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Variability, frequency composition, and complexity of submaximal isometric knee extension force from subacute to
1Center for Neuroscience and Neurological Recovery, Methodist Rehabilitation Center, Jackson, MS, USA.
Neuroscience
|May 21, 2014
Summary
Motor control in stroke survivors improves in force variability from subacute to chronic stages. However, force signal complexity and frequency composition remain impaired, indicating persistent motor deficits long after stroke.
Area of Science:
- Neurology
- Rehabilitation Science
- Motor Control
Background:
- Stroke survivors often exhibit impaired motor control, affecting force production and regulation.
- Understanding the temporal evolution of motor control deficits post-stroke is crucial for effective rehabilitation.
Purpose of the Study:
- To investigate changes in force signal variability, frequency composition, and complexity from the subacute to chronic stages of stroke.
- To compare these motor control parameters between chronic stroke survivors and healthy individuals.
Main Methods:
- Isometric knee extension tasks were performed by subacute and chronic stroke patients, and healthy controls.
- Force signal analysis included coefficient of variation (CV) for variability, power spectrum analysis for frequency, and sample entropy (SampEn) for complexity.
Main Results:
- Force variability (CV) significantly decreased from subacute to chronic stroke stages.
- Chronic stroke patients showed decreased median frequency and altered power distribution (increased in 0-3 Hz, decreased in 4-6 & 8-12 Hz bands) in both affected and unaffected legs.
- Signal complexity (SampEn) was significantly reduced in chronic stroke patients bilaterally.
Conclusions:
- While force variability improves post-stroke, the underlying physiological processes of force control remain less complex and shifted towards lower frequencies.
- Disordered force signal structure persists as a marker of impaired motor control, even with apparent recovery in variability.
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