the absolute angles of the?

thigh and trunk

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92

When the hip angle is positive, the hip is in what position? Angle = zero? Angle is negative?

  • flexed (because it is to the right of the vertical axis)

  • neutral

  • extended (because it is left of the vertical axis)

<ul><li><p>flexed (because it is to the right of the vertical axis)</p></li><li><p>neutral</p></li><li><p>extended (because it is left of the vertical axis)</p></li></ul>
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93

What is the formula for calculating relative hip angle

theta hip = theta thigh - theta trunk

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94

The relative knee angle is based on the absolute angles of the?

thigh and leg

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95

When the knee is in a flexed position the angle is? When the knee is in the extended position? Hyper-extended?

  • positive (extend the shin line upwards and it will end up in the positive right quadrant)

  • neutral

  • negative (extend the shin line upwards and it will be in the negative x quadrant)

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96

What is the formula for calculating relative knee angle?

theta knee = theta thigh - theta leg

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97

The relative ankle angle is based on the absolute angles of the

leg and foot

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98

When the angle is positive, the ankle is in what position? Angle = zero? Negative?

  • plantarflexed

  • neutral position (ex standing)

  • dorsiflexed position

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99

What is the formula for relative ankle angle?

theta ankle = theta leg - theta foot + 90

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100

Define angular acceleration. It is analogous to?

  • rate of change of angular velocity over time

  • analogous to linear acceleration

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