ABSTRACT
OBJECTIVE: To conduct a systematic review of existing literature on cross-education balance effects after unilateral training in the population with chronic ankle instability (CAI). DATA SOURCES: PubMed, SPORTDiscus, CINAHL Plus. STUDY SELECTION: To be included in the systematic review, studies were required to have been published in English, included participants with CAI, had participants undergo a unilateral therapeutic exercise for the lower extremity, and measured balance performance of the untrained lower extremity before and after the intervention. DATA EXTRACTION: The certainty of evidence in each included study was assessed via the Downs and Black checklist. A score of 24 to 28 indicated excellent or very low risk of bias; 19 to 23, good or low risk of bias; 14 to 18, fair or moderate risk of bias; and <14, poor or high risk of bias. We extracted information from each study regarding design, participant characteristics, inclusion criteria, independent and dependent variables, intervention, and results. Baseline and postintervention balance performance data for participants' untrained limbs were used to calculate the Hedges g effect sizes and 95% CIs. DATA SYNTHESIS: Our search returned 6 studies that met the inclusion criteria. The articles' risk of bias ranged from high to low (11-19). In 4 of 5 studies that examined unilateral balance training, the authors reported a cross-education effect. In the lone study that examined resistance training at the ankle joint, a cross-education effect was also present. Several cross-education effects were associated with large effect sizes. This systematic review was limited by a small number of studies that varied in methods and quality. CONCLUSIONS: Our results suggest that unilateral therapeutic exercise can improve balance performance of the untrained limb of individuals with CAI. More work is needed to determine which training protocols are most effective for generating a cross-education effect.
