View Full Version : Normalizing EMG data

Roger James
07-22-1996, 08:30 AM
Dear Biomch-L colleagues,

A graduate student of mine is working on a thesis and has the need
to collect and analyze EMG information for "normal" individuals and
post-op "ACL" patients. In order to compare muscle activity among
subjects and between groups, the EMG data must be normalized in
order to account for "...individual differences in subcutaneous fat, muscle
geometry, and other variances..." (Soderberg & Cook, 1984). Traditionally,
the criterion used to normalize EMG has been a maximum voluntary
contraction, MVC, of the involved muscles, as suggested by a variety
of sources including Basmajian & DeLuca (1985) and Soderberg &
Cook (1984). While the use of MVCs to normalize EMG data have been
recommended, the MVC value is often difficult to obtain and/or difficult
or inappropriate to relate to the functional activity of interest. In the case
of the current study, we are concerned that post-op ACL patients may not be
able to tolerate the forces involved in a MVC. The question is: are there
criterion values other than MVCs (e.g., a submax contraction at a standardized
workload or effort, etc.) that may be appropriate and that will allow valid and
meaningful comparisons among subjects? A search of the Biomch-L
archives and a perusal of approximately 500 titles available on Medline and
WorldCat have been little help relative to this specific question. Additionally,
the International Society of Electrophysiological Kinesiology (ISEK) EMG
Standards (reprinted in Dainty & Norman, 1987) did not really address the
normalization problem. I welcome the opinions, experiences, and
recommendations of this group and will be happy to post a summary of replies.


Basmajian, J. V. & DeLuca, C. J. (1985). Muscles Alive. Baltimore: Williams
& Wilkins.

Dainty, D. A. & Norman, R. W. (Eds.) (1987). Standardizing Biomechanical
Testing in Sport. Champaign, Illinois: Human Kinetics.

Soderberg, G. L. & Cook, T. M. (1984). Electromyography in Biomechanics.
Physical Therapy, 64(12), 1813-1820.

Thank you in advance!


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:: C. Roger James, Ph.D.
:: Assistant Professor, Biomechanics
:: Department of Health, Physical Education & Recreation
:: and
:: Center for Sports Health & Human Performance
:: Box 43011 Texas Tech University
:: Lubbock, Texas USA 79404-3011
:: (806) 742-3371 Phone
:: (806) 742-1688 FAX
:: Email: uncrj@ttacs.ttu.edu
:: [Find us on the Web--http://www.ttu.edu/~hper]
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