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Differences in lateral drop jumps from an unknown height among individuals with functional ankle instability
Adam Rosen1, Charles Swanik, Stephen Thomas
1Department of Kinesiology, University of Georgia, Athens.
Journal of Athletic Training
|August 20, 2013
Summary
Individuals with functional ankle instability (FAI) show reduced muscle activation during lateral jumps, especially without visual cues. This muscle inhibition may impair ankle stability and increase pain.
Area of Science:
- Biomechanics
- Sports Medicine
- Neuromuscular Control
Background:
- Functional ankle instability (FAI) affects 20-50% of ankle sprains, often impacting daily activities.
- Lateral jumping involves complex visual and anticipatory muscle responses for stability, yet these are understudied in FAI.
Purpose of the Study:
- To compare muscle activation strategies in individuals with FAI versus healthy controls during lateral loading.
- To evaluate differences in muscle activation between FAI and stable ankles under anticipated versus unanticipated lateral loads, with and without visual cues.
Main Methods:
- A case-control study involving 40 participants (20 with FAI, 20 healthy controls).
- Participants performed two-legged lateral jumps from varying heights onto a force plate under eyes-open and eyes-closed conditions.
- Electromyography (EMG) of the tibialis anterior (TA), peroneus longus (PL), and lateral gastrocnemius (LG) was measured.
Main Results:
- Participants with FAI demonstrated significantly lower preparatory EMG activity (area and peak) in the tibialis anterior (TA) and peroneus longus (PL) muscles compared to controls.
- These differences persisted regardless of whether the eyes were open or closed, indicating a consistent deficit in muscle activation strategies.
Conclusions:
- Unanticipated lateral loads, exacerbated by the removal of visual cues, coincide with reduced muscle activity in FAI, potentially compromising dynamic restraint.
- Tibialis anterior (TA) and peroneus longus (PL) inhibition in FAI may lead to reduced talonavicular stability, increased joint compression, and heightened pain.
