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STUDY DESIGN: Case-control study.

OBJECTIVE: To compare the effect of dual-tasking on postural and cognitive performance between subjects with functional ankle instability (FAI) and a matched control group without FAI.

BACKGROUND:  Deficit and expertise in sensorimotor functions have been proposed as factors that can modify the interference between postural control and cognition. To the authors’ knowledge, no study has investigated the posture-cognition interaction in individuals with recurrent ankle sprain, an orthopaedic condition with documented sensorimotor deficits.

METHODS: Single-limb postural stability was assessed in 15 recreational athletes with FAI and 15 matched healthy athletes without FAI. Each athlete stood on a Biodex Stability System at platform stabilities of 7 and 5, while they performed or did not perform a digits-backward cognitive task. Overall stability index (OSI), anteroposterior stability index (APSI), and mediolateral stability index (MLSI) were used as measures of postural performance. RESULTS: At stability level 5, the individuals in the FAI group had poorer postural stability compared to those in the group without FAI (OSI, P<.01; MLSI, P<.01). A significant increase in OSI (P<.01) and MLSI (P = .02) was also demonstrated by the individuals in the FAI group during dual-task performance compared to the single-task performance.

CONCLUSION: Subjects with FAI demonstrated poorer postural stability when tested at level 5 on the Biodex Stability System, but not at level 7. Also, the results indicate that concurrent performance of a cognitive task decreased postural stability in the subjects with FAI, suggesting an increased dependency on attentional demands for maintenance of balance in that group. Such findings highlight the need for the assessment of postural control in patients with ankle sprain to include cognitive loading.