Electrotherapy and Muscle Contraction Flashcards Preview

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Flashcards in Electrotherapy and Muscle Contraction Deck (81):
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

Motivation

Good luck on your test you will kill it