Extended Abstract
1.    Introduction
Ankle sprain is one of the most common injuries that occur not only in sports but also in daily life activities, and it is estimated that one person per 10,000 people suffers from an ankle sprain every day (1). The most common factor that causes ankle sprain is a history of previous sprains (2). Lateral ankle sprains usually occur as a result of excessive supination of the ankle while walking or after jumping and landing. Chronic ankle sprain is one of the consequences of sprain in the ankle ligaments and these patients report symptoms such as ankle giving way, pain, and instability. Chronic ankle sprains increase the risk of osteoarthritis and degenerative joint changes (3). Several factors can make individuals susceptible to chronic ankle sprains. One of the disorders that can be observed among people with chronic ankle instability is postural control disorder (1). Balance and coordination exercises are among the most common interventions for the prevention and treatment of ankle sprains (13). In 1965, Freeman stated that balance and coordination exercises would reduce proprioceptive defects in people with ankle sprain (14,15). Balance exercises can be considered as exercises that emphasize awareness of the body position and maintain the center of gravity inside the base of support (16).
2.    Methods
This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (18). The PubMed, Cochrane, Scopus, and PEDro databases were used to identify relevant studies. In addition, a manual search was performed using Google Scholar to identify studies that were not identified in the databases for any reason. The search among studies was performed using the keywords and concepts of postural control, postural sway, postural stability, balance exercises/training, chronic ankle instability/sprain, and functional ankle instability/sprain, until April 2022. The inclusion criteria were all studies that were in English, the full texts of which were available, and the subjects of which were athletes with chronic ankle instability with diagnostic criteria based on the International Ankle Consortium (19). The studies had to include randomized clinical trials, and at least one postural control variable had to be investigated. The exclusion criteria were as follows: studies written in any language other than English, study subjects with acute ankle sprains, and study subjects who were not athletes. Conference studies, seminars, review studies, and letters to the editor were not included in this study. Additionally, the studies were qualitatively evaluated using the PEDro scale.
3.    Results
In the initial search, 1915 studies were identified using the keywords mentioned above. After removing duplicate cases, 1690 studies were reviewed based on the inclusion and exclusion criteria, titles, and abstracts. Finally, nine studies were selected, and after reading the full texts, eight were included in the final analyses. Based on the evaluation of the quality of the studies using the PEDro scale, one study was of poor quality (23), four studies were of moderate quality (24–27) and three studies were of good quality (1,28,29). The average score of the included studies was 5/25 ± 1/29 (Table 1). Among the included studies, six studies investigated the effect of balance exercises on static postural control, and six studies examined the effect of balance exercises on dynamic postural control. The results of these studies showed that balance exercises reduced postural sway, decreased the distribution of center of mass, improved the overall body balance index and anterior-posterior balance index in the Biodex balance system, increased the duration of balance maintenance, and reduced the number of errors in the foot lift test when checking static postural control, and improved the reaching distance in the star balance test when checking dynamic postural control.

4.    Conclusion
The quality of the included studies was moderate, and based on that it can be concluded that balance exercises can improve postural control in athletes with chronic ankle instability whether in static or dynamic conditions. In general, balance exercises can help individuals with chronic ankle instability to control their posture and balance more effectively. This may be due to the nature of closed-chain exercises, by improving the input and output data of the sensory-motor system through the stimulation of the mechanoreceptors of muscles and joints, improving the control of the center of mass, increasing the gamma motor neuron activity, improving muscle activity and co-contraction of agonist and antagonist muscles (1,31).

Ethical Considerations
Compliance with ethical guidelines
There were no ethical considerations to be considered in this research.
Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors.
Authors' contributions
All authors equally contributed to preparing article.
Conflicts of interest
The authors declared no conflict of interest.