The goal of this clinical trial is to evaluate the immediate effects of rigid subtalar sling taping, kinesio subtalar sling taping, and sham taping on balance, proprioception, ankle mobility, and functional performance in physically active adults with chronic ankle instability.

The main questions it aims to answer are:

• Does rigid subtalar sling taping improve dynamic balance, ankle proprioception, ankle dorsiflexion mobility, and functional performance in individuals with chronic ankle instability?
• Does rigid subtalar sling taping provide greater benefits than kinesio subtalar sling taping or sham taping under fatigue and recovery conditions?

Researchers will compare rigid subtalar sling taping, kinesio subtalar sling taping, and sham taping to determine their effects on balance, proprioception, ankle mobility, and functional performance before fatigue, after fatigue, and following recovery.

Participants will:

• Complete baseline assessments of dynamic balance, ankle proprioception, ankle dorsiflexion mobility, and functional performance.
• Be randomly assigned to receive rigid subtalar sling taping, kinesio subtalar sling taping, or sham taping.
• Repeat all outcome assessments immediately after tape application.
• Perform a standardized fatigue protocol consisting of running, hopping, jumping, and heel-raise exercises until predefined fatigue criteria are reached.
• Complete all outcome assessments immediately after the fatigue protocol.
• Rest in a seated position for 20 minutes.
• Complete a final set of outcome assessments following recovery.

The study aims to identify whether subtalar sling taping can improve functional performance and neuromuscular control in physically active individuals with chronic ankle instability and whether these effects are maintained after fatigue and recovery.

Chronic ankle instability (CAI) is a common long-term consequence of lateral ankle sprains and is characterized by recurrent episodes of ankle giving way, impaired sensorimotor control, reduced dynamic balance, and functional limitations during physical activity. Persistent deficits in proprioception, postural control, and movement performance may increase the risk of recurrent injury and negatively affect participation in sports and recreational activities.

External ankle support strategies are frequently used to improve stability and reduce the risk of recurrent ankle sprains. Among these strategies, rigid taping and kinesio taping are widely applied in both rehabilitation and sports settings. Rigid taping is primarily intended to provide mechanical support and limit excessive joint motion, whereas kinesio taping is believed to enhance sensorimotor function through cutaneous stimulation and improved neuromuscular feedback. Despite their widespread use, evidence regarding their comparative effectiveness remains inconsistent, particularly under fatigue conditions.

Fatigue is considered an important contributor to injury risk because it may impair proprioception, dynamic balance, joint stability, and functional performance. Since many ankle sprains occur during the later stages of physical activity when fatigue is present, understanding whether taping interventions can preserve performance under fatigue may have important implications for injury prevention and rehabilitation.

This randomized controlled trial was designed to compare the immediate and fatigue-related effects of rigid subtalar sling taping, kinesio subtalar sling taping, and sham taping in physically active individuals with chronic ankle instability. Assessments were performed before intervention, immediately after tape application, following a standardized fatigue protocol, and after a recovery period to evaluate both immediate responses and the ability of the interventions to maintain performance under physiologically demanding conditions.

The findings of this study may contribute to evidence-based recommendations regarding taping applications for individuals with chronic ankle instability and may help clinicians select appropriate external support strategies during rehabilitation, return-to-sport decision-making, and injury prevention programs.

Inclusion Criteria:

• Age between 18 and 35 years.
• Physically active individuals participating in physical activity at least three times per week.
• History of at least one significant lateral ankle sprain.
• Self-reported episodes of ankle giving way, recurrent sprains, or feelings of instability during the previous six months.
• Cumberland Ankle Instability Tool (CAIT) score ≤24.
• Ability to understand study procedures and provide written informed consent.

Exclusion Criteria:

• Acute lower-extremity injury within the previous three months.
• Previous lower-extremity fracture requiring surgical management.
• History of lower-extremity surgery.
• Vestibular, neurological, or systemic disorders affecting balance, movement, or proprioception.
• Current musculoskeletal pain that limits participation in testing procedures.
• Known allergy or sensitivity to adhesive tape materials.
• Participation in another rehabilitation or intervention study during the study period.
• Inability to complete the fatigue protocol or functional performance assessments safely.

De-identified individual participant data underlying the results reported in this study will be available upon reasonable request to the corresponding author.

Participants will be blinded to group allocation. Outcome assessments will be conducted by an assessor who is unaware of participant group assignment. The investigator responsible for tape application cannot be blinded due to the nature of the interventions and will not be involved in outcome assessment or statistical analysis.