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Coactivation during gait as an adaptive behavior after stroke.
A Lamontagne1, C L Richards, F Malouin
1Rehabilitation and Social Integration Interdisciplinary Research Center, Rehabilitation Institute of Quebec, Quebec City, Quebec, Canada. lamank@globetrotter.net
Summary
Individuals with hemiparesis show altered ankle muscle coactivation, with less on the affected side and more on the unaffected side. These changes correlate with impaired balance and walking ability after stroke.
Area of Science:
- Neurorehabilitation
- Biomechanics
- Stroke recovery
Background:
- Stroke-induced hemiparesis often leads to gait abnormalities and balance deficits.
- Ankle muscle coactivation plays a crucial role in maintaining stability during locomotion.
- Quantifying coactivation patterns in hemiparetic gait is essential for understanding functional impairments.
Purpose of the Study:
- To quantify ankle coactivation differences in paretic and non-paretic legs of hemiparetic subjects.
- To investigate the relationship between ankle coactivation and postural instability.
- To examine the link between coactivation, lower extremity motor deficits, and locomotor performance.
Main Methods:
- Electromyography (EMG) of medial gastrocnemius (MG) and tibialis anterior (TA) muscles recorded bilaterally during gait.
- Study included 30 recent stroke survivors with hemiparesis and 17 healthy controls.
- Ankle coactivation calculated by overlapping MG and TA EMG signals during specific gait phases.
Main Results:
- Hemiparetic subjects showed significantly reduced coactivation on the paretic side during single support (p<0.01).
- Increased coactivation was observed on the non-paretic side during double support phases (p<0.001) compared to controls.
- Greater deviations in coactivation patterns correlated with more severe motor impairments and disabilities.
Conclusions:
- Reduced paretic ankle coactivation may contribute to poor postural stability and impaired gait.
- Excessive non-paretic ankle coactivation during double support might be a compensatory strategy for stability.
- Understanding these altered coactivation patterns is vital for developing targeted rehabilitation interventions for stroke survivors.