LAUSR

CONTEXT Kinetic profiles of athletes performing the tuck jump assessment (TJA) are unknown and may provide insight into the risk of anterior cruciate ligament injury. DESIGN The purpose of this study was to (1) analyze vertical kinetics of the TJA and (2) determine the stabilization of the kinetics across successive jumping cycles. METHODS Twenty-five healthy female athletes (age = 22.0 [4.6] y; height = 1.69 [0.07] m; body mass = 69.3 [10.3] kg) completed one trial of repeated tuck jumps on a force plate for 10 seconds. RESULTS Vertical ground reaction force data were used to calculate the following variables across all jump cycles: time of jump cycle (0.65 [0.04] s), ground contact time (0.22 [0.03] s), flight time (0.43 [0.04] s), duty factor (0.34 [0.05]), jump height (0.23 [0.04] m), peak vertical force (5.52 [0.91] body weight [BW]), peak center of mass displacement (0.15 [0.02] m), vertical leg stiffness (27.09 [7.06] BW·m-1), vertical average loading rate (105.94 [28.43] BW·s-1), vertical instantaneous loading rate (140.90 [28.49] BW·s-1), and net impulse (0.43 [0.03] BW·s). A sequential averaging technique indicated a minimum of 11 jumps were required for stabilization of the kinetics. CONCLUSIONS The TJA exposes athletes to high magnitudes of vertical force. Based on the high variability of performance during early repetitions and the potential to miscategorize high-risk landing in female athletes, practitioners should consider scoring the TJA after 11 successive cycles and using kinetic profiling to support landing assessments.