title: The effect of direction and reaction on the neuromuscular and biomechanical characteristics of the knee during tasks that simulate the noncontact anterior cruciate ligament injury mechanism.
abstract: BACKGROUND
  Jumping and landing tasks that have a change in direction have been implicated as a mechanism of noncontact anterior cruciate ligament injury. Yet, to date, neuromuscular and biomechanical research has focused primarily on straight landing tasks during planned jumps.
  
  
  OBJECTIVE
  Lateral and reactive jumps increase the neuromuscular and biomechanical demands placed on the anterior cruciate ligament, and women perform these tasks differently from men.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  A total of 18 male and 17 female healthy high school basketball players underwent an analysis of the knee during planned and reactive 2-legged stop-jump tasks in 3 different directions that included novel methodology to incorporate a reactive component. Ground-reaction forces, joint kinematics, joint kinetics, and electromyographic activity were assessed during the tasks.
  
  
  RESULTS
  Jump direction and task (planned or reactive) significantly affected joint angles, ground-reaction forces, knee joint moments, and proximal anterior tibia shear forces; female players demonstrated different kinematic, kinetic, and electromyographic characteristics during these tasks.
  
  
  CONCLUSIONS
  Jump direction significantly influenced knee biomechanics, suggesting that lateral jumps are the most dangerous of the stop-jumps. Reactive jumps were also significantly different, suggesting differences between planned laboratory experiments and actual athletic competition. The results of this study indicate that directional and reactive jumps should be included in research methodology and injury-prevention programs.
authors.affiliation: Neuromuscular Research Laboratory,University of Pittsburgh, 3200 South Water Street, Pittsburgh, PA 15203, USA. tcs15@pitt.edu
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Sell
authors.forename: Cheryl M
authors.initials: CM
authors.lastname: Ferris
authors.forename: John P
authors.initials: JP
authors.lastname: Abt
authors.forename: Yung-Shen
authors.initials: YS
authors.lastname: Tsai
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Myers
authors.forename: Freddie H
authors.initials: FH
authors.lastname: Fu
authors.forename: Scott M
authors.initials: SM
authors.lastname: Lephart
mesh_terms: D000293:Adolescent; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008124:Locomotion / Q000502:physiology; D008297:Male; D010414:Pennsylvania