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Summary: EMG placement:Take2

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  • Summary: EMG placement:Take2

    Dear Subscribers,

    Due to a few system failures, I have recieved many requests to place this
    summary on the list for a second time. Good luck with it,

    """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

    Bruce Etnyre, Ph.D., P.T. RRRRRR IIIII CCC EEEEE U U
    Human Performance and Health Sciences R R I C C E U U
    Rice University R R I C E U U
    6100 Main MS 545 R R I C E U U
    Houston, Texas 77005 RRRRRRR I C EEEE U U
    etnyre@rice.edu R R I C E U U
    (713)527-4058 R R I C E U U
    R R I C E U U
    R R I C C E U U ..
    R R IIIII CCC EEEEE UUUU ..


    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%

    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


    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%
    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

    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%
    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
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%
    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
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%
    May I suggest that you look at
    Schmidtbleicher, D. (1980). Maximalkraft und Bewegungsschnelligkeit
    [Maximal strength and the quickness of movement]. Limpert: Bad
    Homburg.

    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%
    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

    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%



    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
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%

    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 * *
    ************************************************** ***********************

    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%
    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
    / \/\ ____ __o email callagha@healthy.uwaterloo.ca
    /\/ \ ___ _\
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