Surface EMG

Question 1

what Hz are considered biological in emg

Answer 1

10-500Hz

Question 2

What is analog filtering

Answer 2

-Lets you cut off frequencies by bringing in different resistors and capacitors

Question 3

Why is sample rate significant

Answer 3

in order to produce acurate same it must be 2n+1 where n is biological frequency

(55=n) need 1001 samples/sec

too low and u will get alaising( not accurate)

Question 4

what are amplifier benifits

Answer 4

1. Makes signal bigger

2. cuts out noise

Question 5

why are 3 points electrodes ideal

Answer 5

able to diferential body signals from background noise as 2 of the electrdes pick up similar energies and 1 picks up noise (common mode rejection ratio)

Question 6

what are he 2 probs with 3 detection amp

Answer 6

1. frequency components far away appear to be moving slower

2. detection distance decreasess becuase events far away will appear similar to 2 electrodes

Question 7

at 1cm how much of the original signal do u get

Answer 7

4%

Question 8

what does peak to peak measurement represent

Answer 8

amount of muscle energy (contractile energy)

Question 9

5 benifits of linear envalope reading

Answer 9

1. smoothens emg
2. used for ave trend
3. avg of particular section
4. low pass filter removes peaks
5. adds a slight delay

Question 10

what is normalization

Answer 10

uses 100% max voluntary contraction to produce max neuroal drive in muscles (normalizes all values to the max)

Question 11

how can u tell a muscle is fatigued on emg

Answer 11

fast twitch fibres drop out which shifts the spectrum to the left