College of Public Health and Human Sciences

Context:

Functional ankle instability (FAI) is difficult to identify and quantify.

Objective:

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

Design:

Case-control compared with t tests and ANOVAs.

Setting:

Sports medicine research laboratory.

Participants:

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.

Results:

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.

Conclusions:

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