Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Kin 147 > Week 9 > Flashcards

Week 9 Flashcards

1
Q

You can measure muscle force with EMG

A

False

You measure electrical muscle activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In general, what does muscle force scale with

A

Electrical activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is electrical activity measured in

A

mV or V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the two types of electrical myography

A

sEMG - surface

Fine wire/needle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the pros of sEMG

A

Non invasive

Re usable

Better for dynamic tasks

Better for measuring more muscle at a time

Better for measuring larger muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the pros of fine wire electrodes

A

Higher accuracy

Can measure a specific portion of muscle

Less noise / cross talk

Better for simple tasks

Better for measuring smaller muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What type of tasks or activities would be better for surface

A

Dynamic tasks

Larger muscles

More muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What type of tasks or activities would be better for fine wire

A

Simple tasks

Smaller muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

sEMG electrodes are either

A

Disposable

or

Re usable (wired or wireless)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the pros and cons of disposable electrodes

A

Pros:
Cheap
Easily applied
Can change the distant apart

Cons:
Less accurate
Less quality

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Re usable electrodes are either

A

Wired or wireless

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What should you look out for when placement of the electrode

A

Generally best to place in the muscle belly

Place electrodes parallel to muscle fiber

Refer to published guidelines for specific muscle locations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The recommended placement of 2 active electrodes is

A

Around 2 cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What factors are influenced by the placement of 2 active electrodes

A

Bigger distance = bigger detection area

Bigger distance = less selectivity and greater chance of cross talk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a ground electrode

A

Helps reduce noise and grounds the electric signal

Place on body landmark
Dont place on a muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What factors affect sEMG Data Quality

A

Cutaneous fat

Muscle depth

Skin impedance

Muscle cross talk

Movement artifact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

More cutaneous fat does what to the signal

A

Dampens and weakens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does the skin impede the signal

A

Oily skin

Hair on the skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Muscle cross talk is

A

When you pick up electrical activity from muscles that are near by

20
Q

Movement artifact is basically

A

When you are moving at high velocity you can add to the electrical signal

21
Q

How would you prepare a participant for data collection

A

Shave hairs in area

Clean skin with alcohol pad - dead skin cells and dirt

Apply conductive electrode gel

22
Q

What is filtering

A

Filter out certain frequencies to eliminate some noise:

Below 20 Hz and above 500 Hz

23
Q

What kind of frequencies are filtered out

A

Non physiologic signals can enter the sEMG data:

Electrical noise (DC offset) from wall outlet
Movement artifact
24
Q

What is smoothing

A

Short transient spikes in your EMG data are common

Therefore smoothing will help eliminate or attenuate these huge spikes

Makes data more representative of the overall muscle contraction and easier to analyze

Most common option is RMS - root mean square

25
Q

What is the most common way to smooth data

A

RMS - root mean square

26
Q

Can you determine the type of muscle contraction with EMG (concentric, eccentric, isometric)

A

False

27
Q

What do you actually measure in sEMG

A

Muscle activity amplitude (peak)

Muscle activity amplitude (average)

Muscle activity timing (onset, offset, duration)

28
Q

What is normalisation

A

People are going to have different levels of factors (e.g hairs etc)

Normalise it to a Maximum voluntary contraction (MVC or MVIC)

This is done by performing a max contraction before testing

Contracting during the test are normalised to this value

e.g. MVC 100mv
Testing = 10 mv
Muscle activation = 10% of MVC

29
Q

MVIC stands for

A

Maximum voluntary isometric contraction

30
Q

What are the limitations of using MVC to normalise

A

Participant does not perform a true maximum contraction

Position of MVC test may not be the same position the muscle will be recorded in during the trial

Participant can exceed 100% MVC if the trial consists of eccentric muscle activity

31
Q

How do you negate them not giving a maximal contraction

A

Have them warm up

Give them encouragement during the test

Multiple trials to get to max

Show them their max and them ask them to beat it - competitiveness

32
Q

MVC during motion is difficult due to

A

Maintaining speed

electrodes can move

etc

33
Q

How do we measure/quantify timing (onset/offset/duration) of the muscle and when it turns on and off

A

Calculations

Visual inspection

34
Q

The method of calculations to determine onset/offset involves

A

A numerical threshold for when the muscle turns on or off is determined by complex formulas or calculations

Types of threshold are:

Number of standard deviations above resting baseline

% of peak EMG

35
Q

The method of visual inspection to determine onset/offset involves

A

Onset/offset is estimated by the researcher visually

Has been proven to be valid and reliable

36
Q

Timing relationship between key events during gait/cutting/jumping

A

Muscle activation onset/offset is generally calculated relative to initial contact (onset) or toe-off (offset)

Example:
Gluteus medius onset occurred 30 ms prior to initial contact

37
Q

Timing relationship between key events in relation to other muscles

A

Muscle onset/offset can be quantified in relation to other muscle onset/offset

Example:
Lateral gastroc activated 20 ms prior to medial gastroc

38
Q

You can measure muscle force with EMG

A

False

39
Q

Surface EMG is better for dynamic tasks compared to fine wire or needle EMG

A

True

40
Q

Electrodes should generally be placed where on the muscle

A

On the muscle belly, parallel with the muscle fibers, with a 2 cm distance between active electrodes

41
Q

Which of the following would not affect sEMG data quality

A

Number of muscles being studied

42
Q

Which of the following is recommended before EMG data collection

A

Clean skin with alcohol pad

43
Q

The purpose of filtering and smoothing your data, respectively, is to reduce or eliminate signal noise, and to make your data easier to analyze

A

True

44
Q

It is acceptable to compare EMG amplitude data between participants without normalizing the data to a maximum voluntary contraction (MVC)

A

False

45
Q

If a participant’s peak EMG during MVC is 250 mV, and during data collection their data EMG is 375 mV, their EMG relative to MVC would be what percent?

A

150%

46
Q

Why might trial EMG exceed MVC EMG

A

The participant was lazy and did not provide a true MVC

The contraction is eccentric, and eccentric contractions can lead to more EMG than isometric contractions

The testing position was not adequate for producing a true MVC

47
Q

Assuming you use the same criteria for each trial and muscle, it is reliable and valid to use visual inspection to determine EMG onset and offset

A

True

Kin 147 (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions