title: Neuromuscular changes after aerobic exercise in people with anterior cruciate ligament-reconstructed knees.
abstract: BACKGROUND
  Anterior cruciate ligament (ACL) reconstructions are common, especially in young, active people. The lower extremity neuromuscular adaptations seen after aerobic exercise provide information about how previously injured patients perform and highlight deficits and, hence, areas for focused treatment. Little information is available about neuromuscular performance after aerobic exercise in people with ACL reconstructions.
  
  
  OBJECTIVE
  To compare dynamic balance, gluteus medius muscle activation, vertical jump height, and hip muscle strength after aerobic exercise in people with ACL-reconstructed knees.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Research laboratory.
  
  
  METHODS
  Of 34 recreationally active volunteers, 17 had a unilateral primary ACL reconstruction at least 2 years earlier and 17 were matched controls.
  
  
  METHODS
  All participants performed 20 minutes of aerobic exercise on a treadmill.
  
  
  METHODS
  We recorded dynamic, single-legged balance electromyographic gluteus medius muscle activation, single-legged vertical jump height, and maximum isometric strength for hip abduction, extension, and external rotation preexercise and postexercise.
  
  
  RESULTS
  Participants with ACL reconstructions exhibited shorter reach distances during dynamic balance tasks, indicating poorer dynamic balance, and less gluteus medius muscle electromyographic activation. Reductions in hip abduction and extension strength after exercise were noted in all participants; however, those with ACL reconstructions displayed greater hip extensor strength loss after aerobic exercise than did the control group.
  
  
  CONCLUSIONS
  Neuromuscular changes after aerobic exercise exist in both patients with ACL reconstructions and controls. The former group may experience greater deficits in hip extensor strength after aerobic exercise. Reduced reach distances in people with ACL reconstructions may represent a protective mechanism against excessive tibiofemoral rotation during dynamic balance. Clinicians should identify weaknesses in the resting state and after aerobic exercise in recreationally active patients and those with ACL reconstructions.
authors.affiliation: Atlantic Physical Therapy, Norfolk, VA, USA.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Dalton
authors.forename: Kate R
authors.initials: KR
authors.lastname: Pfile
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Weniger
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Ingersoll
authors.forename: Daniel
authors.initials: D
authors.lastname: Herman
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Hart
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000502:physiology; D059549:Anterior Cruciate Ligament Reconstruction; D016022:Case-Control Studies; D015444:Exercise / Q000502:physiology*; D005221:Fatigue; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology*; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000502:physiology*; D055815:Young Adult