UNIT 4: Movement Analysis

Question 1

Explain the role of neurotransmitters in stimulating skeletal muscle contraction

Answer 1

Acetylcholine: it is vital to allow us to move, as it send a signal to our muscle receptors to generate muscle contraction 
1. An electrical impulse opens calcium channels and let calcium in
2. They push the vesicles containing acetylcholine, releasing it in the surface 
3. It attaches to sodium channel receptors, letting sodium in the muscle tissue –> this transports the impulse from the neuron to the muscle
Cholinesterase: catabolic enzyme that breaks down acetylcholine to generate muscle relaxation 
1. When trying to relax, the acetylcholine left in the synaptic cleft is broken down by cholinesterase
2. So no impulse is transmitted to the muscle
3. Muscle relaxation happens

Question 2

Explain how skeletal muscle contracts by the sliding filament theory

Answer 2

1. Start at the neuromuscular junction
2. Allows sodium into the cell, impulsing an electric charge on the motor end plate
3. Calcium is released from the sarcoplasmic reticulum into the muscle, arriving at each sarcomere in each myofibril.
4. Every muscle fiber and myofilament is stimulated.
5. Calcium binds to troponin on the tropomyosin which causes it to move
6. ATP on the Mysoin head is hydrolyzed to form ADP + Phosphate
7. Myosin grabs hold of actin –> Cross bridge formed. (cross bridge formation will continue until maximum contraction of the muscle fiber is reached.)

Question 3

Why are muscles striated?

Answer 3

Because the sarcomeres of muscle fibers are visible

Question 4

Outline the movement of flexion and extension. Give examples.

Answer 4

Flexion: decrease the angle on the sagital plane
–> ex. 
- Flexion of the forearm at the elbow
- Flexion of the arm at the shoulder
- Flexion of the thigh at the hip
- Flexion of the knee
Extension: increase the angle on the sagital plane
–> ex. 
- Extension of forearm at the elbow
- Extension of arm at the shoulder
- Extension of leg at the knee
- Extension of thigh at the hip

Question 5

Outline the movement of pronation and supination. Give examples.

Answer 5

Pronation: medial rotation of forearm on transverse plane 
–> ex. thumbs in radius and ulna
Supination: lateral rotation of forearm on transverse plane
–> ex. thumbs out radioulnar joint

Question 6

Outline the movement of abduction and adduction. Give examples.

Answer 6

Abduction: increase angle on the frontal plane 
–> ex. 
- Abduction of the arm at the shoulder 
- Abduction of the thigh at hip
Adduction: decrease angle on the frontal plane
–> ex. 
- Adduction of arm at shoulder
- Adduction of thigh at hip

Question 7

Outline the movement of elevation and depression. Give example

Answer 7

Elevation: Elevating bones
–> ex. elevating shoulders
Depression: Lowering bones

Question 8

Outline the movement of rotation and circumduction. Give examples.

Answer 8

Rotation: Joint rotates
–> ex. in football rotate hip to throw the ball and in swimming you rotate forearm to do backstroke
Circumduction: Combination of flexion, extension, abduction, and adduction (going through all the ranges of motion to create movement)
–> ex. butterfly technique in swimming

Question 9

Outline the movement of dorsi flexion and plantar flexion. Give examples.

Answer 9

Dorsi flexion: upwards flexion of the foot on the sagital plane 
–> ex. toes up
Plantar flexion: downwards flexion of the feet on the sagital plane 
–> ex. toes down

Question 10

Outline the movement eversion and inversion. Give an example.

Answer 10

Eversion: foot is turned medially outwards
Inversion: foot is turned medially inwards
–> ex. when passing the ball in football

Question 11

Outline the types of muscle contraction

Answer 11

Isotonic: the tension and stress remains the same 
- concentric= muscle is constricting 
- eccentric= muscle is lengthening
–> ex. lifting or lowering dumbbells
Isometric: the length remains the same, no shortening, the dimensions stay the same
–> ex. doing a plank or ski sit
Isokinetic: the energy remains the same. Done with machines.

Question 12

Explain the concept of reciprocal inhibition.

Answer 12

Whenever a muscle contracts to produce a movement, an opposite one relaxes.
The muscle that contracts is called AGONIST MUSCLE and the one that relaxes is called ANTAGONIST MUSCLE.

Question 13

Explain DOMS in relation to muscle contractions

Answer 13

Delayed Onset Muscle Soreness
–> Muscle pain that starts 24-48 hours after a very intense work out
CAUSES:
- Overtraining
- No progression in exercise
- Excess of eccentric contractions 
- Overstretching
CONSEQUENCES:
- Inflammation
- Pain
HOW TO PREVENT:
- Reducing eccentric contractions during early training
- Start at low intensity and gradually increase
- Warm up or Cool down

Question 14

Define the term force

Answer 14

The mechanical interaction that goes on between two objects. It is a vector.

Question 15

Define the terms speed and velocity

Answer 15

Speed: distance/time. It is a scalar.
Velocity: distance changed/time. It is a vector.

Question 16

Define the term displacement

Answer 16

How much an object has moved from its position, either laterally, vertically or horizontally. It is a vector

Question 17

Define the term acceleration

Answer 17

Velocity/time. It is a vector.

Question 18

Define the term momentum

Answer 18

Mass of an object x velocity. It is a vector.

Question 19

Define the term impulse

Answer 19

Force x time. It is a vector.

Question 20

Define the term center of mass

Answer 20

The point at which the mass of an object is equally distributed

Question 21

Explain that a change in body position during sporting activities can change the position of the center of mass. Analyze it by using the scissors technique and the fosbury flop.

Answer 21

Scissors technique: the center of mass is inside the athlete’s body and above the bar, so more force is required to jump higher.
Fosbury flop: the center of mass is below the bar, so you don’t need to create as much force to jump higher. You can jump the same height, but with an increased arc in your back, you’ll jump higher. 
WHY IS IT SO EFFECTIVE? You can manipulate your center of mass and jump higher with less force required.

Question 22

Distinguish between first, second, and third class levers

Answer 22

FLE:
1st class lever –> in the middle is the fulcrum
2nd class lever–> load is in the middle
3rd class lever –> effort is in the middle

Question 23

In levers, what is fulcrum, resistance/ load and effort?

Answer 23

Fulcrum: joint
Resistance/load: what is being moved
Effort: muscle contracting

Question 24

Give an anatomical representation of class 1 levers

Answer 24

Extension of forearm 
- Fulcrum is the hinge of elbow joint
- Load is forearm 
- Effort is tricep
- Bones: radius, ulna, humerus

Question 25

Give an anatomical representation of class 2 lever

Answer 25

Plantar flexion 
- Load is all the body weight
- Effort is the gastrocnemius 
- Fulcrum are the ankle
- Bones: Tarsals, tibia, fibula, femur

Question 26

Give an anatomical representation of class 3 levers

Answer 26

Flexion of forearm
- Effort is the bicep, because of tendons across the elbow
- Fulcrum is the elbow
- Load is the forearm
- Bones: radius, ulna, humerus

Question 27

Define Newton’s three laws of motion

Answer 27

1st law: LAW OF INERTIA
An object remains stationary or in constant motion unless an external force is applied to it
2nd law: LAW OF ACCELERATION
FORCE= MASS x ACCELERATION
3rd law: LAW OF REACTION
Any action has an equal, opposite reaction

Question 28

Explain how Newton’s three laws of motion apply to sporting activities

Answer 28

1st: LAW OF INERTIA
A golf ball in the air decelerates because wind, gravity and air resistance are external forces acting upon it.
2nd: LAW OF ACCELERATION
There is always a force required to achieve something, or to enter something somewhere. In basket for the force needed to be achieved, acceleration needs to be changed until scored, as mass can’t be changed.
3rd: LAW OF REACTION
At the start of Olympic sprinting, the runners push downwards and backwards in the sprinting box, and the opposite reaction forces impulsed them forwards and upward.

Question 29

Explain the relationship between angular momentum, moment of inertia and angular velocity

Answer 29

ANGULAR MOMENTUM= moment of inertia x angular velocity
MOMENT OF INERTIA= mass of the body away from the axis of rotation
ANGULAR VELOCITY= amount of degrees per second that an object turns

Question 30

What is the law of conservation of momentum?

Answer 30

That angular momentum remains constant because the moment of inertia is inversely proportional to the angular velocity. So no momentum is lost

Question 31

Explain the factors that affect projectile motion at take-off or release, comparing high jump and long jump

Answer 31

Speed of release, height of release and angle of release.
The height is the same (from the ground=.
The speed in long jump is higher
The angle is much higher in high jump

Question 32

Explain Bernoulli’s principle

Answer 32

Air velocity and air pressure are inversely proportional. Air pressure wants to move from high pressure to low pressure.