title: Patellofemoral joint force and stress between a short- and long-step forward lunge.
abstract: METHODS
  Controlled laboratory biomechanics study using a repeated-measures, counterbalanced design.
  
  
  OBJECTIVE
  To compare patellofemoral joint force and stress between a short- and long-step forward lunge both with and without a stride.
  
  
  BACKGROUND
  Although weight-bearing forward-lunge exercises are frequently employed during rehabilitation for individuals with patellofemoral joint syndrome, patellofemoral joint force and stress and how they change with variations of the lunge exercise are currently unknown.
  
  
  METHODS
  Eighteen subjects used their 12-repetition maximum weight while performing a short- and long-step forward lunge both with and without a stride. Electromyography, ground reaction force, and kinematic variables were put into a biomechanical optimization model, and patellofemoral joint force and stress were calculated as a function of knee angle.
  
  
  RESULTS
  Visual observation of the data show that during the forward lunge, patellofemoral joint force and stress increased progressively as knee flexion increased, and decreased progressively as knee flexion decreased. Between 70 degrees and 90 degrees of knee flexion, patellofemoral joint force and stress were significantly greater when performing a forward lunge with a short step compared to a long step (P<.025). Between 10 degrees and 40 degrees of knee flexion, patellofemoral joint force and stress were significantly greater when performing a forward lunge with a stride compared to without a stride (P<.025).
  
  
  CONCLUSIONS
  When the goal is to minimize patellofemoral joint force and stress during the forward lunge performed between 0 degrees to 90 degrees knee angles, it may be prudent to perform the lunge with a long step compared to a short step and without a stride compared to with a stride, because patellofemoral joint force and stress magnitudes were greater with a short step compared to a long step at higher knee flexion angles and were greater with a stride compared to without a stride at lower knee flexion angles.
authors.affiliation: Department of Physical Therapy, California State University, Sacramento, Sacramento, CA 95819-6020, USA. rescamil@csus.edu
authors.forename: Rafael F
authors.initials: RF
authors.lastname: Escamilla
authors.forename: Naiquan
authors.initials: N
authors.lastname: Zheng
authors.forename: Toran D
authors.initials: TD
authors.lastname: Macleod
authors.forename: W Brent
authors.initials: WB
authors.lastname: Edwards
authors.forename: Alan
authors.initials: A
authors.lastname: Hreljac
authors.forename: Glenn S
authors.initials: GS
authors.lastname: Fleisig
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Wilk
authors.forename: Claude T
authors.initials: CT
authors.lastname: Moorman
authors.forename: Rodney
authors.initials: R
authors.lastname: Imamura
authors.forename: James R
authors.initials: JR
authors.lastname: Andrews
mesh_terms: D000328:Adult; D000465:Algorithms; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D013314:Stress, Mechanical