Background: Lower extremity injuries account for 32.9% of the overall injuries in high school athletes. Previous research has suggested that asymmetry greater than 4 cm using the Y-Balance Test™ Lower Quarter (YBT-LQ) in the anterior direction is predictive of non-contact injuries in adults and collegiate athletes. The prevalence of asymmetries or abnormal YBT-LQ performance is not well documented for adolescents. The primary purposes of this study are: 1) to characterize the prevalence of YBT-LQ asymmetries and performance in a cross-sectional sample of adolescents; 2) to examine possible differences in performance on the YBT-LQ between male and female adolescents; and 3) to describe the test-retest reliability of the YBT-LQ in a subsample of adolescents.
Methods: Observational cross-sectional study. High-school athletes completed the YBT-LQ as main outcome measure.
Results: A total of 51 male and 59 female high-school athletes participated in this study. Asymmetries greater than 4cm in the posteromedial (PM) reach direction were most prevalent for male (54.9%) and female (50.8%) participants. Females presented with slightly higher composite scores. Good reliability (ICC=0.89) was found for the anterior (ANT) direction, and moderate reliability with 0.76 for posterolateral (PL) and 0.63 for PM directions. The MDC95 for the ANT direction was 6% and 12% for both the PL and PM directions.
Conclusions: The YBT-LQ performance can be beneficial in assessing recovery in an injured extremity compared to the other limb. However, due to the large MDC95, noted in the PM and PL directions, the differences between sequential testing cannot be attributed to true change in balance unless they exceed the MDC95. In this study, 79% of the athletes presented with at least one asymmetry in YBT-LQ reach distances. Moderate reliability in the PL and PM directions warrants reexamination of the definition of asymmetry in these directions.