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Andrew Walshe
05-31-1996, 04:51 PM
Biomech-l

On behalf of my associate, thanks to all those who responded to our request
on the correct positioning of EMG electrodes. As promised, below is a
summary of all the replies:-

It sounds as if you are using a proper placement of the EMG electrodes.
The section by DeLuca in the newer edition of *Muscles Alive* by Basmajian
and DeLuca (1985), Williams & Wilkins, pp. 61-64, describes where to
properly locate electrodes. Some older texts recommend attaching
electrodes over the motor point, but DeLuca makes a strong case for not
positioning them over the motor point but rather over the middle of the
muscle belly. The motor point is usually located (which is true for the
pectoralis and triceps muscles you mentioned) approximately one-third of
the distance from the proximal attachment to the distal attachment. I
strongly recommend you acquire a copy of their book. There are numerous
other considerations in the collection of EMG you should be familiar with
before collecting data, such as: electrode separation distance, bandwith
filtering, crosstalk, grounding, preamplification, noise and many others
you will find in their book.

Good luck.

BE

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Human Performance and Health Sciences R R I C C E U U
Rice University R R I C E U U
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Hello Justine,

you question about the long head of the muscle, is a bit confusing.

Is it not just a matter of simple surface anatomy, that you can find
in most basic anatomy books ?

Or

is it to know what configuration of electrode contacts, i.e. where to
place the + where to place the - and where to place the common, if you
are using a bipolar configuration.

if this is the problem, your original posting does not reflect this. You
must explain what you are trying to do. i.e. what are the main aims of
this experiment.


regards


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This may be in complete conflict with what you have already heard or will
hear, but, as a grad student with little EMG experience I have researched
your problem pretty thoroughly. There does not seem to be any definative
support for "exact" placement of EMG electrodes. Just as you're doing
(over the muscle bellies of the intended muscle) seems to be the most
precise of descriptions available. However, you should no that if you
will be doing pre/post measurement then exact placement (for replication)
should be established. This exact placement will vary considerably (over a
given muscle) from person to person. Also the distance which you place
your electrodes apart from each other will effect the aquired mean
frequency. Greater distances also increases cross talk. For some good
information an recommendations try looking up the " neuromuscular research
center" on the WWW (Deluca @ a university in Boston is an EMG expert there
and also lists references on this site).

good luck, and if you find out anything interesting could you please let
me know.

Patrick V. Grant
Cal Poly PE & Kinesiology

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Dear Mr. Walshe,

In response to your posting, we used a more recent work edited by Basmajian in
our protocol to study beneficial changes in typing technique of injured computer
users. The book, "Biofeedback: principles and practices for clinicians",
contained detailed instructions for the placement of electrodes for most major
muscle groups in Chapter 34.

This edition was published by William and Wilkins in 1989. Their offices are in
Philadelphia, but they have an office in Syndey ( or so it says).

Best of luck. If you can't get hold of a copy, I would be happy to send you a
xerox fo that particular chapter.

cheers!

Greg Dempster
Triangle Associates
76521.2365@compuserve.com
PO Box Laguna Beach, CA 92652-0059 USA

714/497-1715 tel/fax
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You can find the motor points of the muscle with the use of a machine which
electrically induces the muscle contraction. For example, we use electrical
stimulation in our athletic training setting to induce a muscle contraction
for muscle re-education following an injury. If you have access to this
type of equipment, or even a TENS (transcutaneous electrical nerve
stimulator) unit, you can apply one electrode to the muscle to stimulate a
contraction. This takes all the guess work out of placing the electrode and
is much better than having a picture. If you want a picture, the Burdick
corporation had a pamphlet published in 1955 which depicts the motor points
and the dermatome charts. I would be happy to share a copy of this with you
if you are interested.


Marilyn Miller
University of Wisconsin - La Crosse
La Crosse, WI 54601
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May I suggest that you look at
Schmidtbleicher, D. (1980). Maximalkraft und Bewegungsschnelligkeit
[Maximal strength and the quickness of movement]. Limpert: Bad
Homburg.

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A great book for electrode placement is:
Delagi EF, Perotto A. Anatomic Guide for the Electromyographer. Charles
C. Thomas, Springfield, IL, USA, 1981.

Good luck!

Kenton Kaufman, Ph.D.
Motion Analysis Laboratory
University of California
Children's Hospital
3020 Children's Way
San Diego, CA 92123
(619) 576-5807
email: kkaufman@ucsd.edu

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Keep the electrodes between the motor point (mid muscle belly?) and the
origin or insertion. You can use an electrical stimulator to find the
motor point by finding the spot where the least current elicits a twitch.
Jean Boucher at Laval (email?) would have more information on how to locate
the motor point.
Be careful with Delagi, since the reference positions are for intramuscular
fine wire or needle electrodes.

Regards,

Bob



Robert A. Hintermeister, Ph.D.
Steadman Hawkins Sports Medicine Foundation
181 West Meadow Dr., Suite 1000
Vail, CO 81657
rah@csn.org
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Try "The Anatomical Guide for the Electromyographer" I think the author
is Delagi. It tells exactly where to place surface electrodes.

Good luck
steve

************************************************** ***********************
* Stephen J. Kinzey, MA * internet: skinzey@uoft02.utoledo.edu *
* Doctoral Candidate * phone : 1-419-530-2753 *
* Dept of Health & Human Perf * fax : 1-419-530-4759 *
* The University of Toledo * *
* Toledo, OH 43606 * *
************************************************** ***********************

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You should probably check out the following article:

Zipp,J.P. (1981) Recommendations for the standardization of lead
positions in surface electromyography. Eur J Appl Physiol 50:41-54

Jack

-- /\ ____ Jack Callaghan Doctoral Candidate
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