Lower-Quarter Y-Balance Test Differs by Age: Younger Athletes May Not Be Generalized to High School-Aged Counterparts.

Background: Given rising youth sport participation, 8 to 10-year-olds increasingly display comparable lower-extremity injury incidence to 11 to 17-year-olds and require effective return to sport criteria. One such criterion which quantifies dynamic stability is the Y-Balance Test (YBT), though it has not been validated in children under age 11. Hypothesis/Purpose: The purpose of this study was to examine the performance of 8 to 10-year-old patients on the YBT after lower-extremity injury and determine how these results compare to larger samples of age-grouped athletes within the validated 11 to 17-year-old range. It was hypothesized that 8 to 10-year-olds would display different normalized YBT distances compared to 11 to 17-year-olds. Study Design: Cross-sectional Study. Methods: Patients (N=1093) aged 8 to 17 who presented to a pediatric sports medicine practice with a lower-extremity injury and completed the YBT between December 2015-May 2021 were included. Anterior, posteromedial, and posterolateral YBT scores were collected at return-to-sport for affected and unaffected limbs. Scores were normalized to limb length, and composite scores were created. Between-limb differences were calculated in groups of ages 8-10, 11-12, 13-14, and 15-17. Groups were also evaluated for differences by sex. Results: A rise in performance was observed in unaffected limb anterior reach from ages 8 to 10 years to 11 to 12 years followed by a subsequent significant decrease at older ages (p<0.001). Affected limb anterior reach differed between the youngest group and two oldest groups (p=0.004). Anterior and composite difference were significantly different between the oldest three groups (p=0.014 anterior; p=0.024 composite). No differences were observed between sexes in 8 to 10-year-olds, though 11 to 12-year-old females reached further during all eight distances. In the older three groups, males generally displayed greater between-limb differences. Conclusion: YBT scores, specifically anterior reach, demonstrated inconsistency by age and sex across a large adolescent cohort. Existing return-to-sport standards should not be used with younger athletes, and individual validation is required. Level of Evidence: Level III.