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Phys Agents > EMG Biofeedback > Flashcards

EMG Biofeedback Flashcards

1
Q

What is EMG biofeedback

A

The therapeutic use of instrumentation to detect and feedback electric signals from motor unit action potentials (MUAP) that are generated by active muscle

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2
Q

What happens to the MUAP signals

A

They are detected, amplified, rectified, filtered, intergrated, and converted into audiovisual signals

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3
Q

What are the audiovisual signals used for

A

Reinforce voluntary muscle control

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4
Q

True or False:

EMG biodfeedback machines measure actual direct physiologic events

A

False

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5
Q

What does EMG biofeedback actually measure

A

Some aspect that is highly correlated with an actual physiologic event

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6
Q

What are 3 examples of correlated aspects

A
  1. Peripheral skin temperature
  2. Finger photo transmission
  3. Electromyography
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7
Q

A muscle contraction is a result of what

A

Depolarization of muscle fibers due to binding of NT released from the alpha motor neuron

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8
Q

What does the depolarization of the muscle fibers result in

A

Increased permeability of the muscle membrane to K+ and Na+

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9
Q

What does the change in permeability cause

A

Changes in the concentration of these ions in the extracellular fluid

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10
Q

How are these changes in concentrations of ions detected

A

By surface electrodes connected to a very sensitive voltage measuring device

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11
Q

What measures the change in voltage

A

EMG

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12
Q

What is electromyography activity

A

Changes in the electrochemical gradient created by the MUAP that is detected by an electrode

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13
Q

What happens as more motor units are recruited

A

Muscle tension increases and more electrical activity is detected by the EMG electrode

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14
Q

What size motor units are recruited first

A

Small motor units

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15
Q

What do faster contractions tend to do

A

Excite larger motor units and depress smaller ones

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16
Q

What is the firing rate and recruitment of motor units dependent on

A

The external force required to perform a task successfully

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17
Q

What does the amplitude of the EMG reflect (5)

A
  1. Size of motor units
  2. Number of active motor units
  3. Distance of active muscle fibers from recording electrode
  4. Size of recording area
  5. Interelectrode spacing
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18
Q

True or False:

EMG has near linear relationship with force produced during carefully controlled isometric contractions

A

True

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19
Q

Does the linear relationship hold true for concentric or eccentric contractions

A

Nope

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20
Q

What is electrical activity of a muscle measured in

A

Micro volts

21
Q

True or False:

Noise must be eliminated before amplification of the detected MUAP can occur

A

True

22
Q

What can noise be defined as

A

Extraneous electrical activity that may be produced by any source other than the contracting muscle

23
Q

How many electrodes are required to eliminate noise

A

3

24
Q

What are the 3 electrodes

A

2 active electrodes and one reference or ground electrode

25
Q

Where are the active electrodes placed in relationship to each other

A

Close to one another

26
Q

Where is the reference electrode located

A

Anywhere in the body

27
Q

What do the active electrodes detect

A

Electrical activity from the motor units firing in the muscle below them

28
Q

True or False:

The magnitude of the voltage picked up by each electrode differ with respect to the reference electrode

A

True

29
Q

What happens to the 2 resulting signals

A

The signal from one active electrode is subtracted from the other leaving only the amplified difference in signals

30
Q

What does the differential amplification do

A

Significantly decreases extraneous noise

31
Q

What is the ability of the differential amplifer to eliminate common noise between the two active electrodes called

A

The common mode rejection ratio (CMRR)

32
Q

What happens once the signal is amplified

A

Any remaining noise in the resultant signal is filtered

33
Q

What is the resulting amplified and filtered signal known as

A

Raw activity

34
Q

What is the raw activity defined as

A

An alternating voltage representative of the true electrical activity in the muscle being monitored

35
Q

True or False:

EMG-B units measure the overall increase and decrease in electrical activity so the raw activity must be rectified

A

True

36
Q

How is the raw activity rectified

A

By flipping all of the negatively deflected signals upward toward the positive pole

37
Q

What happens after the signal is rectified

A

It is smoothed and intergrated

38
Q

What is the purpose of EMG-B (2)

A
  1. Change MUAPs into auditory and/or visual cues for the purpose of increasing or decreasing voluntary muscle activity
  2. To enhance motor learning by providing feedback about performance until motor skills develop sufficiently so that feed back is no longer needed
39
Q

What are the advantages of EMG-B (3)

A
  1. Provides immediate reward for performance changes that may be too small to note without EMG-B
  2. The small changes seen by EMG-B often lead to larger changes in performance improvement
  3. Patient is able to obtain feedback about performance without the constant supervision of the therapist
40
Q

What are the indications for EMG-B for motor recruitment

A

When the goal is to increase the EMG signal from the target muscle

41
Q

What are the indications for EMG-B for motor inhibition

A

When the goal is to decrease the EMG signal from the target muscle

42
Q

What are the indications for EMG-B for total body relaxation

A

Conditions of generalized pain or stress where the goal is to decrease undesirable muscle tension to achieve muscle relaxation and stress reduction

43
Q

What is an example of when you would use EMG-B to increase the EMG signal from the target muscle

A

A muscle that is hypoactive

44
Q

What is an example of when you would use EMG-B to decrease the EMG signal from the target muscle

A

A muscle that is hyperactive

45
Q

What are the contraindications of EMG-B

A

Any condition where muscular contraction might exacerbate the condition

46
Q

When using EMG-B how must you clean the skin

A

By using alcohol

47
Q

True or False:

You want the active electrodes to be parallel to the muscle fibers

A

True

48
Q

Where do you put the ground electrode

A

Over a boney prominence or non contractile tissue

Phys Agents (19 decks)

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