Article

Surface electromyography (sEMG) is used to assess muscle activation during
therapeutic exercise, but data are significantly affected by inter-individual
variability and requires normalisation of the sEMG signal to enable comparison
between individuals. The purpose of this study was to compare two normalisation
methods, a maximal method (maximum voluntary isometric contraction (MVIC)) and
non-maximal peak dynamic method (PDM), on gluteus medius (GMed) activation using
sEMG during three weight-bearing exercises in people with hip osteoarthritis (OA)
and healthy controls. Thirteen people with hip OA and 20 controls performed three
exercises (Squat, Step-Up, Step-Down). Average root-mean squared EMG amplitude
based on MVIC and PDM normalisation was compared between groups for both involved
and uninvolved hips using Mann-Whitney tests. Using MVIC normalisation,
significantly higher normalised GMed EMG amplitudes were found in the OA group
during all Step-up and down exercises on the involved side (p=0.02-0.001) and
most of the Step exercises on the uninvolved side (p=0.03-0.04), but not the
Squat (p>0.05), compared to controls. Using PDM normalisation, significant
between-group differences occurred only for Ascending Squat (p=0.03) on the
involved side. MVIC normalisation demonstrated higher inter-trial relative
reliability (ICCs=0.78-0.99) than PDM (ICCs=0.37-0.84), but poorer absolute
reliability using Standard Error of Measurement. Normalisation method can
significantly affect interpretation of EMG amplitudes. Although MVIC-normalised
amplitudes were more sensitive to differences between groups, there was greater
variability using this method, which raises concerns regarding validity.
Interpretation of EMG data is strongly influenced by the normalisation method
used, and this should be considered when applying EMG results to clinical
populations.
CI - Copyright (c) 2014 Elsevier B.V. All rights reserved.

Langue : ANGLAIS