Ch 4 Fiber Types, Size principle and other important characteristics of muscle tissue Flashcards
What are the different muscle fiber types
Type 1- slow twitch (50%)
Type 2 - fast twitch
Type 2a (25%)
Type 2x (25%)
Strength=
power=
Strength=force
power=force and velocity
What are some genetic factors for muscle fibers
Determine which a-motor neurons innervate fibers
Fibers differentiate based on a-motor neuron
What causes most of loss of type 2 motor units
Aging
Size of type 1 motor unit
smaller neuron, less than 300 fibers
Size of type 2 motor unit
Larger neuron, grater than 300 fibers.
When do muscle fibers reach peak power
at about 20% of peak force
Which muscle is type 1 in everyone
soleus
Which fiber types require oxygen for ATP production
Type 1
(recruited for low-intensity aerobic exercise and daily activities)
Which fiber types Fatigue quickly and produce ATP anaerobically
Type 2
Fibers used for short, intense endurance.
Produce more force
Type 2a
Fibers used for short, explosive sprints
Type 2x
Recruitment order for fibers
Type 1
Type 2a
Type 3a
Less force production=
fewer or smaller motor units
More force production =
more or larger motor units
Explain the size prinicple
Order of recruitment relates directly to size of a-motor neuron. Smaller motor units fire first
What fibers predominate in endurance athletes
Type 1
What fibers predominate in sprinters
type 2
What is fatigue
no more motor units to fire
Contraction where the muscle produces force but does not change in length and the joint angle does not change
Static (isometric)
Contraction where muscle produces force and changes length, and the joint movement is produced
Dynamic (isotonic)
What is a concentric movement
Muscle shortens while producing force.
Sarcomere shortens; filaments slide toward center
What is an Eccentric Movement
Muscle lengthens while producing force.
Cross-bridges form, but sarcomere lengthens
(trying to hold up a weight but it falls down slowly)
What is DOMS
delayed onset muscle soreness. Eccentric motion causes this a lot
What is the length-tension relationship
Optimal sarcomere length equals optimal overlap.
If too short or too stretched, little or no force develops
(ex jumping wind up)
Force-Velocity relationship for concentric movement
Increase force = decrease velocity
Decrease force = increase velocity
Force-Velocity relationship for Eccentric movement
Increase force = increase (negative) velocity
Decrease force = decrease (negative velocity)
What is the velocity at isometric/static movement
0 m/s
