Altered Ankle-Muscle Activation during Jump Landing in Participants with Functional Instability of the Ankle Joint

in Journal of Sport Rehabilitation
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Identification of motor control deficit associated with Functional Instability (FI) of the ankle joint.


T o compare patterns of ankle muscle activation during jump landing in participants with FI and a control group.


Cross-sectional comparison.


Research laboratory.


Twelve participants with FI (6 m, 6 f; age, 26.4 ± 4.6 years) and 10 control subjects (5 m, 5 f; age 24.9 ± 2.5 years).

Main Outcome Measures:

Integrated electromyographic (IEMG) activity of ankle musculature in the 150-millisecond period immediately prior to and post impact during 2 different jump landing activities.


Participants with FI demonstrated a significant reduction in pre-impact peroneus longus IEMG activity during both jumping activities compared to controls (P < .05). There were no significant differences between the groups’ soleus or tibialis anterior IEMG activity during the pre- or post-impact periods.


These results help to further our understanding of changes in control of ankle movement during dynamic activity in participants with FI.

Caulfield, Crammond, O’Sullivan, and Reynolds are with the University College Dublin School of Physiotherapy, Mater Hospital, Dublin 7, Ireland. Ward is with the Dept of Electronic Engineering at the National University of Ireland, Maynooth, Co. Kildare, Ireland.