Solving the muscle redundancy problem with EMG input: application to back muscles for the Sorensen test posture
(2023) ECCOMAS Multibody Dynamics Conference 2023 — Location: Lisbonne, Portugal (24.July.2023)
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- Abstract
- When solving inverse dynamics in the human body with a pure mathematical approach such as optimisation, the problem of muscle redundancy occurs. To solve this problem, cost functions can be found in the literature for the optimisation process to give the most physiological solution. Another approach is to use relevant information such as electromyography (EMG) from an upfront experiment prior to the quantification of muscle forces via a multibody (MBS) model. The idea is to make the most of EMG signals in the MBS model and in the subsequent computation process. In this work, such an EMG-based approach is used to predict muscle forces and intervertebral efforts in the lumbar spine for a static configuration in the Sorensen test posture. Muscles forces and the resulting intervertebral efforts are compared with these from a purely mathematical approach. One male subject was asked to produce three different muscle strategies in the Sorensen test posture. EMG signals of back and abdominal muscles were recorded during the experiment. Each configuration was performed without and with an external mass equal to 20% of the bodymass. An equivalent MBS model of the trunk in the Sorensen test posture including only back muscles was developed. Muscle forces for the EMG-based approach were quantified based on a deterministic muscle force distribution. On the other hand, muscle forces for the optimisation computation were computed with a trust-region algorithm with a constrained optimisation technique with two different cost functions classically used in the literature. As expected, varied muscle strategies were obtained for the different configurations on the basis of recorded EMG amplitudes. These different muscle strategies were obviously not caught by the optimisation computation. In conclusion, EMG seemed to be a valuable input to study different muscle strategies for a same subject that could not be differentiated by optimisation computations.
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Hinnekens, S., & et al. (2023). Solving the muscle redundancy problem with EMG input: application to back muscles for the Sorensen test posture. ECCOMAS Multibody Dynamics Conference 2023, Lisbonne, Portugal. https://hdl.handle.net/2078.5/26168