title: Impact of fatigue on gender-based high-risk landing strategies.
abstract: OBJECTIVE
  Noncontact anterior cruciate ligament (ACL) injuries carry significant short- and long-term morbidity, particularly in females. To combat this epidemic, neuromuscular training has evolved aimed at modifying high-risk lower-limb biomechanics. However, injury rates and the gender disparity in these rates remain, suggesting that key components of the injury mechanism continue to be ignored. This study examined the potential contributions of neuromuscular fatigue to noncontact ACL injuries.
  
  
  METHODS
  Ten male and 10 female NCAA athletes had 3D lower-limb-joint kinematics and kinetics recorded during 10 drop jumps, both before and after fatigue. Mean subject-based initial-contact (N = 9) and peak stance-phase kinematic (N = 9) and normalized (mass x height) kinetic (N = 9) parameters were quantified before and after fatigue and submitted to a three-way ANOVA to determine for the main effects of leg, gender, and fatigue. A Bonferroni corrected alpha level of 0.002 was adopted for all statistical comparisons.
  
  
  RESULTS
  Females landed with more initial ankle plantar flexion and peak-stance ankle supination, knee abduction, and knee internal rotation compared with men. They also had larger knee adduction, abduction, and internal rotation, and smaller ankle dorsiflexion moments. Fatigue increased initial and peak knee abduction and internal rotation motions and peak knee internal rotation, adduction, and abduction moments, with the latter being more pronounced in females.
  
  
  CONCLUSIONS
  Fatigue-induced modifications in lower-limb control may increase the risk of noncontact ACL injury during landings. Gender dimorphic abduction loading in the presence of fatigue also may explain the increased injury risk in women. Understanding fatigue effects at both the central and peripheral levels will further afford elucidation of the ACL injury mechanism and, hence, more successful prevention strategies.
authors.affiliation: Department of Biomedical Engineering, The Cleveland Clinic Foundation, Cleveland, OH, USA. mcleansc@umich.edu
authors.forename: Scott G
authors.initials: SG
authors.lastname: McLean
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Fellin
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Felin
authors.forename: Natalie
authors.initials: N
authors.lastname: Suedekum
authors.forename: Gary
authors.initials: G
authors.lastname: Calabrese
authors.forename: Allen
authors.initials: A
authors.lastname: Passerallo
authors.forename: Susan
authors.initials: S
authors.lastname: Joy
mesh_terms: D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D010865:Pilot Projects; D011187:Posture / Q000502:physiology*; D012307:Risk Factors; D012737:Sex Factors; D013177:Sports / Q000502:physiology*