Comparison of pre-contact joint kinematics and vertical impulse between vertical jump landings and step-off landings from equal heights

The Influence of Asymptomatic Hypermobility on Unanticipated Cutting Biomechanics

“…14 Ankle, knee, hip, pelvis, and trunk angles in all 3 planes of motion were extracted from the first 100 ms after initial contact (minimum, maximum, and range values) and foot-ground angles in all 3 planes of motion one frame before initial contact to explore prelanding strategy. 17 The time frame of 100 ms after initial contact was chosen as this has been reported to be the time within which ACL injuries are most likely to occur. 24 Initial contact was defined as the instance when the cutting-leg foot center of gravity acceleration in the vertical plane of the laboratory coordination system (z) reached a maximum value.…”

Which jump-landing task best represents lower extremity and trunk kinematics of unanticipated cutting maneuver?

“…Ankle, knee, hip, pelvis, and trunk angles and angular velocities, and pelvic linear accelerations were extracted at IC and from the 100 milliseconds after IC (minimum, maximum, and range values). Additionally, foot-ground angles in all three planes were extracted one frame before IC to explore pre-landing strategies [20]. IC was defined based on the peak vertical acceleration from IMU sensors placed above the lateral malleoli for jumplanding tasks, and as the instance when the cutting-leg foot center of gravity acceleration in the vertical plane (i.e., plane perpendicular to the floor) of the lab coordinate system (z) reached a maximum value for the cutting task.…”

Effects of lead leg selection on bilateral landing force‐time characteristics: Return to sport testing implications

“…The step-off technique requires the participant to begin standing on an elevated platform and take a step forward to initiate the landing task. [6][7][8][9] Alternatively, researchers may implement a double leg forward drop, which includes a small forward hop off the elevated platform. [10][11][12] In both cases, there may be a discrepancy between actual drop height, determined by the center of mass touchdown velocity, and platform height.…”

“…8,25,26 Some studies showed that the lead leg experienced higher peak forces and loading rates compared with the trail limb at varying drop heights [25][26][27] ; however, this finding is not universal. 8 Authors have suggested that between-limb differences in peak ground reaction forces may be a result of the step-off technique itself because the trail limb does not have sufficient time to catch up to the lead limb during the free fall. 25,26 As a result, the leading limb made ground contact prior to the trailing limb 25 and had a more extended knee angle at ground contact, 8 thereby contributing a greater fraction to the force-time characteristics.…”

“…11,30,31 As such, discretephase analysis of the landing impulse over time frames relevant to ACL injury (i.e., impulse in the first 100 ms -Impulse 100ms ) may provide additional insight into landing capacity alongside characterization of the force-time curve over a large segment of the landing period compared with discrete time point analysis (e.g., the instantaneous peak vertical ground reaction force). 8,34 Given the paucity of scientific evidence on the influence of leg selection for vertical landing tasks, the relationship between landing kinetics and ACL injury, and the fact landing tests are frequently recommended for return to sport decision making using clinical thresholds, the purpose of this study was to quantify the effect of lead leg selection on the timing of ground contact, peak vertical ground reaction force and early phase kinetic impulse (Impulse 100ms ) during a VDL initiated with a step-off technique in trained population. We hypothesized that the leading leg would make ground contact before the trail leg and contribute more to the peak vertical ground reaction forces and energy attenuation demand.…”