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EMGLAB FORUM >minimal sampling rate for using EMGlab

  Subject:   minimal sampling rate for using EMGlab
 
From:   Michael Wong Date:   09 Feb 2009 11:50 pm  
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  Hello,

If my machine only can capture fine-wire EMG signal at 1984Hz, can I still calculate number of motor unit using EMGlab?

Thanks very much!
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  Subject:   Re: minimal sampling rate for using EMGlab
 
From:   Kevin McGill Date:   12 Feb 2009 11:27 am  
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  If you are using fine-wire electrodes with small lead-off surfaces (< 1 mm of exposed conductor at the wire ends), then a sampling rate of 1984 Hz is too low to capture the fine detail in the MUAP spikes. With this sampling rate you are only able to capture information in frequency bands up to about 1000 Hz, while for decomposition it is often the information above 1000 Hz that is the most discriminative.

A sampling rate of 1984 Hz is adequate for surface EMG signals, and might be adequate for fine-wire electrodes with longer lead-off surfaces (~ 5 mm of exposed conductor). The difficulty with these signals is that the MUAPs don't have the fine details to begin with, and so are usually difficult to discriminate.

You will have to try your signals and see what they look like. You may be able to decompose signals from weak contractions with only two or three active MUAPs. But for more complex signals, it will probably not be possible to decompose them accurately.

The best thing would be be to get the equipment to sample at 10,000 Hz.




Michael Wong wrote:
>Hello,
>
>If my machine only can capture fine-wire EMG signal at 1984Hz, can I still calculate number of motor unit using EMGlab?
>
>Thanks very much!
>
  >> Reply to this message  

  Subject:   Re: Re: minimal sampling rate for using EMGlab
 
From:   Michael Wong Date:   15 Feb 2009 11:31 pm  
Reply via e-mail to Michael Wong.  
  Thanks very much for your detailed reply! Kelvin.
  >> Reply to this message  

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