Kinematic Differences Between Landing Phase During Double And Single Leg Jumping Tasks

Abstract

Anterior cruciate ligament (ACL) injury risk is often examined using the initial landing/takeoff phase following a drop off a box during a drop vertical jump (DVJ) task, while the second landing after maximum jump is not typically examined. As ACL injuries are frequently sustained during similar rapid deceleration maneuvers, the second landing during a DVJ and a single leg countermovement (SLC) jump may better simulate injury risk mechanics. PURPOSE: To investigate differences between landing phases during double and single leg jumping tasks. METHODS: 15 collegiate basketball players (height: 180.8 ± 14.0 cm, mass: 80.8 ± 19.0 kg) completed 3 DVJ and 3 maximum SLC jumps on each limb. Takeoff phase (TO) was defined as the first jump/landing and the landing phase (LN) was defined as the second landing for each task. High performance (HP) side was determined as the limb with the highest SLC jump compared to the low performance (LP) side. Standard 3D motion analysis was used to determine joint kinematics at peak knee flexion during each phase. A two-factor repeated measures ANOVA (p < 0.05) was used to determine differences between phase (TO, LN) and side (HP, LP). RESULTS: A main effect of phase during the DVJ was found for knee flexion (p < 0.001, TO: -83.1 ± 10.6°, LN: -68.6 ± 10.8°), knee abduction (p = 0.004, TO: -7.4 ± 5.2°, LN: -4.7 ± 4.9°), and hip flexion (p < 0.001, TO: 60.5 ± 11.7°, LN: 37.3 ± 13.1°) with a significant interaction between phase and side for hip adduction (p = 0.015). During the SLC jump, a main effect of phase was found for knee (p = 0.002, TO: -66.2 ± 8.7°, LN: -58.3 ± 10.8°) and hip (p = 0.005, TO: 48.7 ± 15.1°, LN: 35.4 ± 10.0°) flexion. A main effect of side was found for hip adduction (p = 0.029, HP: 5.3 ± 6.5°, LP: 8.4 ± 6.7°). No significant main effects were present for knee abduction during the SLC (p > 0.05). CONCLUSIONS: Collegiate basketball players exhibit greater knee and hip flexion and knee abduction during the initial land of the DVJ compared to the landing following maximum jump. Similarly, players also exhibit greater knee and hip flexion during the takeoff phase of a single leg task compared to the landing. However, they exhibit lower hip adduction on their higher performing limb. Between phase differences of each task outline the importance of identifying high-risk mechanics during both takeoff and landing.