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Joint stabilizing response to expected and unexpected tilts.
Gaspar Morey-Klapsing1, Adamantios Arampatzis, Gert-Peter Brueggeman
1German Sport University Cologne, Institute for Biomechanics and Orthopaedics, Car-Diem-Weg 6, Cologne 50933, Germany. morey@dshs-koeln.de
Foot & Ankle International
|October 14, 2005
Summary
Awareness of foot tilt improves ankle stabilization, requiring less muscle activation for the same motion. This suggests supraspinal control, highlighting muscle activation amplitude over timing for effective stabilization.
Area of Science:
- Biomechanics
- Motor Control
- Sports Medicine
Background:
- Ankle joint stabilization research presents conflicting findings, potentially due to varied testing methodologies.
- Understanding the mechanisms of functional ankle stabilization is crucial for injury prevention and rehabilitation.
Purpose of the Study:
- To investigate the influence of expected versus unexpected inversion on ankle and foot motion.
- To compare neuromuscular responses and kinematic parameters between self-perceived stable and unstable ankles.
Main Methods:
- Electromyography (EMG) of six lower limb muscles and 3D foot kinematics were recorded in 22 subjects during controlled foot inversion.
- Subjects were grouped based on self-perceived ankle stability.
- Horizontal ground reaction forces were measured.
Main Results:
- Unexpected inversions elicited greater muscle activation and horizontal force integrals compared to expected inversions, though kinematic differences were not significant.
- No significant differences in EMG or ground reaction forces were observed between stable and unstable ankle groups.
- The stable ankle group exhibited higher amplitude and velocity in kinematic responses.
Conclusions:
- Anticipation of inversion enhances ankle stabilization, enabling greater motion with reduced muscle activation, likely mediated by supraspinal mechanisms.
- Muscle activation amplitude, rather than precise timing, appears more critical for ankle stabilization.
- Findings challenge previous literature by emphasizing EMG amplitude in functional ankle stabilization.