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SEHS > Topic 4: Movement Analysis > Flashcards

Topic 4: Movement Analysis Flashcards

1
Q

Explain the role of neurotransmitters in stimulating skeletal muscle contraction

A
  • Neurotransmitters are chemicals that are used for communication between a neuron at the synapse and another cell.
  • Acetylcholine is the primary neurotransmitter for the motor neurons that innervate skeletal muscle and for most parasympathetic neurons.
  • generally an excitatory neurotransmitter, can have inhibitory effects at some parasympathetic nerve endings, such as the heart. In biochemistry, cholinesterase is an enzyme that catalyzes the hydrolysis of the neurotransmitter acetylcholine into choline and acetic acid, a reaction necessary to allow a neuron to return to its resting state after activation.
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2
Q

Fast twitch muscle fibre

Type 2a

A
  • contract quickly
  • give sharp, powerful muscle contractions
  • dont use oxygen
  • suited for activities with bursts of strength and power
  • tire quickly
  • have fewer mitochondria
  • metabolise ATP more quickly
  • have a lower capillary volume ratio
  • more likely to accumulate lactic acid
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3
Q

Slow twitch muscle fibre

Type 1

A
  • take longer to contract
  • give long sustained muscle contractions
  • not as powerful
  • have a good oxygen supply
  • suited to activities which require long term energy
  • have more mitochondria
  • store oxygen in myoglobin
  • rely on aerobic metabolism
  • greater capillary to volume ratio
  • produce ATM more slowly
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4
Q

Sagittal axis

A

passes horizontally from posterior to anterior and its formed by intersection of sagittal and transverse planes

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5
Q

Frontal axis

A

passes horizontally from left to right and is formed by the intersection of the frontal and transverse planes.

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6
Q

Vertical axis

A

passes vertically from inferior to superior and is formed by the intersection of the frontal and sagittal planes.

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7
Q

Isometric contraction

A

in this form of contraction the muscle length remains constant. It occurs when muscle force balances resistance and no joint movement occurs

  • there is generally no movement resulting from this type of contraction
  • pushing against a fixed object
  • planking
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8
Q

Isotonic contraction

A

an increase in tension results in changes in skeletal muscle length

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9
Q

concentric contraction

A

concerns muscle actions that produce a force to overcome the load being acted upon.
(positive work)
cause the muscle to shorten as it contracts

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10
Q

Eccentric contraction

A

Refers to muscle action in which the muscle force yields to the imposed load.
(negative load)
muscle lengthens as it contracts

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11
Q

Isokinetic contraction

A

When a muscle contracts so that the body segment to which it is attached moves at a constant speed around the joint, rarely found in sport.

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12
Q

Explain the concept of reciprocal inhibition

A

When an agonist contract to move a body segment, it is usual for the antagonist (the muscle with the opposite concentric contraction action) to relax. This means that the agonist is not being opposed by any muscle torque acting in the opposite direction of the motion. This is an automatic action controlled by neurons. When the agonist motoneuron is stimulated the motoneuron to the antagonist is inhibited preventing it from contacting strongly

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13
Q

Type 2b

A

generate the fastest contraction times and largest forces, but fatigue at a high rate and so cannot maintain contractions for a long period of time.

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14
Q

Movement of synovial joints: non-axial

A

In gliding joints the bones slide in rotation to each other. Therefore, there are no axes of rotation in this type of joint

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15
Q

Movement of synovial joints:

Uniaxial

A

in hinge joints and pivot joints there is only one axis of rotation. This means that the structure of the bones as the joint restricts rotation to movement around one axis only.

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16
Q

Movement of synovial joints: Biaxial

A

as condylar joints and saddle joints there are two axes of rotation and therefore the bones can move in two different ways.

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17
Q

Movement of synovial joints:

Triaxial

A

ball and socket joints such as the shoulder and hi allow rotation around three axes. Therefore, these bones permit the greatest movement, as they allow the limbs attached at them to move through a large volume of space.

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18
Q

The anteroposterior axis

A

going back to front

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19
Q

The transverse axis

A

going from left to right

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20
Q

The vertical axis

A

going from top to bottom

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21
Q

Motion in sagittal plane: Flexion

A

closing of the joint angle around the transverse axis at the joint

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22
Q

Motion in sagittal plane: Extension

A

Opening of the joint angle around the transverse axis at the joint

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23
Q

Motion in the frontal plane:

Abduction

A

Opening of the joint angle around the anteroposterior axis at the joint

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24
Q

Motion in the frontal plane:

Adduction

A

Closing if the joint angle around the anteroposterior axis at the joint

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25
Q

Motion in the transverse plane:

Medial rotation

A

The anterior surface of the bone movers towards the medial aspect of the body

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26
Q

Motion in the transverse plane:

Lateral rotation

A

The anterior surface of the moving bone moves towards the lateral aspect of the body

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27
Q
  1. Dorsi flexion

2. Plantar flexion

A
  1. flexion of the ankle
  2. extension of the ankle

These movements move the foot up and down in the sagittal plane.

28
Q
  1. Pronation

2. Supination

A
  1. Medial rotation of the radio ulna joint
  2. lateral rotation on the radio ulna joint

These movement allow the forearm to rotate even when the elbow is flexed.

29
Q
  1. Eversion

2. Inversion

A
  1. Medial rotation of the ankle joint
  2. Lateral rotation of the ankle joint

These movements involve ‘rolling’ of the foot at the ankle.
Inversion=sole of foot inwards
Eversion=sole of foot outwards

30
Q
  1. Horizontal Abduction

2 Horizontal Adduction

A
  1. Opening of the joint angle around the transverse plane.
  2. Closing of the joint angle around the transverse plane
    (both: when the body segment has been flexed to 90)

Common at shoulder.

  • Flexed 90 then brought to midline of body horizontal=horizontal adduction
  • if horizontally away from midline= horizontal abduction
31
Q

Circumduction

A

‘circling’ of a body segment at a joint.

Only occurs at the shoulder, hip, wrist, ankle, thumb=biaxial joint

32
Q

Force

A

a push or pull on an object

33
Q

speed

A

maximum rate at which a person is able to move their body

34
Q

velocity

A

rate at which an object changes position

35
Q

displacement

A

distance measured in a stated direction

36
Q

acceleration

A

rate of change of velocity per second

37
Q

momentum

A

the amount of motion possessed by a moving object

38
Q

impulse

A

force x time

39
Q

Scalar

A
  • length
  • mass
  • area
  • volume
  • speed
  • density
  • pressure
40
Q

Vector

A
  • displacement
  • direction
  • velocity
  • acceleration
  • momentum
  • force
  • impulse
  • weight
41
Q

Centre of mass

A

the point at which the body is balances in all directions

  • can change when the body is moving dynamically
  • not always inside the body, can be outside.
42
Q

COM: High jump example

A
  1. Scissor kick
    - COM is within pelvic girdle, within the body
    - action involves clearing the bar one leg at a time
    - as COM is within the body, it is more likely that the bar will be hit
  2. Frosbery Flop
    - COM externally placed
    - arch of back allows the mass to be shifted to the outside of the body, and there is greater opportunity for clearance
    - the greater the arch of the back, the lower the COM is.
43
Q

Reciprocal inhibition

A
  • when an agonist contracts to move a body segment, its usual for the antagonist to relax
  • therefore agonist is not being opposed by any muscle torque acting in the opposite direction to that of the motion
  • this is reciprocal inhibition
  • automatic action controlled by the neutrons
  • when agonist motoneuron stimulated, the motoneuron to the antagonist is inhibited, preventing it from contracting strongly.
44
Q

Co-activation

A

when reciprocal inhibition is overridden by the voluntary nervous system and both agonist and antagonist contract at the same time

45
Q

Explain DOMs in relation to eccentric and concentric muscle contractions

A

the pain and stiffness felt in muscles several hours to days after unaccustomed or strenuous exercise

DOMs results primarily from eccentric muscle action an is associated with structural muscle damage, inflammatory reactions in the muscle, over stretching and overtraining.

DOMs is prevented/minimised by reducing the eccentric component of muscle actions during early training, starting training at a low intensity and gradually increasing the intensity, and warming up before exercise, cooling down after exercise.

46
Q

What do levers consist of?

A

a rigid rod, a fulcrum (axis), and resistance force and an effort force.

47
Q

1st class levers

A
  • effort and resistance on opposite sides of the fulcrum
  • rare in human body
  • eg the head sitting on top of the vertebrae column
  • muscles in the neck provide the force to overcome the resistance force from the head.

+ relatively small force needed to hold head still.

48
Q

2nd class levers

A

effort and resistance forces on the same side of the fulcrum

  • effort arm longer than resistance arm
  • mechanical advantage greater than 1
  • rare in human in human body
  • eg standing on tiptoes

+small force can overcome large resistance. Rare in human body suggesting that we have not evolved to overcome large forces.

49
Q

3rd class levers

A
  • effort and resistance in the same side
  • effort arm smaller than resistance arm
  • mechanical advantage less than 1
  • very common in human body
  • inefficient, large force required for small resistance.

+but small movement magnified by long lever. Great ROM and speed of movement for relatively low force.

50
Q

Fulcrum

A

the joint

51
Q

resistance

A

body part to be moved

52
Q

effort

A

muscle pull at the muscle insertion

53
Q

1st Law

A

Law of Inertia
An object will remain at rest or constant velocity unless acted upon by an external force.
Example: An athlete at a starting block will not move unless a force acts upon them. The external force comes from the block and this propels the sprinter out of the blocks when they exert a downward and backward force against the blocks.

54
Q

2nd Law

A

Law of Acceleration
The rate of change of acceleration of an object is proportional to the force applied and acts in the direction of the force.
The acceleration of an object is directly proportional to the force causing it and is inversely proportional to the mass of the object.
Example: Two athletes at a starting block both push off, one is lighter (and has a lesser mass) and therefore accelerates quicker. Two athletes at a starting block of the same mass both push off, the one who applied greater force accelerates faster.

55
Q

Third Law

A

Law of Reaction
Third Law (Law of Reaction)
For every action there is an equal and opposite reaction
Example: The sprinter applied downward and backward force on the immovable starting blocks, they exert back with a forwards and upward reaction force on the sprinter, pushing the sprinter forwards. The harder the sprinter pushes, the greater the reaction force will be.

56
Q

Angular momentum

A

the product of the body’s moment of inertia, and its angular velocity. M=I*V

57
Q

Moment of inertia

A

It determines the torque (force that causes rotation) needed for a desired angular acceleration about a rotational axis. It depends on the mass of the object, its shape and its relative point of rotation.

58
Q

Angular velocity

A

is a ratio of the change of angular displacement and the time during which the change occurred. The rate of which a body spins/rotates/turns through an angle.
Angular velocity = angular displacement ÷ time

59
Q

Moment of inertia sporting example: Ice skater spinning

A

Opening arms
-increase moment of inertia
-decrease in angular velocity
=decreases speed

Pulling arms and legs together
-decreases moment of inertia
-increase in angular velocity
=increases speed

60
Q

Explain the interplay between moment of inertia and angular velocity when performing a tucked back somersault in gymnastics.

A
  • Shortly after take off the gymnast moves into a tucked position decreasing moment of inertia
  • moving from a stretched position a take off to a tucked position increases angular velocity and the body rotates faster
  • as the gymnast comes out of the tucked position and extends their body in preparation for landing, the moment of inertia increases and angular velocity decreases.
  • as the moment of inertia increases, angular velocity decreases.
61
Q

Explain why skater pulling arms and legs closer to body makes him rotate faster

A

angular velocity x moment of inertia=angular momentum
Pulling in the arms and legs decreases the moment of inertia, angular momentum is conserved so angular velocity increases.

62
Q

Influences that affect projectile motion: height of release

A
  • the higher the release = the greater distance covered
  • the higher the release = the longer spent in the air
  • the higher the release = the longer the horizontal component will be acting
63
Q

Influences that affect projectile motion: angle of release

A
  • ideal angle of release is 45 degrees

- the angle changes the relationship between the horizontal and vertical components of projectile

64
Q

Influences that affect projectile motion: speed of release (most influential)

A
  • speed is directly related to the distance
  • greater the speed = greater the distance
  • initial vertical velocity increases the height of the trajectory, creating a longer flight path
  • initial horizontal velocity will increase the length of flight time and distance
65
Q

Outline the Bernoulli principle with respect to projectile motion in sporting activities

A

The relationship between air flow velocity and air pressure is an inverse one, and is expressed in Bernoulli’s principle.

The pressure difference causes the spinning golf ball to experience a force directed from the region of high pressure to the region of low air pressure. A gold ball with backspin will experience higher air pressure on the bottom of the ball and lower air pressure on the top of the ball, causing a lift force.

When an object is moving through the air it is important to consider the relative air flow on different sides of the object. The air flow difference between opposite sides (e.g. bottom and top of a spinning golf ball) of the object moving through the air causes a pressure difference between the two sides. The lift force is perpendicular to the direction of the air flow.

SEHS (8 decks)

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