Ankle sprains are the most common injury in basketball, especially involving repetitive maneuvers such as acceleration, deceleration, jumping, and landing. The incidence of ankle sprain is 40% in female basketball players and 75% in male basketball players. It is also known that chronic ankle instability (CAI) develops in 20-40% of cases. The effects of chronic ankle instability on core stabilization, dynamic balance and agility in basketball players have been investigated in the literature, and it has been stated that more studies are needed on the subject.

The aim of this study is to examine the effects of chronic ankle instability on core stabilization, dynamic balance and agility in basketball players playing in the university team.

The hypothesis of the study is that there is a difference between core stabilization, dynamic balance and agility values of basketball players playing in the university team with and without chronic ankle instability.

Approximately 10% to 28% of all sports injuries are ankle sprains. Ankle sprains are the most common injury in basketball, especially involving repetitive maneuvers such as acceleration, deceleration, jumping, and landing. The incidence of ankle sprain is 40% in female basketball players and 75% in male basketball players. It is also known that chronic ankle instability (CAI) develops in 20-40% of cases. People with CAI have several types of deficits, including decreased ankle range of motion, decreased ankle arthrokinematic quality of movement, problems with postural control and strength, impaired proprioception and neuromuscular control, and altered gait patterns. These problems can cause loss of matches, increase in health expenditures and future injuries in athletes. Postural control disorders that play a role in the regulation of balance have been shown to be common in people with CAI and after acute lateral ankle sprain. Postural control requires somatosensory, visual and vestibular stimuli and appropriate motor response to generate the appropriate balance response. In individuals with CAI, the ankle joint and postural control mechanisms that cannot receive appropriate afferent stimulation and cannot reveal the correct efferent stimulation from the central nervous system are impaired.

Agility, the ability to make rapid changes in the direction of movement, is widely regarded as an important criterion for success in basketball. Agility tests require rapid deceleration, change of direction, and reacceleration during movements. Such activities put athletes in a condition that can force the ankle complex into excessive inversion and plantar flexion, which often causes ankle sprain.

The relationship between chronic ankle instability and athletic performance parameters has been investigated in previous studies. However, the relationship between chronic ankle instability and athletic performance parameters has not yet been fully explained, and it has been stated that more studies are needed on the subject.

Core stability is the motor control and muscle capacity of the lumbopelvic complex. Studies have shown that weakness in the core musculature can predispose an athlete to injury, including ankle sprains. Subjects with a history of lower extremity injuries require more trunk muscle contractions to stabilize the body during dynamic tasks compared to healthy subjects. Therefore, core muscles are an important element to be evaluated in athletes with chronic ankle instability. Although the relationship between chronic ankle instability and the strength of the core muscles has been examined in the literature, the relationship between them has not been fully explained.

In this study, the relationship between chronic ankle instability and core stabilization, dynamic balance and agility in Yeditepe University basketball players will be discussed and the results will be presented.

The power analysis of the research was made using the G*Power 3.1 program. The power of the study was determined as 80%. In a similar study, the mean of the Y balance test in individuals with chronic ankle instability was reported as 86.61, standard deviation of 3.98, and standard deviation of 9.51 in individuals without chronic ankle instability. Based on these values, power analysis was made with the G*Power 3.1 program. As a result of the analysis made with 80% power, the number of participants in the experimental and control groups was determined as 10 for each group.

SPSS (version 22.0) will be used in the data analysis of our research. Quantitative data to be obtained from the research will be shown as mean and standard deviation. Kolmogorov-Smirnov test will be used to test numerical variables for normality. According to the conformity of the obtained data to the normal distribution; If the data is normally distributed (parametric), Independent Sample t-test will be used to compare the two groups. If the data are not normally distributed, the Mann-Whitney U test will be used to compare the two groups. Qualitative data of the groups will be displayed with frequency and percentage values. The statistical significance level will be accepted as p<0.05.

Inclusion Criteria:

1. To be a voluntary participant in the research.
2. To be between the ages of 18-25.
3. Experiencing recurrent sprains with inflammatory symptoms (pain, swelling) for individuals in the study group whose initial history of sprains was at least 1 year prior to the study.
4. Playing in the basketball team for at least 1 season.
5. Having a "feeling of insecurity" and instability in the injured ankle as verified by the Cumberland Ankle Instability Tool (CAIT) score of ≤25 for individuals in the research group.
6. For the individuals in the research group, not having experienced an ankle sprain in the last 1 month.

Exclusion Criteria:

1. History of surgery for musculoskeletal structures in both lower extremities
2. History of fracture in both lower extremities
3. Acute injury of the musculoskeletal structures of other joints of the lower extremity affecting joint function and integrity in the last 3 months
4. Presence of bilateral ankle instability
5. Balance or vestibular disorder
6. Abdominal surgery history
7. To have had a musculoskeletal injury of the waist, back and neck in the last 3 months.
8. To have experienced an ankle injury in the last 1 month.

It is planned to include athletes aged 18-25, who play in university basketball teams, with and without chronic ankle instability in our study.

It will include students between the ages of 18-25 who study at Yeditepe University and play in Yeditepe University basketball teams.