Objective: Reduction of attentional resources is readily apparent in cases of reduced or conflicting sensory information. The purpose of this study is to compare attentional demands of postural control between athletes with functional ankle instability (FAI) and healthy matched individuals. 

Materials & Methods: 15 functional unstable ankles college athletes and 15 healthy matched athletes were selected conveniently. This case control, dual-task study was conducted using Biodex Balance System (BBS). To measure overall stability index while subjects experiencing 2 postural task difficulties (stability levels of 5 and 7 of BBS) and 2 cognitive loadings (no load and counting backward). In order to investigate the interactions of independent variables (postural task difficulty, cognitive task difficulty and health status) multi factorial mixed ANOVAs were used. T-Test was conducted to compare means in groups.

Results: Mixed ANOVA showed interaction effects of health status with postural task difficulty and cognitive task difficulty on overall stability index are significant. Patients had significantly more increase in overall stability index when confronting cognitive task and less stable support surface than healthy subjects. (P=0.01, P=0.03).

Conclusion: It seems that functional ankle instability (FAI) is associated with increased attentional demands to semi-dynamic postural control. Cognitive loading may be considered in any exercise program for FAI patients as an effective strategy.