Ex Phys Chapter 1 Structure and Function of Exercising Muscle

what percentage of must muscle is type I fiber? Type IIa? Type IIx

50%, 25%, 25%

when is peak tension reached in slow twitch muscle fibers? Fast twitch

100ms, 50ms

what speed of myosin ATPase do type I fibers have? Type II? and what does this tell us about the contraction cycling

slow myosin ATPase = slow contraction cycling, fast myosin ATPase = fast contraction cycling

Type __ fibers have a more developed sarcoplasmic reticulum compared to Type __ fibers

II, I

how does a more developed sarcoplasmic reticulum contribute to faster speed of contraction?

because they are more adept at delivering calcium into the muscle cell when stimulated allowing a greater contraction speed

How much faster is the speed of contraction in type 1 fibers vs type 2? Calculated power?

5-6x, 3-5x

Type I and II muscle fibers of the same diameter generate about the same force (T/F)

true

how many muscle fibers are in a type 1 motor unit? type 2?

<300 muscle fibers, >300 muscle fibers

the soleus is composed mostly of type ___ fibers in everyone

one

what type of exercise are type 1 muscle fibers recruited for?

high aerobic endurance activity like a marathon

type II muscle fibers produce ____ power but have a ____ amount of endurance

greater, lesser

what determines which alpha-motor neurons innervate our individual muscle fibers

genes, hereditary

myosin heavy chain (MHC) isoforms

the defining feature of muscle fiber types which allow a greater range of contractile function

specialized muscle fibers have ____ hybrid fibers

less

principle of orderly recruitment

motor units are generally activated on the bassi of a fixed order of fiber recruitment

the number of fibers are recruited in what order

type I -> type IIa -> type IIx

size principle

the order of MU recruitment is directly related to the size of their motor neuron

motor units with ____ motor neurons will be recruited first.

smaller

what percentage can training induce on change in fiber type?

10%

a concentric contraction is considered a static contraction (T/F)

false

twitch

the smallest contractile response of a muscle fiber to a single electrical stimulus

summation

a series of three stimuli in rapid sequence, before complete relaxation from the first stimulus, eliciting even greater increase in force or tension

tetanus

a sustained muscular contraction resulting from a rapid series of nerve impulses

rate coding

the process by which the tension of a given motor unit can vary by increasing the frequency of stimulation of that motor unit

length-tension relation

the optimal length for generating force. too short or too stretched = little to no force

force-velocity relation

the ability of the muscle to develop force also depends on the speed of the contraction

during concentric contraction maximal force development _____ as the speed of contraction increases. However, with eccentric contractions, maximal force development _____ increases as speed increases

decreases, increases

satellite cells

single-nucleus stem cells that between myofibers multiply during hypertrophy and fuse with existing muscle fibers and supply additional nuclei as the fibers grow in size