title: Sidestep and crossover lower limb kinematics during a prolonged sport-like agility test.
abstract: BACKGROUND
  Non-contact anterior cruciate ligament (ACL) injuries in athletes occur more often towards the end of athletic competitions. However, the exact mechanisms of how prolonged activity increases the risk for ACL injuries are not clear.
  
  
  OBJECTIVE
  To determine the effect of prolonged activity on the hip and knee kinematics observed during self-selected cutting maneuvers performed in a timed agility test.
  
  
  METHODS
  Nineteen female Division I collegiate soccer players completed a self-selected cutting agility test until they were unable to meet a set performance time (one standard deviation of the average baseline trial). Using the 3D dimensional coordinate data the cut type was identified by the principle investigators. The 3D hip and knee angles at 32ms post heel strike were analyzed using a two-factor, linear mixed model to assess the effect of prolonged activity and cut type on the recorded mean hip and knee angles.
  
  
  RESULTS
  Athletes performed either sidestep or crossover cuts. An effect of cut type and prolonged activity was seen at the hip and knee. During the prolonged activity trials, the knee was relatively more adducted and both the hip and knee were less flexed than during the baseline trials regardless of cut type. Regardless of activity status, during sidestep cuts, the hip was more internally rotated and abducted, and less flexed than during crossover cuts while the knee was more abducted and less flexed during the sidestep than crossover cuts.
  
  
  CONCLUSIONS
  During a sport-like agility test, prolonged activity appears to predispose the athlete to position their knee in a more extended and abducted posture and their hip in a more extended posture. This position has been suggested to place stress on the ACL and potentially increase the risk for injury. Clinicians may want to consider the effects of prolonged activity on biomechanical risk factors for sustaining ACL injuries in the design of intervention strategies to prevent ACL injuries.
  
  
  METHODS
  Level 4.
authors.forename: Danielle
authors.initials: D
authors.lastname: Potter
authors.affiliation: Student, Department of Physical Therapy Quinnipiac University, Hamden, CT, USA.
authors.forename: Kellie
authors.initials: K
authors.lastname: Reidinger
authors.affiliation: Student, Department of Physical Therapy Quinnipiac University, Hamden, CT, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Szymialowicz
authors.affiliation: Assistant Professor, Department of Biomedical Sciences, Quinnipiac University, Hamden, CT, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Martin
authors.affiliation: Research Associate II, Yale University, School of Medicine, New Haven, CT, USA.
authors.forename: Donald
authors.initials: D
authors.lastname: Dione
authors.affiliation: Assistant Professor, Frank H Netter, MD, School of Medicine, Quinnipiac University, Hamden, CT, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Feinn
authors.affiliation: Associate Professor, Department of Physical Therapy, Quinnipiac University, Hamden, CT, USA.
authors.forename: David
authors.initials: D
authors.lastname: Wallace
authors.affiliation: Director, Motion Analysis Laboratory, Clinical Associate Professor, Physical Therapy Department, Quinnipiac University, Hamden, CT, USA.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Garbalosa
keywords: ACL injury; cutting; knee; motion