title: Changing sagittal plane body position during single-leg landings influences the risk of non-contact anterior cruciate ligament injury.
abstract: OBJECTIVE
  To examine the effects of different sagittal plane body positions during single-leg landings on biomechanics and muscle activation parameters associated with risk for anterior cruciate ligament (ACL) injury.
  
  
  METHODS
  Twenty participants performed single-leg drop landings onto a force plate using the following landing styles: self-selected, leaning forward (LFL) and upright (URL). Lower extremity and trunk 3D biomechanics and lower extremity muscle activities were recorded using motion analysis and surface electromyography, respectively. Differences in landing styles were examined using 2-way Repeated-measures ANOVAs (sex × landing conditions) followed by Bonferroni pairwise comparisons.
  
  
  RESULTS
  Participants demonstrated greater peak vertical ground reaction force, greater peak knee extensor moment, lesser plantar flexion, lesser or no hip extensor moments, and lesser medial and lateral gastrocnemius and lateral quadriceps muscle activations during URL than during LFL. These modifications of lower extremity biomechanics across landing conditions were similar between men and women.
  
  
  CONCLUSIONS
  Leaning forward while landing appears to protect the ACL by increasing the shock absorption capacity and knee flexion angles and decreasing anterior shear force due to the knee joint compression force and quadriceps muscle activation. Conversely, landing upright appears to be ACL harmful by increasing the post-impact force of landing and quadriceps muscle activity while decreasing knee flexion angles, all of which lead to a greater tibial anterior shear force and ACL loading. ACL injury prevention programmes should include exercise regimens to improve sagittal plane body position control during landing motions.
authors.affiliation: Sports Medicine Research Laboratory, Department of Health and Sport Management, School of Health and Sport Sciences, Osaka University of Health and Sport Sciences, 1-1 Asashirodai, Kumatori-cho, Sennan-gun, Osaka, 590-0496, Japan. yshimoko@ouhs.ac.jp
authors.forename: Yohei
authors.initials: Y
authors.lastname: Shimokochi
authors.forename: Jatin P
authors.initials: JP
authors.lastname: Ambegaonkar
authors.forename: Eric G
authors.initials: EG
authors.lastname: Meyer
authors.forename: Sae Yong
authors.initials: SY
authors.lastname: Lee
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Shultz
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000517:prevention & control*; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology; D011187:Posture / Q000502:physiology*