The goal of this interventional trial is to evaluate the effectiveness of the simplified four-week Tai Chi training in improving function in people with chronic ankle instability. The main questions it aims to answer are:

1. Does the 4-week Tai Chi training improve ankle neuromuscular responses?
2. Does the 4-week Tai Chi training enhance ankle proprioception?
3. Does the 4-week Tai Chi training improve ankle muscle strength？
4. Does the 4-week Tai Chi training boost balance performance？
5. Does the 4-week Tai Chi training enhance subjective ankle stability and quality of life?

Researchers will compare Tai Chi training to self-management to see if this Tai Chi training works to enhance ankle stability performance.

Participants will:

1. Take self-management and Tai Chi training, and each for 4 weeks
2. Visit the labs every 4 weeks for biomechanical measurements and questionnaires, totally 3 times.

Tai Chi is a traditional Chinese exercise practiced by millions worldwide to stay active and improve health. Based on muscle activation levels across the full set of movements (108 forms), we developed a simplified 16-form Tai Chi routine to enhance ankle stability for individuals with chronic ankle instability.

To evaluate the benefits of this simplified 16-form version for ankle function in people with chronic ankle instability, we are recruiting individuals managing symptoms of chronic ankle instability for a 4-week training program and assess their ankle-related function three times. All participants are randomly allocated to both the Tai Chi training group or a self-management control group, while maintaining their usual lifestyle and exercise routines throughout the study. All participants will complete the same training content and assessment tasks; participants in the control group will be offered the Tai Chi training following completion of the second outcome assessment.

The Tai Chi training includes a total of 12 sessions over 4 weeks, with three sessions per week, each lasting 1 hour (10 minutes of warm-up, 45 minutes of Tai Chi practice, and a 5-minute cool down). Each of the three functional assessments will include consistent measures, including muscle activation, proprioception, muscle strength, balance testing, and self-assessment scales (ankle function and quality of life).

Inclusion criteria:

• Aged from 18 to 40
• A history of at least one significant lateral ankle sprain was associated with inflammatory symptoms (pain, swelling, etc) and disrupted activity
• The initial sprain must have occurred at least 12 months prior to study enrolment
• The most recent injury must have occurred more than 3 months prior to study enrolment
• Reports of feeling instable or "giving way" during daily activities or physical activities and experienced at least 2 episodes in the 6 months prior to study enrolment
• Scoring ≤25 on the Cumberland Ankle Instability Tool

Exclusion criteria:

• Any previous fractures or surgeries on the lower limbs
• Have other muscle, joint or nerve disorders that affect the function of the lower limbs
• Chest pain at rest, dizziness during rest, heart condition, or doctor's advice not to exercise without medical supervision
• Currently enrolled in other ankle rehabilitation programmes
• Already a Tai Chi practitioner
• Pregnant
• Allergic to adhesive tapes

Individual participant data (IPD) will not be shared due to privacy concerns and institutional data protection policies.