The Immediate Effects Of Expert And Dyad External Focus Feedback On Drop Landing Biomechanics In Female Athletes: An Instrumented Field Study

BackgroundAnterior Cruciate Ligament (ACL) injury prevention interventions have used trained experts to ensure quality feedback. Dyad (peer) feedback may be a more cost-effective method to deliver feedback to athletes.PurposeTo determine the immediate effects of dyad versus expert feedback on drop landing kinematics and kinetics in female athletes.Study DesignCohort studySettingCollege gymnasiumMethodsTwo teams (one female basketball and one female volleyball), from a local college, were team randomized to dyad feedback (volleyball team) or expert feedback (basketball team) (13 expert, 19 +/- 0.87years, 1.7 +/- 0.09m, 68.04 +/- 7.21kg) (10 dyad 19.4 +/- 1.07years, 1.73 +/- 0.08m, 72.18 +/- 11.23kg). Participants completed drop vertical jumps at two different time points (pre- and post-feedback). Knee flexion and abduction displacement were assessed with Inertial Measurement Units (IMUs) and vertical ground reaction force (vGRF) was assessed with a force plate during the landing phase of the drop vertical jump and compared across groups and condition (pre- and post-feedback) with a repeated measures ANC OVA a priori alpha <0.02 was set for multiple tests conducted.ResultsThere were no significant differences between groups for flexion displacement. There was a significant change pre- to post- (decrease 4.65 degrees p=0.01) in abduction displacement, with no group effect. There was a significant interaction of group by condition (p=0.01) for vGRF with no difference between groups before feedback (p>0.05). Between groups there was a decrease of vGRF in the expert group (difference 0.45 Nthw-1, p=0.01) at post-feedback relative to dyad. Within the expert group there was a significant difference between pre- and post-feedback (difference 0.72 N*bw-1, p=0.01), while the dyad group did not change pre- to post-feedback (difference 0.18 N*bw-1, p=0.67).ConclusionMovement screening experts giving real-time feedback were successful in improving key injury-risk kinematics and kinetics in female athletes, while dyad feedback only improved kinematics, indicating that expert feedback may be needed to ensure changes in kinematics and kinetics.