Keywords
Tremor; propagation; muscle; tremorogenic; model; simulation
Abstract
Background: It is unclear which muscles contribute most to tremor and should therefore be targeted by tremor suppression methods. Previous studies used mathematical models to investigate how upper-limb biomechanics affect muscles’ potential to generate tremor. These investigations yielded principles, but the models included at most only 15 muscles. Here we expand previous models to include 50 upper-limb muscles, simulate tremor propagation, and test the validity of the previously postulated principles. Methods: Tremor propagation was characterized using the gains between tremorogenic neural drive to the 50 muscles (inputs) and tremulous joint rotations in the 7 joint degreesof- freedom (DOF) from shoulder to wrist (outputs). Each gain can be interpreted as the potential of a muscle to generate tremor in a DOF. Robustness and sensitivity analyses were performed to assess the effects of model parameter variability on gains. Results: Simulations of postural tremor using the expanded model confirmed the previously postulated principles and revealed new insights, including: 1) most of the muscles with the largest gains were among the 15 muscles in the original model; 2) some gains depended strongly on posture; 3) averaged across the postures included in this study, the largest gains belonged to input-output pairs involving biceps/forearm/wrist muscles and forearm/wrist DOF, 4) although some shoulder and extrinsic hand muscles also exhibited large gains, especially in select postures. Discussion: These observations suggest that in the absence of additional information (such as tremorogenic neural drive to muscles), peripheral tremor suppression efforts should start by targeting biceps/forearm/wrist muscles or forearm/wrist DOF.
Original Publication Citation
Baker SA, Beutler LJ, Free DB, Farina D, Charles SK. Potential of Individual Upper-Limb Muscles to Contribute to Postural Tremor: Simulations From Neural Drive to Joint Rotation. Tremor and Other Hyperkinetic Movements. 2025; 15(1): 7, pp. 1–19. DOI: https://doi. org/10.5334/tohm.949
BYU ScholarsArchive Citation
Baker, Spencer A.; Beutler, Landon J.; Free, Daniel B.; Farina, Dario; and Charles, Steven Knight, "Potential of Individual Upper-Limb Muscles to Contribute to Postural Tremor: Simulations From Neural Drive to Joint Rotation" (2025). Faculty Publications. 7811.
https://scholarsarchive.byu.edu/facpub/7811
Document Type
Peer-Reviewed Article
Publication Date
2025-02-25
Publisher
Ubiquity Press
Language
English
College
Ira A. Fulton College of Engineering and Technology
Department
Mechanical Engineering
Copyright Status
© 2025 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See http://creativecommons.org/licenses/by/4.0/.
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