Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5709451 | Journal of Electromyography and Kinesiology | 2017 | 29 Pages |
Abstract
Normalization of the electromyography (EMG) signal is often performed relatively to maximal voluntary activations (MVA) obtained during maximum isometric voluntary contraction (MVIC). The first aim was to provide an inter-session reproducible protocol to normalize the signal of eight shoulder muscles. The protocol should also lead to a level of activation >90% of MVA for >90% of the volunteers. The second aim was to evaluate the influence of the method used to extract the MVA from the EMG envelope on the normalized EMG signal. Thirteen volunteers performed 12 MVICs twice (one week interval). Several time constants (100Â ms to 2Â s) were compared when extracting the MVA from the EMG envelope. The EMG activity was also acquired during an arm elevation. Our results show that a combination of nine MVIC tests was required to meet our requirements including reproducibility. Both the number of MVIC tests and the size of the time constant influence the normalized EMG signal during the dynamic activity (variations up to 15%). A time constant of 1Â s was a good compromise to extract the MVA. These findings are valuable to improve the reproducibility of EMG signal normalization.
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Authors
Cédric Schwartz, François Tubez, François-Charles Wang, Jean-Louis Croisier, Olivier Brüls, Vincent Denoël, Bénédicte Forthomme,