Functional Performance of Subjects with Functionally Unstable Ankle when Performing Single-Limb Hopping and Hurdle Tests

Abstract

Functional ankle instability (FAI) has been denned as a feeling of giving way or instability of the ankle. While FAI affects a large part of the population, inconsistent findings have been reported regarding the existence of functional performance deficits in individuals with FAI. PURPOSE: To examine if functional performance deficits exist in subjects with FAI during two single limb hopping tests. METHODS: Forty subjects participated in this study (21.3 ± 2.8 yrs, 174.3 ± 8.9 cm, 71.8 ± 16.1 kg), 20 subjects with FAI and 20 subjects with no history of ankle injury. FAI was denned as a history of an ankle sprain and residual episodes of “giving way” or instability. The Ankle Instability Instrument was used to report symptoms of FAI. Subjects completed two functional performance tests (FPT), the single limb hopping and the single limb hurdle course. For each FPT, the participants were instructed to hop with maximal effort through the course. All participants performed 5 trials of each FPT. All testing was timed using an electronic stopwatch and the mean of the trials was used for statistical analysis. Additionally, after each FPT subjects were asked “Did you feel unstable during that test?” Two independent two-tailed t-tests were conducted to compare performance differences between the FAI and control group, one for each functional test. RESULTS: There was no significant difference between the FAI and control groups in the hopping (FAI = 7.60 ± 1.56 sec, control = 7.10 ±0.79 sec, t = −1.30, P= .20) or hurdle (FAI = 4.39 ±0.85 sec, control = 4.27 ± 0.51 sec, t =−.53, P = .60) tests. When asked if the subject felt unstable during the hopping test trials, 10 of the 20 (50%) subjects in the FAI group reported feeling of instability, while 0 of the 20 (0%) subjects in the control group reported that they felt unstable. During the hurdle test, 9 of the 20 (45%) subjects in the FAI group and 0 of the 20 (0%) subjects in the control group reported that they felt unstable. CONCLUSIONS: Subjects with FAI appear to be able to perform the hopping and hurdle task without significant performance deficits. However, during these tests, approximately half of the FAI subjects reported a subjective feeling of instability. Continued research is necessary to further evaluate how this subjective feeling of instability translates to actual functional performance.