title: The effects of feedback with and without strength training on lower extremity biomechanics.
abstract: BACKGROUND
  Feedback instruction is a proven modality for the alteration of motion patterns. There are no existing data on the contribution of strength training, when combined with feedback instruction, to the altering of lower extremity biomechanics.
  
  
  OBJECTIVE
  Lower extremity muscle strength training provides an increased capacity to alter knee and hip biomechanics during a stop-jump task in response to a feedback protocol.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Knee and hip 3-dimensional kinematic and kinetic data were collected for 58 female recreational athletes while performing 3 stop-jump tasks after completing a 9-week strength training program (ST-FB; n = 29) or a 9-week period of no strength training (FB; n = 29). Data were then collected for both groups after completing a jump-landing feedback instruction protocol. Knee and hip joint angles, as well as resultant forces and moments, were calculated.
  
  
  RESULTS
  Across all participants, there were decreased peak vertical ground-reaction forces (P < .001) and increased knee flexion (P = .050), hip flexion (P < .001), and hip abduction (P = .032) angles, subsequent to the feedback protocol. Hip abduction angle (P < .001) increased in the ST-FB group but not the FB group, and peak knee anterior shear force (P = .015) decreased in the ST-FB group but increased in the FB group (P = .009).
  
  
  CONCLUSIONS
  The results indicate that strength training, when used in conjunction with video-assisted feedback, may provide an increased capacity for the alteration of knee and hip biomechanics.
  
  
  CONCLUSIONS
  Programs that include both strength training and movement education through feedback may be necessary to increase the effectiveness of anterior cruciate ligament prevention programs. Strength training may provide an increased capacity for athletes to respond to other intervention modalities used in anterior cruciate ligament injury prevention programs.
authors.affiliation: Center for Human Movement Science, Division of Physical Therapy, University of North Carolina, Chapel Hill, North Carolina, USA. dcherman@virginia.edu
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Herman
authors.forename: James A
authors.initials: JA
authors.lastname: Oñate
authors.forename: Paul S
authors.initials: PS
authors.lastname: Weinhold
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Guskiewicz
authors.forename: William E
authors.initials: WE
authors.lastname: Garrett
authors.forename: Bing
authors.initials: B
authors.lastname: Yu
authors.forename: Darin A
authors.initials: DA
authors.lastname: Padua
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D005246:Feedback; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D055070:Resistance Training; D013647:Task Performance and Analysis; D014743:Videotape Recording; D055815:Young Adult