Assessing Functional Ankle Instability with Joint Position Sense, Time to Stabilization, and Electromyography

in Journal of Sport Rehabilitation
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Functional ankle instability (FAI) is difficult to identify and quantify.


To compare joint position sense (JPS), time to stabilization (TTS), and electromy-ography (EMG) of ankle musculature in recreational athletes with and without FAI.


Case-control compared with t tests and ANOVAs.


Sports medicine research laboratory.


20 recreational athletes.

Main Outcome Measures:

Passive angle reproduction, TTS, and mean EMG amplitude of the tibialis anterior, peroneals, lateral gastrocnemius, and soleus muscles during single-leg-jump landing.


No differences in JPS or medial-lateral TTS measures between groups. Significantly longer anterior-posterior TTS (P < .05) in the unstable ankle group. The stable ankle group had significantly higher mean EMG soleus amplitude after landing (P < .05). No other significant differences were found for mean EMG amplitudes before or after landing.


Subjects with FAI demonstrated deficits in landing stability and soleus muscle activity during landing that may represent chronic adaptive changes following injury.

Brown, Mynark, and Guskiewicz are with the Sports Medicine Research Laboratory, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-8700. Ross is with the Dept of Exercise Science, Virginia Commonwealth University, Richmond, VA 23284.