2020 Volume 7 Issue 3 Pages 20-00023
The present paper proposes a model of muscle fatigue and recovery considering both the behavior of slow- and fast-twitch muscle fibers and the role of antagonistic muscles. The proposed model can be used to predict the degree of muscle fatigue of each muscle in the upper arm when the muscle activation pattern of the muscles changes because of the variation of the output force direction at the distal extremity. Furthermore, it can predict the variation in the muscle fatigue not only under maximum voluntary construction but also under any constant applied force or alternating periods of constant output force and rest. To validate the proposed model, case studies were conducted. The parameters necessary to predict the degree of fatigue of each muscle can be determined from a few preliminary experiments in which a participant outputs force in only four directions. The prediction results from the case studies showed good agreement with the measurement results. Therefore, the proposed model can be applied in cases where the output force direction changes with any force magnitude or alternates with periods rest, which is not the case for existing models.
