Ws. Marras et Kg. Davis, A non-MVC EMG normalization technique for the trunk musculature: Part 1. Method development, J ELECTROMY, 11(1), 2001, pp. 1-9
Normalization of muscle activity has been commonly used to determine the am
ount of force exerted by a muscle. The most widely used reference point for
normalization is the maximum voluntary contraction (MVC). However, MVCs ar
e often subjective, and potentially limited by sensation of pain in injured
individuals. The objective of the current study was to develop a normaliza
tion technique that predicts an electromyographic (EMG) reference point fro
m sub-maximal exertions. Regression equations predicting maximum exerted tr
unk moments were developed from anthropometric measurements of 120 subjects
. In addition, 20 subjects performed sub-maximal and maximal exertions to d
etermine the necessary characteristic exertions needed for normalization pu
rposes. For most of the trunk muscles. a highly linear relationship was fou
nd between EMG muscle activity and trunk moment exerted. This analysis dete
rmined that an EMG-moment reference point can be obtained via a set of sub-
maximal exertions in combination with a predicted maximal exertion (expecte
d maximum contraction or EMC) based upon anthropometric measurements. This
normalization technique overcomes the limitations of the subjective nature
for the MVC method providing a viable assessment method of individuals with
a low back injury or those unwilling to exert an MVC as well as could be e
xtended to other joints/muscles. (C) 2001 Published by Elsevier Science Ltd
.