A versatile approach to determine instantaneous co-activation: Development, implementation and comparison to existing measures
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Updated: Feb 3, 2026

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Published on: February 23, 2024
Daniel Viggiani1, Jeff M Barrett2, Kayla M Fewster3
1a Department of Kinesiology , University of Waterloo , Waterloo , ON , Canada.
Abstract:
An adaptable method of computing muscle co-activity is presented. Instantaneous muscle activities from multiple muscles are reduced into commonality and activity level dimensions. Both dimensions are weighted independently and combined into a co-activation measure, Φ. Myoelectric data from relaxed and braced simulated rear vehicle impacts were used to compare Φ to two existing co-activity measures in muscle pair and multi-muscle cases, Φ showed greater sensitivity in the muscle pair case and could better discriminate the relaxed and braced conditions in the multi-muscle case than previous measures. The flexibility of Φ allowed tailoring to reflect the current purpose.
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