Lecture Exam 1 (part 2) Flashcards
List the 3 MF types
SO-slow twitch oxidative
FOG-Fast twitch oxidative glycolytic
FG-Fast twitch glycolytic
Type naming for MFs
Type 1 (SO) Type 2a (FOG) Type 2b (FG)
List how muscle fiber types differ (4)
Stimulus threshold for contraction
fiber type recruitment patterns
speed of contraction
structural differeneces
Lowest stimulus threshold
SO
Highest stimulus threshold
FOG, FG
Fiber type recruitment is not this but this
speed related
intensity related
Low intensity workouts us
SO
Max intensity workouts use
FOG, FG, SO
This increases the number of muscle fibers whos threasholds are met
increase in intensity
most frequently recruited MF
SO
Speed of contraction for ST, FT
110 ms
50 ms to contract
four factors that contribute to speed of contraction
level of myosin ATPase
Myosin Isoforms
Development of SR
Troponin/Ca++ binding
Myosin ATPase, these have low lvls, these have high lvls
ST
FT
More ATPase =
faster contraction
These can be used to determine muscle typing
myosin isoforms
These fibers are not as effiecient in Ca++ release from SR
ST fibers
This affects speed of cycle of myosin/actin binding
ST fibers have poor troponin/Ca++ binding affinity in relation to FT
This are generally smaller than these
ST fibers
FT fibers
T/F: FT fibers similar size
T
indurence trained athletes have larger this than this due to specific training
ST
FT
These are important in aerobic/oxidative ATP production
mitochondria
This indicates the presence of many mitochondria in the cell
Oxidative
FG don’t have mitochondria
F
4 structural differences in between FT/ST
Size
mitochondria concentration
number of capillaries around
glycogen stores
This fiber types have many capillaries around them
SO
FOG
this is a polymer of glucose, animal carbohydrate
glycogen
These fibers have large glycogen stores, these have smaller
FG and FOG
SO
This fiber type do a good job of using fatty acids to produce energy
SO
difference in fiber innervation
smaller neurons innervate ST
Larger neurons innervate FT
This characteristic of neurons is related to conduction velocity
diameter
Biochemical differences in MF types
myosinATPase concentration hexokinase phosphofructokinase isocytrate dehydrogenase mitochondrial enzyme activitiy
these are in higher concentration in glycolytic fibers
hexokinase
phosphofructokinase
This compound effects speed of contraction
myosin ATPase
this puts glucose and glucose 6-phosphate together
hexokinase
this is the compound responsable for the rate limiting step of glycolysis
phosphofructokinase
These have more glycolytic enzymes than these
FG, FOG
SO
All fibers can produce energy in these ways
aerobic
anaerobic
this is the rate limiting enzyme in krebs cycle
isocytrate dehydrogenase
SO and FOG have more of these than FG
mitochondrial enzymes
These fibers are very versital in athletic events
FOG
these are more fatigue resistant but less powerful
oxidative fibers
this are generally more powerful/large
FT fibers
Different muscle in the same individual have this
different muscle fibers
this of the muscle dictate the general fiber type distribution patterns
functional demands
designed to determine if neuron dictates fiber type
cross innervation studies
cross innervation studies proved this
neuron dictates fiber type
Two hypotheses of how neuron dictates fiber type
use/disuse theory
axoplasmic flow theory
neuron dictates stimulus threshold for contraction, fiber adapts to demands placed on it are ideas of this theory
use/disuse theory
unidentified chemical produced in body of LMN flows down the axon of the LMN and is released at the myoneural junction. Chemical tells fiber to take on characteristics of a given muscle fiber type
axoplasmic flow theory
Fiber type distribution patterns have the same in M/F
T
this is the ST/FT ratio in the vastas lateralis
1:1
in an individual the different muscles have different fiber type distribution.
T
What must we do when we say someone has more ST MF
specify the muscle groups
extremes in metabolic distribution means
substantial differeance in MF distribution patterns in different types of athletes
relationship between genotype/phenotype
genotype you are born that way
phenotype is the result of exercise training
you cant convert from these two MF types, but you can in these types
ST to FT
FG to FOG fibers
stop training can turn FOG back to FG
Genotype/phenotype and how it relates to athletic performance in these two group types
heterogeneous group
homogeneous group
genetic predisposition dictates athletic fitness
heterogeneous group, lower lvl athletics
phenotype predominates (diet,exercise), genotype is prerequisite
homogeneous group, highest lvl athletics
Factors that effect force production in a muscle (6)
# of fibers in an activiated motor unit # of activated motor units size of the muscle fiber relationship between stimulation and inhibition speed of movement frequency of stimulation
Which factor of force production does the following represent: some have few, some may have up to 2-3000, more fibers = more force
of fibers in an activated motor unit
Which factor of force production does the following represent: as intensity increases we overcome the thresholds of more motor units
of activated motor units
Which factor of force production does the following represent: large MF stronger than small MF
size of the muscle fiber
Which factor of force production does the following represent: ACh for stimulation, inhibitory neurons at synapse release GABA at UMN and LMN junction.
relationship between stimulation and inhibition
Which factor of force production does the following represent: as velocity increases torque decreases
speed of movement effects force production
Which factor of force production does the following represent: firing rate of motor neuron
frequency of stimulation effects force production
under voluntary conditions we cannot always do this
activate all motor units
this can cause an increase in force past max exertion
electrical stimulation
initial strength increase in training is because of this
decrease in GABA activity
seen in first 4-5 weeks as strength gains are not associated with size gains
relationship between stimulation and inhibition allows us to do this
control force with more precision
As this increases torque decreases
velocity
why does a faster movement reduce force
ST fibers cannot contract rapidly enough to keep up at high velocity muscle movement. Therefore force production of ST fibers is lost
describe the frequency of stimulation effect on force production
additive force effect when stimulation reoccurs before resting state
these modulate torque (2)
recruitment
frequency (rate coding)
How does recrutiment modulate torque
as weight is increased recruitment of muscle fibers and motor units increases
increased freq. of rate stimulation also affected
name of the strategies that are affected by modulation of torque
motor unit-activation strategies or motor recruitment strategies
Some muscles rely more on this and some on this
rate coding
recruitment
The more this the finer control of force production
rate coding
in an arm up to 80-90% of force is produced by this, the last 10-20% of force production capability is this
recruitment and frequency
frequency (rate coding)
all of these muscle movements have different motor recruitment strategies for that type of force.
Isometric
concentric
eccentric
changes in the motor recruitment strategy is this when changing between muscle movements
instantaneous
this does not say will give all available force, only that at stimulus threshold a contraction with occur
all or none principle
