EMG Biofeedback

Question 1

What is EMG biofeedback

Answer 1

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

Question 2

What happens to the MUAP signals

Answer 2

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

Question 3

What are the audiovisual signals used for

Answer 3

Reinforce voluntary muscle control

Question 4

True or False:

EMG biodfeedback machines measure actual direct physiologic events

Answer 4

False

Question 5

What does EMG biofeedback actually measure

Answer 5

Some aspect that is highly correlated with an actual physiologic event

Question 6

What are 3 examples of correlated aspects

Answer 6

1. Peripheral skin temperature
2. Finger photo transmission
3. Electromyography

Question 7

A muscle contraction is a result of what

Answer 7

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

Question 8

What does the depolarization of the muscle fibers result in

Answer 8

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

Question 9

What does the change in permeability cause

Answer 9

Changes in the concentration of these ions in the extracellular fluid

Question 10

How are these changes in concentrations of ions detected

Answer 10

By surface electrodes connected to a very sensitive voltage measuring device

Question 11

What measures the change in voltage

Answer 11

EMG

Question 12

What is electromyography activity

Answer 12

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

Question 13

What happens as more motor units are recruited

Answer 13

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

Question 14

What size motor units are recruited first

Answer 14

Small motor units

Question 15

What do faster contractions tend to do

Answer 15

Excite larger motor units and depress smaller ones

Question 16

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

Answer 16

The external force required to perform a task successfully

Question 17

What does the amplitude of the EMG reflect (5)

Answer 17

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

Question 18

True or False:

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

Answer 18

True

Question 19

Does the linear relationship hold true for concentric or eccentric contractions

Answer 19

Nope

Question 20

What is electrical activity of a muscle measured in

Answer 20

Micro volts

Question 21

True or False:

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

Answer 21

True

Question 22

What can noise be defined as

Answer 22

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

Question 23

How many electrodes are required to eliminate noise

Answer 23

3

Question 24

What are the 3 electrodes

Answer 24

2 active electrodes and one reference or ground electrode

Question 25

Where are the active electrodes placed in relationship to each other

Answer 25

Close to one another

Question 26

Where is the reference electrode located

Answer 26

Anywhere in the body

Question 27

What do the active electrodes detect

Answer 27

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

Question 28

True or False: | The magnitude of the voltage picked up by each electrode differ with respect to the reference electrode

Answer 28

True

Question 29

What happens to the 2 resulting signals

Answer 29

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

Question 30

What does the differential amplification do

Answer 30

Significantly decreases extraneous noise

Question 31

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

Answer 31

The common mode rejection ratio (CMRR)

Question 32

What happens once the signal is amplified

Answer 32

Any remaining noise in the resultant signal is filtered

Question 33

What is the resulting amplified and filtered signal known as

Answer 33

Raw activity

Question 34

What is the raw activity defined as

Answer 34

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

Question 35

True or False: | EMG-B units measure the overall increase and decrease in electrical activity so the raw activity must be rectified

Answer 35

True

Question 36

How is the raw activity rectified

Answer 36

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

Question 37

What happens after the signal is rectified

Answer 37

It is smoothed and intergrated

Question 38

What is the purpose of EMG-B (2)

Answer 38

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

Question 39

What are the advantages of EMG-B (3)

Answer 39

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

Question 40

What are the indications for EMG-B for motor recruitment

Answer 40

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

Question 41

What are the indications for EMG-B for motor inhibition

Answer 41

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

Question 42

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

Answer 42

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

Question 43

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

Answer 43

A muscle that is hypoactive

Question 44

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

Answer 44

A muscle that is hyperactive

Question 45

What are the contraindications of EMG-B

Answer 45

Any condition where muscular contraction might exacerbate the condition

Question 46

When using EMG-B how must you clean the skin

Answer 46

By using alcohol

Question 47

True or False: | You want the active electrodes to be parallel to the muscle fibers

Answer 47

True

Question 48

Where do you put the ground electrode

Answer 48

Over a boney prominence or non contractile tissue