title: Patellofemoral joint force and stress during the wall squat and one-leg squat.
abstract: OBJECTIVE
  To compare patellofemoral compressive force and stress during the one-leg squat and two variations of the wall squat.
  
  
  METHODS
  Eighteen subjects used their 12 repetition maximum (12 RM) weight while performing the wall squat with the feet closer to the wall (wall squat short), the wall squat with the feet farther away from the wall (wall squat long), and the one-leg squat. EMG, force platform, and kinematic variables were input into a biomechanical model to calculate patellofemoral compressive force and stress as a function of knee angle. To asses differences among exercises, a one-factor repeated-measure ANOVA (P = 0.0025) was used.
  
  
  RESULTS
  During the squat ascent, there were significant differences in patellofemoral force and stress among the three squat exercises at 90 degrees knee angle (P = 0.002), 80 degrees knee angle (P = 0.002), 70 degrees knee angle (P < 0.001), and 60 degrees knee angle (P = 0.001). Patellofemoral force and stress were significantly greater at 90 degrees knee angle in the wall squat short compared with wall squat long and one-leg squat, significantly greater at 70 degrees and 80 degrees knee angles in the wall squat short and long compared with the one-leg squat and significantly greater at 60 degrees knee angle in the wall squat long compared with the wall squat short and one-leg squat.
  
  
  CONCLUSIONS
  Except at 60 degrees and 90 degrees knee angles, patellofemoral compressive force and stress were similar between the wall squat short and the wall squat long. Between 60 degrees and 90 degrees knee angles, wall squat exercises generally produced greater patellofemoral compressive force and stress compared with the one-leg squat. When the goal is to minimize patellofemoral compressive force and stress, it may be prudent to use a smaller knee angle range between 0 degrees and 50 degrees compared with a larger knee angle range between 60 degrees and 90 degrees .
authors.affiliation: Department of Physical Therapy, California State University, 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: Rodney
authors.initials: R
authors.lastname: Imamura
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: James R
authors.initials: JR
authors.lastname: Andrews
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D005080:Exercise Test; D005260:Female; D005269:Femur / Q000502:physiology*; D006801:Humans; D008297:Male; D010329:Patella / Q000502:physiology*; D046788:Patellofemoral Pain Syndrome / Q000209:etiology*; D011187:Posture; D016059:Range of Motion, Articular / Q000502:physiology; D013312:Stress, Physiological / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult