Flashcards in Electrotherapy and Muscle Contraction Deck (81)
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1
When do we use accomodation
Chronic pain syndromes
2
True or False:
AP of muscle developed by electrically stimulated motor nerve is similar to that produced physiologically
True
3
How are motor units recruited during a contraction caused by E-stim
Large motor units are recruited first then small motor units
4
What does motor units being recruited from large motor to small units cause in terms of strength
The patient is weaker because the small motor units are not activated to help the large motor units
5
How are motor units recruited during a voluntary muscle contraction
Progressive recruitment of small, slow motor units to large fast motor units
6
What type of contraction has an increased rate of fatigue E-stim or voluntary
E-stim
7
True or False:
Longer rest times are needed between contractions to allow the muscle to be able to produce the same strength
True
8
What are the factors that influence the force-frequency relation for E-stim or voluntary contractions (4)
1. Muscle length
2. Muscle temperature
3. Fatigue state
4. Degree of potentiation of the muscle
9
What is low frequency stimulation of muscle with E-stim
1-2 stimuli per second
10
What does low frequency stimulation of muscle with E-stim cause
Twitch contraction
11
At what frequency will the AP start to summate causing unfused tetanus
15 pps
12
At what frequency will sustained contraction or tetanus occur
30 pps
13
What is the spatial motor unit recruitment for E-stim and voluntary muscle contraction
E-stim: Large to small
Voluntary: Small to large
14
What is the temporal motor unit recruitment for E-stim and voluntary muscle contraction
E-stim: Synchronous
Voluntary: Asynchronous
15
What is the muscle loading to increase strength for E-stim and voluntary muscle contraction
Both against resistance
16
What is the strengthening for E-stim and voluntary muscle contraction
E-stim: Increased motor unit recruitment and increased muscle hypertrophy
Voluntary: Increased motor unit recruitment and increased muscle hypertrophy
17
True or False:
E-stim can accelerate rehab by increasing muscle strength and endurance
True
18
What needs to happen to increase strength in healthy muscle
Stimulated contraction needs to be at least 50% of max voluntary isometric contraction (MVIC)
19
What needs to happen to increase strength in injured muscle
Stimulate contraction need to be only 10% of MVIC
20
Why do you not want a stronger contraction for injured muscle
It will produce greater pain and potential damage the tissue further
21
What is the overload theory
The larger the load placed on a muscle the greater the force of contraction the muscle will produce, thus strength will be greater than if smaller loads are applied
22
When does the overload theory apply to E-stim and voluntary muscle contractions
When the same force is applied
23
What is the specificity theory
E-stim stimulates large fast twitch type II motor units before small slow twitch motor units
24
True or False:
E-stim should produce greater strength gains than exercise alone with the same force contraction
True
25
Why is E-stim able to produce greater strength gains than exercise alone
Because it stimulates large motor units first which are the stronger motor units
26
What is the smoothness of onset of contraction for E-stim
Rapid and more jerky onset of contraction where all motor units of a given size contract simultaneously
27
True or False:
E-stim can support or assist with joint positioning
True it was able to reduce shoulder subluxations
28
True or False:
E-stim can increase blood flow
True
29
What frequency E-stim caused increased blood flow in the extremties
High frequency E-stim
30
How does blood flow increase because of E-stim
Muscle contraction increases venous return and muscles need more blood so heart pumps faster
31
True or False:
E-stim can treat urinary incontinence secondary to pelvic floor dysfunction
True
32
What is a denervated muscle
A muscle that does not receive input from a motor nerve
33
Can a denervated muscle be stimulated by E-stim used for NMES
Nope
34
If the electrical current has a pulse duration greater than what for muscle to contract
10 ms
35
True or False:
DC current can lead to the build up of ions below the electrode leading to potential electrical burns
True
36
True or False:
There is no build up of charge with AC current as long as the positive and negative waves are even
True
37
How does muscle contraction occur in denervated muscle
Contraction due to stimulation of muscle cell membrane and not muscle motor nerve
38
True or False:
The muscle cell membrane does not accomodate
True
39
What can be done because the muscle cell membrane does not accomodate
Slow rising stimulus can be used
40
When is muscle contraction used today sparingly
Bell's palsy
41
What is the pulse duration for a small and large muscle
Small: 150-200 usec
Large: 200-350 usec
42
Who created Russian current and when
Yakov Kots 1977
43
What did Kots claim about Russian current (3)
1. A muscle contraction using this current could generate up to 30% more force than that generated by MVC
2. Application of such current is painless
3. Short-term training could produce lasting gains in muscle strength up to 40% in healthy subjects
44
When was the first Russian stimulator produced in the US and Canada
1980
45
What type of wave does Russian current have
Continuous sine wave
46
What is the carrier frequency of Russian current
2500 pps
47
True or False:
Russian current is burst modulated for fixed for 10 msec periods
True
48
What is the fixed inter burst interval for Russian current
10 msec
49
What is the burst frequency of Russian current
50 bursts per second
50
How does Russian current prevent the uncomfortableness
By stimulating sensory fibers
51
What determines the magnitude of effect of Russian current
Total # of bursts/sec (burst frequency)
52
How is each burst treated at the neuromuscular level
As a single pulse
53
What does repeated delivery of the Russian current bursts lead to
Motor nerve depolarization and tetanic contraction
54
What are the physiologic effects of Russian current (5)
1. Depolarizes both motor and sensory neurons simultaneously
2. Muscle contraction will be painless
3. Higher current amplitudes can be used
4. Motor unit activation
5. Motor unit recruitment deficiency
55
What does a higher current amplitude allow
Stimulate deeper motor neurons
56
True or False:
Russian current preferentially activates type II motor units
True
57
During max voluntary contraction are we able to recruit large numbers of large type II fast twitch motor units
Nope
58
What is the net charge of biphasic and polyphasic balanced pulsed currents
No net charge
59
How are the electrodes oriented in Russian current
Longitundinally
60
What are the 3 types of electrode placement for Russian current
1. Monopolar
2. Bipolar
3. Quadripolar
61
What is monopolar placement of electrodes
One electrode is over the target with the other electrode placed a distance away over nonexcitable tissue
62
What is bipolar placement of electrodes
Both electrodes over the target tissue
63
What is quadripolar placement of electrodes
All four electrodes over the target tissue
64
What are the key parameters of Russian current (4)
1. Current amplitude
2. Burst frequency
3. On:off ratio
4. Training protocol
65
What is the peak current amplitude of Russian current
Generally set at 100 mA
66
What happens as the peak current amplitude gets higher
The higher the carrier frequency and the higher the root mean square amplitude
67
How do you determine the root mean square value
Arms=70.7% of Ap (peak amplitude)
68
What does a higher root mean square mean
The more heat produced in the tissue under the electrode
69
With Russian current do you want to use minimal or maximal current to get desired effect
Minimal current
70
What is the burst frequency of Russian current
50 bursts per second
71
What occurs at 50 bursts per seconds
Fused tetanic muscle contraction is achieved
72
What is the optimal on:off ratio for muscle strengthening
10:50
73
Why do you need a long off time when using Russian current
To give the muscle time to rest to prevent fatigue
74
What does the duty cycle equal
(On/(on+off))*100
75
In Russian current what is synchronous stimuation
Both channels activated at same time
76
In Russian current what is reciprocal stimulation
Both channels activated alternately
77
What is reciprocal stimulation used for
Stimulating agonist and antagonist
78
What is the training protocol for muscle strengthening with Russian current
10 contractions lasting 10 seconds with 50 seconds of rest between contractions
79
What are the contraindications of Russian current (9)
1. Over the anterior cervical area
2. Over the transthoracic region
3. Over the transcranial area
4. Over the lumbar and abdominal area of pregnant women
5. Over superficial metal implants
6. Over hemorrhagic area
7. Over neoplastic area
8. Over electronic implants
9. Over skin areas where sensation is severely impaired
80
Ask about indications for Russian current
Will do
81
