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  1. Nelson Cortes1,
  2. Tijana Popovic1,
  3. Oladipo Eddo1,
  4. Anne Benjaminse2,
  5. Amanda Caswell1,
  6. Shane Caswell1
  1. 1Sports Medicine Assessment, Research, & Testing (SMART) Laboratory, Manassas, VA, USA
  2. 2University of Groningen, Groningen, The Netherlands


    Background 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 Recreational.

    Participants 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.

    • Injury

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