Surface EMG and Biofeedback

Question 1

Clinical Electromyography

Answer 1

used to evaluate the scope of neuromuscular disease or trauma…as well as assist with establishing anticipated goals and expected outcomes

Question 2

Types of EMG

Answer 2

nerve conduction velocity

electromyography

Question 3

Kinesiological Electromyography

Answer 3

used to study muscle activity and establish the role of various muscles in specific activities

Question 4

How is kinesiological primarily carried out?

Answer 4

Electromyography (primarily surface EMG

Question 5

sEMG

Answer 5

can also be used as a kinesiological tool to examine muscle function during specific, purposeful tasks or therapeutic regimens

Question 6

Biofeedback:

Answer 6

describe the use of instrumentation to make covert physiological processes more apparent to the patient.

Question 7

Motor unit:

Answer 7

LMN and all muscle fibers it connects to

Question 8

MUAP

Answer 8

motor unit AP

the electrical activity that comes with the depolarization of a single motor unit

Question 9

CMUAP:

Answer 9

Combined Motor unit AP: the net (sum) of all depolarization (electrical activity) that comes when a patient voluntarily contracts a muscle to move

Question 10

3 phases to any instrumentation that is used to sense and record any electrical activity of muscle:

Answer 10

Input phase
Processing phase
Display (feedback phase)

Question 11

Best and most widely used electrodes?

Answer 11

silver-silver chloride

Question 12

Kinds of electrodes:

Answer 12

reusable/permanent

single use/disposable

Question 13

Permanent:

Answer 13

do not need gel: placed on clean skin and taped on

Question 14

Single use

Answer 14

pre-gelled, self-adhesive

Question 15

Recording electrodes:

Answer 15

2/3 electrodes are recording “active: ones that sense electrical activity

Question 16

Isolation ground/reference

Answer 16

make sure that 2 active electrodes are picking up activity from patient

Question 17

Why do we use 2 active electrodes?

Answer 17

The machine compared the polarity of 2 electrodes.

Question 18

Location of active electrodes?

Answer 18

generally placed at the midpoint of the muscle being recorded in line with the muscle fibers

Question 19

Electrode location placement consideration:

Answer 19

Place electrodes “in position of movement (squat)

Consider how skin may “shift” over the underlying muscle during movement

Question 20

What does spacing effect?

Answer 20

how much of muscle you sample electricity from

Question 21

Volume Conduction

Answer 21

salt water conducts electricity through its volume to surface of the skin

Question 22

Cross talk

Answer 22

if electrodes placed far apart; salt water can conduct electricity from other muscle groups and the electrodes can pick it up

Question 23

Artifact:

Answer 23

An “excess” or “erroneous” signal that is detected and displayed but does not come from the electrical activity of motor neurons or muscle tissue

Question 24

Movement artifact:

Answer 24

cables of machine do not move too much: can cause electrical display to shift
physical movement, not electrical activity

Question 25

Power line interference:

Answer 25

isolation ground not eliminating interference and it shows in recording

Question 26

ECG:

Answer 26

might see PQRS complex if recording near heart

Question 27

Filtering:

Answer 27

the electrical signal from the patient is filtered to only allow frequency components of 80-250 Hertz to pass.

Question 28

Low smoothing:

Answer 28

screen display changes very quickly to follow changes in muscle activity

Question 29

High smoothing:

Answer 29

screen display does not change quickly to follow changes in muscle activity
trend over time

Question 30

Amplification:

Answer 30

Can be used to adjust the “size” of an EMG signal on a given display.

Question 31

Goal/Threshold:

Answer 31

Some level of EMG that a patient can be prompted to “contract up to” or “relax down to

Question 32

Display Modes:

Answer 32

continuous

work/rest

Question 33

Continuous Display:

Answer 33

The unit continuously displays the patient’s electrical activity along with any goals or other feedback

Question 34

Work/Rest Mode:

Answer 34

The unit prompts the patient to contract toward the goal for a specific period of time and then prompts the patient to relax for a specific period of time

Question 35

Types of audio feedback:

Answer 35

tone (changing pitch or volume)

clicks (changing frequency or volume)

Question 36

Audio tones can be:

Answer 36

continuous
on above goal
on or off below goal

Question 37

Video feedback to patient:

Answer 37

Moving trace on computer screen
Bar graphs
Banks of LEDs

Question 38

Concurrent Assessment of
Muscular Activity (CAMA)

Answer 38

the output of the sEMG unit is directed to the patient, who is asked to respond appropriately and modify his or her performance

Question 39

EMG-triggered NMES

Answer 39

CMUAP monitored and threshold is set above what patient can do. Patient contracts target muscle. When threshold is met NMES stimulates a more powerful contraction