Shared Flashcard Set

Details

nmes muscle
nmes muscle
100
Anatomy
Graduate
02/28/2012

Additional Anatomy Flashcards

 


 

Cards

Term
what is the recruitment order of nerve fibers for volitional contractions
Definition
smal diameter nerve fibers before large diameter nerve fibers
Term
what is the recruitment order of motor units for volitional contractions
Definition
slow twitch motor units before fast twitch motor units
Term
why are slow twitch motor units activated before fast twitch motor units in volitional contractions/
Definition
slow twitch motor units are innervated by smaller diameter nerves; fast twitch motor units are innervated by larger diameter nerves
Term
what is the purpose of activating slow twitch motor units before fast twitch motor units in volitional contractions
Definition
Allows you to move smoothly. You start with slow twitch to guage what you need first. The heavier something is or the faster you have to move, the more fast twitch you have to bring in.
Term
what is rate coding?
Definition
the frequency of action potentials required to get the reaction you need
Term
describe rate coding of volitional contractions
Definition
motor units activate asynchronously. They go from motor unit to motor unit to avoid fatigue and to keep the muscle contraction going at the level you need it.
Term
what is the path of the signal in volitional muscle contraction
Definition
signal goes from brain - spinal cord - skeletal motor nerves - muscle contracts
Term
what is the recruitment order of nerve fibers for electrical contractions
Definition
random
Term
what determines the recruitment order of nerve fibers for electrical contractions
Definition
distance of nerves from the electrodes
Term
if 2 nerves are the same distance from stimulation, what determines the recruitment order of nerve fibers for electrical contractions
Definition
the largest diameter nerves will be activated first
Term
why are large diameter nerve fibers activated first in electrical stimulation
Definition
large diameter = lower internal resistance
Term
describe rate coding of electrical contractions
Definition
synchronous: all motor units fire or they don't fire at all. They all fatigue and drop out simultaneously
Term
what is the recruitment order of motor units for electrical contractions
Definition
fast twitch motor units before slow twitch motor units
Term
describe rate coding of volitional contractions as you start to fatigue
Definition
become more syncrhonous as fatigue occurs and motor units start to drop out. Causes vibration
Term
does electrical stimulation only activate motor fibers?
Definition
also activate peripheral sensory fibers as well as nerve fibers of the autonomic nervous system
Term
positive things you get from muscle stimulation
Definition
same metabolic reactions you get from contracting muscles on your own. Improve endurance, function, some strength
Term
limitation of NMES
Definition
only good for strengthening one or a few muscles at a time
Term
what are the desired adaptations caused by stimulating a muscle for strength
Definition
hypertrophy of muscle fibers; increase in number of contractile proteins
Term
describe the type of contractions you want to adapt to in muscle strengthening
Definition
intermittent, high force contractions
Term
how much should you stimulate for strengthening and why
Definition
because fast twitch fibers are activated first, you only need to stimulate at 50% 10RM to overload the muscle (which tells the muscle that it needs more protein.)
Term
what are the desired adaptations caused by stimulating a muscle for endurance
Definition
not after fatigue; want to make adaptations to prolonged, low force contractions
Term
what changes occur in the muscle as it adapts to prolonged, low force contractions for endurance
Definition
increased activity of oxidative enzymes, increased number of mitochondria, increased myoglobin content, increased number of capillaries to muscle fibers
Term
if you're doing muscle stimulation for functional activities like walking, will you stimulate for strength or endurance
Definition
endurance
Term
what is the threshold level for strengthening with e-stim
Definition
50% 10RM
Term
what is the threshold level for strengthening with voluntary contractions
Definition
60-70% 10RM
Term
is there a given current that will stimulate the maximum number of motor axons and the minimum number of nociceptors
Definition
no
Term
how do you set the current amplitude
Definition
set the amplitude based on your “goal” or purpose for the muscle contraction
Term
what to set the current amplitude to for a weak, compromised muscle group
Definition
set to 10% of what the uninvolved side can do to get to the threshold that the muscle needs to improve
Term
what is the most common waveform for muscle stimulation
Definition
biphasic square wave
Term
how to determine current amplitude when there isn't an uninvolved side
Definition
start at a low level and work up to the contraction you want
Term
how to set current amplitude for someone with an SCI
Definition
can be higher because they can't feel it. You can get strong enough contractions to stand them up.
Term
if you have a setup and you aren't getting the reaction you want, what can you change?
Definition
spread electrodes farther apart so that current will go deeper, increase intensity, increase duration
Term
goal for frequency in muscle strengthening
Definition
high enough to produce a smooth or tetanic contraction
Term
what frequency is sufficient to achieve a tetanic contraction in most healthy human skeletal muscle
Definition
50pps
Term
is frequency related to pulse duration in a pulsed waveform?
Definition
no
Term
how many muscle twitches do we get when the frequency is 5 pps
Definition
5
Term
what is the muscle response to a frequency of 15pps
Definition
subtetanic because the muscle fibers don’t have a change to fully relax before the next action potential contracts them again
Term
what frequency is tetanic
Definition
20pps and above
Term
at what point of frequency does the muscle begin to fatigue
Definition
75pps
Term
what is the range of adequate frequency for muscle force for most people
Definition
50-75pps
Term
is it good to go above 75pps for muscle strengthening?
Definition
no. the muscle fatigues too quickly
Term
why must the stimulation be cycled on and off?
Definition
more functional; avoids fatigue
Term
what is the on:off ratio for muscle stimulation for strengthening
Definition
10-15 seconds of contraction: 50-120 seconds of rest
Term
what is the best on:off ratio for people who are very strong
Definition
10:50 seconds
Term
what is the best on:off ratio for people who are very weak
Definition
10:50 seconds
Term
if a person is very weak and you start with 10:50 on:off time, how do you progress?
Definition
decrease the rest time
Term
what is the lowest on:off ratio to use for someone who is weak but progressing
Definition
0.43
Term
should the on or off time be greater?
Definition
off time should be greater
Term
why should off time be greater than on time?
Definition
less fatigue, more building of muscle mass
Term
is a greater intensity needed for strength or for function?
Definition
strength
Term
what is the typical pulse duration range for NMES
Definition
200-600 microseconds
Term
what is the purpose of ramping on/off
Definition
comfort
Term
define ramp
Definition
time it takes the device to get from the minimum intensity to the maximum intensity that you're going to use
Term
define rate ofr ise
Definition
time it takes to get from 0 to the peak for one individual phase
Term
what is the result of using an electrode that is too big
Definition
disperses current over too large an area, decreasing current density and therefore contraction
Term
what determines size of electrode to use
Definition
size of muscle being activated
Term
how does contraction intensity related to strength gains
Definition
increasing contraction intensity increases strength gain
Term
what is dosage
Definition
time of contraction vs. rest
Term
is there an optimal pulse duration for muscle strengthening?
Definition
no, just the range of 200-600 microseconds. Determine what is best for the individual
Term
how does intensity change the depth of stimulation and number of motor units activated
Definition
greater intensity increases depth of stimulation and number of motor units activated
Term
how does electrode placement change the depth of stimulation and number of motor units activated
Definition
electrodes spread farther apart increases depth of stimulatiion and number of motor units activated
Term
what type of frequency is used with russian current
Definition
medium frequency
Term
what is the parameter for medium frequency
Definition
2500 pps
Term
how large are the contractions produced by russian current with medium frequency?
Definition
110-130% MVIC
Term
what does MVIC stand for
Definition
muscle voluntary isometric contraction
Term
can you get strength improvements with low frequency currents
Definition
yes
Term
how to exercise both slow and fast twitch fibers
Definition
patient exercises with muscle stimulation. Muscle stimulation turns on fast twitch, volitional turns on slow twitch
Term
The following questions refer to how to gain strength in lumbar region that has inhibition from swelling
Definition
ok
Term
how many electrode
Definition
4
Term
how many channels
Definition
2
Term
crossed or uncrossed?
Definition
uncrossed
Term
bipolar or monopolar?
Definition
bipolar
Term
where to center the electrodes
Definition
T12-L1
Term
type of current
Definition
brief intense
Term
why to use brief intense
Definition
muscle spasm to try and fatigue the muscle
Term
strength pattern
Definition
contraction-relaxation pattern
Term
how to activate both slow and fast motor units
Definition
patient does lumbar extension exercises during muscle stimulation
Term
on:off ratio to strengthen a weak muscle
Definition
1:5
Term
on:off ratio for functional
Definition
1:3
Term
on:off ratio for muscle pump
Definition
1:1
Term
if phase duration is 20us, what is pulse duration?
Definition
40
Term
difference between phase and pulse
Definition
phase is either pos or negative, pulse is both compined
Term
if pulse duration is 60, what is phase duration
Definition
30
Term
how do we describe the direction of current flow?
Definition
the direction of the movement of positive particles/ions (opposite direction of electrons)
Term
what generates action potentials
Definition
discharging the membrane capacitor, which opens the voltage gated channels
Term
where is the potassium battery?
Definition
inside the cell
Term
where is the sodium battery?
Definition
outside the cell
Term
if we place a positive and a negative electrode near a nerve, what will the positive ions from the capacitor do?
Definition
go towards negative electrode. This change in the position of ions changes the membrane potential. The inside wall will become +, the outside -. The change in voltage triggers the voltage senstive sodium ion channels to open, starting the action potential
Term
what will happen to negative ions in the cell if we place electrodes near a nerve?
Definition
negative ions will be pulled upward by the positive electrodes, which have moved towrads the negative electrode
Term
with the placement of electrodes near a nerve, how has the capacitor changed?
Definition
capacitor has been discharged.
Term
how does the discharging of the capacitor affect the cell?
Definition
the change in polarity of the cell causes the sodium channel to open so that sodium can flow in. a few miliseconds later, the potassium channel opens and potassium flows out.
Term
what is the membrane potential for a steady state
Definition
-70mV
Term
what is the firing threshold when sodium channels open
Definition
-55mV
Term
what happens after sodium channels open and sodium peaks inside?
Definition
potassium channels open
Term
what happens after potassium channels open?
Definition
potassium flows out and sodium is pumped out
Term
what happens as potassium and sodium both leave
Definition
hyperpolarization
Term
what happens to reduce hyperpolarization
Definition
pumps return ions to steady state
Term
how long is the absolute refractory period?
Definition
.5-1ms
Term
what is the absolute refractory period
Definition
the time of the action potential when the action potential can't be stopped and can't be repeated
Term
when is the relative refractory period
Definition
the last 1/3 of repolarization to baseline return
Supporting users have an ad free experience!