Unit 3 Notes

Question 1

Three principal types of internal force

Answer 1

Tensile
Compressive
Shear

Question 2

Tensile Force

Answer 2

Pulling

Question 3

Compressive

Answer 3

Squeezing

Question 4

Shear

Answer 4

Sideways (pushing)

Question 5

Direction of normal or axial stress

Answer 5

perpendicular to analysis plance

Question 6

Direction of Shear Stress

Answer 6

parallel to analysis plane

Question 7

Types of complex load

Answer 7

Bending and Torsion

Question 8

Describe bending

Answer 8

one side experiences compression
one side experiences tension

Question 9

Common bending injury

Answer 9

femoral neck fracture in elderly

Question 10

Describe torsion

Answer 10

one end rotates clockwise
one end rotates counterclockwise

Question 11

Symbol for Stress

Answer 11

𝞼

Question 12

Unit of stress

Answer 12

N/m2 (pascal)

Question 13

What does stress cause

Answer 13

deformation

Question 14

what is deformation

Answer 14

change in shape

Question 15

What is strain

Answer 15

a measure of deformation
a change in length

Question 16

what is the symbol for strain

Answer 16

𝜺

Question 17

Extensibility

Answer 17

ability to stretch without being damaged

Question 18

Elasticity

Answer 18

ability to return to original shape after being stretched

Question 19

Elastic Region

Answer 19

Further stress results in permanent deformation

Question 20

Plastic region

Answer 20

yield point to failure point, permanent deformation returns to new length

Question 21

Cortical bone

Answer 21

compact bone, outside

Question 22

Cancellous bone

Answer 22

trabeular or spongy
inside

Question 23

Factors that influence force production

Answer 23

Temperature
Structural Factors
Neural Factors
Mechanical Factors

Question 24

Structural Factors

Answer 24

Fiber type
Muscle Architecture
PCSA (physiological cross sectional area)

Question 25

Describe strap and fusiform musculotendinous unit

Answer 25

fibers run parallel to tendon, aligned with force

Question 26

Describe unipennate musculotendinous unit

Answer 26

indirect force acting on tendon, not parallel

Question 27

Neural Factors

Answer 27

Number of motor units rate of action potentials

Question 28

Motor Unit

Answer 28

Single motor neuron and all of the muscle fibers it innervates

Question 29

Neural factors for increasing force output

Answer 29

1. recruit more motor units 2. increase rate of action potentials

Question 30

Common method for measuring neural input

Answer 30

EMG (electromyography)

Question 31

What can you see in EMG data?

Answer 31

Onset Offset Magnitude Duration

Question 32

EMG uses

Answer 32

Address Coordination Asssess nerve conduction Biofeedback Predict Isometic muscle force

Question 33

Mechanical Factors

Answer 33

Length Activation History Velocity

Question 34

Stretch Shortening Cycle

Answer 34

Stretch immediately prior to a concentric muscle action Eccentric-Concentric Coordination

Question 35

What happens to muscle force at fast speeds

Answer 35

Fast shortening decreases force Fast lengthening increases force

Question 36

For a given muscle length which type of muscle action produces the highest force?

Answer 36

Eccentric

Question 37

Where does peak power occur?

Answer 37

1/3rd 1RM

Question 38

If muscle force is constant when is muscle torque maximized?

Answer 38

WHen the moment arm is maximized (longest distance)