Jump-landing mechanics following mid-flight external perturbation: anticipation and core muscle endurance.

The purpose was to quantify the effects of anticipation on landing mechanics associated with ACL loading during double-leg landings following mid-flight medial-lateral pushing perturbation. A total of 11 male and 11 female recreational athletes performed a jump-landing task under three perturbation conditions (no, left, vs. right perturbation) and two anticipation conditions (anticipated vs. unanticipated). The perturbation was created by having researchers throw a medicine ball (5% of body weight at an average speed of 4.4 m/s) to contact the participant's lateral trunk near their maximal jump height. The left-and right-perturbation conditions resulted in increased bilateral landing time differences, trunk lateral bending, peak vertical ground reaction forces (VGRF), knee extension moments, and decreased knee flexion angles for the contralateral leg compared to no-perturbation conditions. The anticipated condition showed ~10% decreases in peak VGRF and knee extension moments for the contralateral leg compared to the unanticipated condition, only in the right-perturbation condition. Nonsignificant correlations were found between core muscle endurance, trunk bending, and landing forces. Mid-flight external trunk perturbation increased ACL loading variables for the contralateral leg for both anticipated and unanticipated conditions. Having knowledge of the perturbation alone had some limited effects on ACL loading variables.