Control Deficits and Compensatory Mechanisms in Individuals with Chronic Ankle Instability During Dual-Task...

Area of Science:

• Biomechanics
• Neuromuscular Control
• Sports Medicine

Background:

• Chronic ankle instability (CAI) results from ankle sprains, causing recurrent injuries and balance issues.
• Dual-task (DT) conditions worsen postural control, particularly during stair descent, a common fall scenario.
• The biomechanical basis of stair-to-ground transitions in CAI under DT remains unclear.

Purpose of the Study:

• To investigate the biomechanical mechanisms of stair-to-ground transitions in individuals with CAI under single- and dual-task conditions.
• To analyze gait parameters, center of pressure (COP) metrics, and joint work contributions.
• To determine the relationship between ankle function, postural stability, and compensatory strategies.

Main Methods:

• Sixty individuals with CAI and controls performed stair-to-ground transitions under single- and dual-task conditions.
• 3D motion capture, force plates, and musculoskeletal modeling assessed spatiotemporal gait, COP, ankle inversion, and joint work (Ankle%, Knee%, Hip%).
• Correlation and regression analyses examined relationships between ankle contribution, stability, and proximal compensations.

Main Results:

• CAI group showed deficits in gait speed, step width, COP stability, and ankle kinematics, worsened by DT.
• Reduced ankle plantarflexion moment and Ankle% were observed in CAI, with increased knee and hip contributions.
• Ankle% significantly predicted COP-ml RMS and gait speed, indicating ankle's critical role in dynamic stability.

Conclusions:

• CAI involves global neuromuscular control deficits, including distal insufficiency and proximal compensation, exacerbated by DT.
• Ankle dysfunction is central to widespread instability in CAI, influencing lower-limb kinetics.
• Rehabilitation should integrate coordinated lower-limb training and progressive DT to enhance motor control and dynamic stability.