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Mike Gross
12-15-1994, 12:36 AM
Happy holidays to all subscribers. One of our students is interested
in measuring muscle cocontraction of shoulder muscles as subjects perform
closed chain activities such as the push-up. EMG data will be acquired from
antagonist muscles such as the anterior and posterior deltoid muscles.
Several methods have been considered for the operational definition of
cocontraction, including the suggestion of Falconer and Winter:

Common Area of Muscles A and B
% Cocontraction = 2 X ------------------------------- X 100%
Area Muscle A + Area Muscle B

The areas in question in this formula are the areas under the full-wave
rectified, demeaned, linear envelope signals for each muscle.
We would appreciate any information from subscribers regarding the pros
and cons of using this or other operational definitions of muscle
cocontraction. A summary of responses will be posted, as usual. Best regards,

Michael Gross
CB #7135
Division of Physical Therapy
Univeristy of North Carolina at Chapel Hill
Chapel Hill, NC 27599-7135

EMAIL Address: Mike=Gross%PT%MAH@css.unc.edu