title: Strain on the anterior cruciate ligament during closed kinetic chain exercises.
abstract: OBJECTIVE
  The purpose of this investigation was to characterize the ACL strains produced during four commonly prescribed CKC exercises; the step-up, the step-down, the lunge, and the one-legged sit to stand. We hypothesized that the ACL strains produced during the lunge and one-legged sit to stand exercises (the exercises that challenge the leg musculature to a greater extent and utilize greater hip flexion) would be less than those produced during the step-up and step-down exercises.
  
  
  METHODS
  The strains in the anteromedial bundle of the ACL were measured while nine subjects, who had normal ligaments, performed the four exercises. Peak ACL strain values and the ACL strain patterns as a function of knee flexion angle were compared between exercises.
  
  
  RESULTS
  No significant differences were found between the peak ACL strain values (mean +/- SEM) between exercises (step-up: 2.5 +/- 0.36; step-down: 2.6 +/- 0.34; lunge 1.9 +/- 0.50; one-legged sit to stand: 2.8 +/- 0.27). The mean ACL strain values as a function of knee flexion angle were not significantly different. On average, there was a significant increase in ACL strain as the knee was extended for each exercise.
  
  
  CONCLUSIONS
  The ACL strain responses produced during these CKC exercises were equal and similar to those produced during other rehabilitation exercises (i.e., squatting, active extension of the knee) previously tested.
authors.affiliation: Section of Sports Medicine, Department of Surgical Science, Karolinska Hospital, Stockholm, Sweden. heijne@telia.com
authors.forename: Annette
authors.initials: A
authors.lastname: Heijne
authors.forename: Braden C
authors.initials: BC
authors.lastname: Fleming
authors.forename: Per A
authors.initials: PA
authors.lastname: Renstrom
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Peura
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Beynnon
authors.forename: Suzanne
authors.initials: S
authors.lastname: Werner
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000502:physiology* / Q000503:physiopathology; D015444:Exercise; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged