Date: Thu, 16 Oct 1997 12:48:38 GMT-10
Reply-To: Kevin Sims
Sender: Biomechanics and Movement Science listserver

From: Kevin Sims
Organization: Dept of Physiotherapy, Uni. of Qld
Subject: summary of emg normalisation

Here is a summay of the replies to my original question about
normalisation of emg data. I have omitted the names of the
contributors but if you would like to know who said what then I can
let you know. Thanks to all who replied.

In the neurologically impaired population (CP, adult neuro etc),
mostpeople tend to normalise EMG to gait max, because of the reason
you mentioned - VMC is variable and not always accurate in this
population. In CP especially, selective control is a big issue when
muscle testing. Also, fatigue is also an issue to be taken into
account. I think most labs working with non-impaired individuals use
VMC's, though. If you decide to go that route, it is imperative to
have a very well defined muscle testing protocol. It's easy to
collect VMC's as well as gait max and process the data both ways to
compare. It's just important to know how the data was normalised when
interpreting.

1. Yang JF; Winter DA. Electromyographic amplitude normalization
methods: improving their sensitivity as diagnostic tools in gait
analysis. Archives of Physical Medicine and Rehabilitation, 1984 Sep,
65(9):517-21.

Surface EMG profiles during different walking cadences in humans. Yang
JF; Winter DA Electroencephalogr Clin Neurophysiol, 60(6):485-91
1985 Jun

As part of my master's thesis, I am looking at EMG amplitude around
the hipjoint during gait. I have used MVC (isometric hip abduction) as
thebaseline for normalizing. I am using absolute values during gait
(inmicrovolts*seconds) in the numerator, over microvolts*seconds in
thedenominator (during isometric hip abduction). I have also been
gettingquite variable data (especially comparing them between people)
and was alsoworried that my method may not be the best. Hope this
helps.

We happen to do the same thing that you are doing. I do have
areference for you:

Selected Topics in surface Elecromyography for Use in
OccupationalSetting: Expert Perspectives U.S. Department of health
and Human Services Public Health ServiceCenters for Disease Control
National Institute for Occupational Safety and Health

Unfortunately, there are no standardized protocols for emg
normalization. I suggest you look through the BIOMCH-L archive for a
similar posting by Roger James. He posted a nice summary of responses
on emg normaliztion in July1996. There was an extensive bibliography.
A couple sources left off the list (or more recent) are:

Bamman, M.M. et al. 1997 Evaluation of surface electromyography
duringmaximal voluntary contraction. Journal of strength and
conditioning research11, 68-72

Kelly, B.T. et al. 1996 Optimal normalization tests for shoulder
muscleactivation: an electromyographic study. Journal of orthopaedic
research 14, 647-653

Zabik, R.M. & Dawson, M.L. 1996 Comparison of force and peak emg
during amaximal voluntary isometric contraction at selected angles in
the range ofmotion for knee extension. Perceptual and motor skills,
83, 976-978.

Heinonen, A. et al. 1994 Reproducibility of computer measurement of
maximalisometric strength and electromyography in sedentary
middle-aged women. European journal of applied physiology, 63,
309-314.

Knudson, D. & Johnston, D. 1993 Comparison of emg normalization
methods in asit-to-stand movement. Journal of human movement studies,
25, 39-50.

Winter, D.A. 1991 Electromyogram recording, processing, and
normalization: procedures and considerations. Journal of human muscle
performance, 1(2), 5-15.

You might want to look at Carlo DeLuca's excellent article on EMG that
appeared in the most recent issue of J Clinical Biomechanics. He
presents an excellent review of this topic.

Carlo De Luca (1997) " The use of surface electromyography in
biomechanics" Journal of Applied Biomechanics, 13:135-163.






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