Abstract: OBJECTIVE: Chronic ankle instability is mainly characterized by symptoms such as muscle weakness, intermittent pain, and repeated sprains, which seriously affect exercise and daily life. Loss of proprioception, prolongation of fibular reaction time, and weakening of valgus force may be the main symptoms of chronic ankle instability, so exercise intervention can effectively improve the symptoms related to ankle instability. Meta-analysis was used to quantitatively evaluate the effect of balance training on the rehabilitation intervention of chronic ankle instability, providing a reliable theoretical basis and practical basis for chronic ankle instability patients to scientifically formulate exercise prescriptions.
METHODS: The randomized controlled trial of balance training on symptom rehabilitation and dynamic equilibrium of patients with chronic ankle instability was retrieved on CNKI, VIP, Web of Science, and PubMed. The literature was published from the inception to November 23, 2022. Two reviewers were included to evaluate the quality of the included literature based on the physical therapy evidence scale. The primary outcome measure is the Self Functional Rating Scale, and the secondary outcome measure is the Star Shift Balance Test, both of which are continuous variables. Forest mapping, meta-regression, subgroup analysis, sensitivity analysis, and publication bias evaluation were performed on the included literature using RevMan 5.3 and Stata-SE 15 software.  
RESULTS: (1) A total of 18 articles of randomized controlled trials were screened and 641 patients with chronic ankle instability were included in the study. Overall, the methodological quality of the literature was relatively high. (2) Meta-analysis results showed that balance training improved the functional rehabilitation effect of chronic ankle instability patients (SMD=0.82, 95%CI:0.41-1.23, P < 0.000 1). Meta-regression exhibited that intervention time might be the main reason for heterogeneity (P=0.008). (3) The subgroup analysis results revealed that 6 weeks of intervention (SMD=0.98, 95%CI:0.31-1.65, P=0.03), more than 3 interventions per week (SMD=0.87, 95%CI:0.30-1.44, P=0.003), and each intervention time less than 20 minutes (SMD=0.89, 95%CI:0.61-1.66, P < 0.000 1) were the best rehabilitation plans to improve the functional rehabilitation effect of chronic ankle instability patients. (4) Meta-analysis results also showed that balance training improved the stretching degree of the anterior side (SMD=0.56, 95%CI:0.31-0.80, P < 0.05), posterior inner side (SMD=0.88, 95%CI:0.45-1.32, P < 0.05), and posterior outer side (SMD=0.84, 95%CI:0.22-1.46, P < 0.05) of the star shift balance test.
CONCLUSION: Current clinical evidence shows that balance training can improve ankle instability symptoms and elevate dynamic equilibrium ability in chronic ankle instability patients. It is recommended to intervene more than 3 times a week, with each intervention lasting less than 20 minutes, to achieve better rehabilitation effects. 

Key words: chronic ankle instability, balance training, dynamic balance ability, functional rehabilitation, star excursion balance test, self-reported function scale, meta-analysis, ankle injury, neuromuscular control, proprioception