Module 5 Flashcards
If the force of the muscle’s contraction is greater than the resistance to the muscle’s contraction…
the muscle will shorten
What is a concentric contraction?
Where the muscle contracts and shortens
If the force of the antagonist is greater than the force of the muscle…
the muscle will lengthen instead of shorten (eccentric contraction)
What is an eccentric contraction?
When the muscle contracts and lengthens
If the force of the muscle’s contraction is exactly equal to the resistance force, then the muscle will…
neither shorten nor lengthen (isometric contraction)
What is the mover?
Muscle that generates the force that moves a body part to create the joint action that is occurring (“the action in question”).
If the force of the weight of the forearm is greater than the force of the brachialis contraction, the brachialis is eccentrically contracting. What is the mover and what is the antagonist?
Mover: gravity
Antagonist: brachialis
What are resistance exercises?
Exercises that incorporate weights, bands, tubing, etc. to train the muscle to contract with greater force than the resistance
What is an isometric contraction?
When the muscle contracts and stays the same length (force of muscle is same as force of resistance)
Why is aqua therapy important for rehabilitation programs?
Supports the body part being moved and decreases the resistance force to the muscle’s contraction; gentle way to begin strengthening exercises
If an arm is held out at 90 degrees and we start to adduct, what keeps us from smacking the arm into the body (from gravity’s pull)
Eccentric contraction of the abductor muscles, slowing down the movement
What defines a muscle contraction?
When cross-bridges form and create a pulling force toward the center of the sarcomere (even in eccentric/isometric contractions)
If a Z-line is fixed, how does the sarcomere shorten?
Myosin on fixed side slides instead of actin
What is tension?
A pulling force
A muscle is defined as contracting when it generates a _____ force toward its center
pulling (tensile)
What is tone?
Muscle generating tension
What is gravity?
Force caused by the mutual attraction of all physical matter (mass of objects).
Largest mass is Earth, so gravity pulls us downward
The force that gravity exerts on the mass of an object is defined as the _____ of the object
weight
What is gravity-neutral motion?
One in which gravity neither resists the motion nor aids it (when body part is being moved horizontally)
Ex: scapular retraction is a concentric contraction that is gravity-neutral
What kind of contraction is required if we want to move the arm downward faster than the force of gravity (or against a resistance pulling upward)?
Concentric
What is a negative contraction?
Another term for eccentric contraction because the contraction opposes the force that is creating the action that is occurring (acts as antagonist)
When do eccentric contractions occur?
Usually when force of eccentric contraction is needed to slow down a movement caused by gravity or some other external force
What direction is the force of an eccentric contraction when slowing down act of gravity?
upward
How does eccentric contractions work in slowing momentum of horizontal motion?
If muscle that initated movement were to relax, momentum would keep the body part moving farther than we might want - use eccentric to slow it down
Can we use eccentric contraction to slow momentum of vertical upward motion?
yes - if body part is moving upward too quickly
Which car pedal relates to concentric contractions? eccentric?
Concentric: gas pedal
Eccentric: brake pedal
Although muscles can shorten, lengthen, or stay the same length, the muscle is always generating a _______ force toward its ______
pulling force toward its center
Concentric contraction _____ movement
Eccentric contraction _____ movement
Isometric contraction ______ movement
creates
modifies
stops
A muscle that holds a body part in a static position is said to ______ that body part
fix / stabilize
Muscles that fix a body part in place are called
Fixator or stabilizer muscles