title: Knee kinematics is altered post-fatigue while performing a crossover task.
abstract: OBJECTIVE
  To examine the effect of a sequential fatigue protocol on lower extremity biomechanics during a crossover cutting task in female soccer players.
  
  
  METHODS
  Eighteen female collegiate soccer players alternated between a fatigue protocol and two consecutive unanticipated crossover trials until fatigue was reached. Lower extremity biomechanics were evaluated during the crossover using a 3D motion capture system and two force plates. Repeated-measures ANOVAs analysed differences between three sequential stages of fatigue (pre, 50, 100%) for each dependent variable (α = 0.05).
  
  
  RESULTS
  Knee flexion angles at initial contact (IC) for pre (-32 ± 9°) and 50% (-29 ± 11°) were significantly higher than at 100% fatigue (-22 ± 9°) (p < 0.001 and p = 0.015, respectively). Knee adduction angles at IC for pre (9 ± 5°) and 50% (8 ± 4°) were significantly higher (p = 0.006 and p = 0.049, respectively) than at 100% fatigue (6 ± 4°).
  
  
  CONCLUSIONS
  Fatigue altered sagittal and frontal knee kinematics after 50% fatigue whereupon participants had diminished knee control at initial contact. Interventions should attempt to reduce the negative effects of fatigue on lower extremity biomechanics by promoting appropriate frontal plane alignment and increased knee flexion during fatigue status.
  
  
  METHODS
  III.
authors.affiliation: Sports Medicine Assessment, Research & Testing (SMART) Laboratory, George Mason University, Manassas, VA, USA, ncortes@gmu.edu.
authors.forename: Nelson
authors.initials: N
authors.lastname: Cortes
authors.forename: Eric
authors.initials: E
authors.lastname: Greska
authors.forename: Jatin P
authors.initials: JP
authors.lastname: Ambegaonkar
authors.forename: Roger O
authors.initials: RO
authors.lastname: Kollock
authors.forename: Shane V
authors.initials: SV
authors.lastname: Caswell
authors.forename: James A
authors.initials: JA
authors.lastname: Onate
mesh_terms: D000293:Adolescent; D001696:Biomechanical Phenomena; D005080:Exercise Test; D005221:Fatigue / Q000503:physiopathology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000503:physiopathology*; D035002:Lower Extremity / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology; D012916:Soccer / Q000502:physiology*; D055815:Young Adult
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