Muscle Fatigue Enhance Beta Band EMG-EMG Coupling of Antagonistic Muscles in Patients With Post-stroke Spasticity

Frontiers in Bioengineering and Biotechnology, 2020 · DOI: 10.3389/fbioe.2020.01007 · Published: August 18, 2020

Simple Explanation

This study investigates how muscle fatigue affects the coordination between opposing (antagonistic) muscles in individuals who have spasticity after a stroke. The researchers measured electrical activity in muscles (EMG) of the arm while participants performed a sustained elbow flexion until they were tired. They found that in stroke patients, muscle fatigue led to a greater connection between the signals of the opposing muscles, particularly in the beta frequency range.

Study Duration

Not specified

Participants

10 patients with chronic hemiparesis and spasticity and 12 healthy adults

Evidence Level

Not specified

Key Findings

1
Maximal torque decreased significantly after the fatiguing contraction in both stroke and healthy groups, indicating muscle fatigue.
2
In the stroke group, EMG-EMG coherence in the alpha and beta frequency bands was significantly increased during severe fatigue compared to minimal fatigue.
3
The coactivation of antagonistic muscles increased progressively during the sustained fatiguing contraction in the stroke group but not in the healthy group.

Research Summary

This study examined the influence of fatigue on antagonistic muscle coupling in limbs with spasticity after stroke by comparing sEMG activation and coherence between antagonist muscles during a sustained elbow flexion contraction. The study found that intermuscular coherences between the antagonistic BB and TB muscles in the alpha and beta frequency bands were significantly increased during the second half of the contraction in the stroke group. The researchers suggest that the increased antagonistic muscle coupling induced by muscle fatigue may offer insights for designing training programs for post-stroke spasticity patients.

Practical Implications

Rehabilitation Program Design

Findings suggest that incorporating fatigue-inducing exercises could be a beneficial strategy in rehabilitation programs for patients with post-stroke spasticity to improve muscle coordination.

Understanding Corticospinal Drive

The study enhances our understanding of how fatigue affects the corticospinal drive to antagonistic muscles in individuals with post-stroke spasticity, which can inform targeted interventions.

Neuromuscular Control

The results provide insight into neuromuscular control mechanisms related to movement and can potentially gauge the functional integrity of corticomotor tracts during motor tasks in stroke patients.

Study Limitations

1
The study lacks a comparison group of stroke survivors without spasticity, making it difficult to isolate the direct correlation between spasticity and muscle coupling.
2
The results may be closely related to cortically originated muscular discoordination or motor recruitment rather than spasticity in passive motion.
3
Further research is needed to determine if spasticity significantly influences EMG coupling of antagonistic muscles in stroke patients.

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