THE RELATIONSHIP BETWEEN Y-BALANCE TEST SCORES AND KNEE MOMENTS DURING SINGLE-LEG JUMP-LANDING IN NETBALL.

BACKGROUND: Using 3-dimensional motion analysis to derive knee moments that may contribute to non-contact anterior cruciate ligament (ACL) injuries during single-leg jump-landing is expensive and time consuming. Severe ACL injuries that are inappropriately rehabilitated can potentially end athletes' careers. Consequently, a quick-and-simple to administer screening tool that can be used to infer knee moments during single-leg jump-landing could be useful for regular screening of netballers' predispositions to increased knee loading during single-leg jump-landing.
PURPOSE: The purpose of this study was to investigate whether knee moments during weight-acceptance phase of a forward single-leg jump for maximal distance were correlated with reach scores in the Y-Balance Test (YBT). STUDY
DESIGN: Cross-sectional, Correlation.
METHODS: Twenty-one female national-level netballers performed two and three successful trials on the YBT and forward single-leg jump-landing, respectively, with the non-dominant leg. A three-dimensional motion analysis system captured trunk and lower limb kinematics and ground reaction forces of the non-dominant leg during landing. Averages of peak knee flexion-extension, valgus-varus and internal-external rotation moments across jumps were calculated and correlations with peak directional reach scores were examined.
RESULTS: A strong positive correlation existed between posteromedial reach with externally applied flexor moments (r = 0.56, p = ≤ 0.01). A moderate negative correlation existed between anterior reach distances with internal rotation moments (T b = -0.32, p = 0.05). No correlation was found between valgus moments and YBT reaches.
CONCLUSIONS: The YBT shows potential to indicate externally applied flexion- and internal rotation moments during forward jump-landing on the non-dominant leg. LEVEL OF EVIDENCE: 3.