This study will evaluate whether tissue flossing with different pressure levels, when combined with exercise training, improves ankle function in young adults with chronic ankle instability. Forty-eight participants will be randomly assigned to one of three groups: a control exercise group, a 150 mmHg tissue flossing plus exercise group, or a 200 mmHg tissue flossing plus exercise group. All groups will complete the same 6-week rehabilitation program, three times per week. Outcomes will be assessed at baseline and after the intervention, and long-term follow-up data will also be collected.

Chronic ankle instability is characterized by recurrent ankle sprains, a feeling of giving way, pain, swelling, reduced function, and impaired balance control. Exercise-based rehabilitation is a cornerstone of nonoperative management, but adjunctive strategies that may enhance recovery remain of interest.

Tissue flossing is a compression-based intervention in which an elastic band is wrapped around the target joint or limb segment during exercise. It may influence mobility, neuromuscular control, proprioception, and symptom perception. However, the optimal pressure level for long-term rehabilitation in chronic ankle instability remains unclear.

This single-center, assessor-blinded, three-arm parallel randomized controlled trial will be conducted at Chengdu Sport University. A total of 48 young adults with chronic ankle instability will be allocated in a 1:1:1 ratio to a control exercise group, a 150 mmHg tissue flossing plus exercise group, or a 200 mmHg tissue flossing plus exercise group. All participants will complete the same 6-week rehabilitation program, with 3 sessions per week and 18 sessions in total. The two tissue flossing groups will receive pressure-calibrated flossing during the main training phase, while the control group will perform the same exercises without compression.

The primary outcome will be the change in Foot and Ankle Ability Measure Activities of Daily Living score from baseline to 6 weeks. Secondary outcomes will include sport-related foot and ankle function, functional movement screening, ankle range of motion, ankle isometric strength, Biodex balance-related measures, pain, long-term follow-up outcomes, adherence, and adverse events.

Inclusion Criteria:

• Young adults aged 18 to 30 years.
• History of at least one recurrent ankle sprain or repeated episodes of ankle giving way in the affected limb.
• Subjective ankle instability, with or without pain, swelling, or activity limitation.
• Reduced balance ability, movement ability, or foot and ankle function on screening assessment.
• Symptoms lasting at least 6 months.
• No recent structured ankle rehabilitation before enrollment.
• No plan for vigorous additional exercise during the intervention period.
• Willing to participate and able to provide informed consent.

Exclusion Criteria:

• Latex allergy or intolerance to floss band material.
• Previous ankle dislocation, fracture, complete ligament rupture, or other severe structural injury.
• Most recent ankle sprain within 1 month before enrollment.
• Recent ankle surgery or acute ankle injury.
• Receipt of other ankle-related treatment, rehabilitation, or additional training during the study period.
• Diabetes, hyperlipidemia, or other conditions that may affect vascular status.
• Neurological disease, major musculoskeletal disease, vestibular disorder, visual disorder, or other lower-limb conditions that could affect assessment.
• Determined by the study physician or investigator to be unsuitable for participation.

Outcome assessments will be performed by an assessor blinded to group allocation. Because the pressure intervention is perceptible, participants and the treating therapist will not be blinded.