I have been collecting EMG from the Soleus muscle while subjects walk on
a treadmill. On some subjects there is an oscillation in the EMG baseline
immediately around the time of heel strike, which is large enough to make
the EMG level useless. The electrodes are firmly attached and sway of the
wires is minimized as much as I see is possible. I have not used active
electrodes before, but I assume that one of their purposes is to boost the
EMG signal well beyond this noise level.
I use standard passive disc electrodes, Grass Amplifiers, and Cambridge
Electronic Designs A/D system.

So here are three questions:
1) Will the use of active electrodes increase the signal to noise
(movement artifact) ratio, and so eliminate my problem of the baseline

2) What active electrodes are commercially available to be added to an
existing system such as mine (i.e., feed a signal into my Grass amps)?

3) Any other comments or suggestions people have?

Thanks for your time. I will post a summary of replies.

Gordon Chalmers

************************************************** ***********
Gordon Chalmers, Ph.D.
Dept. of Physical Education, Health and Recreation
Western Washington University, M/S 9067
Bellingham WA

Phone: (360) 650-3113
FAX: (360) 650-7447

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