Cross-Education Balance Effects After Unilateral Rehabilitation in Individuals With Chronic Ankle Instability: A Systematic Review

Abstract

Objective To conduct a systematic review of existing literature of cross-education balance effects after unilateral training in the CAI population. Data Sources PubMed, SPORTDiscus, CINAHL Plus Study Selection To be included in the systematic review, studies were required to be published in English, include participants with chronic ankle instability, have participants undergo a unilateral therapeutic exercise for the lower extremity, and measure balance performance on the untrained lower extremity before and after the intervention. Data Extraction The certainty of evidence within each included study was assessed via the Downs and Black checklist. A score of 24–28 is “excellent” or “very low risk of bias,” 19–23 is “good” or “low risk of bias”, 14–18 is “fair” or “moderate risk of bias”, and less than 14 is “poor” or “high risk of bias.” We extracted information from each included study regarding their design, participant characteristics, inclusion criteria, independent and dependent variables, intervention, and results. Baseline and post-intervention balance performance data for participants' untrained limbs were used to calculate Hedge's g effect size and 95% confidence intervals. Data Synthesis Our search returned six studies that met the inclusion criteria. The articles' risk of bias ranged from high to low (11–19). Four of five studies that examined unilateral balance training reported a cross-education effect occurred. The lone study that examined resistance training at the ankle joint also reported a cross-education effect occurred. Several cross-education effects were associated with large effect sizes. This study was limited by a small number of studies that varied in methodology and quality. Conclusions The results of this systematic review suggest that unilateral therapeutic exercise can improve balance performance on the untrained limb of individuals with CAI. More work is needed to determine which training parameters are most effective for generating a cross-education effect.

Cross-Education Effects of Hip Strengthening in Individuals with Chronic Ankle Instability

“…Moreover, hip strengthening in a cohort with CAI led to improved balance performance of the ipsilateral limb (10). In regard to previous evidence of cross-education effects in the CAI population, our current findings remain mostly incongruous with others that reported cross-education effects were achieved in this population (19). However, most studies reported contralateral improvements in balance performance only after a unilateral balance training protocol.…”

“…To determine need, we encourage clinicians to complete bilateral assessments of outcomes, because impairments in those with CAI may occur unilaterally or bilaterally (11,12). Although unilateral balance training may alleviate bilateral impairments (19), we did not find that hip strength produced the same cross-education effects. Balance training and hip strengthening are established as effective interventions for CAI patients (10,31), although the value of lumbopelvic stabilization exercises in this population is not entirely clear.…”

“…The performance of unilateral exercises controlled by the contralateral cerebral hemisphere results in activation of the ipsilateral cerebral hemisphere and, ultimately, performance gains in the contralateral limb (18). A recent systematic review investigating cross-education in individuals with CAI concluded that unilateral balance training and ankle joint strengthening effectively improved balance performance in the contralateral limb (19). Although cross-education has shown promise for those with CAI, it remains unknown if unilateral hip strengthening leads to a cross-education effect in this population.…”

Effect of Using Different Intensities in Resistance Training for Muscle Hypertrophy Gains—A Narrative Review

“…However, more studies are needed to differentiate such results from what is observed during the cross-education effect. This mechanism is very well described in the literature and may have influenced the results related to strength improvement and anabolic environment (29).…”

Responsiveness of monopodal postural stability tests in recreational athletes

“…A possible explanation is that the balance intervention on the dominant lower limb favours it going further during the mSEBT when it is not the support lower limb. Another possible mechanism is the effect of cross-education, which is defined as adaptation of an untrained limb after unilateral training of the contralateral limb ( Son & Kang, 2020 ) and whose improvements appear to reflect use-dependent plasticity within the central nervous system ( i.e ., interhemispheric communication in the brain, primarily through the corpus callosum) ( Lawry-Popelka, Chung & McCann, 2022 ).…”