The Musculoskeletal System [1] Flashcards
(22 cards)
What are the 2 main types of muscle contraction?
- Isometric
- Isotonic
Describe isometric contraction?
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)
Describe Isotonic contraction?
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
What is an isokinetic contraction
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
What is a muscle agonist, antagonist, and synergist?
- 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
Describe elbow flexion in terms of agonist, antagonist, and syngergist?
- Agonist: biceps brachii/ brachialis/brachio radialis
- Antagonist: triceps brachii
- Syngergist: deltoid
What is the length-tension relationship?
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
Draw the force-velocity relationship curve of a muscle
It also shows us the lengthening contraction (eccentric) is our strongest contraction
What is active insufficiency and passive insufficiency?
- 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
What is a first class lever?
Force and resistance/load are on opposite sides with the fulcrum in the middle (well balanced)
- ex: seesaw, scissors, cervical flex/extension
Describe 2nd class levers?
Resistance/load is between fulcrum and force
- effort is always longer than RA
- maximizes effort with little force
- sacrifices ROM
- Ex: wheelbarrow, WB plantarflexion
Describe a 3rd class lever?
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
What are moment arms?
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
Describe the concept of moment arm when using muscles as a force?
from the perspective of a muscle the longer the moment arm is the stronger it is
What is torque?
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
Explain torque and muscle contraction
Isometric: Tmuscle = Tweight
Concentric: Tmuscle > Tweight
Eccentric: Tmuscle < Tweight
Explain torque using the patella/leg
the patella acts as the fulcrum so when we fully straighten our leg our “lever” goes away making it harder to move our leg
What is the agonist for knee flexion?
hamstrings
A stronger concentric contraction will occur faster or slower?
slower. This is why when you are going for a PR in bench press, it takes max contraction to push upwards and is slow
A stronger eccentric contraction will be fast or slow?
It will be fast. This is because it is easier to go down fast with power on bench press
Will a MUSCLE be stronger or weaker when its moment arm is longest?
it will be stronger
How can we use moment arms to make a deadlift more difficult?
have the bar farther away from our body so that it is harder
