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Eversion Strength and Surface Electromyography Measures With and Without Chronic Ankle Instability Measured in 2
Lindsy Donnelly1, Luke Donovan2, Joseph M Hart3
11 Department of Kinesiology, University of Virginia, Charlottesville, VA, USA.
Foot & Ankle International
|April 11, 2017
Summary
Individuals with chronic ankle instability (CAI) exhibit reduced eversion strength compared to healthy controls. Peroneal muscle activation did not differ, and force output was only related to muscle activity in healthy individuals.
Area of Science:
- Biomechanics
- Sports Medicine
- Orthopedics
Background:
- Chronic ankle instability (CAI) is associated with strength deficits.
- The impact of ankle position on eversion strength and peroneal muscle activation in CAI is not well understood.
Purpose of the Study:
- To compare eversion force and peroneal muscle (peroneus longus and brevis) surface electromyography (sEMG) amplitudes in neutral and plantarflexion positions between individuals with and without CAI.
Main Methods:
- Cross-sectional study involving 28 adults with CAI and 28 healthy controls.
- Isometric eversion contractions measured using a hand-held dynamometer in neutral and plantarflexion positions.
- Peroneal muscle sEMG recorded and force normalized to body mass; sEMG normalized to resting period.
Main Results:
- Individuals with CAI demonstrated significantly less eversion force than controls in both neutral (1.64 Nm/kg vs. 2.10 Nm/kg) and plantarflexion (1.40 Nm/kg vs. 1.73 Nm/kg) positions.
- No significant differences in sEMG amplitudes were found between groups or muscles.
- Force measures correlated with peroneal muscle sEMG in healthy controls but not in the CAI group.
Conclusions:
- Individuals with CAI exhibit reduced eversion strength regardless of ankle position (neutral or plantarflexion).
- Peroneal muscle activation patterns do not differ between CAI and healthy groups, nor are they selectively activated by position.
- The relationship between force output and muscle activation is present in healthy individuals but absent in those with CAI, suggesting potential neuromuscular deficits.