Chronic ankle instability refers to a combination of persistent mechanical and functional instability symptoms following an ankle sprain. Along with these symptoms, decreased proprioception, reduced neuromuscular control, poor postural control, limited dorsiflexion range of motion, decreased ankle strength, and altered lower-extremity biomechanics during functional activities are also observed. In addition, individuals with chronic ankle instability have been shown to exhibit limitations in energy transfer across the lower extremity. These symptoms may hinder patients' physical activity levels and athletic performance and negatively affect their quality of life. Since the lower extremity functions as a unit, changes in adaptive strategies at the ankle can lead to kinematic alterations in proximal joints. Although the instability originates at the ankle, higher-level joints are also affected, and it has even been reported that in this population, lower-extremity stability is primarily achieved through the hip joint. While the effectiveness of hip-focused exercises has begun to be investigated in the literature, the superiority of different muscle groups has not yet been compared.

Chronic ankle instability is characterized by persistent mechanical and functional impairments that may develop following a lateral ankle sprain. Individuals with this condition commonly exhibit reduced proprioception, impaired neuromuscular control, limited dorsiflexion range of motion, and altered lower-extremity biomechanics, all of which may negatively affect daily activities and athletic performance. These deficits often lead to compensatory strategies at more proximal segments, and emerging evidence suggests that hip musculature plays a meaningful role in maintaining dynamic ankle stability. However, the specific contribution of individual hip muscle groups has not yet been clearly defined.

This study is designed to compare the effects of strengthening different hip muscle groups -the gluteus medius and gluteus maximus- on functional and neuromuscular outcomes in individuals with chronic ankle instability. Participants will be randomly assigned to one of three parallel groups: a gluteus medius strengthening group, a gluteus maximus strengthening group, or a control group performing standard balance exercises. Each intervention group will follow a structured and progressively loaded exercise program targeting the designated muscle group. All participants will complete supervised training sessions throughout the intervention period.

The study protocol includes a baseline assessment session, a multi-week intervention phase, and a post-intervention evaluation. Outcome measures will include functional performance tests, assessments of neuromuscular control, and metrics related to dynamic stability. These outcomes will be collected before and after the intervention to determine differences between groups.

The aim of this protocol is to determine whether targeted strengthening of specific hip muscle groups yields superior improvements in individuals with chronic ankle instability. The findings are expected to enhance understanding of the role of proximal musculature in lower-extremity stability and contribute to more precise and effective rehabilitation strategies for this population.

Inclusion Criteria:

Professional athletes aged between 18 and 40 years

Participation in sports for at least 3 years

History of at least one lateral ankle sprain that occurred at least 12 months prior to enrollment

At least two episodes of perceived ankle "giving way" and/or at least two recurrent lateral ankle sprains within the past 6 months, and/or a subjective feeling of ankle instability on the injured side

Exclusion Criteria:

History of lower extremity surgery

History of fracture involving the lower extremity

Any lower extremity injury within the past 3 months that limited physical activity for more than one day

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