KINE 403 Midterm Study

What are the two functions of a lever system?

Overcoming a resistance > effort applied, increase speed/RoM a resistance can be moved

What is a muscle tendon unit composed of?

Elastic component, Contracticle component

Describe Stress

Resistance of intermolecular bonds to the strain caused by the load

Describe Strain

Deformation of an object that occurs as a result of a load

List the 3 types of load:

Shearing, Compression, Tension

List the two combinations of load:

Bending, and torsion

Factors that determine stability/mobility:

Shape of articular surfaces, ligaments crossing joints (joint capsule), muscle arrangement

List the different muscle fiber types and examples of their use

Slow - Type I

Posture and writing

Fast - IIb

Running, jumping

How will the Parallel Elastic Component (PEC) store and release strain energy?

The entire muscle fiber has to lengthen

What are the two types of muscle-tendon units?

Parallel Elastic Component and Series Elastic component

Describe the PEC and give an example

Elastic component which run parallel to muscles. The activity in the muscles is off, and the PEC is passive. HAs high toughness and is very resilient

ex: Elbow flexors surrounding the bicep which keep the elbow from extending past 180 degrees.

Connective Tissues

Describe SEC and give an example

Elastic component which stores elastic strain energy and lies outside of muscular elastic component, connecting it to the bone. Makes up the "slack" of the muscle

Tendonous tissue which attaches muscle to bone

Give an example where an action is both PEC and SEC

A penalty kick in soccer where the kick action has a large range of motion but happens very quickly.

What is the Stretch-shortening cycle? (SSC)

A sequence of muscle activity involving an eccentric contraction followed immediately by a concentric contraction

Two main benefits of employing Strain energy (SE)

Enhances force production and lowers metabolic cost

Factors for hip fractures

Bone fragility, lower bone mineral density, age, increased body mass

List three types of joints

Fibrous, cartilagenous, synovial

List and describe the regions of a stress-strain curve in order

Hookean region- Linear region where if an object deformed, will go back to original shape.

Elastic Region- Entire region of an object on a stress-strain curve where it will return to original shape. (Rubber band)

Plastic Region- Region where an object stressed past this point will only return to greatest length achieved. Cannot regain original shape. (Rubber band that is excessively loose)

Failure Point- Region where an object is no longer elastic and will be completely deformed. (Snapped rubber band)

3 main functions of the musculoskeletal system

Maintain upright posture

Manipulate Objects

Body Transport

What are the benefits of improved congruence?

Reduce compression stress on opposed articular surfaces

Help maintain normal joint movement

Improve shock absorption

Active Insufficiency

When a muscle cannot shorten anymore, occurs with the agonist.

Passive Insufficiency

When a muscle cannot lengthen anymore, occurs with antagonist.

MA > 1

Advantage in effort (force)

MA < 1

Advantage in speed/range of motion