Neuromuscular constraints on muscle coordination during overground walking in persons with chronic incomplete spinal cord injury
Heather B Hayes, Stacie A Chvatal, Margaret A French, Lena H Ting, Randy D Trumbower, Heather B Hayes, Stacie A Chvatal, Margaret A French, Lena H Ting, Randy D Trumbower
Abstract
Objective: Incomplete spinal cord injury (iSCI) disrupts motor control and limits the ability to coordinate muscles for overground walking. Inappropriate muscle activity has been proposed as a source of clinically observed walking deficits after iSCI. We hypothesized that persons with iSCI exhibit lower locomotor complexity compared to able-body (AB) controls as reflected by fewer motor modules, as well as, altered module composition and activation.
Methods: Eight persons with iSCI and eight age-matched AB controls walked overground at prescribed cadences. Electromyograms of fourteen single leg muscles were recorded. Non-negative matrix factorization was used to identify the composition and activation of motor modules, which represent groups of consistently co-activated muscles that accounted for 90% of variability in muscle activity.
Results: Motor module number, composition, and activation were significantly altered in persons with iSCI as compared to AB controls during overground walking at self-selected cadences. However, there was no significant difference in module number between persons with iSCI and AB controls when cadence and assistive device were matched.
Conclusions: Muscle coordination during overground walking is impaired after chronic iSCI.
Significance: Our results are indicative of neuromuscular constraints on muscle coordination after iSCI. Altered muscle coordination contributes to person-specific gait deficits during overground walking.
Keywords: Modules; Motor control; Muscle coordination; Spinal cord injury; Walking.
Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
Figures
![Figure 1. Schematic of experimental setup and…](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/4133333/bin/nihms567314f1.jpg)
![Figure 2. Persons with iSCI exhibit fewer…](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/4133333/bin/nihms567314f2.jpg)
![Figure 3. Inter-subject reconstructions show that AB…](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/4133333/bin/nihms567314f3.jpg)
![Figure 4. Motor modules exhibited by each…](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/4133333/bin/nihms567314f4.jpg)
![Figure 5. Motor modules and activations exhibited…](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/4133333/bin/nihms567314f5.jpg)
Figure 6. Modules differ between subject groups…
Figure 6. Modules differ between subject groups in number, composition, and activation
Comparison of modules…
Figure 7. AB subjects reduce their module…
Figure 7. AB subjects reduce their module number and activation when walking at matching iSCI…
Figure 8. Motor module number versus overground…
Figure 8. Motor module number versus overground self-selected cadence in subjects with iSCI and age-matched…
![Figure 6. Modules differ between subject groups…](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/4133333/bin/nihms567314f6.jpg)
![Figure 7. AB subjects reduce their module…](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/4133333/bin/nihms567314f7.jpg)
![Figure 8. Motor module number versus overground…](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/4133333/bin/nihms567314f8.jpg)
Source: PubMed