Chapter 12: Types of Muscle Contractions
Stability does what?
Fix or stabilize Stop movement or hold it still,
Isometric Contractions-def.
Force of muscle contraction-Resistance force Muscle will neither shorten or lengthen Contraction occurs, but length stays the same No movers and no antagonists to identify
Contraction
Myosin grabbing actin and attempting to pull the sarcomeres closer to each other
Is all lengthening a contraction? Ex.
No, Ex. Muscle attachments moving away from eachother
Muscle Structure is:
organ attaching from bone to bone-tendon Composed on muscle fibers, which are composed of myofibrils, which is composed of sarcomeres-sliding filament
When do eccentric contractions occur?
when force is needed to slow down a movement caused by gravity or another external force
Three Types of Muscle Contractions
Concentric, Eccentric and Isometric
Scenario 3- Slowing Momentum of a Vertical Upward Motion
Controlled, basketball
Muscles:
Create forces to increase mobility and stability of joints
Concentric Contractions-movement
Create movement
Resistance Exercises & Example
Adds to the resistive force the contracting muscles must work against. May also want to reduce resistive forces. Ex.-Therapy
Three Scenarios-gravity
Against gravity, gravity neutral( doesn't exist), with gravity
Against Gravity
Basic, concentric, move against, vertically upward, most common
If contraction doesn't happen what happens?
Eccentric or isometric. Must ask what type of tensile force is created
What is it caused by?
External force
With Gravity
Gravity does its own work, want down motion to be faster-golf
Scenario 2- Against any Force other Than Gravity
Hold body part in position
Scenario 1-Against Gravity
Holding body part up
Gravity Neutral
Horizontal, not moving against or with gravity, rotational movements
Eccentric Contractions do what to movement?
Modify movement
Scenario 1-Slowing Gravity's Vertical Downward Motion
Most common, setting cup down
Mobility
Movement
Eccentric Contraction-def.
Muscle contraction that is lengthening, keep going until signaled to stop
Eccentric contractions
Muscle contracts and lengthens, opposes concentric contractions
Concentric contractions-def.
Muscle contracts and shortens, muscle is termed the mover
Isometric Contractions def.
Muscle stays the same length
Fixator (Stabilizer)
Muscle that acts to fix or stabilize a body part-isometic muscle contractions
Three Scenarios: Eccentric
Slowing Gravity's vertical downward motion, Slowing momentum of horizontal motion, Slowing momentum of vertical upward motion
Isometic Contractions do what with movement?
Stop movement
Must consider any additional forces
Weight, resistance
When do Concentric contractions occur?
When force is needed to move a body part
When do they occur?
When force is needed to stop a body part form moving
Resistance force
antagonist
Eccentrically contracting muscles
antagonists, negative contraction
Motor unit sizes
are as big as its branches
Must also consider any additional forces exist beyond that of the body part itself
beyond gravity
A Mover is a muscle that
concentrically contracts
what does a muscle mover do
creates the movement of the joint action
Nervous system control
muscle is innervated by a motor nerve, messages are sent to all fibers of a motor unit
Eccentric contraction is the result of
slowing down the movement of the external force
Opposing force:
stops muscle from contracting-gravity or internal force such as another muscle within our own bodies
