title: Relationships between knee valgus, hip-muscle strength, and hip-muscle recruitment during a single-limb step-down.
abstract: BACKGROUND
  Reduced strength and activation of hip muscles might correlate with increased weight-bearing knee valgus.
  
  
  OBJECTIVE
  To describe relationships among frontal-plane hip and knee angles, hip-muscle strength, and electromyographic (EMG) recruitment in women during a step-down.
  
  
  METHODS
  Exploratory study.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  20 healthy women 20 to 30 years of age.
  
  
  METHODS
  Frontal-plane hip and knee angles were measured. Gluteus maximus and medius recruitment were examined with surface EMG. Hip-abduction and -external-rotation strength were quantified with handheld dynamometry.
  
  
  METHODS
  The authors analyzed correlation coefficients between knee and hip angles, gluteus maximus and medius EMG, and hip-abduction and -external-rotation strength.
  
  
  RESULTS
  Hip-adduction angles (r = .755, P = .001), gluteus maximus EMG (r = -.451, P = .026), and hip-abduction strength (r = .455, P = .022) correlated with frontal-plane projections of knee valgus.
  
  
  CONCLUSIONS
  Gluteus maximus recruitment might have greater association with reduced knee valgus in women than does external-rotation strength during step-down tasks. Gluteus medius strength might be associated with increased knee valgus.
authors.affiliation: Program in Physical Therapy, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Hollman
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Ginos
authors.forename: Jakub
authors.initials: J
authors.lastname: Kozuchowski
authors.forename: Amanda S
authors.initials: AS
authors.lastname: Vaughn
authors.forename: David A
authors.initials: DA
authors.lastname: Krause
authors.forename: James W
authors.initials: JW
authors.lastname: Youdas