Abstract
This work examined if currently available electromyography (EMG) driven models, that are calibrated to satisfy joint moments about one single degree of freedom (DOF), could provide the same musculotendon unit (MTU) force solution, when driven by the same input data, but calibrated about a different DOF. We then developed a novel and comprehensive EMG-driven model of the human lower extremity that used EMG signals from 16 muscle groups to drive 34 MTUs and satisfy the resulting joint moments simultaneously produced about four DOFs during different motor tasks. This also led to the development of a calibration procedure that allowed identifying a set of subject-specific parameters that ensured physiological behavior for the 34 MTUs. Results showed that currently available single-DOF models did not provide the same unique MTU force solution for the same input data. On the other hand, the MTU force solution predicted by our proposed multi-DOF model satisfied joint moments about multiple DOFs without loss of accuracy compared to single-DOF models corresponding to each of the four DOFs. The predicted MTU force solution was (1) a function of experimentally measured EMGs, (2) the result of physiological MTU excitation, (3) reflected different MTU contraction strategies associated to different motor tasks, (4) coordinated a greater number of MTUs with respect to currently available single-DOF models, and (5) was not specific to an individual DOF dynamics. Therefore, our proposed methodology has the potential of producing a more dynamically consistent and generalizable MTU force solution than was possible using single-DOF EMG-driven models. This will help better address the important scientific questions previously approached using single-DOF EMG-driven modeling. Furthermore, it might have applications in the development of human-machine interfaces for assistive devices.
Highlights
Human movement is the result of the actuation of joints in upper and lower extremities
This study investigated the limitations associated to the currently available state of the art EMG-driven musculoskeletal models that constrain musculotendon unit (MTU) to satisfy joint moments with respect to a single degree of freedom (DOF)
It aimed to show the importance of using a more comprehensive EMG driven model that accounts for multiple DOFs and for a larger set of MTUs
Summary
Human movement is the result of the actuation of joints in upper and lower extremities. The multiple MTUs spanning a joint reflect the redundancy of the human neuromuscular system in which a prescribed joint moment and motion can be the result of different MTU excitation strategies. Understanding how this redundancy is solved in humans and how MTUs develop force during movement is one of the biggest challenges in biomechanics. It has been shown that in humans the neuromuscular redundancy is solved by means of the neural drive to MTUs, or MTU excitation In this scenario, MTUs are recruited independently of the final joint moment and position, but rather based on the motor task to be performed [4,5,6], and on the personal history of training and pathology [7,8]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
