Lower extremity(LE) patterns have been altered using implicit(IF) and explicit(EF) feedback motor learning strategies, however, it remains unclear which strategy may be more effective for injury prevention.Objective
To examine the effects of reduced relative IF and EF video-feedback on LE biomechanics.Design
Randomized Controlled Trial.Setting
30 participants were randomly assigned to 3-groups: control (CG) (n=10, 24±2 years, 1.68±0.1 m, 68±14 kg), IF (n=10, 25±3 years, 1.72±0.1 m, 69±12 kg), and EF (n=10, 23±2 years, 1.74±0.1 m, 74±8 kg). Exclusion criteria: no LE injury 6-months prior to testing, no ACL reconstruction, and no history of participation in supervised LE injury prevention programs.Interventions
Twelve drop-jumps were performed 3-times a week for 5 weeks. IF group focused attention on overall jump performance, whereas EF group focused attention on knee mechanics. 3D LE biomechanics were tested after 1-week (PST1), 2-weeks (PST2), and 5-weeks (PST3), and 1-month retention (RTN). Participants viewed 2-videos for sagittal and frontal planes, in normal speed and slow motion. Video-feedback was provided along a reduced feedback continuum partitioned into 100%, 33% and 16.6% feedback frequency phases.Main Outcome Measurements
Linear mixed-effects models were conducted to assess group and time differences for peaks of hip abduction(HA°), knee abduction(KA°), and vertical ground reaction force(vGRF,N), p<0.05.Results
No group-time interaction was found(p>0.05). Group effects were attained(p<0.05) for HA: IF was lower than EF and CG, and for KA, where PST3 was closer to neutral when compared to PST1. Time effect for vGRF(p<0.05) was observed: PST3 and RTN were lower than PST1.Conclusions
Retention and retrieval of learned movement patterns seemed to follow identical attrition patterns. It is feasible to suggest that both motor learning strategies produced similar outcomes. Future research should expand the retention period and retrieval of learned skill movements to enhance the effectiveness of injury prevention programs.