Chronic ankle instability and fatigue create proximal joint alterations during performance of the Star Excursion...

Area of Science:

• Biomechanics
• Sports Medicine
• Neuromuscular Control

Background:

• Chronic ankle instability (CAI) is prevalent, yet its interaction with lower extremity fatigue on neuromuscular control remains unclear.
• Dynamic postural control, assessed via the Star Excursion Balance Test (SEBT), is crucial for athletic performance and injury prevention.

Purpose of the Study:

• To examine how chronic ankle instability (CAI) affects dynamic postural control (SEBT performance) following fatiguing activities.
• To differentiate the effects of general lower extremity fatigue versus isolated ankle fatigue on individuals with and without CAI.

Main Methods:

• Thirty participants (14 with CAI, 16 without) performed the SEBT (anterior, medial, posterior reaches) before and after two fatigue protocols: lunging and open-chain ankle isokinetic.
• Kinematic data of the stance leg and normalized reach distances (%MAXD) were analyzed.
• Regression models assessed the influence of CAI and kinematic variables on %MAXD.

Main Results:

• After lunging fatigue, CAI and altered knee/hip flexion explained 49% of the variance in anterior reach %MAXD (p=.001).
• CAI explained 20% of the variance in medial reach %MAXD under lunge fatigue (p=.014).
• Isolated ankle fatigue did not yield significant group differences in SEBT performance.

Conclusions:

• Chronic ankle instability significantly impairs dynamic balance after general lower extremity fatigue, especially in anterior and medial directions.
• The findings highlight the complex interplay between CAI, fatigue, and neuromuscular control during functional tasks.