The effect of adding a tuck to the drop vertical jump test in collegiate soccer players

BACKGROUND: Anterior cruciate ligament (ACL) injuries are one of the most common sports-related injuries in female athletes. Thirty-two percent of all women soccer players sustain ACL tears at the collegiate level and most injuries occur during competition. Validated and reliable tools like the drop vertical jump (DJ) assess ACL injury risk; however, the current screening tools may not be complex enough to simulate landing during competitive play. A tuck jump is a more complex task than a DJ and by adding a tuck to the drop vertical jump test may provide more game-like landing mechanics to the ACL risk screening. The aim of this study was to investigate the effects of adding a tuck to the drop vertical jump on the landing mechanics of college soccer athletes. METHODS: Twenty-three subjects from two intercollegiate soccer teams (9 men, 14 women) completed testing. After a dynamic warmup, participants were outfitted with markers on their lower extremities to measure joint angles. The athletes performed three trials of both the standard DJ and the drop tuck jump (TJ) in randomized order. Two digital cameras (60 Hz, 720 d) recorded landing mechanics in the frontal and sagittal planes. Data processing (2D) was completed using video analysis software (Dartfish USA, Alpharetta, GA, USA). Initial knee flexion angle, maximum knee flexion angle (MKFA), and maximum frontal plane projection angle (at MKFA) were measured and analyzed during first (drop) and second (jump) landings. Data were compared between genders and jump landings. Analysis was performed using MANOVA on SPSS (SPSS Inc., Chicago, IL, USA; P<0.05). Effect size and CV% were also calculated. RESULTS: The TJ resulted in a significantly larger knee flexion angle at initial contact (IC) of the jump landing as compared to the DJ (P<0.05). Maximal knee flexion showed no significant differences between the DJ and TJ in either the drop or jump landings (P>0.05). No significant differences were found between the TJ and DJ in either knee flexion at IC of the drop landing or frontal plane projection angle (FPPA ) (P>0.05). CONCLUSIONS: In the frontal plane, the TJ demonstrated similar results to the DJ. In the sagittal plane, IC knee flexion after jumping was greater during the TJ. This is consistent with previous research which found an increase in maximal knee flexion during landing of more complex tasks. Additionally, there was no difference in knee flexion at initial contact of the drop landing which is most likely due to the jump procedure being identical up through that point. Further research with a larger number of subjects from additional at-risk sports is needed. The TJ promotes greater initial contact knee flexion during the jump landing. Landing in smaller knee flexion angles results in larger forces on the ACL increasing risk of injury. Therefore, the TJ may be a good training tool to promote landing in greater knee flexion when performing jumping tasks.