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Standing on one leg, reach the free foot as far as possible in three directions (anterior, posteromedial, posterolateral); normalized reach distances and side-to-side asymmetry index dynamic balance and injury risk.
The Y-Balance Test (YBT) is a standardized, instrumented version of the Star Excursion Balance Test (SEBT). The participant balances on one leg on a central platform and pushes a reach-indicator as far as possible with the free foot in three directions: anterior (A), posteromedial (PM), and posterolateral (PL) (the three arms form a "Y"). An upper-quarter version exists for the shoulder/trunk.
Protocol: practice trials, then record the maximum reach (cm) in each direction per leg (best of 3), reaching without touching down, losing balance, or kicking the indicator. Normalize each reach to limb length (reach ÷ limb length × 100) and compute a composite score = (A + PM + PL) / (3 × limb length) × 100%.
Interpretation: used for dynamic balance and injury-risk screening. Reported risk markers: anterior-reach asymmetry > ~4 cm between legs, and a composite score below ~89–94% (population-dependent) associate with higher lower-extremity injury risk. (cut-points vary by sport/population) Standardize footwear, instructions, and the same tester for re-tests.
Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.