5010 Kinesiology: Basic Kinetics

Question 1

Open Kinetic Chain

Answer 1

when the distal segment of the extremity is free to move in space (distal on proximal movement)
i.e: throwing

Question 2

Closed Kinetic Chain

Answer 2

when distal segment of extremity is fixed and thus unable to move freely (proximal on distal)
i.e: handstand, pull-up

Question 3

Types of Forces applied to segments of the body

Answer 3

1. Tension
2. Compression
3. Bending
4. Shear
5. Torsion
6. Combination

Question 4

Internal forces vs. External forces

Answer 4

Internal: produced by structures in body (MUSCLES). Help w/ movement and stability.

External: produced by forces outside of body. Weight of a body segment (GRAVITY), free weights, friction, etc.

Question 5

Joint Rxn Force

Answer 5

Equal and opposite in direction to the net difference between internal and external forces.

Muscle forces typically cause compression to the joint, which contributes to joint stability.

Question 6

Net Compressive Force
or
Net Destraction Force (Tension)

Answer 6

Fi > Fe = Net Compressive Force

Fe> Fi = Net Destractive Force

Question 7

How can we use vectors?

Answer 7

Graphic depiction of Forces
Shows: location, magnitude, and direction

Allows combination of multiple muscle forces/directions to determine Resultant muscle action.

Question 8

Muscle FORCE

Answer 8

Linear force created by muscle contraction

Question 9

TORQUE

Answer 9

Rotary moment produced by applied force

Torque= Force X Moment Arm Length

Question 10

Moment Arm

Answer 10

shortest distance between axis of rotation and muscle force

Question 11

Leverage

Answer 11

determined by the force with the greatest moment arm

In body: mechanical advantage is defined as ration of internal to external moment arm.

Question 12

Mechanical Advantage

Answer 12

Distance (internal) / Distance (external)

When >1, internal force has mechanical advantage

When

Question 13

Factors Influencing Muscle Strength

Answer 13

1. Muscle size & structure
2. Length of muscle
3. Muscle moment arm
4. Velocity of contraction
5. Fiber type within the muscle
6. Level of muscle fiber recruitment

STRENGTH = TORQUE

Question 14

Active force (tension): what causes it?

Answer 14

it is related to the amount of overlap and the number of actin-myosin cross bridges.
Produced by active muscle contraction

Question 15

Passive Tension

Answer 15

Potential energy due to elastic component; produced by stretch on muscle

Question 16

Total tension

Answer 16

active + passive tension = linear muscle force

Question 17

Strength is a measure of what?

Answer 17

Torque

Question 18

Difference between Length-Tension curve and Torque curve

Answer 18

Length-Tension Curve: ONLY muscle force

Torque Curve: muscle force AND length of moment arm.

Question 19

Force Couple

Answer 19

when 2 or more forces pulling in different directions produce angular (rotational) movement in the same direction

Question 20

Upward Rotation: why is it important?

Answer 20

Moves accromion out of the way.

Increases ROM for elevation

Maintains optimal length-tension relationship for supraspinatus.

Question 21

Rotator Cuff Role

Answer 21

Stabilization: keep humeral head firmly located in the glenoid (SS)

Depression: Allows clearance of humeral head (IS and TMinor)

Question 22

Active Insufficiency

Answer 22

decreased ability of muscle to develop active tension because muscle fibers are in shortened position