Unit 2

Question 1

Myotatic/Stretch reflex

Answer 1

responds to quick stretch with muscle contraction

Question 2

Where/what is receptor in stretch reflex

Answer 2

muscle spindle in the muscle belly

Question 3

tendon reflex

Answer 3

responds to muscle tension with muscle relaxation

Question 4

where/what is receptor in tendon reflex

Answer 4

golgi tendon organ in tendon

Question 5

force

Answer 5

pushes or pulls through direct mechanical contact or through force of gravity to alter motion of an object
-pushes or pulls
-ability to accelerate or decelerate
-ability to deform object

Question 6

vector quanity

Answer 6

has magnitude, direction, and point of application

Question 7

Muscle force vectors

Answer 7

LOA with force vector arrows
- longer arrow means more force
- arrowhead shows direction of force
- point of application is origin/insertion

Question 8

Force of a muscle determined by

Answer 8

• generally # of muscle fibers contracting determines total muscle force
• muscle size, shape, and fiber arrangement

Question 9

what are the two types of fiber arrangements

Answer 9

parallel and pennate

Question 10

Parallel fiber arrangement

Answer 10

arranged parallel to the length of the muscle, produce most ROM
- brachioradialis, sartorius, rectus abdominus, pectoralis major

Question 11

Pennate fiber arrangement

Answer 11

fibers arranged obliquely to their tendon, produce the most force
- tibialis posterior, rectus femoris, deltoid

Question 12

what is maximal force influenced by

Answer 12

• nervous system activation
• muscle length
• muscle velocity

Question 13

how does nervous system activation influence maximal force

Answer 13

highest with high frequency of firing of motor units

Question 14

how does muscle length influence maximal force

Answer 14

close to resting generates more force than shortened or lengthened position

Question 15

how does muscle velocity influence maximal force

Answer 15

as resistance increases, maximal velocity a muscle can contract concentrically decreases

as resistance increases, eccentric velocity increases

Question 16

Angle of pull

Answer 16

angle between LOA and the bone on which it inserts (angle toward the joint)

Question 17

moment force (rotary force)

Answer 17

when a muscle pulls straight up from the bone, it has the most movement force (90 degree angle of pull)
-closer to 90 degrees, the more movement force

Question 18

Stabilizing force (non-rotary force)

Answer 18

smaller angle of pull = higher stabilizing force

Question 19

destabilizing force (non-rotary force)

Answer 19

greater angle of pull is more destabilizing >90

Question 20

how does muscle’s AOP change

Answer 20

changes with joint motion, even if muscle force stays the same, movement force and stabilizing force changes as the joint moves

Question 21

stabilizing muscles

Answer 21

small angle of pull regardless of joint position
- rotator cuff, subclavius, deep lateral rotators of the HJ, popliteus

Question 22

patella role

Answer 22

changes the angle of pull of muscle providing force
- increases AOP
- increases moment arm
- increases movement force,
- increase effort torque
- decreases stabilizing force

Question 23

torque

Answer 23

a turning effect produced by a force
- force not through center of mass or axis of rotation produces torque

Question 24

torque equation

Answer 24

force magnitude X length of the moment arm

Question 25

Moment arm

Answer 25

perpendicular distance from the line of force to the axis of rotation or center of mass

Question 26

resistance torque

Answer 26

torque created by weight you are trying to move

Question 27

effort torque

Answer 27

torque created by your muscles

Question 28

concentric movement

Answer 28

effort torque > resistance torque

Question 29

Isometric movement

Answer 29

effort torque = resistance torque

Question 30

Eccentric movement

Answer 30

effort torque < resistance torque

Question 31

how can force and moment arm modify resistance torque

Answer 31

force: light or heavier weights Moment arm: modify technique - change either axis of rotation/cm of where the resistance force is applied

Question 32

how can force and moment arm modify effort torque

Answer 32

Force: ns activation, muscle length, contraction velocity Moment arm: change joint angle

Question 33

rotary force

Answer 33

does not pass through axis of rotation, produces torque

Question 34

non-rotary force

Answer 34

passes through axis of rotation, no moment arm, doesn't produce torque

Question 35

lever

Answer 35

a rigid bar that can rotate around a fixed point when an effort force is applied to overcome a resistance force

Question 36

what is the fulcrum/axis of rotation in the bodies

Answer 36

joints

Question 37

what is the effort force in joints

Answer 37

contracting muscles

Question 38

effort arm

Answer 38

moment arm of the effort force - perpendicular distance from LOA of a muscle to the joint

Question 39

Resistance arm

Answer 39

moment arm of the resistance force - perpendicular distance from the resistance force to the joint

Question 40

balance of levers

Answer 40

MA = 1, the product of the effort and effort arm equals the product of the resistance and resistance arm

Question 41

Mechanical advantage

Answer 41

MA >1 easier to move resistance

Question 42

Mechanical disadvantage

Answer 42

MA < 1 more effort for less resistance but resistance moves further and faster

Question 43

MA equations

Answer 43

R/E EA/RA

Question 44

Agonist muscles

Answer 44

the concentrically or eccentrically contracting muscles during the exercise - active

Question 45

Prime movers

Answer 45

muscle that contributes most to the movement

Question 46

Assisters/synergists

Answer 46

muscles that assist with the movement

Question 47

Antagonist

Answer 47

muscle that would perform an action opposite the antagonist - passive when performing a lift or controlled lowering exercise - opposite side of joint to the agonist

Question 48

Stabilizer (fixator)

Answer 48

contract isometrically to fixate or stabilize the area to enable another segment to move

Question 49

Neutralizers

Answer 49

prevent undesired action of one of the agonists

Question 50

Steps to naming agonist group

Answer 50

1. determine which phase of the exercise is the lifting phase 2. determine action during this phase

Question 51

horizontal movement agonist group

Answer 51

muscle group causing (starting) the movement is the agonist