Characteristic of COP sway and EMG during toe balance for athletes with chronic ankle instability

Abstract

The purpose of this study was to identify characteristic of COP sway and EMG during toe balance test (TBT) for athletes with chronic ankle instability（CAI）. The study subjects included athletes with CAI and 12 healthy athletes. In all the subjects, the center of pressure (COP) and the ankle inversion/eversion and dorsal/planter flexion angles, and the electromyography (EMG) activities of the tibialis anterior (TA) and peroneus longus (PL), lateral gastrocnemius (LG), medial gastrocnemius (MG) were measured during the single-leg balance (SLB) and TBT. The COP pathlength during the TBT was greater than that during the SLB test (p < 0.05). The COP pathlength during the TBT was not significantly different between the healthy and CAI groups (p > 0.05). The EMG activities of the TA (p < 0.01) and MG (p < 0.01), PL (p < 0.05) were greater in the CAI group than in the healthy group. We suggest that the TBT is a more difficult test than the SLB test and that CAI controlled posture using muscle activities different from those in the healthy group.