Neuromuscular constraints on muscle coordination during overground walking in persons with chronic incomplete spinal cord injury

Clin Neurophysiol, 2014 · DOI: 10.1016/j.clinph.2014.02.001 · Published: October 1, 2014

Spinal Cord Injury Neurology Biomechanics

Simple Explanation

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. Muscle coordination during overground walking is impaired after chronic iSCI.

Study Duration

Not specified

Participants

8 persons with iSCI and 8 age-matched AB controls

Evidence Level

Not specified

Key Findings

1
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.
2
Persons with iSCI required fewer motor modules to account for their muscle coordination patterns during overground walking as compared to AB controls
3
In subjects with iSCI, motor modules consisted of greater muscle co-activity (Wmus), as well as, higher contributions (Wsum) from the composing muscles as compared to AB controls.

Research Summary

Persons with iSCI have fewer “building blocks” for constructing muscle activity, limiting the complexity of muscle coordination for overground walking. iSCI modules cannot explain the diversity of muscle coordination patterns expressed by AB controls, reflecting limited flexibility in neuromuscular control that likely contributes to constraints on gait speed and overground walking independent of walking aids. Subject-specific alterations in module composition and activation reveal neuromuscular mechanisms underlying gait deficits, potentially providing guidance for targeted and individualized rehabilitation plans.

Practical Implications

Targeted Rehabilitation

Understanding neuromuscular deficits can lead to tailored therapies for improving community ambulation in persons with chronic iSCI.

Clinical Assessment

Module analysis may offer a more sensitive tool for identifying diverse neuromuscular mechanisms that constrain overground walking after iSCI, beyond traditional clinical tests.

Increased Complexity

Therapies aimed at facilitating increased complexity of muscle coordination may improve self-selected walking speed and community ambulation in persons with iSCI.

Study Limitations

1
Small sample size and heterogeneity of injury compromise the ability to identify relationships between module number and gait deficits.
2
The mechanical function of modules in iSCI and how alterations affect mechanical output remains unconfirmed.
3
The number of modules may likely be affected by whether the more or less impaired limb was tested.

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