Adding secondary cognitive tasks to drop vertical jumps alters the landing mechanics of athletes with anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) reinjury rates among athletes remain very high despite screening protocols designed to assess readiness for return to sport. To better identify biomechanical risk factors for ACL injury, combining neurocognitive challenges and high-impact tasks would more closely resemble sporting demands. We investigated the influence of secondary cognitive tasks on landing mechanics during bilateral drop vertical jumps (DVJs) among athletes following ACL reconstruction and whether sex affected these results. We also assessed whether adding secondary cognitive tasks to DVJs influenced loading asymmetries. Forty individuals (20 males) performed three DVJ conditions: (1) without secondary cognitive tasks (DVJ), (2) with secondary cognitive tasks targeting fast decision-making and inhibitory control of the motor action (DVJmot), and (3) with secondary cognitive tasks targeting fast decision-making, inhibitory control, attention, and short-term memory (DVJcogmot). We collected movement mechanics time-series data during the first 100 ms of landing using a motion capture system and force plates and compared outcomes between the three DVJs using functional t-tests. Secondary cognitive tasks altered trunk, hip, knee, and ankle landing mechanics (adjusted p-values < 0.05), representing more upright and stiffer landings. Loading asymmetries were increased by unloading the injured limb (adjusted p-values < 0.05). We found no differences between DVJmot and DVJcogmot or between males and females. Adding secondary cognitive tasks to DVJs better identifies landing mechanics associated with an increased ACL injury risk and inadequate rehabilitation. Future research should focus on optimizing the challenge point of the cognitive and motor tasks and how to best integrate them in RTS testing.