The Musculoskeletal System [1]

Question 1

What are the 2 main types of muscle contraction?

Answer 1

1. Isometric
2. Isotonic

Question 2

Describe isometric contraction?

Answer 2

Equal length: The muscle does NOT get shorter or longer
- it allows for max force within a restricted ROM

Disadvantages: less ROM, not good for building strength and power that an athlete needs

Advantages: max force, and protects the joint (useful with an injury/rehab post surgery)

Question 3

Describe Isotonic contraction?

Answer 3

Equal tension; the muscle shortens or lengthens
- Eccentric: muscle lengthens
- Concentric: muscles shortens (contracts)

Advantages: more ROM
Disadvantages: more susceptible to injury bc its more demanding on muscles

Question 4

What is an isokinetic contraction

Answer 4

Equal motion: the speed of the contraction is constant (no matter how hard you kick the bar, the speed will remain the same. It is under the machines control not human control

Advantage: a more objective review of someones ability
Disadvantage: the person doing it needs to actually put in effort for results to be true

Question 5

What is a muscle agonist, antagonist, and synergist?

Answer 5

• Muscle agonist: the muscle doing the motion (main mover)
• Muscle antagonist: opposes the agonist
• Synergist: helps stabilize but is not contributibg directly to the movement of the muscle

Question 6

Describe elbow flexion in terms of agonist, antagonist, and syngergist?

Answer 6

• Agonist: biceps brachii/ brachialis/brachio radialis
• Antagonist: triceps brachii
• Syngergist: deltoid

Question 7

What is the length-tension relationship?

Answer 7

every muscle has an optimum length at which it produces the greatest force (too short or too long it can’t provie max force)
- 120% of resting length is optimal (slightly stretched) = greatest force

Question 8

Draw the force-velocity relationship curve of a muscle

Answer 8

It also shows us the lengthening contraction (eccentric) is our strongest contraction

Question 9

What is active insufficiency and passive insufficiency?

Answer 9

• Active insufficiency: when a joint position puts a muscle on slack (shortened), muscle force production is limited
• Passive insufficiency: when a muscle is stretched (lengthened), total ROM is limited

Question 10

What is a first class lever?

Answer 10

Force and resistance/load are on opposite sides with the fulcrum in the middle (well balanced)
- ex: seesaw, scissors, cervical flex/extension

Question 11

Describe 2nd class levers?

Answer 11

Resistance/load is between fulcrum and force
- effort is always longer than RA
- maximizes effort with little force
- sacrifices ROM
- Ex: wheelbarrow, WB plantarflexion

Question 12

Describe a 3rd class lever?

Answer 12

The force is between the fulcrum and resistance
- maximizes speed and ROM
- sacrifices amount of force produced
- most joints fall under this category
- ex: biceps brachii, quadricpes

Question 13

What are moment arms?

Answer 13

The perpendicular distance from a force’s line of action to the axis of rotation
- 90 degrees from line of action to rotation
- the longer the moment arm is (externally: the weight) the more difficult it gets

Question 14

Describe the concept of moment arm when using muscles as a force?

Answer 14

from the perspective of a muscle the longer the moment arm is the stronger it is

Question 15

What is torque?

Answer 15

It is the moment of force/ the measure of rotational movement
- force x moment arm = torque
- the door handle is farthest away from the hinge bc it makes it easier to overcome
- OR when changing a tire, we should use a big wrench bc it lengthens the moment arm to make it easier

Question 16

Explain torque and muscle contraction

Answer 16

Isometric: Tmuscle = Tweight
Concentric: Tmuscle > Tweight
Eccentric: Tmuscle < Tweight

Question 17

Explain torque using the patella/leg

Answer 17

the patella acts as the fulcrum so when we fully straighten our leg our “lever” goes away making it harder to move our leg

Question 18

What is the agonist for knee flexion?

Answer 18

hamstrings

Question 19

A stronger concentric contraction will occur faster or slower?

Answer 19

slower. This is why when you are going for a PR in bench press, it takes max contraction to push upwards and is slow

Question 20

A stronger eccentric contraction will be fast or slow?

Answer 20

It will be fast. This is because it is easier to go down fast with power on bench press

Question 21

Will a MUSCLE be stronger or weaker when its moment arm is longest?

Answer 21

it will be stronger

Question 22

How can we use moment arms to make a deadlift more difficult?

Answer 22

have the bar farther away from our body so that it is harder