Effects Of Reduced Relative Implicit And Explicit Feedback On Lower Extremity Jump-landing Mechanics

Abstract

Implicit (IF) and explicit (EF) feedback are two motor learning strategies that have been demonstrated to alter biomechanical movement patterns. While both strategies have been utilized for injury prevention, it remains unclear which strategy may be more effective. PURPOSE: To examine the effects of reduced relative IF and EF feedback on lower extremity landing mechanics. METHODS: Seventeen participants (23.5±0.9 years, 1.72±0.1m, 67.7±11.5kg) were randomly assigned to three groups: IF (n=6), EF (n=5), and Control (CG) (n=6). A box-drop jump task was performed three times a week for six weeks. Testing occurred before and after 6 weeks of intervention. IF and EF were provided by ? video feedback with instructions, while CG received no feedback. IF were instructed to focus their attention outside their body, while EF were instructed to focus their attention to their lower extremities. Intervention sessions were partitioned into 100% feedback, 33% feedback, and 16.6% feedback frequency phases. Participants viewed video recordings of their task to analyze their jump-landing mechanics from both a sagittal and frontal plane cameras. Participants viewed 2 video recordings per camera, once in real-time and once in slow motion. Multivariate analysis of variance was conducted to compare differences between groups and time for hip abduction angle (HA), knee abduction moment (KAM), and knee flexion angle (KF). RESULTS: No statistically significant difference (p>0.05) was found for: HA (CG:pre=-9.85±5.3, post=-7.36±8.65; IF:pre=-4.17±2.67, post=-7.52±5.27; EF:pre=-5.68±6.12, post=-5.98±5.43), KAM (CG:pre=-0.5±0.3, post=-0.34±0.13; IF:pre=-0.5±0.21, post=-0.48±0.13; EF:pre=-0.48±0.12, post=-0.46±0.26), and KF (CG:pre=-92.26±9.12, post=-100.33±15.2; IF:pre=-106.37±16.34, post=-103.45±19.97; EF:pre=-100.32±11.4, post=-112.4±18.22). CONCLUSION: We did not find statistically significant differences for any dependent measures between groups from pre to post-test. It should be noted that IF HA slightly decreased from pre to post-test whereas it increased for CG. For KAM, CG was lower on post-test comparing to IF and EF. EF and CG trended to decrease from pre to post-test, while IF slightly increased KF. Our preliminary findings partially support that implicit and explicit feedback alters lower body mechanics while jumping.