Abstract
Objective
To identify the smallest combinations of maximum voluntary isometric contraction (MVIC)
tests that produce near-maximum voluntary activation (MVA) for a large proportion
of participants for the shoulder girdle muscles.
Design
Cross-sectional study.
Setting
Research center.
Participants
Healthy participants (N=38).
Interventions
Not applicable.
Main Outcome Measures
The electromyography of 12 shoulder muscles was recorded while participants performed
15 MVIC tests. The smallest combinations of MVIC tests that met our acceptance criterion
(ie, produce 90% of MVA for 90% of participants) were identified. Optimal combinations
were identified for each of the 12 muscles individually and for the 12 muscles simultaneously.
Electromyographic activation levels of the 95th highest percentile obtained with our
optimal combinations and with the Four Normalization Tests previously recommended
were compared using paired t tests.
Results
Between 2 and 6 MVIC tests were required for each of the 12 muscles, and 12 MVIC tests
were required for the 12 muscles to meet the acceptance criterion. These optimal combinations
produced electromyographic activation levels of the 95th highest percentile comprised
between 97% and 100% of MVA. These electromyographic activation levels were significantly
higher than the electromyographic activation levels obtained with the Four Normalization
Tests.
Conclusions
Although the number of MVIC tests to normalize 12 shoulder muscles was increased compared
with previous recommendations, the proposed method ensures that near-MVA (>90%) was
obtained for a large proportion of participants (>90%). Moreover, because electromyographic
activation levels of the 95th highest percentile were at least 97% of MVA, the identified
combinations could reduce the interparticipant variability. The proposed combinations
could help to improve electromyographic normalization and therefore reduce the misinterpretations
regarding shoulder muscle activation levels.
Keywords
List of abbreviations:
MVA (maximum voluntary activation), MVIC (maximum voluntary isometric contraction)To read this article in full you will need to make a payment
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Article info
Publication history
Published online: January 19, 2016
Footnotes
Supported by the Natural Sciences and Engineering Research Council of Canada, Médicus, and the Research Group in Biomedical Sciences and Technologies.
Disclosures: none.
Identification
Copyright
© 2016 by the American Congress of Rehabilitation Medicine
