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Phys Agents > Electrotherapy and Muscle Contraction > Flashcards

Electrotherapy and Muscle Contraction Flashcards

1
Q

When do we use accomodation

A

Chronic pain syndromes

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2
Q

True or False:

AP of muscle developed by electrically stimulated motor nerve is similar to that produced physiologically

A

True

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3
Q

How are motor units recruited during a contraction caused by E-stim

A

Large motor units are recruited first then small motor units

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4
Q

What does motor units being recruited from large motor to small units cause in terms of strength

A

The patient is weaker because the small motor units are not activated to help the large motor units

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5
Q

How are motor units recruited during a voluntary muscle contraction

A

Progressive recruitment of small, slow motor units to large fast motor units

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6
Q

What type of contraction has an increased rate of fatigue E-stim or voluntary

A

E-stim

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7
Q

True or False:

Longer rest times are needed between contractions to allow the muscle to be able to produce the same strength

A

True

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8
Q

What are the factors that influence the force-frequency relation for E-stim or voluntary contractions (4)

A
  1. Muscle length
  2. Muscle temperature
  3. Fatigue state
  4. Degree of potentiation of the muscle
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9
Q

What is low frequency stimulation of muscle with E-stim

A

1-2 stimuli per second

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10
Q

What does low frequency stimulation of muscle with E-stim cause

A

Twitch contraction

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11
Q

At what frequency will the AP start to summate causing unfused tetanus

A

15 pps

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12
Q

At what frequency will sustained contraction or tetanus occur

A

30 pps

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13
Q

What is the spatial motor unit recruitment for E-stim and voluntary muscle contraction

A

E-stim: Large to small

Voluntary: Small to large

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14
Q

What is the temporal motor unit recruitment for E-stim and voluntary muscle contraction

A

E-stim: Synchronous

Voluntary: Asynchronous

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15
Q

What is the muscle loading to increase strength for E-stim and voluntary muscle contraction

A

Both against resistance

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16
Q

What is the strengthening for E-stim and voluntary muscle contraction

A

E-stim: Increased motor unit recruitment and increased muscle hypertrophy
Voluntary: Increased motor unit recruitment and increased muscle hypertrophy

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17
Q

True or False:

E-stim can accelerate rehab by increasing muscle strength and endurance

A

True

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18
Q

What needs to happen to increase strength in healthy muscle

A

Stimulated contraction needs to be at least 50% of max voluntary isometric contraction (MVIC)

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19
Q

What needs to happen to increase strength in injured muscle

A

Stimulate contraction need to be only 10% of MVIC

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20
Q

Why do you not want a stronger contraction for injured muscle

A

It will produce greater pain and potential damage the tissue further

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21
Q

What is the overload theory

A

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

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22
Q

When does the overload theory apply to E-stim and voluntary muscle contractions

A

When the same force is applied

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23
Q

What is the specificity theory

A

E-stim stimulates large fast twitch type II motor units before small slow twitch motor units

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24
Q

True or False:

E-stim should produce greater strength gains than exercise alone with the same force contraction

A

True

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25
Q

Why is E-stim able to produce greater strength gains than exercise alone

A

Because it stimulates large motor units first which are the stronger motor units

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26
Q

What is the smoothness of onset of contraction for E-stim

A

Rapid and more jerky onset of contraction where all motor units of a given size contract simultaneously

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27
Q

True or False:

E-stim can support or assist with joint positioning

A

True it was able to reduce shoulder subluxations

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28
Q

True or False:

E-stim can increase blood flow

A

True

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29
Q

What frequency E-stim caused increased blood flow in the extremties

A

High frequency E-stim

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30
Q

How does blood flow increase because of E-stim

A

Muscle contraction increases venous return and muscles need more blood so heart pumps faster

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31
Q

True or False:

E-stim can treat urinary incontinence secondary to pelvic floor dysfunction

A

True

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32
Q

What is a denervated muscle

A

A muscle that does not receive input from a motor nerve

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33
Q

Can a denervated muscle be stimulated by E-stim used for NMES

34
Q

If the electrical current has a pulse duration greater than what for muscle to contract

35
Q

True or False:

DC current can lead to the build up of ions below the electrode leading to potential electrical burns

36
Q

True or False:

There is no build up of charge with AC current as long as the positive and negative waves are even

37
Q

How does muscle contraction occur in denervated muscle

A

Contraction due to stimulation of muscle cell membrane and not muscle motor nerve

38
Q

True or False:

The muscle cell membrane does not accomodate

39
Q

What can be done because the muscle cell membrane does not accomodate

A

Slow rising stimulus can be used

40
Q

When is muscle contraction used today sparingly

A

Bell’s palsy

41
Q

What is the pulse duration for a small and large muscle

A

Small: 150-200 usec
Large: 200-350 usec

42
Q

Who created Russian current and when

A

Yakov Kots 1977

43
Q

What did Kots claim about Russian current (3)

A
  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
Q

When was the first Russian stimulator produced in the US and Canada

45
Q

What type of wave does Russian current have

A

Continuous sine wave

46
Q

What is the carrier frequency of Russian current

47
Q

True or False:

Russian current is burst modulated for fixed for 10 msec periods

48
Q

What is the fixed inter burst interval for Russian current

49
Q

What is the burst frequency of Russian current

A

50 bursts per second

50
Q

How does Russian current prevent the uncomfortableness

A

By stimulating sensory fibers

51
Q

What determines the magnitude of effect of Russian current

A

Total # of bursts/sec (burst frequency)

52
Q

How is each burst treated at the neuromuscular level

A

As a single pulse

53
Q

What does repeated delivery of the Russian current bursts lead to

A

Motor nerve depolarization and tetanic contraction

54
Q

What are the physiologic effects of Russian current (5)

A
  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
Q

What does a higher current amplitude allow

A

Stimulate deeper motor neurons

56
Q

True or False:

Russian current preferentially activates type II motor units

57
Q

During max voluntary contraction are we able to recruit large numbers of large type II fast twitch motor units

58
Q

What is the net charge of biphasic and polyphasic balanced pulsed currents

A

No net charge

59
Q

How are the electrodes oriented in Russian current

A

Longitundinally

60
Q

What are the 3 types of electrode placement for Russian current

A
  1. Monopolar
  2. Bipolar
  3. Quadripolar
61
Q

What is monopolar placement of electrodes

A

One electrode is over the target with the other electrode placed a distance away over nonexcitable tissue

62
Q

What is bipolar placement of electrodes

A

Both electrodes over the target tissue

63
Q

What is quadripolar placement of electrodes

A

All four electrodes over the target tissue

64
Q

What are the key parameters of Russian current (4)

A
  1. Current amplitude
  2. Burst frequency
  3. On:off ratio
  4. Training protocol
65
Q

What is the peak current amplitude of Russian current

A

Generally set at 100 mA

66
Q

What happens as the peak current amplitude gets higher

A

The higher the carrier frequency and the higher the root mean square amplitude

67
Q

How do you determine the root mean square value

A

Arms=70.7% of Ap (peak amplitude)

68
Q

What does a higher root mean square mean

A

The more heat produced in the tissue under the electrode

69
Q

With Russian current do you want to use minimal or maximal current to get desired effect

A

Minimal current

70
Q

What is the burst frequency of Russian current

A

50 bursts per second

71
Q

What occurs at 50 bursts per seconds

A

Fused tetanic muscle contraction is achieved

72
Q

What is the optimal on:off ratio for muscle strengthening

73
Q

Why do you need a long off time when using Russian current

A

To give the muscle time to rest to prevent fatigue

74
Q

What does the duty cycle equal

A

(On/(on+off))*100

75
Q

In Russian current what is synchronous stimuation

A

Both channels activated at same time

76
Q

In Russian current what is reciprocal stimulation

A

Both channels activated alternately

77
Q

What is reciprocal stimulation used for

A

Stimulating agonist and antagonist

78
Q

What is the training protocol for muscle strengthening with Russian current

A

10 contractions lasting 10 seconds with 50 seconds of rest between contractions

79
Q

What are the contraindications of Russian current (9)

A
  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
Q

Ask about indications for Russian current

81
Q

Motivation

A

Good luck on your test you will kill it

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