Investigation of the Relationship Between Frontal Plane Knee Projection Angle and Dynamic Balance, Agility, and Ankle Dorsiflexion Mobility in Adolescent Female Volleyball Players

This observational, cross-sectional study aims to investigate the relationship between frontal plane knee projection angle (FPPA), dynamic balance, agility performance, and ankle dorsiflexion mobility in adolescent female volleyball players. Volleyball is a sport that requires repeated jumping, landing, lateral movements, and rapid changes of direction, which place considerable biomechanical demands on the lower extremities. In adolescent female athletes, lower-limb movement patterns may be influenced by growth, maturation, and neuromuscular control, making this population important for biomechanical assessment.

The primary study variable will be frontal plane knee projection angle, assessed during a single-leg squat using two-dimensional video analysis. Secondary measures will include dynamic balance assessed with the Lower Quarter Y-Balance Test, agility assessed with the T-Test, and ankle dorsiflexion mobility assessed with the Weight-Bearing Lunge Test. All assessments will be completed in a single session under standardized field conditions. No intervention, treatment, or experimental exercise program will be applied.

The study is designed to explore whether frontal plane knee alignment is associated with functional performance measures in adolescent female volleyball players. A better understanding of these relationships may contribute to the identification of biomechanical characteristics related to lower-extremity movement quality and potential injury risk in this population.