Evaluation of the Accuracy of the Postural Stability Measurement with the Y-Balance Test Based on the Levels of the Biomechanical Parameters of 14-Year-Old Girls.

Background: Dynamic balance monitoring involves the assessment of the muscular control during changes of the centre of gravity location in space above the supporting plane. We aimed to determine the structure of the Y-Balance Test and its accuracy based on measurements of strength and resistance to fatigue of muscles acting on the knee joint under static conditions, as well as joint motion ranges and static balance in girls aged 14 years. Methods: The study included 40 girls aged 14, who attended Gymnasium No. 2 in Cracow (Poland). The research was conducted in October 2020. Postural stability was examined with the use of the YBT. The measurements of muscle strength and knee joint extensor and flexor resistance to fatigue during an isometric contraction were performed in a standard position on the test bench. The measurements of lower extremity joint range of motion were performed in accordance with the SFTR methodology. Static balance was assessed with the use of the modified FBT. Results: The factor structure obtained for both lower extremities has satisfactorily explained the common variance (about 70%) and showed slight differences between the left and right extremities. Conclusion: The factor structure in the group of examined girls suggests a highly hybrid nature of the Y-Balance Test with a wide spectrum of biomechanical variables that have little influence on the measurement results.