Abstract
[Purpose] This study examined the electromyographic characteristics of one-leg standing (OLS) of subjects with functional ankle instability (FAI). [Subjects] The study group consisted of 11 patients with unilateral FAI. [Method] The subjects performed OLS after taking a side step either towards the affected or unaffected side and electromyographic data was collected using an EMG system. [Results] A comparison of the measurements showed that the mean power frequency of the EMG from the tibialis anterior muscle and the peroneus longus muscle were significantly higher on the affected side than on the unaffected side. The percentage of the maximum voluntary contraction of the gluteus medius muscle was significantly lower on the affected side than on the unaffected side. The motion time was significantly prolonged on the affected side than on the unaffected side. [Conclusion] FAI causes characteristic changes in the muscle activity pattern, and a person with FAI needs a much longer time to achieve stability during single-leg standing motion.
