Cross-Education for Chronic Ankle Instability

Chronic ankle instability (CAI) results in neuromuscular impairments compromising balance, lumbopelvic stability, and hip strength. Balance training has proven to be an effective intervention for individuals with CAI. Additionally, unilateral balance training for those with CAI has previously led to cross-education effects in which the untrained limb exhibited improved balance performance. However, the ability of unilateral balance training to improve contralateral hip strength and lumbopelvic stability in those with CAI is unknown. The purpose of this study was to determine the cross-education effects of balance training on hip strength and lumbopelvic stability in individuals with CAI.

Thirty individuals with CAI will be randomized into control (CON) and balance (BAL) groups. Baseline testing include a unilateral hip bridge, hip strength, and balance tests of the uninvolved limb. For the unilateral hip bridge, the participant will hold a bridge through the test limb for maximum time. Isometric hip strength will be measured for external rotation (ER), extension (EXT), and abduction (ABD) using a handheld dynamometer. The star excursion balance test (SEBT) requires participants to maintain a single-leg stance while reaching for maximum distance with the opposite leg in three directions: anterior (SEBT-ANT), posterolateral (SEBT-PL), and posteromedial (SEBT-PM). The BAL group will participate in a progressive balance training program three times a week for eight weeks for the involved limb, whereas CON will not. All baseline measures will be reassessed at the end of the 8 weeks. Separate 2-way repeated measures ANOVAs will analyze the effects of group and time on each outcome. Additionally, each group's mean changes from baseline to post-intervention will be assessed with Cohen's d effect sizes. Statistical significance is set a priori at P\<0.05.


Eligibility Criteria:
Inclusion Criteria:

* All participants were required to have CAI based on guidelines published by the International Ankle Consortium. Participants were required to have a history of at least one acute LAS that resulted in swelling, pain, and at least one day of missed activity. The initial LAS must have occurred at least 12 months before study enrollment and the participants needed to be free of ankle sprains in the past three months. Participants were also required to report at least two events of "giving way" of their ankle, instability, or reinjury within the previous six months. Lastly, participants had to record scores of ≥5 on the Ankle Instability Instrument (AII), \>11 on the Identification of Functional Ankle Instability (IdFAI), and \<24 on the Cumberland Ankle Instability Tool (CAIT).2 One member of the research team completed all screening procedures. The same person block randomized participants into two groups, control (CON) and balance training (BAL), by selecting a sealed envelope that contained group designation.

Exclusion Criteria:

* Participants were excluded if they had any history of lower extremity or spine fracture or surgery, any lower extremity or spine injury besides LAS within the past two years, and any significant ankle injury within the past three months.